Bioenergy: Impacts on Environment and Economy 9819930014, 9789819930012

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Energy, Environment, and Sustainability Series Editor: Avinash Kumar Agarwal

Praveen Kumar Ramanujam Binod Parameswaran B. Bharathiraja A. Magesh   Editors

Bioenergy Impacts on Environment and Economy

Energy, Environment, and Sustainability Series Editor Avinash Kumar Agarwal, Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, India

AIMS AND SCOPE This books series publishes cutting edge monographs and professional books focused on all aspects of energy and environmental sustainability, especially as it relates to energy concerns. The Series is published in partnership with the International Society for Energy, Environment, and Sustainability. The books in these series are edited or authored by top researchers and professional across the globe. The series aims at publishing state-of-the-art research and development in areas including, but not limited to: • • • • • • • • • •

Renewable Energy Alternative Fuels Engines and Locomotives Combustion and Propulsion Fossil Fuels Carbon Capture Control and Automation for Energy Environmental Pollution Waste Management Transportation Sustainability

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Praveen Kumar Ramanujam · Binod Parameswaran · B. Bharathiraja · A. Magesh Editors

Bioenergy Impacts on Environment and Economy

Editors Praveen Kumar Ramanujam Arunai Engineering College Tiruvannamalai, Tamil Nadu, India B. Bharathiraja Department of Chemical Engineering Vel Tech High Tech Dr. Rangarajan Dr. Sakunthala Engineering College Chennai, Tamil Nadu, India

Binod Parameswaran Microbial Processes and Technology Division CSIR-National Institute for Interdisciplinary Science and Technology Trivandrum, Kerala, India A. Magesh Department of Chemical Engineering Annamalai University Chidambaram, Tamil Nadu, India

ISSN 2522-8366 ISSN 2522-8374 (electronic) Energy, Environment, and Sustainability ISBN 978-981-99-3001-2 ISBN 978-981-99-3002-9 (eBook) https://doi.org/10.1007/978-981-99-3002-9 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Contents

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Bioenergy—Impacts on Environment and Economy . . . . . . . . . . . . . . R. Praveen Kumar, B. Bharathiraja, A. Magesh, and P. Binod

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Need of Bioenergy—An Insight Into Global Perspective . . . . . . . . . . . K. Srinivasan, J. S. Sudarsan, and S. Nithiyanantham

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Sustainable Development of Bioenergy and Its Impacts on Ecosystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Vidhyarathi, S. Chozhavendhan, G. Karthigadevi, V. Nirmal Kannan, and R. Praveen Kumar

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Integrated Approaches for Economic Sustainability of Biofuel Industries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. Chozhavendhan, G. Karthigadevi, R. Praveen Kumar, D. Karthiga, and A. Magesh

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The Impact of Bioenergy Resources for Sustainable Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bhuvaneshwari Segaran and Chelladurai Guruswami

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The Impact of Bioenergy Utilization on the Ecosystem—Toward a Sustainable Future . . . . . . . . . . . . . . . . . . . . . . . Ramansh Bajpai

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Impact of Emulsified Bio-Fuel on the Environment . . . . . . . . . . . . . . . A. R. Pradeep Kumar, N. Shankar Ganesh, and P. Vignesh

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Recent Development of Biomass Energy as a Sustainable Energy Source to Mitigate Environmental Change . . . . . . . . . . . . . . . 119 Simatsidk Haregu, Yigzaw Likna, Degafneh Tadesse, and Chandran Masi

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Rice Straw Biomass and Agricultural Residues as Strategic Bioenergy: Effects on the Environment and Economy Path with New Directions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Venkatramanan Akshaya, Ilangovan Akila, Raju Murali, Devarajan Raajasubramanian, Narendra Kuppan, and Subramani Srinivasan

10 Weed—An Alternate Energy Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 R. Ramya, J. Adur Alaknanda, D. Raajasubramanian, S. Srinivasan, K. Narendra, and M. Manjushree 11 Biomethanation for Energy Security and Sustainable Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 Kalyanasundaram GeethaThanuja, Divya Thiyagarajan, Desikan Ramesh, and Subburamu Karthikeyan 12 Recent Technologies for the Production of Biobutanol from Agricultural Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 A. Anuradha, B. Bharathiraja, Muthu Kumar, and R. Praveen Kumar 13 Microalgal Biomass and Lipid Induction Strategies for Bioenergy Production as a Renewable Resource . . . . . . . . . . . . . . 243 B. Subha, K. S. Nathiga Nambi, R. Dineshkumar, A. Ahamed Rasheeq, M. Durai Murugan, P. Arun, P. Alaguraj, T. Dharshinipriya, U. Namitha, and P. M. Swetha 14 Recent Trends in Microbial Fuel Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 S. Sivaprakash, Prabhavathy Sivaprakash, and V. Saraswathy

Editors and Contributors

About the Editors Prof. Praveen Kumar Ramanujam an undergraduate in chemical engineering and postgraduate in industrial biotechnology from Annamalai University, is working as Head of the Department in Department of Biotechnology, Arunai Engineering College, Tiruvannamalai, Tamil Nadu, India. His area of research includes renewable energy from biomass and municipal waste. He chaired the 1st, 2nd, 3rd, 4th and 5th International Conference on Bioenergy, Environment and Sustainable Technologies. He has organized various national-level symposiums and conferences and served on the scientific advisory committees of several national and international events. He visited EPFL, Switzerland, as Visiting Researcher in the Bioenergy and Energy Planning Research Group from October to November 2018. He has visited multiple countries, including the USA, Australia, China, Switzerland, Italy, Hong Kong and Bangladesh, to attend various conferences. He has chaired sessions and delivered invited talks in various national and international conferences. He has provisional registrations for four patents. He has published more than 65 papers in peer-reviewed journals, 17 book chapters and seven edited books and delivered 12 invited lectures and presentations and 33 other presentations. He was invited as a resource person for 10 national and international forums. He is Life Member in various professional societies, including BRSI, IIChE, IBA-IFIBiop, BigFin, ISTE, and EWB India. He has served as Management Council Member in BRSI. He was awarded with the ISTE-Syed Sajid Ali National Award for outstanding research work in the field of Renewable Energy for the year 2017, award instituted by the Indian Society for Technical Education, and “Outstanding Young Investigator Award” for excellence in research and teaching in a rural setting, awarded by RAISE Rural. Dr. Binod Parameswaran is currently working as Principal Scientist in the Microbial Processes and Technology Division of CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, India. He obtained a Ph.D. in biotechnology from the University of Kerala, Thiruvananthapuram, India. Later, he worked

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as a post-doctoral fellow at the Korea Institute of Energy Research, Daejeon, South Korea, and later joined as Scientist at CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, India. His areas of interest include sustainable bioprocesses, biomass to fuels and chemicals, biopolymers, and enzyme technology. He has more than 210 research publications with an h-index of 48. He has published five books and 80 book chapters. His name is listed in the world’s top 2% scientists for the whole career as per the study by Stanford University and Elsevier BV. He has received several awards and fellowships, including the Young Scientist Award from International Forum on Industrial Bioprocesses, France; Kerala State Young Scientist Award from Kerala State Council for Science, Technology and Environment; Prof. S. B. Chincholkar Memorial Award of the Biotech Research Society, India; Pandey Research Excellence Award from IBA; Elsevier Impactful Research Award; Elsevier Renewable Energy Best Paper Award; Visiting Fellowship, EPFL, Switzerland and Marie Curie Fellowship, among others. He is a Fellow of International Society for Energy, Environment and Sustainability (ISEES). He is an Editorial Board Member of Bioresource Technology, Journal of Environmental Science and Engineering, Bioengineered and Frontiers. He is a National Honorary Advisory Board Member of Centre for Energy and Environmental Sustainability (CEES), India; Central Office Executive of the Biotech Research Society, India and Indian Coordinator of International Bioprocessing Association. Dr. B. Bharathiraja is working as Head of the Department in the Department of Chemical Engineering, Vel Tech High Tech Dr. Rangarajan Dr. Sakunthala Engineering College, Chennai, India. He has more than 14 years of experience in teaching. His area of research includes biofuels from biomass and municipal waste. He has published more than 70 publications in peer-reviewed journals, two books, and seven book chapters. He has served as the Chief Editor of International Journal of Bioprocess Technology and Polymer Sciences, the Editorial Board Member in various journals and the International Scientific Advisory Committee Member in the 2012 Asian Biohydrogen and Bioproducts Symposium (ABBS), conducted by Chongqing University between 9 and 12 November 2012 in Chongqing, China. He has visited various countries, including the USA, China, Bangladesh and Hong Kong, to attend international conferences. He has chaired sessions and delivered invited talks in various international conferences, including the conference on “Bioenergy, Environment and Sustainable Technologies (BEST)—2013, 2015 and 2017 Tiruvannamalai India”. He is Life Member in various professional societies, such as BRSI, IIChE, BigFin, ISTE and EFB. Dr. A. Magesh is working as Assistant Professor in the Department of Chemical Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu, India, with more than 18 years of experience. He completed his bachelor’s in chemical engineering, master’s in industrial biotechnology, and Ph.D. from Annamalai University. His area of research includes biotechnology. He has chaired multiple sessions and delivered invited talks in various national and international conferences, including conferences in Malaysia . He has published more than 15 papers in peer-reviewed journals. He

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is Life Member in several professional societies, including the Indian Society of Technical Education (ISTE). He has also organized an entrepreneurship program for students of science and engineering, funded by the Department of Science and Technology (DST), New Delhi.

Contributors J. Adur Alaknanda Department of Environmental Science, Surana College, Peenya, Bangalore, Karnataka, India Ilangovan Akila Department of Biochemistry, Government Arts College for Women, Krishnagiri, Tamil Nadu, India Venkatramanan Akshaya Department of Biochemistry, Government Arts College for Women, Krishnagiri, Tamil Nadu, India P. Alaguraj Department of Microbiology, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu, India A. Anuradha Department of Bio-Engineering, Birla Institute of Technology Mesra, Ranchi, Jharkhand, India P. Arun Department of Microbiology, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu, India Ramansh Bajpai Environmental Science and Engineering, C.E.D., HBTU, Kanpur, UP, India B. Bharathiraja Department of Chemical Engineering, Veltech High Tech Rangarajan Dr Sakunthala Engineering Collge, Chennai, Tamil Nadu, India P. Binod CSIR-NIIST, Trivandrum, India S. Chozhavendhan Vivekanandha College of Engineering for Women, Thiruchengode, Tamil Nadu, India T. Dharshinipriya Department of Microbiology, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu, India R. Dineshkumar Department of Microbiology, Vivekanandha Arts and Science College for Women, Sankagiri, Tamil Nadu, India Kalyanasundaram GeethaThanuja Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Tamil Nadu, Coimbatore, India Chelladurai Guruswami Department of Zoology, G. Venkataswamy Naidu College (Autonomous), Kovilpatti, India Simatsidk Haregu Department of Biotechnology, College of Biological and Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa,

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Ethiopia; Center of Excellence, Bioprocess and Biotechnology, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia D. Karthiga V.S.B. Engineering College, Karur, Tamil Nadu, India G. Karthigadevi Sri Venkateswara College of Engineering, Chennai, Tamil Nadu, India Subburamu Karthikeyan Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Tamil Nadu, Coimbatore, India; Department of Renewable Energy Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Tamil Nadu, Coimbatore, India Muthu Kumar Department of Bio-Engineering, Birla Institute of Technology Mesra, Ranchi, Jharkhand, India R. Praveen Kumar Department of Biotechnology, Arunai Engineering College, Tiruvannamalai, Tamil Nadu, India Narendra Kuppan Department of Botany, Faculty of Science, Annamalai University, Cuddalore, Tamil Nadu, India Yigzaw Likna Department of Environmental Engineering, College of Biological and Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia A. Magesh Department of Chemical Engineering, Annamalai University, Chidambaram, Tamil Nadu, India Chandran Masi Department of Biotechnology, College of Biological and Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia; Center of Excellence, Bioprocess and Biotechnology, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia M. Manjushree Faculty of Science, Rotary Educational Society, Mandya, Karnataka, India Raju Murali Department of Biochemistry, Government Arts College for Women, Krishnagiri, Tamil Nadu, India; Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Cuddalore, Tamil Nadu, India M. Durai Murugan Department of Microbiology, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu, India K. S. Nathiga Nambi Department of Biology, Gandhigram Rural Deemed to be University, Dindigul, Tamil Nadu, India

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U. Namitha Department of Microbiology, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu, India K. Narendra Department of Botany, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu, India V. Nirmal Kannan V.S.B. Engineering College, Karur, Tamil Nadu, India S. Nithiyanantham Post Graduate and Research Department of Physics, (Ultrasonic/NDT and Bio-Physics Divisions), Thiru. Vi. Kalyanasundaram Govt Arts and Science College (Affiliation—Bharadhidasan University, Thiruchirapalli, Thiruvarur, Tamil Nadu, India A. R. Pradeep Kumar Department of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India R. Praveen Kumar Arunai Engineering College, Tiruvannamalai, Tamil Nadu, India Devarajan Raajasubramanian Department of Botany, Faculty of Science, Annamalai University, Cuddalore, Tamil Nadu, India; Department of Botany, Thiru. A. Govindasamy Government Arts College, Tindivanam, Tamil Nadu, India Desikan Ramesh Department of Renewable Energy Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Tamil Nadu, Coimbatore, India R. Ramya Surana College, Peenya, Bangalore, Karnataka, India A. Ahamed Rasheeq CAS in Marine Biology, Faculty of Marine Sciences, Annamalai University, Chidambaram, Tamil Nadu, India V. Saraswathy CSIR—Central Electrochemical Research Institute, Karaikudi, India Bhuvaneshwari Segaran PG and Research Department of Zoology, Bishop Heber College (Autonomous), Tiruchirappalli, India N. Shankar Ganesh Department of Mechanical Engineering, Kingston College of Engineering, Vellore, India Prabhavathy Sivaprakash CSIR—Central Mechanical Engineering Research Institute, Durgapur, India S. Sivaprakash CSIR—Central Electrochemical Research Institute, Mandapam, India Subramani Srinivasan Department of Biochemistry, Government Arts College for Women, Krishnagiri, Tamil Nadu, India; Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Cuddalore, Tamil Nadu, India

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K. Srinivasan Department of Civil Engineering, PSNA College of Engineering and Technology, Dindigul, India S. Srinivasan Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu, India; Department of Biochemistry, Government Arts College for Women, Krishnagiri, Tamil Nadu, India B. Subha Department of Microbiology, Vivekanandha Arts and Science College for Women, Sankagiri, Tamil Nadu, India J. S. Sudarsan School of Energy and Environment, NICMAR University, Balewadi, Pune, India P. M. Swetha Department of Microbiology, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu, India Degafneh Tadesse Department of Biotechnology, College of Biological and Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia Divya Thiyagarajan Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Tamil Nadu, Coimbatore, India A. Vidhyarathi V.S.B. Engineering College, Karur, Tamil Nadu, India P. Vignesh Department of Mechanical Engineering, Indira Institute of Engineering and Technology, Thiruvallur, India

Chapter 1

Bioenergy—Impacts on Environment and Economy R. Praveen Kumar, B. Bharathiraja, A. Magesh, and P. Binod

1.1 Introduction Bioenergy is one of the promising and sustainable energy sources in context of the depleting resources of non-renewable energy. This is one of the fastest growing sectors across the globe, and several research activities are going on to make it economically feasible. The contribution of bioenergy sector would enhance substantially in future, providing several environmental benefits such as greenhouse gas savings. It would also contribute to the energy security, improve trade balances and also provide wide opportunities for social and economic development in rural communities. Another advantage is the proper management of the waste and resources. However, the production of bioenergy is not always environmentally friendly. In the production process of various biofuels, there are several environmental-related issues which needs to be addressed.

R. Praveen Kumar (B) Arunai Engineering College, Tiruvannamalai 606 603, Tamil Nadu, India e-mail: [email protected] B. Bharathiraja Vel Tech High Tech Dr. RR Dr. SR Engineering College, Chennai, Tamil Nadu, India A. Magesh Department of Chemical Engineering, Annamalai University, Chidambaram, India P. Binod CSIR-NIIST, Trivandrum, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_1

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1.2 Raw Materials for Bioenergy Production Several waste raw materials can be utilized for the production of bioenergy which include agro-industrial and municipal solid waste. Many methods are already known for the pre-processing of biomass and its conversion to energy. Biomass is used for the production of heat and power, and the technologies for this are well developed. It is similar in the case with the first-generation liquid fuels. Other conversion technologies are being developed which offers wide prospects on improved efficiency and cost-effectiveness. However, several challenges still exist in most of these processes. The problem associated with the conversion of crop land for bioenergy plants is a serious threat. The agricultural practices need to be improved for the better productivity. The bioenergy much is made available with better pricing, and it needs to be competitive with other sources. Another issue is associated with the logistics and infrastructure issues which needs to be addressed before the initiation of bioenergy establishments. Technological advancement also need to be adopted for better efficiency and cleaner conversion process.

1.3 Types of Bioenergy Bioenergy includes biogas, bioethanol, biodiesel, biobutanol and other renewable fuels that can be produced using biomass.

1.4 Biogas Biogas is a gaseous fuel which has the potential to replace the conventional fuels in both rural and urban areas. It mainly consists of methane, CO2 and small quantities of other gases produced by anaerobic digestion of organic matter. The composition of biogas mainly depends on the feedstock used and also the production pathway. Three main technologies are involved in their productions, which are biodigester, landfill gas recovery systems and waste water treatment plants. The strong barriers for dissemination of biomethanation technology are technological and implementation challenges, quality feedstock availability, and weak supply chain logistics (Mittal et al. 2018). The major challenges faced for implementation of biomethane projects are almost similar to other biofuel projects. Lack of continuous availability of biogas feedstocks, cost of biogas production, poor supply chain and logistics for biomethane distribution and supporting biofuel polices for better adoption needs government incentives/waiving of taxes for successful implementation of biomethane projects.

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1.5 Biobutanol Biobutanol is another renewable fuel that can be produced using waste biomass feedstocks. This fuel can be produced through either thermo-chemical or biochemical routes. Both the conversion methods appear promising, but their commercial feasibility is limited. ABE fermentation of crop residues to produce biobutanol is a safe and environmentally friendly technology. However, it faces some obstacles, such as low yield and productivity due to inhibitors. These can be overcome using genetically modified microorganisms. Thermo-chemical conversion of biomass is an increasingly viable way to use agricultural crop residues to fulfil energy needs and has several advantages over biochemical conversion.

1.6 Algal Fuels The productions of biofuels from microalgae received wide attention recently and have high potential to replace fossil fuels. The fuel production from algae holds several advantages over the second-generation fuels. The productivity of algal fuels depends on the oil content of algae during its cultivation. Generation of high biomass is one of the major challenges to address in this research, and several types of bioreactors have been proposed to improve the process.

1.7 Microbial Fuel Cell Microbial fuel cell (MFC) is a bio-electrochemical system which helps to generate electricity at atmospheric temperature conditions with/without existence of intermediator using bacteria or microorganism. This technology is very important for future sustainable technology for biodegradable materials using microorganism. In microbial fuel cell, microbes undergo catabolism reaction for easy energy generation. Energy produced is relatively of low intensity due to its nature of mimicking bacterial interactions. However, as per Carnot cycle, efficiency of energy level in MFC is relatively more than 50%. Views on various aspects of MFC will be explained from different resources in terms of their electrochemical performance using their morphology, catalyst arrangement, and activation of microorganism including cathode, anode, and separator along with catalyst.

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1.8 Bioenergy and Ecosystem The currently used methods of energy generation and resource utilization significantly affect the habitability on earth. For example, the energy generation from coal contributes about 0.3 °C of the 1 °C rise in temperature (Jonas et al. 2017). There are reports on the negative impact of energy extraction on forest ecosystems, food security, climate change, biodiversity conservation and land resources management (Duguma et al. 2020). Similar to the conventional energy generation methods, the non-conventional and renewable energy production methods also need to be examined based on ecological point. The understating of the responses of fauna and flora towards bioenergy production and utilization is also very crucial. Land use change is one of the major ecological threats that bioenergy causes. The effects of increased bioenergy production on biodiversity and ecosystems across the planet remain unclear till now. The first-generation biofuel production will have more impact on biodiversity than the second-generation biofuels because of the competition for land with food production. Further, the second-generation biofuel production which depends on unused biomass resources such as forest residues may create problems on wildlife conservation and biodiversity changes. Technological innovation is inevitable for sustainable development of the ecosystem. Industrial ecology made an entry with the aim of enhancing the efficiency of the ecosystem along with the system applied in technology during the past three decades. The use of biomass for the production of bioenergy has both favoured and adverse effects on air quality. The traditional method of utilization of solid biomass for energy by direct burning generates greenhouse gases like carbon mono oxide, nitrogen oxides, sulphur dioxide, etc. The modern method of conversion of lignocellulosic biomass to biofuel has less impact on atmospheric air quality. Another environmental impact of bioenergy that needs to be reviewed is the impact of water quality and water utilization. The bioenergy crops mainly require more water that other crops and the conversion of land for bioenergy crops may hamper the water resources. The primary water quality concern regarding the increasing cultivation of bioenergy crops is nutrient pollution resulting from surface run-off and infiltration to groundwater. The practical impact on water quality is the consumption of water by the crops required for bioenergy production. It is also necessary to analyse the impact of bioenergy production on soil. The conversion of traditional agricultural lands for cultivating bioenergy crops may affect on land use change, and it leads to the soil infertility and soil erosion. Erosion reduces soil quality and thus decreases the efficiency of natural and agricultural ecosystems.

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1.9 Integrated Approaches for Economic Feasibility Economic feasibility is one of the major challenges in biomass to energy production. Most of the developed methods of the second-generation bioethanol production are economically not feasible in comparison with the conventional liquid fuel: gasoline. The introduction of the biorefinery approach helps the biomass valorization for the effective production of bioenergy and other bioproducts by reducing the waste and reusing the waste acquired after recycling for the effective production of bioenergy with zero waste liquid discharges (Taylor 2008). Techno-economic (TE) models enable to realize the cost competitive of the bioenergy production.

1.10 Conclusion The following chapters in this book depict the detailed and updated information on all these aspects discussed now. The improved processes and technologies and critical evaluation on each topics have been covered in subsequent chapters. The chapters have been divided into five parts. Part I gives a detailed introduction about the book by the editors. Part II discusses the need of bioenergy and its perspectives. Part III covers the main theme of the book, the impacts of bioenergy on environment and economy which has five chapters discussing various impacts. Part IV covers recent developments in bioenergy research. The last part (VI) covers the biomass energy resources and various forms of bioenergy and its impacts.

References Duguma L, Kamwilu E, Minang PA, Nzyoka J, Muthee K (2020) Ecosystem-based approaches to bioenergy and the need for regenerative supply options for Africa. Sustainability 12:8588. https://doi.org/10.3390/su12208588 Jonas H, Abram NK, Ancrenaz M (2017) Addressing the impact of large-scale oil palm plantations on orangutan conservation in Borneo: a spatial, legal and political economy analysis. IIED, London, UK, p 94 Mittal S, Ahlgren EO, Shukla PR (2018) Barriers to biogas dissemination in India: a review. Energy Policy 112:361–370. https://doi.org/10.1016/j.enpol.2017.10.027 Taylor G (2008) Biofuels and the biorefinery concept. Energy Policy 36:4406–4409

Chapter 2

Need of Bioenergy—An Insight Into Global Perspective K. Srinivasan, J. S. Sudarsan, and S. Nithiyanantham

Abstract Bioenergy, rather renewable energy, producing a share of 37%, is made from biomass or biofuel, nevertheless and depends on the availability of organic source materials of forestry, agricultural, municipal, and industrial waste sectors of wood, energy crops, and waste from forests, yards, or farms and primary feedstock such as wood pellets, wood charcoal, and energy-sensitive crops. Bioenergy is sufficiently the fastest growing sector, typically providing the second most significant employment through more than 55 responsible organizations across the world and the third-largest producer typically occupying 96% of the sheer renewable energies. Bioenergy sector accounting more than two-thirds of the renewable energy mix and 13–14% of the total energy consumption with an average growth rate is larger than 8%. The heat source is of more than 95% with its particular significance in the heat generation sector and a wiser option of decarbonising. Sustainable development in the bioenergy sector in common is through its broader certain socio-economic benefits and negative environmental effects. The study was conducted on various government and private organizations steps towards a cost-effective way of production techniques, broader use of energy crops harming food security, accumulation of indoor air waste matter, use of chemicals and fertilizers, and environmental issues with present technologies showed that there is a real amount of alternative available to adopt for improving the sectoral benefits. Also, the following scenarios such as various countries recently accepting the Paris climate change agreement, generation of revenue opportunities through biogas, biofuels, and biomethane, increasing financial investments, impact in the transportation sector, and increasing of production capacity by major producers were major areas of focus considered in the present K. Srinivasan Department of Civil Engineering, PSNA College of Engineering and Technology, Dindigul 624622, India J. S. Sudarsan School of Energy and Environment, NICMAR University, 25/1, Balewadi, Pune 411045, India S. Nithiyanantham (B) Post Graduate and Research Department of Physics, (Ultrasonic/NDT and Bio-Physics Divisions), Thiru. Vi. Kalyanasundaram Govt Arts and Science College (Affiliation—Bharadhidasan University, Thiruchirapalli, Thiruvarur, Tamil Nadu 610003, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_2

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study. Further, in years to come, bioenergy through solid biomass would be having a major contribution in the sector when compared to liquid biofuels and biogas. Desk research and primary research were conducted during the present study. Keywords Bioenergy · Solid biomass · Socio-economic · Environment impact · Renewable energy

2.1 Introduction Sustainable circular economy of recycle, reuse, repair, and remanufacture contributes to climate target and balanced ecology through the active utilization of energy sources of biomass. Bioenergy is a carbon neutral fuel and a step towards an insignificant carbon footprint in the form of electricity and gas. Solid biomass, through wood chips, wood pellets and traditional biomass sources, accounts for 85 90%, liquid biofuel accounts for 7–9%, municipal solid waste and industrial waste accounts for 5–8%, and biogas accounts for 3%. Bioenergy industries supply chain involves, viz. production, processing, transport and use of bioenergy, and its associated emissions (World Council for Renewable Energy https://www.wcre.org; International Renewable Energy Agency https://www.irena.org). Production of bioenergy becomes indigenous to a country where it could provide socio-economic benefits and environment sustainability. Biomasses are used directly as wood pellets and indirectly as biofuels for the generation of bioenergy. The independent World Council for Renewable Energy and the International Renewable Energy Agency (International Renewable Energy Agency https://www. irena.org) are the two leading organizations which are focusing for the development of policies and strategies for renewable energy sector; the World Bioenergy Association (World Bioenergy Association https://www.worldbioenergy.org/) represents global bioenergy sector (Uslu et al. 2008; Wicke et al. 2008; Watanabe and Maeda 2007).

2.1.1 Bioenergy Sector Renewable energy sources are inexhaustible, naturally replenishing and limited amount of available energy per unit of time. Various sources of renewable are biomass, hydropower, geothermal, wind, and solar. Renewable energies are region specific. For example, tropical regions have higher sources of wind and solar, while temperate regions have good sources of geothermal energy. The sector accounts for about a ten per cent of today’s world total primary energy. Domestic purposes are primarily utilized more than industries, commercial cooking, and electricity generation.

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Recent advantages of utilization of renewable energy sources are as follows (Global bioenergy statistics 2020). Gross energy consumption was 471 EJ with a 17% share through renewable energy sources; heat produced globally was 15 EJ among which 96% was shared by biomass sources; use for direct heating in domestic purposes by bioenergy was more than 95%; transport sector with biofuels was more than 3%. Biomass have strong contribution in the energy sector are as follows. Out of 637 TWh of electricity generated, 66% was contributed from solid biomass; and out of 1.12 EJ of heat produced, 53% was contributed from solid biomass. Wood pellets have 38.9 million tonnes of production and wood charcoal have 53.1 million tonnes of production. Out of 160 billion litres of biofuels produced, 62% was contributed from bioethanol, 26% was contributed from FAME biodiesel, and 12% was contributed from other forms of biodiesel. Out of 11.5 million job opportunities developed, an estimated 3.58 million jobs were contributed from bioenergy. Cons of biomass are as follows. Open field burning of agricultural wastes that cause air pollution, machineries which produce renewable energy possibly produce considerable amount of CO2 , releases various harmful gases that contributes in the pollution of surrounding atmosphere, requires strict adherence to sustainable land management, and affects biodiversity, the wildlife, and ecosystems due to consumption for feedstock, expensive extraction of biomass materials due to larger variability in sources, increased transportation cost due to the presence of moisture content, requirement of larger storage space, and construction and operation costs. Drawbacks of its utilization could be substituted with torrefaction, and co-firing processes could substantially support and replace import of fossil fuels, respectively (Williams et al. 2018; Nzotcha and Kenfack 2019).

2.1.2 Bioenergy Technologies Conventional technologies [10..5] are (i) thermochemical processes involve direct combustion process works on combustion of solid biomass feedstock to produce steam in the presence of excess oxygen; pyrolysis process at high temperatures and pressure in the absence of oxygen decomposes organic matter; and gasification process through chemical or heat converts solid fuel to gas, (ii) biochemical processes involve anaerobic digestion that in the absence of oxygen decomposes organic or biological waste; and fermentation process converts sugars into alcohol, and (iii) trans-esterification process converts oils or fats into biofuel. Modern technologies are (i) bioenergy with carbon capture and storage process as shown in Fig. 2.1 extracts bioenergy from biomass and captures and stores the carbon. Useful forms of energy extracted by the process are electricity, heat, and biofuels. Application of geologic sequestration for the removal of CO2 during the process enables BECCS a negative emissions technology. Renewable energy credits (Renewable energy credits and (RECs) https://www.ene rgysage.com/) are as follows. The first-generation technologies those are established are economical such as sources of biomass, heat, geothermal, and hydroelectricity.

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Fig. 2.1 Bioenergy with carbon capture and storage (Elrapto—Own work https://commons.wik imedia.org/w/index.php?curid=7781853)

The second-generation technologies that are available are sources of modern forms of bioenergy, solar thermal power stations, photovoltaic, solar heating, and wind power. The third-generation technologies required continuous Research and Development, much larger global scale contributions such as hot-dry-rock geothermal power, advanced biomass gasification, and ocean energy. However, still methods and technologies are to be developed with a refined framework in order to achieve a zero-emission world.

2.2 Financial Demand In the demand analysis (Global Bioenergy Partnership Report http://www.fao.org), a steady potential for biomass-derived products in all the sectors was observed. However, this intense demand for biomass can be reduced with the necessary improvements adopted in various energy efficiency processes of generation. There is an impact on the financial sector by the increased use of bioenergy on the following economic activities, viz. international trade, gross domestic product, employment sector, energy security, and in infrastructure requirements. Due to the dense population and associated growing demand for economic activities, the potential for biomass sourced energy production was large across BRICS nations than G7 and rest of the world. There are still uncertainties existing on the predicted demand growth. With these points, the necessity for developing a required mix of policies for assessing the demand and for optimizing the utilization of biomass resources by various sectors of the economy with a suitable sustainable and cost-effective options is needed. Further, with the data on population and gross domestic product, the necessary demand for food and energy can be obtained. Financial wants, needs, and requirements related to the deployment of bioenergy and energy security are other aspects of economic development.

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The economic assessments of various options to replace fossil fuels are through the continuous supply of biomass and sufficient potential for bioenergy production. Various sources of biomass are straw of grain crops, rape straw, waste of corn and sunflower production, agricultural waste recycling, wood biomass, biodiesel from rape, bioethanol from sugar beet and corn, biogas from by-products of agroindustries, biogas from domestic solid wastes, biogas from domestic sewage, and grown energy crops and peat. In general, the economic potential of both agricultural waste and energy crops is in between 14 and 15 million tonnes, and in between 9 million tonnes and 10 million tonnes of fuel equivalent per year, respectively. For both traditional and modern technologies, the determining factors to be considered are (i) production price of energy per unit, (ii) required seed capital for infrastructure, and (iii) future risks. Influence of price rise of fossil fuels and cost of environmental effects are to be studied. Possible financial sources for bioenergy projects are national and state budget, loans, grants, enterprise own funds, commercial loans, financial leasing, technical project support, and public–private partnership. Financial demand could be achieved through the reformation of energy sector and optimizing and implementing innovative methods and technological facilities. Economic evaluation indicates that with the strong availability of wood wastes, investments in the cost of construction facilities towards infrastructure for bioenergy generation would become cost effective for increase of efficiency during the fuel conversion with the implantation of modern facilities because bioenergy industries provide higher returns. Socio-economically, through the implementation of bioenergy industries, potential jobs in rural areas could be generated and the problems of unemployment and poverty can be eradicated; additionally, increasing the demand for bioenergy industries can slow down the speedy pace of rapid urbanization, provides a good scope for self-sustained living standards in rural areas, and provides socio-economic development and welfare of the region and environmental safety, and more importantly, ecological balance. Also, through the constant motivation and support, biomass energy generation facilities provide independency status to the industrial society which is an essential component for political and economic stability. Furthermore, socio-economic aspects of bioenergy with regard to employment opportunities are highly engineered production, reduction of energy tariffs, provision of autonomy from centralized power grids, and reduction of costs of energy for agrarian industries; creation of new work opportunities, growth of workplaces, diversification of income; effective utilization of biomass waste resources, and reduction of ecological load level. There are some initiatives existing across the globe in order to develop and meet the financial requirements. For example, the International Sustainability and Carbon Certification System is a certification system for sustainability and greenhouse gas emission savings. Secondly, bioenergy is obtained with different sources of financial instruments, where other renewable options are not available as an alternative and where bioenergy is currently not cost effective. Others are, various policy measures, designed and executed on a long-term basis, preferential loans, national long-term

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strategies, encouragement to research and development, tax reductions, technological standardization and demonstration through pilot projects, and industrial field training and industrial technical support offered for utilizing solid biomass (Renewable energy credits and (RECs) https://www.energysage.com/; Global Bioenergy Partnership Report http://www.fao.org).

2.2.1 Key Policy Mechanisms 2.2.1.1

Feed-In Tariffs

Feed-in tariffs, the widely used long-term contract on Renewable Energy Policy across most of the countries, would help to encourage investments for energy incentive projects, and further this could be adopted for innovative projects. These tariffs favour reducing transaction costs and guaranteed minimum energy price. As followed in some countries, feed-in tariffs could also be varied or a dynamic system of pricing based on the source of energy such as wind, solar, geothermal, algae, small hydro, and biomass. Feed-in tariffs for electricity presently exist in China, India, France, Germany, Italy, the UK, and the USA. However, China has additional feed-in tariffs for heat. Grants for electricity, heat, and transport fuel are available in India, Canada, and EU. Most of the other countries have grants for electricity and some for heat.

2.2.1.2

Taxes

In general, sectoral growth and development depend on the availability of different tax incentives and penalties. A similar scenario is existing across the world for the utilization of bioenergy. This in future would determine the position of bioenergy in the energy market.

2.2.1.3

Preferential Purchasing

Purchasing a particular percentage such as between 25 and 30% of electricity obtained from renewable energy sources by various governments could be an encouraging mechanism for both individuals and groups to adopt bioenergy industries. Countries are adopting different forms of direct incentives for the application of bioenergy as shown in Fig. 2.2. Transport fuels sector is more concentrated than heat and electricity. Understanding the requirements of biofuels, the above figure shows that the sector consumption increases ahead in future.

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Fig. 2.2 Countries providing direct incentives on various forms of bioenergy

2.2.1.4

Recent Updates

Recent technological development in the sector for financing was through block chain. Enerchain project for trading in the energy sector has benefitted and is getting attention, and this was practised by prosumers of the industry. UN’s environmental programme has given some guidance as follows. Pay-as-you-go for the utilization of resources and peer-to-peer distribution and supply of energy resources are to mention a few. Green bond and green securities are another source of options available for attracting investments in the sector. Banco Bilbao Vizcaya Argentaria (BBVA | The digital bank of the 21st century https://www.bbva.com) in Spain and SociétéGénérale in France (SocieteGenerale Group https://www.societegenerale.com) are some of the major initiators in the sector. Similarly, crypto-currency transactions also have major contribution in the development of the sector; however, these are at the initial stages only and require in-depth analysis. Further, value transfer risks, smart contract risks, and endpoint vulnerabilities are to be studied in the aspects of cybersecurity and risk management in the online transaction which are susceptible to hacking.

2.3 Environmental Demand Sustainability issues of biomass are as follows: environment, society, and economy. With the increase in the fossil fuel prices, higher domestic energy consumption and global awareness towards utilization of bioenergy have showed the significance of bioenergy trade in the form of compacted and densified biomass of wood pellets, charcoal briquettes, and manufactured logs. In near future, the electricity price through solar power could become a benchmark price for other fuel prices. Most of the major

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players in the manufacturing of biofuel have showed substantial growth in the recent years. European Union has showed bioenergy trade in countries such as the Netherlands, Sweden, Latvia, Estonia, Poland, Lithuania, Austria, Denmark, and Germany. Also in the trade were North America, the Baltic States, Canada, and Malaysia and have made the trade and transport a more cost-effective one. The USA was the major importer of bioethanol while Brazil being the major exporter and China stands next.

2.3.1 Environmental Factors As bioenergy markets are getting geared up in recent decade, government priorities and policies across the world become important to be considered. The pros and cons of various options of bioenergy have both the environmental and social implications. Awareness and importance, increasing demand for energy prices, energy security, climate change, rural development and increasing concern on air pollution, soil protection, and land reclamation, and residues and waste treatment are major factors to be considered on the aspects of the importance of bioenergy.

2.3.1.1

Awareness and Importance

Reduction of wastes, reduction of cost of energy, and scope for newer revenue generation were the importance of utilizing bioenergy. Human population need to have more and more awareness on the use and benefits of bioenergy. A cultural change on the use of bioenergy would become an inevitable practice in near future. More and more modern application should adopt using bioenergy although traditional use has showed a good progressing. People should have a strong hope that bioenergy is a substitute and replaces other conventional fuels. In the every aspects of utilizing an energy source, people should feel that there is an alternate available and that would reduce the emissions of GHG, thereby would give a sustainable environment. Primary bioenergy consumption accounts for a total of 10–14% in the world. Rural people have been educated, and at present, they depend on bioenergy sources in the developing countries, while it has showed lesser in developed countries. At present, African countries, Central American countries, and Asian countries have major dependence on this source of energy. Increased greenhouse gas emission was due to the continuous utilization of fossil fuels, and consequently, the major drawbacks of such mining have caused land, air, and water pollution. Expanding energy deficit and increased cost of energy imports have focused many countries to march towards developing and utilizing the alternative sources of renewable energies. Rural development and its economy could be improved through the implementation of various schemes that are available in support of utilization of agro-waste or biomass. Major contributions of green peace

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such as “Go beyond Oil” (Beyond and Oil—Greenpeace USA https://www.greenp eace.org) and reducing emission from deforestation and forest degradation (UNREDD Programme https://www.un-redd.org/) have paved the way for utilizing the alternate sources of energy for consumption, further, in the move to reduce GHG through Kyoto treaty, and reduce the risks and impacts of climate change through Paris Agreement (Kyoto Protocol and the Paris Agreement https://unfccc.int).

2.3.1.2

Increasing Demand for Energy Prices

Rapid depletion and increased dependability on primary fuels have diverted countries to look for alternatives by various sectors. Other factors that influence the electricity price are maintenance, operation, transmission, and distribution costs of power plants and the loss of generation of energy due to extreme weather conditions. The demand for bioenergy could rise up to 108 EJ by 2030 which is twice the present requirement. The projected demand for the bioenergy is up to about 100 EJ in 2055 and of about 300 EJ in 2095 with a simulated price increase up to 7 US $ per GJ in 2095 (Global Bioenergy Supply and Demand Projections: A working paper for REmap 2030).

2.3.1.3

Energy Security

Instability on the bioenergy price and its supply, in future, would cause a threat and bioenergy insecurity. Access to affordable, reliable, and adequate energy without any interruption becomes essential factors. The price and availability of the energy are two determinate factors for energy security. Each and every country must give considerations to their political stability, supply and sources of energy, and infrastructure facility for development in order to avoid any threats in future. At present, Mexico is the most energy secured country due to its higher domestic oil reserves and relatively lowers per-capita energy need.

2.3.1.4

Climate Change

Global acceptance to reduce the greenhouse gas emissions has focused the application of bioenergy, a low-carbon emission fuel source, as an alternative fuel for sustainable environment. Use of bioenergy would reduce above-ground biomass and improve soil carbon stabilization (Elrapto—Own work https://commons.wikimedia.org/w/index. php?curid=7781853). Innovative methods and technologies are to be adopted for the production and use of energy which would contribute to climate change.

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Rural Development

One of the sources of bioenergy is being agricultural waste; participation of farmers is the utmost need. Provision of local technology and employment opportunities to village people would help to develop the factor. The role of government and its policy decisions are other aspects to be considered. Still there should be a mechanism to be followed in order to use various biological and thermal process such that agricultural waste could be processed efficiently.

2.3.1.6

Air Pollution

Advanced and hybrid technologies are required for the generation of bioenergy which would eventually lower and reduce the adverse effects of pollutants. Implementation of biofuel would reduce the GHG emission and improve air quality.

2.3.1.7

Soil Protection and Land Reclamation

Soil upgradation and restoration through suitable feedstock growth and reclamation of land through the growth of energy crops are required.

2.3.1.8

Residues and Waste Treatment

With the existing technologies for the treatment of wastes and residues, still there is an industrial need for waste management; hence, the process of generation of bioenergy could be a solution to this waste treatment.

2.3.2 Key Policy Factors of BRICS and G7 Countries Key policy factors are shown in Fig. 2.3 that shows the implementation of such factors by various countries. In the BRICS countries, energy security and rural development are the two key factors given with wider importance, while the G7 countries have climate change as their important factor. Among the BRICS countries, Brazil and Russia are the two major contributors, while in the G7 countries, Germany is the major contributor. Rural development for socio-economic benefit and energy security for sustained and integrated development were the significant key policy factors included in the BRICS nations. Climate change was the significant key policy factors among G7 countries including the EU nations. In the present scenario, with the existing awareness on bioenergy and available technologies for the generation of bioenergy, the volume of feedstock would resemble

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Fig. 2.3 Key policy factors: a BRICS countries and b G7 countries

higher than the volume of non-renewable sources. Also, when the consumption of bioenergy sector reaches to an exponential demand, then the existence of feedstock source would become questionable. Hence, strict and stringent requirements for adherence to certain policies on agricultural and forestry industry by various countries in order to avoid depletion of the feedstock sources and to protect ecological balance become mandate. Mandatory targets become a legal requirement in the country than voluntary and no targets. Figure 2.4 represents the legal contributions by various countries. Transport fuels are the major factor considered in the use of bioenergy, followed by electricity and heat factor. However, among these, there are different target levels adopted by various countries. The G7 countries contribute more on heat than BRICS countries. The role of Russia in the contribution is in the discussion. Various biomass potentials are theoretically viable, technically manageable, and economically viable. Resource oriented and dedicated on energy needs that the technologies available for the generation of biomass energy compared to similar types of renewable sources and traditional fuels are evaluated along with the an economic effect of adopting such alternate energy sources. Potential energy sources through agriculture and forestry are about 70–80 billion tonnes that is about 11 times

Fig. 2.4 Mandatory targets (M), voluntary targets (V), and no targets (N) on bioenergy: a BRICS countries and b G7 countries

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higher than other traditional fossil fuels. It gives a gross energy potential of about 1000–1100 W which place it significantly in global energy balance. Medium- and small-scale industries have renewable energy sources as a sustainable source of their power supply. Similarly, for un-important and official purposes, heavy industries use renewable energies as an alternate source. Availability of domestic methodologies and technological developments provides the necessary energy generation at low cost fulfilling the local society and the consumer needs, with a shorter payback period that encourages to active participation in the industry. That domestic would have awareness in the protection of their ecology. Further technological transformation and modernization through innovation necessitate investment and environmental support and benefit. Biomass energy would provide 4–5 times higher energy through nuclear and power industries. Bioenergy is economically feasible as the present cost per Joule is less when compared with other sources. Ensuring environmental safety through the reduction of greenhouse gas effect, damage on environment through waste collection systems, provision of closed environmental-friendly energy generation system, installation of effective recycling of livestock wastes, forestry waste in cutting down, and timber wastes from the industry and city garbage dump yards. Ecological position arises due to neglecting the objective laws of natural resource complex for sustained duration, higher utilization of resource-intensive and wider adoption of energy-intensive technologies in the production of livestock, and lower environmental alertness in the culture which are major factors that significantly influence the degradation of ecological systems. Also, ecologically oriented businesses are the driver for market functioning and through a mandate system of regulation for implementation and green purchases. Active development of bioenergy industries requirement is as follows: (i) increased production capacity, (ii) implement innovative and ecological-oriented technologies to reduce the ecological burden, (iii) update mandate regulation, (iv) through the development of international cooperation, and (v) implement intensive projects.

2.3.3 Environmental Policy Factors Various policies that have influence on environmental scenario are as follows.

2.3.3.1

Indirect Policy for Energy

Discontinuing the practice and production of energy using fossil fuels and implementing higher import and export taxes would significantly benefit the growth and development of bioenergy industries.

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Indirect Policy for Agricultural and Forestry Policy

Provision of encouragement and financial support for the farmers in order to the growth of energy crops would facilitate increase in the production of bio-feed stock, thereby benefitting the input for bioenergy industries. The authors here strongly place that simultaneous efforts on afforestation should be in practice, while developing countries rapidly move towards bioenergy technologies. Otherwise, developing countries would become a developed country then, where the need for import would arise.

2.3.3.3

Indirect Policy on Climate Change

Industries that reduce CO2 and GHG emissions during the production process would divert the industries to move towards utilizing bioenergy fuels.

2.3.3.4

Indirect Policy on Environment

Reduction of pollution and regulation of utilization of bioenergy practice through implementation of mandatory targets would favour for a sustainable environment. In favour of tropical regions, algae oil could replace the crude oil in near future. Awareness to renewable energy certificate and carbon credit are to be encouraged. Figure 2.5 shows the production capacities of top ten countries for the year 2020. It was clearly evidenced that developing BRICS countries have shown drastic increase in their production when compared to G7 countries. The increase in fold is much larger and highly competitive. However, as discussed earlier, ecological and environmental balances are mandatory requirements while moving along this scenario. Alternate to biomass from wood and forest is solar and wind. Hence, efforts should be in place to accommodate more innovations and support for the development of these two alternate sources. Zero- or low-carbon, efficient, and environmentalfriendly energy source is the need of the hour (Renewable Capacity Statistics 2021). The production of an unsustainable biomass that would not damage environmental advantage due to the use of it is essential. However, at this instance, during the pandemic COVID-19, lockdown measures taken by various countries to combat the situation also had its effect in the bioenergy sector. Mainly, it has affected the supply chain of the sector and has created possible shortage of labours across the globe. More predominantly, there existed a scenario that many governments’ revenue has been diverted towards the various measurements during this period. While the situation has occurred earlier in urban areas, it was then later transformed to the rural areas as well affecting the growth and progress of the sector.

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10518

9916

5393

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3835

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Fig. 2.5 Leading energy producing countries for 2020—values in MW (Renewable Capacity Statistics 2021)

On the other hand, there is a mixed opinion that in order to neutralize the effects or loss due to this condition, predictions are there for a reduction of fossil fuel prices which may attract the consumers to lessen their move towards biofuel.

2.4 Contributions by Some of the Major Players There are enormous numbers of organizations that are taking part in the contribution to bioenergy in various forms such as in biomass production, bio-feed, forest and agriculture conservation, and consultants. In the following section, some of the leading organizations were discussed. The role of biofuels, primarily, in the transport sector have wider scope that global countries have their projected average share between 10 and 20%. AperamBioEnergia in Brazil has its role in ecological protection of flora, fauna, and water reserves. It has an energy-efficient carbonization process for the production of charcoal for an active substitution for coke. It has its major contribution in the processes such as carbon sequestration, soil enrichment, and erosion control with provision of shelter to the wildlife for assuring a carbon positive forest reserve, carbon sink with higher biological efficiency, and providing sustainability of local resources. AlternaVerdein Mexico has its role in the manufacturing of anaerobic digesters for the conversion of residual waste into bio-fertilizer, thereby creating energy sufficient to power the homes and industries through the adoption of modern technologies. Further, it adds to reduce carbon emissions, providing long-term cost savings with greater efficiency. Enviva in the USA produces sustainable wood pellets for displacing the consumption of coal. It actively takes part in growing more trees for fighting climate change, reducing carbon emissions, and limiting dependence on

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fossil fuels. It has its major contributions in providing larger employment opportunities. Södra in Sweden develops new and sustainable climate-smart products, building systems, and completes the biomass value chain. Bioendevin Sweden has developed torrefaction process for the production of black pellets that are hydrophobic and carbon neutral, with a unique higher energy density than white pellets. Tata chemicals in India produces bioethanol and biodiesel. Investancia in Paraguay produces oil and bio-protein using Pongamia tree. Lantmännen in Sweden manufactures agriculture, machinery, bioenergy, and food products and also involves in the manufacture of market sustainable ethanol, starch products, protein feed, potable spirits, alkylate petrol, and gluten. Pelletmx in Mexico is contributing to the construction and management of production plants for pellets. Here, the agricultural and forest residues are processed, dewatered, and compressed in order to improve the performance of combustion and energy density. Serge Energy in Finland provides clean-energy investments across geographically safer and politically secured locations in Europe along with the production and sale of renewable energy. Herz in Austria manufactures of pellet plants, wood gasification boilers, heat pumps, and wood chip plants. ePURE in Belgium takes part in the reduction of greenhouse gas emissions. Syncraft in Austria has its unique selfdeveloped and patented technology for a climate-positive energy system. It generates electricity, heat and natural gas substitute, and vegetable carbon from various sources. UABIO in Ukraine has its participation in uniting businesses and experts for sustainable bioenergy development. Energigården in Norway serves as consultants in the production and uses of bioenergy by assisting companies in several fields related to renewable energy for design of bioenergy plants and switching to sustainable use of biofuels. Svebio in Sweden promotes the bioenergy exchange market through a digital trading platform for pellets and wood chips. ValBiom in France works on assessment and diagnosis on pre-feasibility studies, techno-economic studies, and specific communication strategies and communication tools and provides first line support in the field. Litbioma in Lithuania associates with the suppliers and producers of solid biomass and local renewable resources, such as wood, energetic willows, straw, and peat. Further, it associates with the designers and producers of solid biomass equipment and boiler rooms. They develop academic institutions and plantations across the region. N-BiG in Namibia provides technical expertise on biomass value chains and explores various market opportunities in biomass utilization. The Coherent Market Insights (Market and Insights https://www.coherentmark etinsights.com/) has estimated solid biomass fuel market across the globe that will be US$ 425.8 billion by end of 2027 with a CAGR of 8.5%. In a recent US Energy Information Administration, electricity production through renewables sources is expected to increase to 23% in the year 2022, from waste biomass and wood biomass. Future consideration for bioenergy market segments includes product type, application, region, and the end-users. The key regions of bioenergy markets are as follows. In Asia Pacific are Australia, India, China, Southeast Asia and Japan; in Latin America are Argentina, Brazil, and Colombia; in Africa and the Middle East; in Europe are the UK, Germany, Italy, France, Spain, Benelux, and Russia; and in North America are Canada, the USA, and Mexico. In order to improve the transition, utilization

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of ethanol and other renewable fuels are to be encouraged so that a net-zero carbon future is possible. On the other hand, the UK government has recently announced in a move to omitting the use of bioenergy, in favour to welcoming planting trees targets. While in India, the Ministry of Power with a move in contribution to its National Clean Air Programme (NCAP) plans to use biomass for coal-based thermal power plants to provide solutions to reduce carbon footprints, increase the level of co-firing, support carbon neutral power generation, initiate research and development in the boiler design to protect it from the effects of silica and alkalis during the production of biomass pellets, and steps to overcome the constraints in supply chain of biomass pellets and agro-residue.

2.5 Valorization and Bioenergy Valorization is the transformation of waste/biomass to valuable materials that requires interdisciplinary approaches in circular bio-economy. Bioenergy requires energy balance and economic feasibility of existing systems with a multidimensional analysis for sustainability and application. Recent development of Oak Ridge National Laboratory (National and Laboratory) multifunctional catalyst system converts ethanol into butane-rich C3 + olefins for energy efficiency through valorization. Similarly, a novel technology for improving the hydrogen production efficiency was developed with the electron produced during the decomposition of waste wood biomass, making it a high value-added compound.

2.6 Carbon Sequestration and Climate Change Intergovernmental Panel on Climate Change (Intergovernmental Panel on Climate Change https://www.ipcc.ch) included carbon sequestration as one of the ways to combat climate change along with other known ways. Natural method of carbon sequestration helps at most by the intake of carbon/carbon dioxide and giving out of friendly oxygen, with due consideration to maintaining the ecological balance of the local, too. Carbon capture of microalgae is also another source (Yang et al. 2022). However, the cost and technologies are yet to be noted and advanced in order to assess the effects of this carbon sequestration method on the effects of cultivable and non-cultivable soils.

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2.7 Conclusions This review consists of the need of bioenergy which is good for environment on human community. The finding of this survey to pave the information on bioenergy as a fuel worldwide includes developing, developed countries like Group A and Group B categories also. (i) The bioenergy is mostly from biomass like wood, charcoal, crops, agricultural waste, etc. (ii) Bioenergy is the fast-growing fields with more employment opportunities, environmentally good and economically less. (iii) Many industries from government and private sector involve in bioenergy production due minimizing the cost. (iv) Many countries are following Paris climate change agreement, generation of revenue opportunities through biogas, biofuels, and biomethane, increasing financial investments and impact in the transportation sector. (v) Once the era will come, biomass is the good substitute for bioenergy to reduce the environmental issue and save the earth with minimum expenditure. Future suggestions To conduct nationwide project on bioenergy from other continents to develop the systems and technologically and increase the percentage of biofuels towards the betterment of this earth systems.

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Oak Ridge National Laboratory. https://www.ornl.gov/ Nzotcha U, Kenfack J (2019) Contribution of the wood-processing industry for sustainable power generation: Viability of biomass-fuelled cogeneration in sub-saharanafrica. Biomass Bioenergy 120:324–331 Renewable Capacity Statistics 2021. https://www.irena.org SocieteGenerale Group. https://www.societegenerale.com UN-REDD Programme. https://www.un-redd.org/ Uslu A, Faaij A, Bergman PC (2008) Pre-treatment technologies, and their effect on international bioenergy supply chain logistics—techno-economic evaluation of torrefaction, fast pyrolysis and pelletisation. Energy 33(8):1206–1223 Watanabe T, Maeda S (2007) Trends and outlook in high-temperature fuel cells for clean coal technology. Sci Technol Trends Q Rev, ISSN 1349-3671, No 23, April 2007 Wicke B, Dornburg V, Faaij A, Junginger M (2008) Different systems and greenhouse gas implications of palm oil for energy purposes. Biomass Bioenerg 32(12):1322–1337 Williams O, Taylor S, Lester E, Kingman S, Giddings D, Eastwick C (2018) Applicability of mechanical tests for biomass pellet characterisation for bioenergy applications. Materials 11:1329 World Bioenergy Association. https://www.worldbioenergy.org/ World Council for Renewable Energy. https://www.wcre.org Yang L, Qisi S, Si B, Zhang Y, Zhang Y, Yang H, Zhou X (2022) Enhancing bioenergy production with carbon capture of microalgae by ultraviolet spectrum conversion via graphene oxide quantum dots. Chem Eng J 429(1):132230

Chapter 3

Sustainable Development of Bioenergy and Its Impacts on Ecosystem A. Vidhyarathi, S. Chozhavendhan, G. Karthigadevi, V. Nirmal Kannan, and R. Praveen Kumar

Abstract Ecology is dependent on the biological system and ethics adapted by living beings. In ecosystem, sustainability focuses on the endurance of both humans and non-humans. The system is productive over time. It deals with the long-term process that every human works for their well-being. It includes the maintenance and the cycle of bio-system and natural resources. The possibilities of sustainability in the ecosystem are applied in every aspects of the life of beings on earth over ages. The pollutant from factories causes a great damage to water with the mixture of oxygen, nitrogen, and carbon that play a major role of the lives of both human and nonhumans since earlier times. The lifestyle of humans proves various aspects of living conditions including eco-villages, eco-municipalities, and sustainable cities and also reappraisal of economic sectors including permaculture and green building. Since ages, biomass remains the prevailing supporter of supplying energy in countless agricultural nations. In such nations, it serves the family energy needs that cross the level of 33% of mankind in conventional gas stoves or open flames. Endeavors to lessen the colossal human well-being, financial and ecological effects on moving to cleaner gas stoves, and cleaner biomass-determined powers have had some achievement perhaps including the extended utilization of fossil-inferred fills. Simultaneously, biomass is quickly extending as a business fuel source, particularly for transport fills. Bioenergy emphatically adds to environment objectives and provincial occupations; it fuels corruption of land, water bodies, and biological systems and diminishes food security and increment ozone depleting substance with the discharges of greenhouse gases. For huge scope business, biofuels to add to supportable advancement require A. Vidhyarathi (B) · V. Nirmal Kannan V.S.B. Engineering College, Karur, Tamil Nadu, India e-mail: [email protected] S. Chozhavendhan Vivekanandha College of Engineering for Women, Thiruchengode, Tamil Nadu, India G. Karthigadevi Sri Venkateswara College of Engineering, Chennai, Tamil Nadu, India R. Praveen Kumar Arunai Engineering College, Tiruvannamalai, Tamil Nadu, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_3

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reasonable strategies in agriculture and markets that give upgraded work openings and impartial terms of exchange. The test lies in making an interpretation of the chance into the real world. Keywords Sustainability · Overpopulation · Reappraisal · Biodiesel · Biofuels · Biomass

3.1 Introduction The anticipated energy requirement for the upcoming years will increase up to 50% more rather as it is today. Around 90% of transportation sectors depend on fossil fuel for fueling the vehicles. Demand of fuel for transportation sector is expected to increase 2% per year (Chozhavendhan et al. 2018). Society has to adapt the aspects of the ecosystem to provide wealth adequately to cater to the needs of the overpopulated world. The ecosystem faces the needs of the confrontation in order to fulfill the needs of the beings. The role of technology involves in the process of the intrusions of innovations in the industrial society. The innovation includes both the social and organizational innovation. The ecosystem shows its dependence with the changes in socio-technical aspects. With the practice of conscious design in the ecosystem is probably dependent on engineering since decades. The advantages of the design are treated as futile, and it has to be believed that its involvement has a lesser focus on contribution to larger global issues. The various levels of changes are identified in technology ranging from (i) single artifacts with incremental optimizations, (ii) major changes of artifacts, (iii) changes in the ecosystem, and (iv) transitions of technology (including changes in consumption and production).

3.2 Impact of Bioenergy on Economy and Its Monetary Effects Maintainable advancement generally alludes to an improvement that has financial and social advantages and restricts its negative ecological effects. The three standards, alongside the accessible advances, are in this way the three most inescapable elements—social, economical, and ecological elements that will influence the conduction of a venture. Bioenergy projects are, along these lines, like different ventures and furthermore should be assessed dependent on the advantages it can give to the economy, to society, and the advantages and negative impacts it will have on the climate. The initial phase in any task consistently concerns the assessment of the expenses and the normal incomes. Bioenergy projects consistently need to create energy in a financially savvy route contrasted with other regular techniques for energy creation. Bioenergy is attempted regardless of the way that different choices appear

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(wind, solar, and hydro energy) on a present moment, to be more beneficial, due to the decline of fossil fuel resources or higher social or ecological advantages that will prompt expanded administrative commitments (Chozhavendhan et al. 2020a, b).

3.3 Social Effects Development of bioenergy projects influence the networks, wherein they are executed different methods. It transits from improved water quality to the production of new positions in monetarily discouraged districts. A few employments of bioenergy require a feedstock dependent on devoted field creation, (e.g., energy harvests) or build-ups from farming creation (Breeze 2019). Some horticultural fields are peripheral for food creation, and bioenergy creation could improve these negligible terrains. The creations of energy yields detrimentally affect food security. A genuine model on the social effects of bioenergy concerns with corn ethanol and rising oil costs (Popp et al. 2014). Corn plays a major role in energy-concentrated harvest and focuses on the purpose of petroleum derivatives that leads to the expense of the barrel of oil; it parallels and includes the cost of creation that is identified with corn creation. Simultaneously, this expansion in oil costs expands the benefits a rancher can make from the creation of corn ethanol. Under aggressive economic situations, the expansion in oil costs restricts the provisions of yield feedstocks and favors the change of corn supplies to corn ethanol. These outcomes limit the stock of corn for creature and human utilization that influence the worldwide costs of corn, making it a more expensive item.

3.4 Ecological Effects As indicated by the World Health Organization, the major sources of youngster mortality (under 5 years of age) in helpless nations are intense respiratory contaminations. Such kinds of contaminations are brought about by a lacking ventilation framework to empty the aggregation of indoor air poisons brought about by the utilization of biomass as a cooking fuel. Bioenergy detrimentally affects air quality. The utilization of pesticides and composts influences water quality. Thus, an appropriate appraisal of the natural effects is frequently needed before the execution of bioenergy advances, to improve the personal satisfaction of individuals who receive gain with this innovation. The utilization of briquettes, for instance, has been examined as a low-innovation, cost-proficient fuel that is utilized in non-industrial nations to improve the effectiveness of cooking energizes and to improve indoor air quality.

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3.5 Strategies Certain fields of bioenergy are still new advancements, and a ton of issues are set out to permit social acknowledgment. For instance, hereditary designing of non-food items is an innovation that is presently commonly considered as protected. Bioenergy has certain adverse consequences on worldwide food stocks or on water contamination. Governments and researchers in this manner need to get the fundamental data about the total bioenergy advances field to recognize the outcomes of these activities, which assists governments with settling on choices on the best strategy to take to help gainful bioenergy advances and help society.

3.6 Energy Innovations in Technology The effect of advances in bioenergy involves a great support in ecosystem in various ways. The impact falls on agriculture, niche, and technology. Discussion endures inside the logical examination local area about the genuine environment effects of increasing biofuels and bioenergy. Concerns proceed over roundabout land use change, the sequestration opportunity expenses of changing over developed terrains into biofuel feedstocks versus reforestation, and appeal for farming grounds to meet the food security needs of a developing populace (Thompson 2012). However, bioenergy is as of now a significant sustainable power asset, representing 9.5% of allout essential energy supply and 70% of environmentally friendly power use today. Generally, bioenergy has appeared as consuming wood and charcoal for cooking and warming. Rise of bioenergy applications incorporates structure and industry warming, power creation, and transportation. An unmistakable benefit of biofuels is that they can override baseload power requests right now met through consuming petroleum derivatives. Biofuels are likewise a generally minimal expense option in contrast to the high-energy thickness energizes required in flight and transportation. The application of transition innovation from the existed system of ecosystem to the new system is reachable with the minimum exploration of resource and pollution that affects the process of bioenergy on transition with its expansion of minimum strategies of encompassing innovative techniques including system innovations and optimization of products. Funded research on Bioenergy Technologies Office displays the limits of traditional science in the bioenergy market. The emergence of bioenergy is included with few innovations in chemicals, fuels, and products; it reduces both the emission of greenhouse gases and petroleum imports in the transportation sector. The examples are on chaos from transition innovation in the ecosystem to the competence of new system in the environment. It includes guidelines for enhancing government policies and corporate strategies. It is a belief that there has to be a scope for market niches for new system to bring innovations that would be a great support for the entry of new experiments that paves way to the transition innovation.

3 Sustainable Development of Bioenergy and Its Impacts on Ecosystem Fig. 3.1 Diagram describes the difference between architectural, niche, incremental, and technological systems innovations in sustainability in ecosystem

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Agricultural Innovation System

Niche Innovation System

Technological Innovation System

Incremental Innovation System

Technological innovation is inevitable for sustainable development of the ecosystem. Industrial ecology made an entry with the aim of enhancing the efficiency of the ecosystem along with the system applied in technology during the past three decades. The focus of the system is on optimization. The focus and scope of the sustainability of ecosystem frame a system for long-term sustainability in the policy of technology. The ecologist Ehrlich and Holdren proved their logic with the equation I = P × A × TI = P × A × T. In Fig. 3.1, IPAT equation is explained. I stands for environmental impact and P for population. The focus of status among class-based society in developing countries shows their gradual rise and the environmental efficiency of technology; the values of T stand for technology and prove its improvement with a factor 4–40 to sustain the environmental burden and the same in the present scenario (Ruttan 1993).

3.7 Technologies for Sustainable Development In the current scenario, the application of various technologies on bioenergy is experimented to the extent to develop into a significant supporter of worldwide supply of energy. In spite of the fact that the facts confirm that bioenergy has numerous expected ethics, it has similarly striking risks and the wry axiom; the present arrangements are the upcoming issues that are not permitted to remain constant for bioenergy. Undoubtedly, one can without much of a stretch envision biomass creation frameworks that are undeniably fit to their current circumstance. It paves a way to support showing the improvement in the climatic conditions by revegetating in fertile land, settling and renewing dirt, securing watersheds, recovering salinated and waterlogged soils, giving environment to neighborhood species, and sequestering carbon—meanwhile adding to occupations of rustic networks. In any case, a similarly conceivable

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vision is that of biomass creation frameworks that are non-renewable energy source escalated, fume the dirt of supplements, compound disintegration, exhaust or debase water assets, lessen biodiversity by dislodging living space, increment ozone harming substance (GHG) emanations, and contend with creation of food for arable water and land assets (Freedman 2018). It subverts the occupations of country networks. Challenging improvement with a reasonable aspect is to cultivate the development of an advanced biomass framework that satisfies the guarantee and maintains a strategic distance from the traps. This part surveys the significant components of the practical advancement moves vital to customary and current biomass energy. The entry for innovation in the development of sustainability in the ecosystem is apparent on the implication. The application of techniques focuses its contribution on exploiting the burden on the environment due to human activities. The implementation of new technologies focuses on social changes. The entry of new technologies is a platform for changes in socio-technical aspects. The discussion on the issues of ecosystem is displayed in the proceeding statements. The categorization of such technologies is based on the degree of ‘radicalism’ (Braat and Groot 2012); it is explained as such the impact on the existed technological patterns such as preindustrial solutions, technologies of the existing environmental patterns, housekeeping technologies in good criteria, end-of-pipe technologies, adaptation of process in the existed pattern and preventing damage, and sustainability in technological adaptation. The implication of technology for the protection of human’s inhabitants from the exploitation of nature including barriers and vaccination plays the role of nonenvironmental technologies. The exclusion is used for the purpose of measurement and analysis. Technologies that are used for the purpose of restoration include soil remediation. The following category is examined for various purposes on the sustainability of ecosystem. Since ages, the role of technology in human’s culture is countless; it includes exploitation of natural resources and pollution that causes damage to the environment. The issues arouse due to human population that is comparatively less giving lesser impact. Historically, the rise of issues since the earlier ages is due to local exploitation of nature. The remedy of such issues is possible with the implication of the three D technologies (Ferranato and Vincenzo 2019): (1) dumping (wastage of pits and so on), (2) displacement (pollution that caused due to sewerage, smoke tracks, and so on), and (3) dilution (wastages from gaseous and liquids). Pollution that affects the production of biomass causes greater damage to society that affects and the measures on preventing such cause have been taken. The mode of prevention finds its way with the initiatives such as the constraints in production reduce pollution. The initial measures for such precaution are named housekeeping or the three M: monitoring, management, and maintenance. The wastages are reduced with the support of end-of-pipe technologies (King 2014) that are (1) incineration, (2) pyrolysis, (3) separation, (4) fermentation, (5) transformation of chemicals, (6) reduction in catalysis, and (7) shielding (noise and radiation). The process of recycling that transforms waste product into productive is termed as end-of-pipe. The waste is used as a fuel. It requires less energy comparatively; the existing product produces much pollution. The process of recycling is sustainable (as in reprocessed metals).

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3.8 Bioenergy and Its process—The Source of Changes in Ecosystem Choosing the suitable innovation with the conversion of natural resources to bioenergy is critical to streamlining energy creation. The accessibility in bioenergy is separated into three classifications: thermochemical, biochemical, and different cycles.

3.8.1 Thermochemical Process Direct Ignition: Direct ignition is the most well-known type of bioenergy and is commonly utilized at non-renewable energy source terminated force plants. The cycle includes the ignition of strong biomass feedstock, regularly some kind of waste in the sight of inadequacy of oxygen in evaporator to create steam that is changed over to power. The warmth created from the ignition cycle is utilized in direct warm applications, for example, to warm a building. In common, materials, like cellulosic, are not reasonable for the medicines depicted above because of their troublesome nature for the separation of ethanol (Song et al. 2009). Materials like wood, grass, waste, and harvest build-up are on the whole great feedstocks for both the transformation of thermochemical and biochemicals. Thermochemical change utilizes warmth and synthetics to separate the cellulose to make syngas in the feedstock (Nuss et al. 2012). The particular cycles are as follows. Pyrolysis: It utilizes high temperatures and pressing factor without oxygen to deteriorate natural matter that brings gas, pyrolysis oil (bio-oil), or charcoal (bio-roast). Bio-oil is the most well-known item as it has the most end uses, for example, for nuclear power that is utilized to warm structures or water or for power age. The temperature of the response decides the final result. Gasification: Gasification changes strong fuel over to gas using a substance or warmth measure. Strong biomass like woody waste reaches the maximum temperature while boiling (over 700 °C) with restricted oxygen. It changes over the feedstock into a combustible amalgamation gas known as ‘syngas’ (David 2008)’. Syngas is then either combusted to deliver steam in a heater for power or warmth for warm applications.

3.8.2 Biochemical Process Biochemical change can utilize an assortment of high temperature, high pressing factor corrosive, chemicals, or the proceedings of other treatment to separate the hemicelluloses and lignin that encompass the cellulose (Chozhavendhan et al. 2020a,

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b). Hydrolysis utilizing catalysts and acids separates the cellulose into sugar that is aged to deliver ethanol (Ziolkowska 2020). The connected cycles are as follows. Anaerobic Digestion: Absorption of anaerobic includes the disintegration of natural or organic waste by microorganisms without oxygen. The cycle creates a gas made generally out of methane and carbon dioxide (CO2 ) (Chezeau and Vial 2019). Utilization of methane is to create power or warmth in much a similar way with the above depicted strategies. Maturation: Plants that are starchy are frequently utilized in the process of biochemical aging cycle for the transformation of sugars to liquor. The most widely recognized cycle is used to produce ethanol from and sugarcane and corn. Transesterification: It is a process of conversion from oil or fat to biodiesel in the presence of alcohol and catalyst and yields crude glycerol as by-product (Chozhavendhan et al. 2021). The cycle includes the expulsion of water and foreign substances from the feedstock, the blending in with liquor (normally methanol), and an impetus (like sodium hydroxide). Unsaturated fat with the creation of methyl esters and glycerin is treated as side effects in the process. The glycerin is utilized in drugs and makeup, while the esters include biodiesel, and is utilized as vehicle fuel. The denouncement of end-of-pipe technologies creates new problems accordingly the measures for prevention the way it has been emitted is treated and discharged in various ways. The alternative approach is attained by the input of huge efforts. The end-of-pipe technology includes restoration technology (Zotter 2004) that records the pollution rate that controlled the inclusion of bioenergy in the ecosystem from the past; it is a proven fact of the less polluted environment. Restoration technology requires the following perspectives: (1) polluted lands, (2) polluted river and lake, (3) space debris, (4) sediments of plastic wastes in the oceans, (5) nuclear waste, and (6) inclusion of non-indigenous species into ecosystems. The process of clean production reduces environmental burden and resource consumption. The process of redesigning in production leads to environmental gains and cost reduction on materials and resources (Rankin 2014). The tools that are applied for the purpose are available in the proceeding points: (1) Industrial systems reduce consumption on resources and waste production with the support of upcoming technologies. (2) Assessment on life cycle evaluates the entire production chain that displays the aspects of target for the improvement of environmental and resource. (3) Pinch technology displays the less involvement of resource consumption in the process of production with minimum process redundancies. The effect of such application of technologies is developed for sustainable consumption and production (Ford and Despeisse 2016). Sustainable technologies exceed the aspects of environmental technologies, but the latter deals with the production of goods and services by reducing pollution. The aim of sustainable technologies is on a broader aspect to cater to the needs of the entire humanity without the exhaustion of the non-renewable resources of the earth. It exceeds capacity of ecological recovery and the consolidation of promoting inequity. The responsibility of such technologies for enabling humanity thrives for the betterment of the survival. The

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necessary condition of sustainable technologies paves a way for the survival of human civilization.

3.9 Taxonomy of Technological Innovation Around Bioenergy Taxonomy of technological innovation was introduced by Abernathy and Clark. It projects the distinguishion between architectural, niche, incremental, and technological systems innovations (Genus and Coles 2008). Since biomass and bio-waste to energy frameworks consolidate exercises that have significant financial and ecological manageability impacts, it is significant that reasonability and effect contemplates have a financial measurement, past the technomonetary and institutional perspectives. The restricted and dispersed accessibility of biomass or its deposits follows the connections to agricultural and ranger service exercises and related financial maintainability issues like harvesting, transporting, and monetary change plant supplies. Such financial examinations, done preceding the task, mirror a great deal on the possibility of ventures, likely effects and even assistance to improve office areas, network arrangements, or armada, and the executives at different focuses or all in all the production network. When the examinations are done by and large of the venture, as effect contemplates, they show how bioenergy activities change social orders. The effect studies are able to be valuable antecedents to comparative tasks inside a similar nation/district or other comparative regions.

3.10 Optimal Utilization of Existing Innovation in Bioenergy Challenges associated with biomass coordinations, exchange, and end use are overwhelmed by moving up to normalized and more energy-thick bioenergy transporters. Advances like pelletization, torrefaction (strong items), and pyrolysis (bio-oils) assume a critical part in this regard. Such energy transporters work with the change of fossil plants to biomass for enormous scope, in this way additionally adding to the matrix strength considering the increase of variable renewable energy (RE) force creation. The expansion in the accessibility of RE force additionally opens up for mixture plants utilizing renewable energy source (RES) ability to deliver hydrogen for use in other biofuels plant or for the change of CO2 stream to biofuels or sustainable energizes contingent upon the wellspring of the CO2 . Both thermochemical and biochemical change courses are sent in the following decade to deliver biofuels like ethanol, methanol, and FT-diesel. Likewise, in thermochemical to deliver biofuels like intermediates, for example, bio-oils are created by measures like pyrolysis and with respect to high-dampness content feedstocks, by

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aqueous liquefaction (Karthiga Devi et al 2019a). Such intermediates transcendently are changed over to drop-in biofuels by treatment facility like cycles, either as a coordinated biofuel esteem chain or as a co-feed to a fossil processing plant esteem chain. Key advancements on bioenergy for the following 10 years are required to happen both by development of advances presently being exhibited or directed and by improvement of new advances that are in certain years perhaps arrive at such a phase. Some new mechanical advancements on bioenergy and biofuels are portrayed in the following areas, lined up with European Technological and Innovation Platform on Bioenergy (ETIP-Bioenergy) current worth chains for cutting-edge biofuels and warmth and force. Biomass releases carbon dioxide (CO2 ) during creation of bioenergy from carbon that courses the air in a circle through the cycle of photosynthesis and deterioration. Creation of bioenergy does not contribute additional CO2 to the environment like petroleum derivatives. Petroleum derivatives are a limited asset created through land measures more than a long period of time, and their utilization addresses a single direction stream of GHGs from underneath the world’s surface to the environment.

3.11 Implication of Bioenergy on Reducing Greenhouse Emissions The degree of GHG outflows decrease fluctuates generally and relies upon numerous elements including the biomass (feedstocks) utilized, how they are created and acquired, and the sort and proficiency of the innovation used to deliver bioenergy. By and large, GHG outflows decrease from bioenergy frameworks which the is most noteworthy where squander biomass is changed over to warm or consolidated warmth and force in present-day plants situated close to where the waste is generated. Bioenergy’s GHG decrease benefits are conceivably more prominent than those of other renewables. For instance, stubble that is bound to be scorched in the field is reaped and combusted in an emanations controlled bioenergy plant. Henceforth, GHG outflows decreases are made twice—once in the field through diminished consuming nonrenewable energy source replacement from bioenergy creation. Impressive exploration is in progress all throughout the planet to evaluate the all-out life cycle effects of different bioenergy and other sustainable power frameworks. For instance, through the International Energy Agency (IEA) Bioenergy Task 38 venture ‘Ozone harming substance Balances of Biomass and Bioenergy Systems’.

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3.12 Impact of Technology on Biofuels Technical choices for utilizing biomass energy for a huge scope are separated into two classifications: biopower and biofuels. Biofuels allude to liquid fills created from biomass, in transportation sector. Biopower alludes to power delivered from biomass which includes framework and non-grid use. It centers on biofuels, as a result of the great present degree of interest in quickly growing the utilization of biomass-based fills as an option in contrast to oil-based energizes for transport. Without a doubt, biofuels are a little however quickly developing supporter of the vehicle powers market.

3.13 Aspects of Energy and Environment in the Production of Biofuels Biomass is identified a ‘renewable’ source of energy. The term is applied in fossil fuels with other finite resources including land and water in biomass production that requires non-renewable resources. The degree in the usage of biofuel is a sustainable power source which relies upon the measure of the inputs of non-renewable energy comparative with the energy yields of the biofuel cycle. Investigators have introduced different strategies for examining. Some have utilized the balanced net energy (the energy yields of the biofuel cycle less the energy inputs); some have utilized the energy proportion (energy yields of the biofuel cycle isolated by the energy sources of info; and some have utilized the converse). Some have included the energy with the exemplifications of the co-products to the biofuel energy; others have deducted it from the energy inputs. Energy inputs change significantly among biomass alternatives inferable from the diverse farming creation frameworks and biofuel transformation measures. Life cycle inputs incorporate, for instance, fills devoured by ranch hardware in land readiness, planting, tending, water system, gathering, stockpiling, and transport; fossil feedstocks are used to deliver synthetic sources of info like herbicides, pesticides, and particularly manures (which will in general be energy serious) and energy needed for the transition of the biomass feedstock into a biofuel. Qualities of energy are by and large preferred for enduring harvests over for yearly yields, which include more noteworthy utilization of homestead apparatus and a more significant level of substance inputs. Numerous rural or ranger service build-ups are considered basically inexhaustible in light of the fact that unimportant non-renewable energy source is devoured to acquire the deposits notwithstanding what is needed to deliver the essential yield. The net energy equilibrium and carbon dioxide effects of biofuels are issues of extraordinary interest, given the developing size of their utilization as a GHG alleviation choice. The energy proportion is characterized as energy yields in biofuel and co-products separated by energy inputs.

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3.13.1 Emission of Greenhouse Gases Biofuels are consistently summoned as a significant GHG decrease alternative attributable to the case that they are zero-carbon fuel sources in light of the fact that the measure of carbon dioxide transmitted during burning is no more prominent than was ingested during the climate where the process of photosynthesis reaches its development. Inputs of different fossil energy needed to create biofuels, an intensive investigation of life cycle with the outflow of GHG, are expected to decide a given biofuel’s net environment benefits. Moreover, the GHG emanations comparing to upstream petroleum derivative utilization, a few different components of the existence cycle, are found to have the impact of positive or negative GHG: change in land use [e.g., from transformation of peatlands to palm oil manor], methane spillage [e.g., discharges from biogas frameworks and expulsions from redirected squander streams], subterranean biomass [e.g., from high-variety fields], compost use [e.g., for soybeans], biomass taking care of [e.g., from outflows emerging from chipping of backwoods build-ups with the coproduction of energy, e.g., from utilization of lignin as a fuel source in creation of cellulosic], capacity [e.g., from wood chip stockpiling], and uprooting energy coproduct [e.g., creature feed].

3.13.2 Agro-Ecological Concerns Agriculture is a land-concentrated, earth high-sway undertaking. The extension of biomass energy will fuel the malicious impacts of the horticulture area or relieve such effects which is of focal concern. At present, the transcendent biomass crops— sugarcane, maize, assault, and soybeans—are developed utilizing the concentrated techniques for current farming. Consequently, a comprehension of the likely ecological effects of increasing the creation of energy feedstock in biomass requires an appraisal of the natural exhibition of current farming strategies and of the chances for the improvement of such presentation. The principle highlights of current escalated agriculture control the yields (through hereditary qualities), of soil ripeness by means of compound preparation and water system, and of irritations (weeds, bugs, and microorganisms) by means of synthetic pesticides. Simultaneously, editing rehearses have advanced toward monocultures, serious culturing, and water system. Agriculture is as of now immensely affecting environments and their properties. Agribusiness ranges the maximum wellspring of overabundance phosphorous and nitrogen to streams and seaside regions, prompting eutrophication and nitrification of huge water bodies. The deficiency of nitrogen (as nitrous oxide) from croplands additionally contributes fundamentally to outflows of GHG. More than 40 million ha overall were assessed in 1990 to be experiencing moderate or solid salinization that addressed around one-sixth of the overall inundated cropland around then. Around 1.5 million ha of arable land and $11 billion underway are lost to salinization consistently, addressing about 1% of the worldwide

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flooded region and yearly worth of creation, individually (Machado and Serralheiro 2017). Around 40% of worldwide croplands is encountering some level of soil disintegration or diminished ripeness; horticultural botch was assessed for soil corruption on 552 million ha in 1990 that ranges 33% of the worldwide cropland (Machado and Serralheiro 2017). Monocultures lead to impacts on natural parts of environments like the vermin complex (that may turn out to be less different yet more bountiful) and soil biota; simultaneously, horticultural frameworks may affect close by or even far off biological systems. Editing and culturing rehearses likewise affect soil natural matter—change of local vegetation to cropland under concentrated plowing rehearses, for instance, adds to decrease in soil natural matter through disturbance of soil totals and expands microbial movement and disintegration. Around 1 million poisonings and 20,000 passings happen from pesticides every year through wordrelated openness among horticultural works with pesticide security being a specific issue in non-industrial nations. The drawn out impacts of pesticides are as yet not completely seen however are presently accepted to incorporate raised malignant growth dangers and disturbance of the body’s regenerative, insusceptible, endocrine, and sensory systems. Horticulture represents that an expected 70–80% of the worldwide utilization of water is comparatively high in other nations (Gornall et al. 2010). The water prerequisites related to enormous scope bioenergy harvests may build the water pressure in numerous nations. Despite the fact that it is preposterous to expect to evaluate the general expenses in monetary terms of current ‘impractical’ farming, investigations propose that these expenses are significant. On account of the USA, yearly natural and well-being costs related to agribusiness are evaluated $5.7–16.9 billion [Pimentel infers that the natural and expenses of pesticide utilize alone in US surpass $8 billion]. In the UK, the absolute yearly outer expenses and appropriations are £8.95 billion that works reach 11% expansion to the food costs paid by shoppers. Agriculture practices diminish the environmental effects of biomass creation by expanding supplement and water-use proficiency, keeping up and reestablishing soil fruitfulness, and utilizing improved techniques for infection and bug control. Such a push toward practical farming ought to be comprehensively founded on the agro-ecological standards of adjusted conditions and supported yields organically intervenes soil fruitfulness and regular vermin guideline through the plan of broadened agroecosystems and the utilization of low-input advances. Incorporated vermin the board that takes into account bug control through a wise utilization of pesticides in blend with approaches, for example, more assorted editing frameworks and designated trimming rehearses; exactness cultivating, which depends on applying supplements at the appropriate time and improved trimming rehearses, for example, polycultures, crop turn, diminished (or no) culturing, cover yields, and neglected periods that helps to sustain and reestablish soil richness. To be effective, manageable farming should be custom-made to neighborhood needs, assets, and ecologies. It will be best on the off chance that it joins conventional information and trimming rehearses with present-day methods. Indeed, manageable farming is information serious instead of information escalated. Moreover, interest in manageable agriculture for certain many years now, progress has been horrendously lethargic [as it has likewise been in maintainable ranger service]. Current motivating forces, truth

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be told, favor expansions in rural creation without giving adequate consideration to protecting environments administrations. In 1990s, an audit of the Organisation for Economic Co-operation and Development (OECD) (Cocklin and Heller 2007) involvement with the blended outcomes in securing the climate; it is difficult to gauge natural exhibition of agriculture. The development of bioenergy is always earth favorable. On account of palm oil (a biodiesel feedstock), an increase in biodiesel request was an essential supporter of deforestation and waste of peatlands in Southeast Asia—an expected 40% of the getting free from peatlands is owing to palm oil estates. Outflows (through peat oxidation just as flames) from Southeast Asian peatlands are around 2 billion tons of carbon dioxide which is about 8% of the worldwide carbon dioxide emanations from petroleum product consuming. New palm oil manors are allotted for 87% of the deforestation in Malaysia between the years 1985 and 2000. Subsequently, the enormous scope utilization of biofuels got from corn, soybeans, or sugarcane will be united with reasonable improvement just if there are sound arrangements and motivations to move away from escalated farming and toward economical horticulture (Karthiga Devi et al. 2019b). The new presentation of the idea of multifunctionality into farming arrangement conversations support advances the reason for practical horticulture by expressly perceiving that agribusiness may facilitate a few social destinations simultaneously. The ethanol cellulose course provides the possibility to utilize a more noteworthy.

3.13.3 Socioeconomic Issues Developing bioenergy markets is a great support for financial improvement in agricultural nations, catching these advantages won’t occur of course. There are two significant manners by that bioenergy meets with financial government assistance. The first identifies with the capacity for bioenergy markets to impact food markets and influence food security. The biofuels depend on food crops (corn, stick, soy, assault, palm oil), which prompts direct contest between biofuel handling offices and food-preparing offices for similar food products. The ordinary market reaction to such a circumstance is an ascent in costs. Biofuels were received from non-food crops (e.g., cellulosic feedstocks or unpalatable oils), they put an extra interest on farming assets, explicitly land and water but lead to an ascent in food costs. When the biofuel industries follow the concept of integrated biorefinery system, it has numerous benefits like self-disposal and self-clearance and develops both socioeconomically in a sustainable manner. Human beings burn through a specific greatest measure of food that places an upper bound on the interest for farming items. The development of a biofuel market accordingly acquaints an in a general sense new powerful with agrarian business sectors. With the new blast in creation of biofuel, such an ascent in food costs is surely being seen. The expanding interest for ethanol creation in the process of corn in USA has heightened the cost of corn in Mexico (dramatically increasing and

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even nearly significantly increasing in certain parts somewhere in the range of 2006 and 2007) and has prompted a tortilla emergency in that country. It is an issue past culinary or social hints since helpless Mexicans get over 40% of their protein from tortillas (Sausser 2007). There is a rise that has additionally been noted in other major biofuel feedstock markets such as sugar, rapeseed oil, palm oil, and soybean. The possibility that this is in excess of a transient impact is upheld by new projections contrasting the cost of specific staples in a forceful biofuels situations (in which 20% of transportation fills are uprooted by biofuels by 2020, incorporating cellulosic ethanol beginning in 2015) to a reference situation. The costs of sugar beets, wheat, maize, sugarcane, oilseeds, and cassava were 10%, 16%, 23%, 43%, and 54% higher, respectively, than their standard costs in 2020 (Noguiera et al. 2008). In a situation where ethanol cellulose does not get business and food crop yields remain steady at the present levels, the cost ascends for these harvests on the request for twice as extraordinary. A new investigation of the USA rural area arrived at comparable resolutions. An ascent in food costs is a blade that cuts both ways. It can profit nations and families that are net makers of food that includes the rustic helpless; such jobs are intently attached to the farming economy. The metropolitan poor—the utilization of calorie among the poor is assessed to decay by 0.5% for each 1% ascent in the cost of significant food staples. Biofuels do not have to antagonistically influence food security (David 2008). On a fundamental level, biofuels could depend on lower-quality land and not vie for prime cropland. To the extent that it increases country livelihoods on a fundamental level empowers interest in usefulness upgrades. Biofuels give energy benefits that upgrade food security, for example, food products that are transported from homesteads to business sectors. Purposeful advances are expected to guarantee that the strategy setting and market climate in which bioenergy was growing are organized to keep food security from being settled. Bioenergy meets with financial government assistance identified with its likely commitment to practical vocations. To make a considerable commitment to reasonable turn of events, bioenergy markets have to profit little ranchers in non-industrial nations. The circumstance of such gatherings has been more terrible in numerous occurrences as the costs of rural wares have shown a decrease over the long haul as well as momentary unpredictability; the decrease in food costs demands helps this gathering since they are not buyers of food. With the proceeding with decrease in costs of their items (and frequently increments in input costs), even expanded yield may in any case prompt diminished excesses, prompting what has been named as pain initiating development and a requirement for non-agricultural pay for making a decent living. Little ranchers as of now have low capital stock in essential horticulture and by not having the option to remain over the financial recharging limits; they restore ranch devices and sources of info required, prompting declining farming stock in genuine terms. Consequently, it is basic that any push to utilize bioenergy markets to advance maintainable improvement should discover approaches to incorporate this gathering. The pattern toward huge scope, in an upward direction coordinated organizations that have more prominent command over horticultural item chains, makes it hard for limited scope makers to profit with the market for rural items and bioenergy markets

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adapt the equivalent trend. Confirmation frameworks to advance maintainability may help guarantee that advantages accumulate to limited scope makers, albeit some have brought up the burdensome weight affirmation that can force on little ranchers. Farming appropriations in created nations can extraordinarily misshape the worldwide agribusiness advertises and push down ware costs—maker support in OECD nations was assessed to be 280 billion dollars in 2005 (Louis et al. 2008). Corn ethanol program of the USA adapts a similar way that is determined by corporate interests and political economy as opposed to sound science. For exchange farming wares to help helpless nations, OECD nations will be needed to end the methods of help for their agribusiness areas that collapse non-industrial nations. Viable administration of dangers brought about by bad ware value stuns with the accessibility of better market. A large portion of the worth expansion in biofuels is derived coming from the preparing of the biomass feedstock to the last biofuel (with the cost of the biofuels far-fetched to decrease a lot attributable to limits underway combined with expanding request to the cost of oil-based fills). For this situation, the costs of biomass remain generally low. Given the expanding refinement of the biochemical transformation advances for cellulosic ethanol, many non-industrial nations do not have the mechanical ability to assemble or work these plants natively, making it hard to climb the worth chain in the biofuels market [paralleling the customary rural world, where the absence of agroprocessing capacities seriously totters the profits ranchers to get from their produce]. Tax acceleration, i.e., the inconvenience of taxes with the maximum for products that have gone through more prominent handling, by created nations obstructs non-industrial nations in their endeavors to build up preparing businesses for trades at beginning. Still, probably some non-industrial nations possibly create a biofuels industry that fills in as an establishment for more extensive mechanical turn of events. The incorporation of little ranchers into a bioenergy technique does on a basic level offer an advantageous chance to propel the supportable improvement plan. It should start by zeroing in on the multifunctional idea of little ranches, which are as of now frequently very effective and useful and add to monetary improvement that supports country networks. The following suggests the qualities of bioenergy that would support the sustainability of ecosystem.

3.14 Qualities of Bioenergy . Producing the Quality of Better Air: Bioenergy fixes the advantages of air quality where biomass deposits are open consumed in the field or woods, like stubble, tree prunings, or backwoods slice, eliminated and consumed in a highlevel emanations controlled bioenergy plant.

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. The Conversion of Biofuels to Biodegradable: Oil-based fills and petrochemicals are unsafe to the climate and are significant surface and groundwater toxins. Biofuels like biodiesel and ethanol are less poisonous and are used for the purpose of biodegradable. . Bringing Employment Opportunities to Rural Economic Development: Worldwide and Australian investigations show that bioenergy makes numerous continuous positions, by and large more than most different sorts of sustainable power. Bioenergy animates territorial monetary turn of events and work by giving new, decentralized, and expanded revenue streams from bioenergy and biomass creation. It offers landholders more market choices for their conventional rural and tree crops and for the utilization of waste streams like excrements. It might likewise open up freedoms to develop new harvests, particularly on minimal or low precipitation farmland, for example Juncea for biodiesel as a low precipitation break crop. New work openings emerge from developing and reaping biomass, transport, taking care of, and through obtainment, development, activity, and support of bioenergy plants. . A Great Support to Agricultural and Food Processing Industries: Utilizing biomass supports fabricate flexibility in rural, lumber, and food-preparing businesses. Bioenergy offers utilization to their waste streams that assist them with diminishing their energy costs and conceivably add another income stream on the off chance that they can sell biomass-inferred heat or potentially trade ‘green’ power to the lattice. . Cost Savings: Utilizing the right bioenergy innovation accomplishes more noteworthy expense investment funds than utilizing petroleum products. For instance, regions that are dependent on LPG for warming (not connected to flammable gas), regions distant from, or close to the furthest limit of the force framework, subject to ‘power outages’ and ‘brownouts’ and where power transmission misfortunes and expenses to overhaul the influence supply are maximum. Utilizing waste streams to create bioenergy saves the natural and financial expenses of removal in landfills and decreases pollution chances. . Energy Reliability: Provincial and local energy dependability and security are upgraded by giving a homegrown fuel source that runs constantly, or at busy times as needed by the power market with more prominent adaptability to increase creation at short notification than huge coal-terminated plants. . Applications of Technologies in the Growth of Biomass: Biofuel and bioenergy creation interfaces with the advancement of other biotechnologies and biotechnologies. For instance, natural digestates created as a bi-result of anaerobic processing; it is utilized as a manure or soil enhancer. Biomass can create valuable synthetic substances as a feature of an incorporated biorefinery framework in petroleum treatment facility. . Environmental Benefits on Bioenergy Crops: Bioenergy yields are filled in regions that profit with the extra vegetation cover. For instance, trees are developed and reaped for their biomass from woods on ranches in setups that give ranch cover, conceal, saltiness control, biodiversity, and carbon sinks. Species, for example, Mallee eucalyptus, are generally filled in Australia and because of their capacity

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to coppice (re-shoot) are regrown to give sustainable power and other territorial and on-ranch benefits.

3.15 Conclusion Biomass remains a significant piece of the non-commercial energy field. Similarly as with other conceivably appealing environmentally friendly power sources, biomass energy has an unequivocal commitment to make to reasonable turn of events. The capacity of the source of fuel is to add the reasonable improvement plan, which, however, relies upon how it is created, changed over, and utilized. It requires a wide view that incorporates the numerous components of ecological maintainability— carbon adjusts (extensively characterized), air contamination, assets of water and soil, and biodiversity—and furthermore perceives the human and financial elements of manageability: well-being, food and energy security, and jobs. The misuse of bioenergy while taking this extensive, supportability focused view at humble scopes is simple. The genuine test comes in increasing execution with the goal that it makes a critical commitment toward fulfilling a huge segment of the neglected requirement for clean energy administrations. The different difficulties and clashes examined in this section become trickier. On account of family bioenergy, the extent of the issue remains totally gigantic. The direst concerns emerge from the government assistance and well-being effects of the work serious and profoundly dirtying nature of conventional biomass use. Along these lines, certain perfect consuming petroleum products, for example, LPG, are considered as a component of the general exertion to extend clean energy supplies instead of spotlight just on biomass-inferred supplies. Moreover, the methodology (improved cookstoves, biomass-determined or fossil-based clean energizes), giving cleaner energy to helpless families, requires deliberate endeavors and more prominent assets. One approach to produce more assets is by recognizing this present gathering’s generally minor commitments to the environment issue and investigating arrangements to repay them for sharing barometrical space to other GHG producers. On the business biofuels front, there has been a new blast in interest in industrialized and non-industrial nations. The subsequent strategy advancements have been driven by environment concerns, energy security worries, just as freedoms to profit agrarian ventures and add to rustic turn of events.

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Breeze P (2019) Biomass-based power generation. In: Power generation technologies, 3 edn, pp 315–374 Charis G, Edison M (2019) A review of the application of GIS in biomass and solid waste supply chain optimization: gaps and opportunities for developing nations. 6:96–106 Chezeau B, Christophe V (2019) Modeling and simulation of the biohydrogen production processes. In: Biohydrogen, 2nd ed, pp 445–483 Cocklin C, Heller T (2007) Sustainable development and mitigation. Clim Change Sustain 12:691– 743 Chozhavendhan S, Praveen Kumar R, Elavazhagan S, Barathiraja B, Jayakumar M, Sunita JV (2018) Utilization of crude glycerol from biodiesel industry for the production of value-added bioproducts, Chap 4. In: Waste to wealth, energy, environment, and sustainability, pp 65–82 Chozhavendhan S, Vijay Pradhap Singh M, Fransila B, Praveen Kumar R, Karthiga Devi G (2020a) A review on influencing parameters of biodiesel production and purification processes. Curr Res Green Sustain Chem 1(2):1–6 Chozhavendhan S, Rajamehala M, Karthigadevi G, Praveenkumar R, Bharathiraja B (2020b) A review on feedstock, pretreatment methods, influencing factors, production and purification processes of bio-hydrogen production. Case Stud Chem Environ Eng 2:100038 Chozhavendhan S, Rajamehala M, Karthigadevi G, Praveenkumar R, Bharathiraja B, Jayakumar M (2021) Application of nanotechnology for the sustainable development of algal biofuel industries, Chap. 19. In: Nanomaterials: application in biofuels and bioenergy production systems, pp 401–410 David TJ (2008) Food vs. fuel: diversion of crops could cause more hunger. PMC 116(6):254–257 Deitz TD, Eugene AR (1999) Effects of population and affluence on CO2 emissions. PMC 94(1):175–179 Ferranato N, Vincenzo T (2019) Waste mismanagement in developing countries: a review of global issues. PMC 16(6):1060 Ford S, Mélanie D (2016) Additive manufacturing and sustainability: an exploratory study of the advantages and challenges. J Clean Prod 137:1573–1587 Freedman B (2018) Environmental science: non renewable resources. Open Library King AA (2014) End-of-pipe treatment and waste reduction. The judgment of garbage. Manage Sci 60(7):1812–1828 Genus A, Anna-Marie C (2008) Rethinking the multi-level perspective of technological transitions. Res Policy 37(9):1436–1445 Gornall J, Betts R, Burke E, Clark R, Camp J, Willett K, Wiltshire A (2010) Implications of climate change for agricultural productivity in the early twenty-first century. PMC 365(1554):2973–2989 Karthiga Devi G, Chozhavendhan S, Bharathiraja B (2019a) Thermochemical conversion: bio-oil and syngas production, Chap. 9. In: Prospects of renewable bioprocessing in future energy systems, biofuel and biorefinery technologies, pp 251–267 Karthiga Devi G, Chozhavendhan S, Jayamuthunagai J, Bharathiraja B, Praveenkumar R (2019b) Conversion of biomass to methanol and ethanol, Chap. 4. In: Horizons in bioprocess engineering, pp 61–73 Kassio FM, Stella AC, Rodrigo FP, Valdemar LT (2018) Glucose mineralization in soils of contrasting textures under application of S-metolachlor, terbuthylazine, and mesotrione, alone and in a mixture. Soil Plant Nutr 77(1):1678 Machado RMA, Serralheiro RP (2017) Soil salinity: effect on vegetable crop growth. Management practices to prevent and mitigate soil salinization. MDPI 3(2):13–16 Noguiera LA, Horta JEAS, Leal MRLV, Poppe MK (2008) Sugarcane based bioethanol: energy for sustainable development. J Nat Sci Res 1:68–77 Nuss P, Stefan B, Kevin HG (2012) The longterm option. Waste-to-materials. 55:1–26 Oladeji JT, Itabiyi EA, Okekunle PO (2015) A comprehensive review of biomass pyrolysis as a process of renewable energy generation. J Nat Sci Res 5(5):99–106 Popp J, Lakner Z, Harangi-Rákos M, Fari M (2014) The effect of bioenergy expansion: food, energy, and environment. Renew Sustain Energ Rev 32:559–578

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Rankin J (2014) Treatise on process metallurgy: industrial processes. Sustainability 3:1376–1424 Ruttan WV (1993) Population growth, environmental change, and innovation: implications for sustainable growth in agriculture: population and land use in developing countries: report of a workshop. Natl Acad Sci Eng Med 8:124–161 Sausser B (2007) Rising corn prices are already affecting everything from the cost of tortillas in Mexico city to the cost of producing eggs in the United States. MIT Technol Rev 5:33–36 Savic D (2017) Managing diversity in the international nuclear information system. Grey J 13(1):55– 62 Song JH, Murphy RJ, Narayan R, Davies GBH (2009) Biodegradable and compostable alternatives to conventional plastics. PMC 364:2127–2139 Thompson P (2012) The agricultural ethics of biofuels: the food vs. fuel debate. MDPI 2:339–358 Ziolkowska JR (2020) Biofuels technologies: an overview of feedstocks, processes and technologies, Chap. 1. In: Biofuels for a more sustainable future, pp 1–19 Wypych, AG (2014) Fatty acid methyl esters, Chap. 3. In: Databook of green solvents, pp 135–203 Zotter ZK (2004) End-of-pipe ‘versus ‘process-integrated’ water conservation solutions a comparison of planning, implementation and operating phase. J Clean Prod 12:685–695

Chapter 4

Integrated Approaches for Economic Sustainability of Biofuel Industries S. Chozhavendhan, G. Karthigadevi, R. Praveen Kumar, D. Karthiga, and A. Magesh

Abstract A modern bioenergy application is a low-carbon energy source and ecofriendly in the conversion of the biomass into bioenergy. The depletion and oscillating prices of fossil fuels greenhouse effect led the researchers to reach the transition from traditional bioenergy to modern bioenergy applications. Bioenergy, especially biofuels economy, is dependent on market supply and demand. The implementation of zero-wastage liquid discharge from the bio-based industries addresses valorization of biomass effectively for the production of other high-value products. In this perspective, the integrated approaches for sustainable development and bio-economic development with the exploration of biomass for biofuel production were assessed. The integrated biorefinery aims at achieving sustainability in energy, economic and environmental aspects with the production of energy and reducing greenhouse gas emissions. This chapter focused on how the production of bioenergy and bioproducts from the biomass feedstock under biorefinery model plays an instrumental role in the development of the technological and socioeconomic aspects. Assessment of circular economy, bioeconomy under green economy with various assessment indicators led to the production of greener products and long-term sustained economic development of biofuel industries. Keywords Biorefinery · Circular economy · Green economy · Sustainable development · Bioenergy S. Chozhavendhan (B) Vivekanandha College of Engineering for Women, Tiruchengode, Tamil Nadu, India e-mail: [email protected] G. Karthigadevi Sri Venkateswara College of Engineering, Chennai, Tamil Nadu, India R. Praveen Kumar Arunai Engineering College, Tiruvannamalai, Tamil Nadu, India D. Karthiga V.S.B. Engineering College, Karur, Tamil Nadu, India A. Magesh Department of Chemical Engineering, Annamalai University, Chidambaram, Tamil Nadu, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_4

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4.1 Introduction The uncontrolled population growth and rapid urbanization and industrialization created an exponential demand for non-renewable energy resources (Khalil et al. 2019; Yi et al. 2018). This scenario is expected to be worse in the future since the human inhabitants are projected to increase up to 5 billion by 2050 (Abdul et al. 2018). Similarly, energy consumption is also expected to increase nearly by 50% due to the promising developing nations like India, China, Brazil and other nations. Currently, fossil fuels are commonly used fuel sources and further rising population. The depletion of fossil fuels triggers the common universal ecological issues like greenhouse gas emission and local and regional degradation of air quality. The life form of earth with health threat is persistently looked at and that led the researchers to explore novel sustainable clean energy resources (Shariat et al. 2020; Chozhavendhan et al. 2020). Non-sustainable energy sources are being substituted with 53 forms of sustainable renewable energy for human mankind such as geothermal, marine, solar, hydropower, wind, biomass-derived energies as per the global energy statistics energy book 2020 (Rincon et al. 2019). Among the various renewable source of energy derived from the biomass is considered as bioenergy that is environmentally renewable sustainable energy source which is further used to produce electricity, transportation fuel heat and other products (Karthiga Devi et al. 2019a; Vaez and Zilouei 2020). As per the global energy statistics in 2020, the utilization of renewable energy is increased around 1% when compared with the previous year. The International Energy Agency (IEA) has set a goal for biofuel to contribute 25% of worldwide transportation by 2050 (Pandey et al. 2016). Many of the energy policymakers also set a goal with the strategic expansion in green technology to maximize the utilization of renewable energy. The approach toward socioeconomic development identifying appropriate and sustainable energy sources lead to decrease the reliance on fossil fuels and take the edge off the carbon dioxide emission (Aziz and Hanafiah 2020).

4.1.1 Bioenergy Bioenergy is a versatile renewable energy source and the oldest among all possible biomass exploitation technologies that can be converted into bioenergy. Biomass is a natural, renewable carbon source derived from either live or dead organism as chemical energy in it (Karthiga Devi et al. 2019b). Sometimes biomass can also be referred to as a wide range of energy crops, residues and other biological resources that generate diverse renewable energy. In traditional, the bioenergy implies the utilization of solid waste for the generation of heat; however, the modern bioenergy was commonly defined by three products, namely bioethanol, biodiesel and biogas. Based on the feedstock used, the biomass is transformed into gaseous energy carriers through direct combustion, thermochemical or biochemical transformation (Perna et al. 2018). Bioenergy is classified as solid bioenergy, liquid bioenergy and

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gas bioenergy based on the final product. The other recovery process in addition to bioenergy production involves waste volume reduction, waste disposal management and minimizing land utilization for discarding the waste. The increased usage of bioenergy may help in stabilizing supply security and reduces the dependence on fossil fuels and decreases the levels of greenhouse gasses that reduce the dangerous atmospheric concentration and mitigating climate change (EC 2018). The conversion of biomass to bioenergy, the biomass composition varies accordingly (variation in biomass species, geographical location and crop growing condition). The lignocelluloses, forestry municipal waste, algal biomass and animal waste are generally reported as biomass (Rathankumar et al. 2020). However, introduction of the biorefinery approach helps the biomass valorization for the effective production of bioenergy and other bioproducts. Thus, it strives to reduce the waste and reuse the waste acquired after recycling for the effective production of bioenergy with zero waste liquid discharges (Taylor 2008). Food and pharmaceutical compounds, platform chemicals, polymers, biofuel and bioenergy are examples of bio-based products that can be coproduced in a multi-process industrial plant called biorefinery.

4.2 Biorefineries Biorefineries are promising industrial system which aims at the sustainable and nifty deployment of biomass that delivers various useful bioenergy and bioproducts (Budzianowski 2017). The concept of biorefining is to increase the attention for its integral process to achieve sustainable future economy. National Renewable Energy Laboratory (NREL) states that a biorefinery is a facility that integrates the biomass conversion processes and equipment to produce fuels, power and chemicals from biomass (NREL 2015), and the International Energy Agency (IEA) states biorefinery is the sustainable processing of biomass into a spectrum of marketable products (food, feed, materials, chemicals) and energy (fuels, power, heat) (IEA 2014). The biorefinery concept emphasizes the utilization of renewable biomass for the production of bioenergy and biochemicals (Mahmoud and Shuhaimi 2013). In general, the biorefinery approach involves a multistep process that usually involves the screening and processing of biomass as initial process. The second step comprises pretreatment and saccharification process, involving the extraction of fermentable sugar from biomass. The last and final stage involves the biological or chemical treatment of the reducing sugar for the synthesis of bioenergy products (Hazeena et al. 2019). In particular, biorefinery plays a vital role in bioeconomy in which renewable and bio-based materials replaces fossil products (Sauvee and Viaggi 2016). Biorefinery has the potential to offer sustainability and conquers several markets replacing a current fossil fuel-based industry that acts as a bridge between triple bottom line standards and adequate interaction with the complete value chain including environmental, social and economic (Budzianowski and Postawa 2016). The development of bioenergy, biorefinery and bioeconomy contributes to national socioeconomic growth.

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4.3 Types of Biorefineries The integrated biorefinery model is initiated for the effective usage of biomass including the waste or byproduct generated in various conversion pathways; it converts them in high-value products. Various feedstocks like lignocelluloses, algae, industrial waste and organic fraction of municipal waste are utilized in the biorefinery concept. The biorefineries comprise a range of transfer technologies like biological, biochemical, thermochemical process that are integrated competently to produce sustainable bio-based merchandise streams such as bioenergy, biofuels, biochemicals and more high-value bioproducts (Cherubini 2010). The biorefineries are generally distinguished into two broad groups based on biomass and chemical nature on biomass.

4.3.1 Biomass-Based Model On the basis of the usage of biomass, it is classified further into Phase I, Phase II and Phase III biorefineries. The Phase I biorefinery utilizes a single feed to produce a single product and has fixed processing. For example, the phase I biorefineries produce bioethanol and other feed product from corn grain (Kamm and Kamm 2004). Phase II is analogous to Phase I and can produce products from the single feedstock that has more processing flexibility. The products like corn oil, ethanol and high fructose corn syrup are produced from corn. Phase III is an advanced model and uses various types of feedstock to produce numerous products employing a choice of combination technologies. This model produced high-value chemicals along with the co-production of ethanol. It follows the principle of high-value low-volume (HVLV) and low-value high-volume (LVHV) products utilizing a series of technologies. Further, Phase III is classified into four types as (i) whole crop biorefinery, (ii) green refinery, (iii) lignocelluloses biorefinery and (iv) two platform concept biorefinery. (i) Whole crop biorefinery uses whole crop as a raw material to attain useful goods. Raw materials such as wheat, rye and maize are used as biomass and converted into bioenergy by various processes. (ii) Green biorefinery is a multi-product system that uses green feedstock like grass, green plants. The green biomass contains nutrient-rich green juice and fiber-rich press cake. The green juice contains protein, amino acids, dyes, enzymes, etc. The press cake contains cellulose, starch, pigment and other organics which are used for chemical’s production like levulinic acid and the production of synthetic fuels. (iii) Lignocelluloses biorefinery feedstock consists of dry biomass as a major feedstock and would generate fuels, chemicals, biomaterials and bioenergy.

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(iv) Two platform concept biorefinery consists of sugar and syngas platform and uses several conversion technologies to reduce the overall cost; it has more flexibility in product generation.

4.3.2 Based on the Chemical Nature of Biomass The biorefinery models are further distinguished based on chemical nature and compositions of the feedstocks are as follows: (i) Triglyceride biorefinery utilizes vegetable oil, animal fat, algal oil and waste cooking oil as a feedstock for biofuel production. The triglycerides are converted into biofuel in the presence of alcohol and catalyst via the transesterification process and produce glycerol as byproduct (Chozhavendhan et al. 2015). (ii) Sugar and starchy biorefinery well-developed industrial fermentation technologies for ethanol production. The feedstocks like sugar beet, corn, maize are reduced to monomers to produce ethanol (Demirbas and Demirbas 2011). (iii) Lignocellulosic biorefinery includes wood, straw, grasses, etc., to produce a broad spectrum of products by utilizing various advanced technologies.

4.4 Lignocellulosic Biorefinery Lignocellulosic biomass is popularly known as second-generation feedstock and generally acknowledged as plant-based biomass and eliminates the potential competition with edible crops (Ma et al. 2019). Lignocelluloses generally composed of three polymers, namely cellulose (35–50 wt%), hemicelluloses (20–35 wt%) and lignin (10–25 wt%). The abundant presence of C6 (cellulose) and C5 (hemicelluloses) in the lignocelluloses materials made it utilized in the biorefinery industries. Lignin acts as a protective sheet and as an effective precursor for several extraction processes of C6 and C5 compounds to produce value-added products (Ubando et al. 2020). Lignin will also inhibit microbial growth and mask the availability of C6 and C5 compounds during a fermentation process. Hence, the lignin should be digested by either chemical or enzymatic hydrolysis for the effective utilization and conversion of polymeric carbon sugar into simple monomeric sugar. To capitalize on, complete utilization of lignocelluloses biomass material, numerous technologies of biorefinery concept is adopted for the generation of biofuels and multiple products with zero waste discharge. Various technologies like milling, grinding, chemical hydrolysis (acid or alkali), biological hydrolysis (enzyme or whole cell), ionic liquid extraction, ultrasonication, microwave irradiation are used for biomass decomposition (Faba et al. 2015). For the liberation of glucose from cellulose, hemicelluloses pretreatment is carried out to release hemicelluloses from lignin and cellulose and followed by breakage of β

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(1–4) glycosidic linkages from cellulose. The C6 and C5 compounds have numerous applications. The hydrolysis of cellulose to glucose produces ample useful products like biofuels (ethanol, butonal) and other biological products (acetic acid, succinic acid) by a microbial fermentation process. The xylose from hemicelluloses can be converted into furfural an important starting material for nylon (Kamm and Kamm 2004). Otherwise, cellulose and hemicelluloses undergo thermochemical process like pyrolysis, gasification or liquefaction for the energy products, and the waste is converted into activated carbon, biochar (Foong et al. 2020). If Lignin is isolated efficiently in an economical way, it has a significant perspective to produce a wide variety of monoaromatic hydrocarbons and restricted usage of fuel in the direct incineration process. The use of cellulose, hemicelluloses and lignin could significantly add value to the lignocelluloses refinery process.

4.5 Microalgae/Triglyceride Biorefinery Microalgae are the simplest photosynthetic living organism in an aquatic environment and are capable of converting CO2 and H2 O into biomass in the presence of sunlight (Ozkurt 2009; Chozhavendhan et al. 2021). The biological inert matrix for microalgal cell structure used to store high energy molecule incorporating solar energy and carbon sequestration mechanism to produce high-value products from the biomass. Algal biomass is renewable, non-toxic, cheap and generally considered as third-generation biomass for the production of carbon–neutral biofuel providing more productivity and yield when compared with lignocelluloses biomass. Various factors like light intensity, temperature, pH, nutrients, salinity influence the growth of microalgae. Microalgae are able to grow in wastewater, freshwater with various nutritional modes (Devi et al. 2013; Chandra et al. 2014). The expansion of microalgaebased biorefinery assists the high-value bioproducts production from seaweeds (Ingle et al. 2018). Various biorefinery pathways are proposed using microalgae as biomass and are converted to produce numerous value-added products like biofuels and biochemical sustainably (Chew et al. 2017). Thus, the photosynthetic organism provides a sustainable life for mankind through the development in multi-dimensions of biofuel and renewable energy province. Biofuel production from the algae requires implementation of an enormous integrated upstream and downstream process. Introducing the integrated biorefinery conception of utilization is wastewater for the growth of algal biomass that reduces the enduring waste components; it leads to sustainable economic growth. Besides, algae produce biodiesel, bioethanol, biobutanol, biogas, biohydrogen and other bioenergy products through the process of different conversion (Wirth et al. 2018; Nagarajan et al. 2020). The biomass derived from algae is converted into biofuels via thermochemical, biochemical, transesterification and photosynthetic microbial fuel cell process. Thermochemical conversion technologies employ thermal energy and involves in the conversion of algal biomass for the synthesis of bio-oil and biochar which are further transformed into biofuels via chemical or biological routes

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(Rastogi et al. 2018). In the biochemical route, enzymes are used for the hydrolysis of biomass for obtaining glucose-based carbohydrates for bioethanol production. In biochemical process, the residual biomass (deoiled cake) is subjected to anaerobic digestion for the generation of methane and biohydrogen. The extracted lipids from microalgae are converted into biodiesel via transesterification process in the presence of alcohol and catalyst; it produces more versatile glycerol as byproduct (Chozhavendhan et al. 2018). The high-value byproducts are preferred to support the main process economically.

4.5.1 Other Valuable Products from Microalgae Biorefinery Microalgae are capable of fixing CO2 and help to maintain the atmospheric equilibrium. They can grow in a variety of water bodies and produces numerous amounts of valuable economic compounds like pigment, lipids, protein, carbohydrates, vitamins and fine chemicals for cosmetics and pharmaceutical industries (Zhang et al. 2016). The biorefinery approaches that exploit intracellular compounds and metabolites have gained renewed interest due to their high market value (Chew et al. 2017). The multi-dimensional utilization of microalgae for the production of various products is depicted in Fig. 4.1. The photosynthetic activity of microalgae results in pigments like chlorophylls, carotenoids and phycoblins. These pigments have high nutritional and bioactive value which is used as a natural colorant in food industries. They also possess antioxidants, anti-aging anti-inflammatory properties (Begum et al. 2016). Apart from pigments, the algal biomass possesses compound like protein, vitamins and polyunsaturated fatty acids. The high concentration of protein contains all essential amino acid, and they also hold a massive amount of omega-3 fatty acids content. The presence of other intracellular compound suggests the algal biomass as a food and feed additive for human and animal. An alga in feed increases the metabolism, guts function, weight and reduces the cholesterol level. The addition of microalgae into poultry feed replaces 5–10% of conventional protein and helps to improve the quality of meat and egg without causing any negative effect (Ledda et al. 2016). Microalgae have widely used in wastewater (agro-industrial, urban/domestic and others) treatment to remove the organic matter providing oxygen to the bacteria. The wastewater is then transformed into suitable biomass for bioenergy, bio-based product production within the economic framework (Taelman et al. 2015). The polyhydorxybutyrate (PHB) an intermediate ingredient of bioplastics falls in the category of polymer class and is produced from microalgae. The bioplastics produced from microalgae are more eco-friendly and biodegradable when compared to conventional plastics (Chozhavendhan et al. 2016a). The microalgae are used as effective biomass under an integrated biorefinery approach through techno-economic assessment and life cycle analysis. The production of low-value biofuels needs to be coupled with the production of high-value products which could make the economic sustainability of bio-based industries.

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Fig. 4.1 Multi-dimensional utilization of microalgae for the production of various products

4.5.2 Utilization of Crude Glycerol for Integrated Biorefinery Concept Transesterification of triglycerides (lipids extracted from algae) in the presence of alcohol and catalyst yields biodiesel and crude glycerol as byproduct. During the transesterification process, 10:1 ratio of biodiesel and crude glycerol are produced (Chozhavendhan et al. 2018). Crude glycerol is generally viscous, alkaline pH and consists of a copious amount of impurities like water, soap, ash and methanol. Glycerol is a versatile compound and used as a sole carbon source by many organisms for the production of high-value products like ethanol, 1,3 propanediol, succinic acid, dihydroxyacetone, acetic acid, etc. (Chozhavendhan et al. 2016b). It includes the applications such as plasticizer, lubricants in softening yarn and fabrics of textiles industries and as a major ingredient in toothpaste. Apart from this application, crude glycerol is used at low concentration for broiler and pig feed. Crude glycerol is sometimes used as an alternate for boiler fuel or thermal energy cogeneration due to its high energy content (McLea et al. 2011). Utilization of crude glycerol under integrated biorefinery concept is displayed in Fig. 4.2. The application of integrated biorefinery concepts made the biofuel industries to enjoy numerous benefits like zero liquid discharge, self-clearance, avoid the risk of contamination. The deployment of inexpensive crude glycerol from biofuel industries of microalgae provides an opportunity for the extensive production of high-value platform chemical products and thus provides a building block for biorefinery.

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Fig. 4.2 Utilization of crude glycerol under integrated biorefinery concept

4.6 Challenges in Establishing Biofuel Industries The main challenges involved in biofuel industries involve in the conversion of the technology from the lab level to industrial levels. Well-defined research and development set up with proper technical support shows good improvement in product separation and recovery rate (Karthiga Devi et al. 2019c). The uniformly accepted technologies across the regions of the same nation were also failed due to diverse climatic zones and produce a different quality and quantity feedstock (Mal et al. 2016). The geographic aspects of biomass also pose a vital dilemma in a regular practice of identifying the source, source collection, transport; storage of collected materials has a direct influence on effective utilization of feedstocks for the production of bioproducts. Temmes and Peck (2019) stated that still there is a colossal space between the exception and genuine recital of biofuel industries. The other major issue associated with the development of biofuel industries exacerbates the water scarcity level which put additional pressure on water demand. The demand for more lands to the non-food crops will also create a negative impact on the natural habitat, biodiversity (Nicolae et al. 2015). The increased demand for biomass and bioproducts will create a question about food security and create impacts on the prices of food materials. The lack of proper framework and strong law enforcement on land enforcement can bring a negative impact on the environment, agriculture and forest management (Budzianowski 2017). The policy framework and incentive systems should be associated with the comprehensive scientific outcome and concerned with strong mutual relationship among stakeholders, local and national government and nongovernment agencies and private companies (Aristotle et al. 2020). The developments of technoeconomic (TE) modeling enable to realize the cost-competitive for the biomass. The initiative budget planning for biofuel production and commercialization is achieved

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by TE modeling through the various integrated biochemical conversion processes or catalytic conversion of biomass to bioproducts. In the end, the assessment model should try to use the real data and avoid the uncertainties or assumption data for the evaluation process of biofuel industry setup. Apart from all strong leadership, long-term consistent policies and strategies only attract investors to invest in the quite risky domain of the bioenergy sector.

4.7 Economic Development Biofuel Industries The evolution of new ideas and innovative technologies is a great support for the market expansion of biofuel industries that lead to the satisfaction of the consumers of a growing society. Thus, the transformation of industries into more stable economically and environment is friendly (Rosales-Calderon and Arante 2019; Lourdes et al. 2021). For the economic development of biofuel industries, it is mandatory to widen the usage of renewable biomass to the core for the replacement of fossil fuels. The renewable bioresources should be cheap and available locally throughout the year to minimize the product cost. The few common feedstocks are agricultural residues and industrial waste and organic fractions of municipal waste. These effective feedstocks are converted into biofuel and other value-added platforms chemicals to enhance economic feasibility and sustainability via integrated biorefinery concepts (Zhao and Liu 2019). According to Hilbert (2015), economic sustainable development of biofuel industries is achieved via the integrated biorefinery concept. In his study on the biomass conversion, pyramid model, bioenergy and biofuel are placed in the base of the pyramid. This indicates the bioenergies and biofuels are produced from the biomass in large volume, and hence, low-value products are placed at the base of the pyramid. Moving up to the pyramid, the human and animal feed are placed as it requires the few treatment technologies in process input to give the nutritious product (p63—Chiesa and Gnansounou 2011). Higher in the pyramid has the biomaterials especially some of the biopharmaceuticals, biocosmetics and bionutrients has high market value and relatively produced in low quantities. This product requires unique and advanced technologies and thus increases the value of the product (Shikinaka et al. 2020). Finally, the promising high-value bioproducts like phytochemicals, nutraceutics and plant and animal extracts are placed at the pyramid top because of their supply and demand in the market. Pyramid biomass conversion into energy and bio-based products are depicted in Fig. 4.3. The specific nature of biomass and the specific facilities and their performance with ample amalgamation help to develop a high-value chain including, environmental and social dimensions (Budzianowski and Postawa 2016). The high-volume biofuels and low-volume bioproducts are economically transported for longer distances with comfortable prices. Hence, integrated understanding of innovations in industrial sectors are considered right from the flow of biomass to bioproducts production processes for modern bioeconomy development aspirations (Rama Mohan 2016).

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Fig. 4.3 Pyramid biomass conversion into energy and bio-based products

For the zero waste initiative and to maximize the economic status of bioenergy sector, the byproducts produced from the primary processes are processed further to produce other value-added products and finally using them as manure for the least value product (Dahiya et al. 2018). To improve the economic viability and effective utilization of resource in biofuel industries are achieved adopting various approaches as follows. (i) (ii) (iii) (iv)

Selection of renewable biomass for high-value product generation Production of HVLV products Business development of biorefineries Employing integrated biorefineries concepts for the production high-value bioproducts simultaneously with biofuels.

4.8 Circular Economy, Bioeconomy and Green Economy The integrated biorefinery has the competence to integrate a variety of biomass transformation process to produce power, fuels and chemicals. The refineries models are shaped by the following input features like feedstock, process technologies, intermediate/value-added co-product and the desired high-value products (Luguel 2011). In the past two decades, sustainability played a key role in political agendas

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and has strong impacts on ecological, economical and societal developmental goals (D’Amato et al. 2017). Sustainability concepts are projected in various aspects, and among them, three concepts are mainstreamed globally such as circular economy (CE), Bioeconomy (BE) and green economy (GE) (Murray et al. 2017). The three concepts are aimed at transforming the existing conventional economy into a more sustainable one (Szekacs 2017). CE, BE and GE as input and interconnected concepts in sustainable development are discussed in Table 4.1. The CE or Circular Economy Biorefinery is very clear and has gained evident attention of all researchers throughout the globe by the number of papers published in the journal in the last two decades. The CE professed the concept of sustainability on transforming the industrial waste discharge as a feedstock/substrate for another value-added product production. This concept can enhance the consumption of resource and recovery with the goal of zero waste discharge (Stegmann et al. Table 4.1 CE, BE and GE input and interconnected emerging concepts in sustainable development Sustainable concepts/ indicators

Circular economy

Bio-economy

Green economy

Definition

Circularity of economy practices to a sustainable production system

Achieving sustainable bioeconomy development by bio-based substituent as industrial input and output

Nature-based solution for green economy progress

Environmental

Recycling/ reuse, efficiency, industrial cooperation

Provides biosecurity by utilizing renewable resources

Conservation of land, water biodiversity and food security

Social

Sustainable economic development and utilization

Rural policies and application in health sciences

Sustainable development—Green investments and development in education, employment and tourism

Industrial

Production of multiple products with zero waste discharge

Production of eco-friendly products

Reduction in carbon emission, GHG and increasing green investment

Overlaps

Industrial efficiency with BE and resource efficiency with GE

Industrial efficiency with Resource efficiency with CE CE and territorial resilience and territorial resilience with with GE BE

Divergence

Resource centered

Resource centered

Conservation and restoration of a natural process

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2020). CE is predominately known for how resources are used. After analyzing, various definitions for CE Kirchherr et al. (2017) reported that CE was adequately linked with reducing, reusing and recycling actions. CE is considered to be opposite to linear economy executing zero effect to the environment and also address the social and environmental concerns (Giampietro 2019). CE, for instance, reduces the waste and utilizes the renewable resource via chemical, biological or biochemical process for the production of value-added chemicals. Besides, CE provides a remedy for improving the economic position of the bio-based industries with closed loops. The benefit of the CE includes improved usage of resource and eco-efficiency, lower GHG emissions and valorization of agro-based waste materials. Hence, CE show signs on developing sustainable and greener environment potentially (Venkata Mohan et al. 2016). The bioeconomy (BC) has gained its attention in later 2000. BE promises to reduce climate change and creates the economic upliftment of rural people providing the employment. BE is defined as the utilization of different biological renewable sources for food, feed, biochemicals and bioenergies production. The BE biorefineries have received more attention because of its approach toward waste management. Bioprocessing waste resources and conversion of biomass to produce biomaterials and biofuels could prevent the depletion of natural resources and fossil fuels (Mishra et al. 2019). BE brings the industries close to the environment by encouraging the utilization of renewable resources and quickly reaches the limit of sustainability. Uniting the CE and BE was termed as Circular Bioeconomic (CBE). CBE adopts the closed framework of CE and applies the concept of sustainability and economic viability utilizing the raw materials for high-value products. Introducing the circular bioeconomy into biorefinery facilitates the efficient utilization of waste resources and produces multiple value-added products and biofuels. The main concept of CBE is eliminating the usage of toxic chemicals and utilization of renewable energy through proper design in all steps in the business model (Carus and Dammer 2018). CE and BE are involved in mobilizing the resources and increases yield through recycling and reducing the end uses of renewable sources. In general, BE principles will transform the chemical industries into bio-based industries with the available feedstock from agricultural biomass. The feedstocks are readily converted into biofuels and chemicals which generate chain connectivity between the biomass production site and industrial center. The innovation and market expansion in turn will create a new challenge for thrust for the researchers and offers new potential opportunities to the manufacturing industries. Green economy includes independent development, sustainable, resilient and low carbon development and preservation of biodiversity for the next generation (Cooper et al. 2019). The concept of GE is to bring together environmental conservation and eradicate poverty with the establishment of many policy agendas linked to weak sustainability in terms of energy and pollution. The GE concepts and frameworks must coexist, overlaps, divergences, limits with other sustainable concepts like CE and BE (D’Amato et al. 2017). GE includes the idea of utilizing the renewable biomass resource efficiently and results in envision green growth investing to promote restoration, conservation and sustainable management. United National

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Environmental Protection (UNEP) stated that GE outcomes in improving human comfort by appreciable plummeting the environmental risk and ecological shortage (Georgeson et al. 2017). CE and BE are resource-oriented and whereas GE refers to a range of biodiversity processes and encourages conservation and restoration of natural process at the regional level developing eco-tourism, education and enterprises. For the measurement of GE toward sustainability of biofuel industries, many indicators are required. Most prominently, the economic measurement of GE has the potential to measure the green transformation and its activities toward the environment–economy–society interactions. Loiseau et al. (2016) reported that CE and BE are allied to GE. All three concepts largely clinch the scheme of current economic improvement into a sustainable one.

4.9 Sustainability Assessment of Biorefineries Biorefineries need to be stable, cheap source or no cost biomass residues for the production of various bioenergies and bioproducts to meet the existing demands without increasing the greenhouse gas emission, impact on biodiversity, water usage and land utilization (Van Dael et al. 2014). A lot of attempts are made to create a uniform technology that should stimulate regional and rural economic development but were failed due to various climatic zones and quantity and quality diversification in biomass feedstock materials (Richa et al. 2020). The greatest challenges in the sustainability of the biorefineries are applied for the integration of the technologies and to inflate the horizons to integrate the bioprocesses and biological systems across the waste management system. Biomass valorization helps to enrich the value of biomass wherein the utilization of biomass in biorefinery is limited by the quality and quantity of biomass and conversion technologies (Cardoen et al. 2015). Further, Liu et al. (2019) suggested high conversion yields with minimum cost for the co-product production, and separations are the fundamental requisite for the accomplishment of biomass valorization in biorefineries at the techno-economic level. Similarly, Hemalatha et al. (2019) proposed that the processing and circular cascading of valorization of biomass at all stages is achieved by self-sustainable biorefinery model. Understanding the innovation and bringing together different technologies to fit in will bring favorable economic growth and sustainable industrial development. For the sustainable development of bio-based industries and the modern drive bioeconomy objective, it is forced to understand the value of materials and waste resource management (Rama Mohan 2016). The performance of biorefinery was earlier evaluated by economic value and now exclusively analyzed with either economic or environmental or with the combination of both. Nowadays, the sustainability of biorefineries is assessed by the triple bottom line framework consists of environmental, economic and social aspects (Tuazon et al. 2013). Many research and suggestion revealed the sustainability concern of incorporated biorefineries with their strength and weakness following the triple bottom line. The outcomes exposed that biofuel production preferentially reduced GHG emission

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and has favorable impact on the rural community on by providing job. However, operational and investment cost is the major barrier along with the biomass availability (Liew et al. 2014). Hence, multi-product integrated biorefineries can adapt immediately to the market fluctuations and are more stable when compared to single product biorefineries (Cheali et al. 2015). In the biorefinery concept, the biofuel industries/ bio-based industries can enjoy numerous benefits like zero liquid discharge, eliminating the risk of contamination and allowing the industries to produce a gamut of high-value platform chemicals (Chozhavendhan et al. 2019).

4.10 Verification of Sustainable Development The development and utilization of biofuels reduce environmental pollution and significant improvement in the economic level. Bioenergy provides the energy security and economic development of the country. The National Renewable Energy Laboratory (NREL), USA, stated that the usage of biodiesel instead of fossil fuels helps to reduce 90% of the air pollution. They also stated that blending 20% of biodiesel with fossil fuel helps to reduce 20–40% of air pollution (Repo et al. 2015). Every nation in the world has its own agencies and policy decision for the sustainable development of bioenergy and bioeconomy. Renewable Energy Directive (RED) was established in 2009 with the target of contributing 20% of renewable energy to the total energy supply in the European Union with at least 10% in the transportation sector. In 2018, the revised Renewable Energy Directive (RED II) sets the target of using 32% renewable bioenergy to the total energy consumption with 14% in the transportation sector before 2030 (EU 2018). RED II proposes an effectual sustainability criterion to respond to the sustainability concerns and provides good recommendations based on the practices of policymakers, certification bodies, voluntary scheme owners and auditors involved in the sustainable development criteria of bioenergy for the long-term process (Mai-Moulin et al. 2021). The Government of India also continuously launches many programs like nationalized Policy on Biofuels, New National Biogas and Organic Manure Program (NMBOMP) to resolves future energy challenges. Dissemination of bioenergy resources, biomass, technologies and policies connected to biofuels in government web portal are very useful to educate the stakeholders of bioenergy sector. Some indicators are used to examine various overlaps between the environmental and socioeconomic impacts for the sustainable development (Diaz-Chavez 2011). The indicators are used to evaluate local and national concert and progress in the public issue, revenue, education, health and well-being. The indicators are useful to monitor the development over time; progress is in standard level or per certification scheme, with qualitative and quantitative data, etc. The first indicator is basic information which provides backdrop information of the preferred studies and next the socioeconomic indicators provide influences raised by the bioenergy crop production and various chain processes to produce biofuel. The

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final environmental indicators refer to the biodiversity impacts concerned with the socioeconomic uniqueness of the community. The Round table on Sustainable Biomaterials expands its compass in 2013 to cover biomaterials (liquid biofuel and biomass for biogas generation) and bio-based compounds (biochemicals). The sustainability requirement should address all criteria for diverse uses of biomass which includes foodstuff, feed, chemical, biofuels, bioenergy and biomaterials (RSB 2014). The sustainability standard is achieved through enforcement of strong sustainability criteria, strict requirements in structure and mode of operation in certification systems and verification practices (Nicolae and Jean-Francois 2011).

4.11 Socioeconomic Framework Analysis The socioeconomic analysis (SEA) is liable and more complicated for observing and measuring as it requires more survey, intensive studies, exclusive and timeconsuming process. The socioeconomic analysis is examined to investigate a meticulous social phenomenon of the entire society. The SEA studies exploit to assess the local, regional and national allegation in state of affairs to economic indicators like employment and pecuniary gains. Over the period of time, the development has made in the qualitative and quantitative analysis within the standard or certification scheme on the supply chain) from the feedstock production to conversion into bioproducts. Biomass utilization, biofuel technologies and their market vary considerably from country to country. This analysis clearly illustrates that the use of biofuel is significantly increased its share in the total energy supply. In nature, the socioeconomic impacts on biofuel will be diverse because of technology, confined economic structure and social profile and production processes. Hasenheit et al. (2016) also stated that the socioeconomic analysis is not only restricted to the production of biofuel but also extend the farms where the feedstocks are cultivated. The biomass production from agricultural waste provides economic autonomy and additional activity to the local farmers which help them for sustainable development both economically and energetically (Edouard and Donatien 2018). The evaluation of socioeconomic analysis of the rural or regional biorefinery is also integrated with the life cycle assessment (LCA) of the feedstock. The LCA mainly comprises life cycle inventory, impact assessment, goal, scope and validation of outcomes. LCA method employs for determining environmental issues in the product life cycle including the assessment of feedstocks and its challenges in the analysis (Nizami et al. 2017). Thus, aims at in identifying the opportunities for the improvement of biofuel industries under the integrated biorefinery concept. The makeover of the existing industrial production process into a bio-based product with the help of biotechnological techniques and integrated biorefinery concept will widen the market of bio-based product. The growth and economic development of biofuel industries depend on the capacity how much it replaces the fossil fuels and

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the competitive product cost of bioproducts with lesser GHG emissions. The potential socioeconomic benefits by the development of biofuel industries are numerous and few of them are listed as follows: (i) development of rural infrastructure, (ii) creating new employment opportunities, (iii) expansion of rural market, (iv) increase in productivity, (v) eradication of poverty and (vi) improvement in skill acquisition and literacy level.

4.12 Conclusion The depletion of fossil fuels and the detrimental effects like increasing GHG, environmental pollution made the researchers to work on renewable and sustainable energy. Bioenergy provides the energy security and economic development of the country. Production of numerous products from cheap, renewable biomass leads to the development of a holistic biorefinery model. Implementation of waste to energy in biorefinery concept introduces zero liquid discharge, which avoids the risk of environmental pollution and legal sanctions. For the sustainable development of bioenergy in general, 5% of biomass should yield 1.5 fold increases in profitability. The integrated biorefinery model should extend the maximum utilization of biomass from any source and produces numerous products like biofuel, bioethanol, biogas and other valuable biochemical products used in various food, cosmetics and pharmaceutical industries. The development and implementation of various strategic plan help to proliferate the economic sustainable development of biofuel industries under integrated biorefinery roof. The bioeconomy development represents reducing GHD footprints and resolves the environmental problems and food security. The integration of CBE in biorefinery addresses several environmental problems and constitutes economic sustainable development with high energy restoration. For the long-term sustainable development of biofuel, biorefineries should possess a good infrastructure and adopt various technologies for source segregation, process development and production of multiple value-added products from single biomass.

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Chapter 5

The Impact of Bioenergy Resources for Sustainable Environment Bhuvaneshwari Segaran and Chelladurai Guruswami

Abstract Bioenergy is a consistent source for a country. Many developing countries fabricate its foundation for renewable energy. The eventual conception behind bioenergy is the nix shortage of raw materials. In many places, management of wastes especially the municipal waste is a toughest task due to the rapid increase of population; hence, it is very imperative to manage such wastes. Highly populated and the civilized country also have a critical situation to meet the essential needs like fossil fuels. In this case, the developing countries in joint venture with the advanced conversion technology raised up the bioenergy to fulfill the need of a country. Moreover, a country’s wealth is dependent on the capital productivity of such resources. Bioenergy also plays a vital role in the reduction of carbon emissions which is the need of the hour to minimize pollution and global warming. The increased bioenergy production has noteworthy impact on the sustainable development which raises the wealth of a nation. Keywords Bioenergy · Fossil fuels · Sustainable development · Global warming · Waste management

5.1 Introduction Bioenergy is a renewable source of energy such as power, heat, solid, liquid and gas that are generated from the organic matter named as biomass that can be derived from living biological materials such as plants and animal wastes. Even nowadays, the raw materials are derived from food, agricultural, municipal and sewage wastes. Many countries are focusing on fossil fuels because it provides 500EJ per year hence B. Segaran (B) PG and Research Department of Zoology, Bishop Heber College (Autonomous), Tiruchirappalli 620 017, India e-mail: [email protected] C. Guruswami Department of Zoology, G. Venkataswamy Naidu College (Autonomous), Kovilpatti 628 502, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_5

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the demands increase, but the biomass supply only 50EJ per year. This is mainly due to the traditional usage of biomass. Biomass has to be renovated through various treatment that enhances the value of waste materials and converted into useful forms. In general, this process is known as supply chain. Jack (2009) described that biomass has a low bulk density as a consequence, reduced energy density, the best conversion facility size is often determined by biomass transportation cost, and feedstock supply are shifting toward smaller, more scattered, and specialized facilities. Modern bioenergy production with advanced technologies has multiple applications in industries, transportation, residents and even for commercial uses (Dornburg et al. 2010). Ecofriendly and economically alternative renewable energy source is essential to meet the need of a country. Global warming, excessive climate change, food security, safety and energy security are the threat and made the people to think an alternative source of energy in a sustainable way that brings life and raise to a national economy (Konur 2012). The ultimate concept is bioenergy produced from the waste materials did not emit more carbon di oxide. Worldwide utilization of bioenergy helps to decline the adverse effect of greenhouse gases (GHC) in the atmosphere and meet the needs of Framework Conversion on Climate Change (FCCC) Fischer and Schrattenholzer (2001), but the land use of biomass leads to high GHC emissions. Subjective changes, including shifting current agricultural output to other locations, can indeed result in a “negative GHG balance” owing to bioenergy usage (Searchinger et al. 2010). During palm oil production the entails the conversion of forests and grasslands, the GHC emission balance can be negative, but in other land use instances, the GHC balance will be positive (Wicke et al. 2008). The major benefits of bioenergy production can increase the supply of clean energy resources, less dependency for oil from foreign countries, create fresh job for the youngsters and revive the economic status of a country. Hence, bioenergy can create security and sustainability to a country. As per a report from International Renewable Energy Agency (IRENA) three-fourth of the world’s population depends on the renewable energy. In 2015, 10% of the bioenergy is used for energy consumption and 1.5% of bioenergy of for power generation. The amount of biomass utilized for energy production will be definitely regrown. The current article discusses about the role of bioenergy resources in the future and their sustainable requirements for a better environment.

5.2 Raw Materials for Bioenergy Production A processed biomass is known as feedstock. The term feedstock plays an essential role in bioenergy production. The biomass obtained mainly from the wastes turns into usable bioenergy is not possible in a single step. It has to be processed through series of transformations and alterations through heat, chemicals or microbial actions. The chief raw materials for the production of bioenergy are retrieved form three

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Fig. 5.1 Types of feedstocks and its production

sources, namely (i) lipid feedstocks, (ii) sugar feedstocks and (iii) cellulose feed stocks (Fig. 5.1).

5.2.1 Lipid Feed Stocks Lipids are naturally occurring organic components made up of hydrophobic molecules with enriched source of energy and considered as an excellent sustainable source for the production of bioenergy. Lipid feedstocks are obtained from oily seeds. The derivatives of lipids are oil, wax and fats, mainly obtained from the non woody plants and also from some forms of algae. The most common oil seeds found worldwide are soyabean, oil palm, sunflower, canola, camelina, safflower and cotton seeds. These seeds are good source of biomass derived from agricultural sources can be used as a source of biodiesel. These oil seeds obtained from the various lands are seasonal and region specific. Phukan et al. (2011) analyzed Microalgae Chlorella Sp.

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[MP (1)] for innovative research and confirmed MP (1) is a wholesome bioenergy resource. Hence, chlorella biomass can be used as renewable feedstock through series of thermo chemical and biochemical transformations which brings a great demand of biofuels in the upcoming generations.

5.2.2 Cellulose Feedstock The cellulose is rich in plant sources specially in the plant cell walls. The bioenergy production of the cellulose in combination with lignin names as lignocellulose is doing wonders. Lignocellulose is rich in corn stover, rice husk, wheat straw, sugarcane baggage, poplars, willows, switch grass, Miscanthus, big bluestem, Altai wildrye, alfalfa and yellow sweet clover. This cellulose material can act as a substitute material for canes and maize in biofuel production. Cellulose material can be used in biodegradation too because it plays a vital role in carbon recycling (Aguiar and Ferraz 2011). The substantial cellulose and hemicellulose content of lignocellulosic biomass make it an excellent source of sugars for ethanol production. Energy crops developed for a specific purpose, such as vegetative grasses and short-rotation forests, offer a lot of potential for producing second-generation biofuels (Ahorsu et al. 2018). Vegetative grasses and short-rotation forest are considered as the energy crops which are grown deliberately for the production of second-generation biofuels (Demirbas 2009). Field et al. (2008) stated that among all the varieties of cellulose materials, Swiss grass is highly effective material for the production of biofuel at lower cost. It is highly possible due to the increased stress tolerance capacity and acclimatization of various climatic conditions and soil types. Even aquatic weeds are considered as rich source of cellulose with less lignin material which in turn bring the effective biofuel production with advanced technologies and a good model of aquatic systems in the production of sustainable and economical bioenergy for the upcoming generations (Kaur et al. 2018). As an overall report, cellulose has zero or little nutritional value for human being. As a result, advanced biofuels provide a chance to utilize these ingredients in the manufacture of high-value energy products.

5.2.3 Sugar Feedstock The commonest and essential and sustainable feedstock among all other feedstocks is sugars and starch. Plant-based feedstock is an adaptable technique for bioenergy production which is quite common nowadays. It is mainly used for the surplus quantity of starch and sugar content. Kindberg (2010) explained that countries like USA and Brazil are depending upon the sugarcane and corn starch for the production of bioethanol because of the increased production of alcohol. This indicates that the yield of alcohol is proportional to the number of fermentable sugars in feedstock.

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Balat and Balat (2009) described that the prevailing sugar-based bioethanol production is due to the excessive fermentation of sucrose. Some sources of sucrose in sugar feedstocks are sugarcane, sweet sorghum, sugar beets, cheese whey, brewery and fruit beverage wastes. Corn, milo, wheat, rice, potatoes, cassava, sweet potatoes and barley are starch rich sugar feedstocks. Asian countries which have high production of sugarcane are cultivated on tiny plots of land owned by local farmers. European countries depend upon beet molasses for sucrose-based feedstock (Cardona and Sanchez 2007). Mostly, sugar-based bioethanol production need distillation but starch need hydrolysis for the production of bioethanol (Sanchez and Cardona 2008).

5.3 Biowaste Resources and Management Accumulation of excess waste is an alarming sign that brings massive problems for this universe. To overcome this issue, waste management is essential. Many ancient processes like incineration and landfills were practiced, but the emission of gases that contribute global warming. The tremendous growth in population and industries the energy consumption is also rapidly increasing. To keep up with the rising demand, every country has to adapt an alternative way to improve the standard of living and to maintain sustainability. Hence with the modern technological resources, biowastes can be converted into alternative green energy sources. Bhattia et al. (2018) mentioned about the need of modern researchers, technicians to transform various biowastes to bioenergy using several technologies like digestion, transesterification and microbial fuel cells. The government organizations and stake holders should stretch their hands for the complete transformation of biowastes into energy like biogas, biodiesel, bioalcohol and bioelectricity to meet the needs of the society. Biowastes are primarily made up of biomass; thus, it may degrade in both aerobic and anaerobic environments. It is crucial to monitor biowaste in a cost-effective manner in order to maintain the environment and raise living standards. As a nutshell, merging it with energy-generating technology may aid in the resolution of energy and waste management issues and lead pathway for generating revenue (Kadam and Panwar 2017). In general, biowastes can be based classified into five categories; they are as follows (Fig. 5.2).

5.3.1 Forest and Wood Processing Industry Mostly, forest-based industries are good sources of lignin and cellulose compositions and the wood biomass from the timber and plywood industries. All wood wastes are accumulated in this universe due to various processing techniques for human needs such as clearing the forests for roads, cutting and smoothing processes in furniture and wood house making industries (Top 2015). In forests, each and every species of plants have various components of biomass and the treatment of such

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Fig. 5.2 Bioenergy production from different wastes

wastes differs according to the nature of components, and the variations are measured through oxygen bomb calorimeter. This information is easy to execute the exact waste management (Gravalos et al. 2016). Mostly, less lignin source is considered as a best source for bioenergy production, and the biomass consumption and utilization will help to prevent forest based natural calamities like landslides and forest fires (Doerr and Santin 2016).

5.3.2 Food Processing Waste The increase of food wastes is due to upsurge of population that brings out various food processing industries to meet the need of the people. All the food processing industries produce solid and the liquid wastes like pulp making, meat processing, oil manufacturing, etc. Each type of wastes has different components like peels pulps, sludge, washed water that are used for the bioenergy production (Ravindran and Jaiswal 2016). The unprocessed food wastes bring pollution due to the less water solubility and these problems are rectified through biorefining processes which results in the production of bioenergy like fuels and enzymes.

5.3.3 Paper Industry Paper pulp is very much essential for the production of paper. The paper industries convert wood source into pulp with enormous methods and chemical treatments.

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Generally, the quality of paper is determined by the pulp making process. Rahman et al. (2014) stated that basically there are two methods for paper pulp production out of which the paper produced through mechanical method of pulp production can be used for single use like newspapers and tissue wipes and with the chemical treated pulp special quality of papers, rayon and even photographic film sheets are produced. Different toxic pollutants like resins, terpenes and chlorinated resins were used in pulp production generate more wastes. Managing the sludge form the industries is a risky task, and the application of new technologies helps to convert the wastes into energy.

5.3.4 Municipal Solid Wastes Nowadays, urbanization and increased population growth leads to increased municipal waste. Mostly, the developing countries produce 100–400 kg of municipal wastes per year. Islam (2016) expected that in most of the developing countries like India, China Bangladesh and Thailand produce 2.2 billion municipal wastes in 2025, and it double up in 2050 which affects public health, quality of life in human and pollute the environment severely. The government finds bit tough to manage these issues, and day by day the higher officials in waste management sector have to face new problems and an emerging techniques like recycling of wastes, and different stages of treatments should be introduced to prevent our mother earth from pollution.

5.3.5 Animal Wastes Mostly in developing countries, the need of animals and animal-based products is high. Hence, the waste produced from those processing unit will be high, and if it is untreated, it leads a path for the spread of multiple diseases in human being. High populated countries like India are enriched with the livestock in association with agriculture, and the maintenance of the wastes is essential. Many remote rural areas are depending upon the wastes for biogas production and bio manure preparation, but this treatment alone can’t subside the problem to maintain the animal wastes because the treatment can contaminate the natural resources like water streams; hence, the country has to imply new technologies to manage the animal wastes. Gebrezgabher et al. (2010) explain about the natural decomposition of animal wastes produce methane which is more dangerous to the environment. Animal waste storage tank runoff has the potential to pollute groundwater if it infiltrates the water table. Over the last decade, there has been a surge in the conversion of animal waste into biofuel, but the expense and upkeep of digesters has put a stop to it. The solid animal wastes especially the excreta can be used as biogas all over the country because it contains more microbes that helps to digest the wastes and also in conversion of energy.

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All the above-described biowastes have to be pretreated to convert into useful bioenergy resources. The biowastes from agriculture, animal wastes, municipal wastes and food processing unit are made up of aromatic polymers, carbohydrate polymers, proteins and lipids. Bhatia et al. (2018) explained that the majority of biomass is in a refractory state that makes it unsuitable for microbial fermentation and necessitates pretreatment to make it digestible. To make carbohydrate polymers available to different hydrolases, pretreatment is necessary to break the supramolecular structure that binds the cellulose–lignin–hemicellulose matrix. The meat business produces animal fat waste as a byproduct. Solid or semisolid animal manure is crushed into a uniform size before being exposed to high temperatures (115–145 °C) to remove moisture and release fat during the rendering process. Melting and supercritical CO2 are two ways for recovering useable fat from animal manure that have been described and employed When an equivalent amount of meat by-products is rendered, composted, and anaerobic digested, the rendered products have an economic value at least three times that of the anaerobic digestion products, and at least five times that of the value added to compost by include the meat by-products. Because of these distinctions, rendering is the most environmentally friendly way to handle big quantities (Gooding and Meeker 2016).

5.4 Bioenergy Production Through Technologies Almost all the wastes specially biowastes produced in major cities can be converted into bioenergy through various processes. The various bioenergy products are biogas, biodiesel and bioelectricity. Due to the increasing population, bioenergy is an alternative source for a developing country to meet the needs of people. The developing countries can gain more products through wastes. Mostly, all the wastes are treated biologically by anaerobic digestion, fermentation, transesterification and microbial fuel cells and physiochemically by pyrolysis, gasification, incineration, hydrothermal carbonization and landfills. Breaking down of biological compounds through microbes without the presence of oxygen is considered as anaerobic digestion in which the biowastes can be converted into biogas with the components of methane and carbon di oxide. The biogas production through anaerobic digestion is a step-by-step process through hydrolysis, acidogenesis, acetogenesis and methanogenesis. In hydrolysis, the conversion of complex substances such as polysaccharides, fats, proteins and nucleic acid into simple forms such as monosaccharides, fatty acids, amino acids and nitrogenous bases like purines and pyrimidines. In acidogenesis, molecules get converted into volatile fatty acids and gaseous components and reduced into acetic acid through acetogenesis. Finally with sequential steps of fermentation, the methanogenic process occurs for the production of biogas. Almost all types of wastes like food waste, agro-industrial wastes, animal wastes and municipal wastes can be treated. The physicochemical methods produce greenhouse gases which is again a threat to the environment. Hence, the biological method of waste treatment is the

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best method for treating wastes (Bhatia et al. 2017). The waste of biogas production can be converted into biofertilizer and provide a valuable and constant income to the developing countries that adapt the biological technologies (Khalid et al. 2011). Biodiesel a valuable biofuel extracted from various sources of wastes such as sludge, animal fats, waste cooking oil etc. Using different methods like microbial treatments, rendering and pretreatment were applied to extract the oil from the above-mentioned wastes. Initially, oil was extracted in the form of triglycerides, and with sequential steps of transesterification through chemical or enzymatic method, biodiesel can be produced. Biodiesel can be used in purest form of mixture of other fossil fuels which gives variety of combinations that can be used for engines and vehicles. Hence, biodiesel production from wastes is an alternative solution for fossil fuels, and it saves the economy of every individual (Pollardo et al. 2017). Jeon et al. (2018) described the synthesis of bio-alcohol is very much essential, and it ranks next to fuels to meet a country’s demand. Most of the bio-alcohols like ethanol are derived from substrates such as coffee wastes, banana stem, food wastes, fruit and vegetable peels, butanol are derived from cassava, date palm spoilages, rice straw and sugar canes. The above wastes are treated with microorganisms such as Saccharomyces cerevisiae and Clostridium acetobutylicum. More accumulation of bio-alcohol due the fermentation process of wastes stops the growth of microbes, several new techniques like vacuum recovery technology have been adopted for maintaining the bioreactors under vacuum (Huang et al. 2015). Hence, using trash as a raw material might be a way to avoid fuel and food production becoming competitive. Microbial fuel cells may use biowaste as a raw source to generate energy (i.e.) the conversion of chemical energy into electrical energy to produce bioelectricity using organic carbons under anaerobic conditions. Microorganisms consume organic matter in order to grow and reproduce, and the different intermediates created during catabolism undergo a number of oxidation and reduction processes, creating electrons and protons. An electron passes via an external circuit after being transferred to an electrode, and protons diffuse through the solution to the cathodic chamber, where they mix with oxygen to form water. The potential in the anodic chamber falls as the substrate oxidizes, resulting in a potential difference between two electrodes, which generates a current (Wang and Ren 2013). Two types of methods are adapted for electricity generation: One is the mixture of wastes and electrodes in a single chamber, and the other is the separation of wastes in one chamber and the electrodes in other chamber to generate electricity. Aeromonas, Escherichia, Saccharomyces, Candida, Clostridium, Klebsiella, and Shewanella have all been observed to create energy. Bioelectricity production with a microbial fuel cell (MCF) is still unfeasible due to the MFC’s limited current generation capability. In addition, because most reactions are catalyzed by mesophilic microorganisms, this technology requires a lower temperature (Islam et al. 2018).

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5.5 Impact of Bioenergy in Sustainability The Government of India is constantly introducing new policies and initiatives, as well as revising old ones. In order to revamp the existing policies, the Indian government in 2018 has launched the three major initiative policies in the area of bioenergy, namely (1) New National Policy on Biofuels, (2) New National Biogas and Organic Manure Program (NNBOMP) and (3) Program on Energy from Urban, Industrial and Agricultural Wastes (Kothari et al. 2020). Different bioenergy technology initiatives have been developed with direct Ministry of New and Renewable Energy (MNRE) assistance to promote bioenergy technologies through various financial incentives such as concessional duty/customs free import and soft loans for production. But the investors are facing lot of challenges in bioenergy sectors (Luthra et al. 2015). A country’s sustainable development depends on the energy resources. Deep research analysis proves that bioenergy is a master key that plays a major role in sustainable energy mix in the future. Bioenergy has the potential to provide significant long-term advantages for sustainable development and may directly contribute to several of the policy goals like energy supply diversity and security, Equitable energy access, rural development, employment, health benefits, food security, reduction of greenhouse gas emission, climate change adaptation, biodiversity and landcover and deforestation (Souza et al. 2015).

5.6 Conclusion The current study concludes that bioenergy is an appropriate opportunity to convert all the feedstocks and wastes into sustainable energy resources that brings to the development. Bioenergy system’s versatility is obtained from feedstocks processed through various conversion paths, serving various end applications, being generated at various sizes, and catering to both domestic and international markets. The practical application will allow for advice on the creation of technologies and supply chains that include social and environmental consequences and acceptability, as well as socioeconomic hurdles to adoption. Bioenergy policies, programs and initiatives at the municipal, regional and national levels are informed by a thorough evaluation of the economic, social and environmental consequences in order to promote sustainability. Acknowledgements We the authors wholeheartedly thank the management of Bishop Heber College (Autonomous), Tiruchirappalli, and Kamaraj College, Thoothukudi, for their constant guidance, support and prayers to complete this work successfully.

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Kothari R, Vashishtha A, Singh HM, Pathak VV, Tyagi VV, Yadav BC, Ashokkumar V, Singh DP (2020) Assessment of Indian bioenergy policy for sustainable environment and its impact for rural India: strategic implementation and challenges. Environ Tech Innov 20(2020):101078 Luthra S, Kumar S, Garg D, Haleem A (2015) Barriers to renewable/sustainable energy technologies adoption: Indian perspective. Renew Sus Energy Rev 41:762–776 Phukan MM, Chutia RS, Konwar BK, Kataki R (2011) Microalgae Chlorella as a potential bioenergy feedstock. Appl Ener 88(10):3307–3312 Pollardo AA, Lee HS, Lee D, Kim S, Kim J (2017) Effect of supercritical carbon di oxide on the enzymatic production of biodiesel from waste animal fat using immobilized Candida antarctica lipase B variant. BMC Biotech 17:70 Rahman M, Hussain A, Basri H (2014) A critical review on waste paper sorting techniques. Int J Environ Sci Technol 11:551–564 Ravindran R, Jaiswal AK (2016) Exploitation of food industry waste for high-value products. Trends Biotechnol 34:58–69 Sanchez OJ, Cardona CA (2008) Trends in biotechnological production of fuel ethanol from different feedstocks. Bior Tech 99:5270–5295 Searchinger T, Heimlich R, Houghton RA et al (2010) Use of U.S cropland for biofuels increase greenhouse gases through emissions from land use change. Science 319(5867):1238–1240 Souza GM, Victoria RL, Joly CA, Verdade LM (2015) Bioenergy and sustainability: bridging the gaps. Scope 72:1–734 Top Y (2015) Waste generation and utilization in micro-sized furniture manufacturing enterprises in Turkey. Waste Mgt. 35:3–11 Wang H, Ren ZJ (2013) A comprehensive review of microbial electrochemical systems as a platform technology. Biotechnol Adv 31:1796–1807 Wicke B, Dornburg V, Junginger M et al (2008) Different palm oil production systems for energy purposes and their greenhouse gas implications. Biom Bioe 32(12):1322–1337

Chapter 6

The Impact of Bioenergy Utilization on the Ecosystem—Toward a Sustainable Future Ramansh Bajpai

Abstract Energy is an essential requirement, which needs everything to work. However, the world population is dependent on non-renewable energy sources for their daily energy requirements, which is limited and has many adverse effects on our environment. The petroleum fuels and burning of fossil fuels are the main culprit of global warming because of GHG emission. The demand for fossil fuels, mainly in the transportation industry, is increasing daily, which led us to search for alternative energy sources to meet the growing needs. Bioenergy is sustainable renewable energy, which can trace back to ancient times from burning a wood log to get fire and heat to utilize the steam to generate electricity. Bioenergy production on local community empowerment and sustainability is the primary source of sustainable energy. The use of agro-industrial waste to produce biofuels is also used as an alternative for petrol and diesel in the transportation sector. Biomass energy gives energy security, reduces toxic chemicals use, brings jobs to rural areas, and improves our trade balance. Bioenergy research integrates many disciplines that include agronomy, biology, chemistry, engineering, and economics to achieve these benefits. Out of all energy resources, we consider green power solar, wind, biomass, and geothermal the cleanest form of energy. This research focuses on the possible impacts of all types of bioenergy utilization on our ecosystem and the potential use of bioenergy in all the industrial sectors of the world. The rise of greenhouse gases, mainly CO2 , becomes the main concern since global climate change shows adverse effects, so bioenergy can be an essential source of energy that can help us in this matter. The study of the negative impact of bioenergy has also been conducted, and the research concentrates on all aspects of utilizing bioenergy as a sustainable energy source. Keywords Fossil fuels · Bioenergy · Biofuels · GHG emission · Clean energy · Environmental sustainability

R. Bajpai (B) Environmental Science and Engineering, C.E.D., HBTU, Kanpur, UP, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_6

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6.1 Introduction Concern for the environment is gaining attention as days pass by. We are looking for new and more innovative ideas to deal with environmental problems, new and more sustainable technologies to overcome these situations. The greatest challenge we face today is the energy and its sources, its impact on our planet. Bioenergy, or sometimes we can call it clean energy, may possess the solution we have been looking for so long. Compared with conservative fossil fuels, bioenergy has evident advantages due to its renewability and large quantity and thus plays a vital role in helping defend energy security. However, bioenergy development may cause severe environmental alterations, which remain unclear. Energy is the essential requirement of the growth in almost every aspect of society globally, and it is also needed by the existence of ecosystems, life itself, and human civilizations (Ozturk et al. 2017). From ancient times to the modern days, we developed using energy; the first energy source is fossil fuels, which are non-renewable energy sources; the overutilization of conventional fuels may give rise to severe crises. Second, the use of traditional fuels can also be responsible for polluting the environment. We cannot rely on it for much of our needs; the emission of CO2 (Carbon dioxide) and other greenhouse gases can accelerate global warming. Third, the emitted nitrogen oxides due to fossil fuel combustion compromise air quality and harm human health (Hoekman and Broch 2018). Unfortunately, world energy consumption depends heavily (80%) upon fossil fuels and will increase by more than 50% in the next 20 years (Ozturk et al. 2017). Therefore, bioenergy, the powerful renewable substitution of fossil fuel, has been developing during the past decades, especially in North American and Europe, aiming to meet the growth of the world population, safeguard energy security, and mitigate global warming (Hoekman and Broch 2018). The utilization of bioenergy for electricity production is essential; the Paris agreement between the different countries of the world aiming at a net-zero carbon economy in this century can be made possible by replacing fossil fuels as an energy source for electricity production with biofuels. Sustainable bioenergy production can efficiently decrease the risk of energy poverty and contribute to economic development, especially in developing countries (Schroder et al. 2018). Governments worldwide are thus promoting bioenergy production and looking for appropriate policies and laws to regulate its development. For instance, the US implemented the Energy Independence and Security Act (EISA) in 2007, aiming to increase the availability of renewable energy through biofuel production (U.S. Congress 2007). The use of waste biomass to produce biofuels became a real thing today; bioethanol and other biofuels in the transportation induction are increasing and showing some changes. Agriculture wastes that give serious threats like stubble burning, especially in northern and central India, can be overcome by producing biofuels. Cereal crops, pulse crops, and harvestable palm oil biomass are grown in large amounts worldwide annually (Rajaram and Verma 1990). Great efforts made worldwide to develop technologies that generate clean, sustainable energy sources from non-food biomass feedstocks that substitute fossil fuels (Ragauskas 2006; Levin et al. 2006). Using these feedstocks for second-generation

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biofuel production would significantly decrease the potential pressure on land use, improve GHG emission reductions compared to some first-generation biofuels, and lower environmental and social risks (Bauen et al. 2009 IEA Report).

6.2 Scenario of Bioenergy Production Bioenergy production depends upon its requirement and utilization. Long dependence on fossil fuels for energy is now proving harmful and uneconomical for the world. To overcome this dependence, we must increase the production and use of bioenergy in every possible sector. Biomass feedstocks include dedicated energy crops, agricultural crop residues, forestry residues, algae, wood processing residues, municipal waste, wet waste, bioenergy sources. Still, hydropower is the most widely used renewable power source. The global hydroelectric installed capacity is more than 1300 GW (gigawatts), accounting for more than 18% of the world’s total installed power generation capacity and more than 55% of the global renewable power generation capacity. The leading countries for installed renewable energy in 2020 were China, the USA, and Brazil. China is leading in renewable energy installations with a capacity of around 900 GW. The USA, in second place, had a total of about 293 GW. The sources for producing bioenergy are mainly biomass feedstocks that sometimes are termed as waste materials. As long as these wastes are coming, we can produce more and more bioenergy, giving a solution to the two most significant problems that the world is facing today, mainly developed countries. India has a potential of about 18 G.W. of energy from biomass. Currently, more than 30% of the total primary energy used in India is resulting from biomass. More than 70% of the country’s population depends upon biomass for its energy needs. India has 5 G.W. capacity biomass-powered plants: 83% are grid-connected while the remaining 17% are off-grid plants. The off-grid plants are divided between cogeneration plants that do not utilize bagasse, biomass gasifiers for rural applications, and biomass gasifiers for thermal applications in industry. Around 70 Cogeneration projects are under implementation with surplus capacity combining 800 MW.

6.2.1 State-Wise Bioenergy Production in India India is a developing country, so the requirement for energy is enormous. Most of the Indian population resides in villages whose needs for energy are much higher than is provided to them. Since India is an agro-based country, the biomass produced in the country is sufficient for production as much as bioenergy needed by the country. Many Indian states produce bioenergy to fulfill their energy needs by using biomass from agriculture and other wastes. The leading states are Karnataka, Maharashtra, and Uttar Pradesh. All these states have more than 1.0 G.W. of Grid interacted biomass

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Fig. 6.1 Bioenergy power potential in India. Source Renewable and Sustainable Energy Reviews, April 2014, p. 510

power. Other states with constructive policy and chances in biomass are Punjab and Bihar (Fig. 6.1).

6.2.2 Clean Energy versus Bioenergy Production Clean energy and bioenergy are renewable energy sources and can be the solution for fossil fuels for energy production. Clean energy is the energy harnessed from natural sources like sunlight, wind, water pressures, and others. The most widely used clean energy is from hydropower plants. Solar energy is also one the most commonly

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8000

INSTALLED SOLAR ENERGY IN MW

7000

7100

6000 5000

Karnataka

5000 4000

Telangana

4400

Rajasthan 3470

3000

Andhra Pradesh 2654

2000

Gujarat

1000 0 STATES

Fig. 6.2 Graphical representation of top five Indian States Solar Energy Installed Capacity in MW

used and popular energy sources; it is most feasible and can be used anywhere by installing solar plants. India is installing large solar power systems termed ‘Solar parks,’ which aim to provide more energy and decrease the country’s dependence on fossil fuels. It can also help reduce the carbon footprints and make the environment more sustainable. Presently, India has more than 95 G.W. of installed renewable power and, of that, 40.5 GW comes from solar, which spreads across the country. The large-scale adoption of renewable power, including a severe push to solar, is crucial for India’s clean energy transition goals. Karnataka is the leading state with about 7100 MW (megawatt) solar energy, followed by Telangana, Rajasthan, Andhra Pradesh, and Gujarat (Fig. 6.2).

6.3 The Global Market of Bioenergy The markets of bioenergy have been developing at a tremendous pace. The most unusable form of renewable energy is now bioenergy. Many different processes to convert the biomass feedstocks into electrical and thermal energy are available in commercial markets. There is still research ongoing on the various approaches for getting more advanced and economical energy by using these biological feedstocks. Biomass feedstocks are readily available worldwide; global leaders and industries should develop new technologies to harness more and more energy from biomass to achieve sustainable development goals. Traditional bioenergy means the biomass

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Non- Biomass Energy 82.10%

Fig. 6.3 Estimated bioenergy and biomass share in total energy consumption of the world

used as burning fuel for cooking and other minor works in village areas. In contrast, modern bioenergy sources are mostly agriculture industry feedstocks. Contemporary bioenergy is being used for power generation, like biofuels, for heat generation, and research is going on to use it in jet engines in Japan. The total and final energy consumption shares until 2018 are approximately 82% from non-biomass sources while 6.90% from traditional biomass and nearly 11% from modern bioenergy, as depicted in Fig. 6.3. Despite being carbon neutral, bioenergy is still very far from the expected. Still, as more emphasis is now on using biomass to develop more modern bioenergy, we hope it will reach its target values easily and early. In 2017, the gross final energy consumption was 370 EJ (Exajoules)—an increase of 2% over the past year.

6.3.1 Bioenergy in Transportation Sector Bioenergy in the transportation industry is in the liquid biofuels forms. The importance of biofuels is increasing day by day. The production of biofuels is growing from 18 billion liters in the year 2000 to nearly 144 billion liters in 2020, an 11.6% drop from 2019’s record output and the first decrease in annual production in two decades. The slow growth after 2017–18 is due to the impact of the COVID-19 pandemic situation, and many biofuels industries halted their work due to the shortage of workforce and other financial issues resulting from the COVID-19 case. The growth in biofuels production is approximately 87.50% from 2000 to 2020, showing biofuels’ feasibility as an alternative to fossil fuels like oils and gases. The biomass feedstocks from agriculture industries (Jatropha, corn, sugar cane, and other crops) are mainly used to produce biofuels for the transportation industry. Most countries should consider their potential feedstocks to produce biofuels with the highest possible efficiency.

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161 153 144 134138 128

160

Production in Billion Liters

85

140 120

106

100 80 60 38

40 20 0 1995

18

2000

2005

2010

2015

2020

2025

Year Biofuel Production in Billion Liters

Fig. 6.4 Year-wise global growth in biofuels production in billion liters

For example, bioethanol is made from wheat in Canada, Spain, Sweden, and China, sugar beet in France, and cassava and rice in Thailand (Sanchez and Cardona 2008). Liquid biofuels are produced from crops, e.g., cereals, sugarcane, sugar beet, sweet sorghum vegetable oil, and biogas, referred to as first-generation biofuels. In contrast, those produced from lignocellulose biomass and non-food crops are second-generation biofuels (Yuan et al. 2008). Biofuels made from algae are termed third-generation biofuels (Brennan and Owende 2010) (Fig. 6.4). The sharp rise in biofuels production started from 2005, which was 38 billion liters in 2005. It reaches approximately 161 billion liters in 2019 but drops more than 11% in the year 2020. It was the first reduction in biofuel production in decades. Bioethanol produced from sugar crops (sugarcane, corn) accounted for 65% of the global biofuel production. USA and Brazil continue to dominate bioethanol production. Biodiesel production volume of nearly eight billion liters in 2019, Indonesia rose to be the world’s largest biodiesel producer that year. The other biofuels include those not categorized into bioethanol or biodiesel, and fuels such as cellulosic ethanol and hydrotreated vegetable oil (HVO) fall in this group. Americas—mainly North America, accounted for the considerable share of other biofuels, which accounted for more than 90% of the worldwide production.

6.3.2 Bioenergy for Power Generation After the industrial revolution, fossil fuels dominated the world’s energy supply. Coalbased power plants are the primary source of electricity that grew with rapid speed in the nineteenth century. As the electricity demand increased, coal consumption also

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increased, leading to environmental and soil pollution. The ash left after burning coals in large kilns was of no use, which became a severe problem for power plants until the researcher found out that the fly ash (waste from coal burning in power plants) can be used in construction as a part of cement. The infrastructure development leads to more power consumption, which leads to more and more burning of fossil fuels that are limited in nature. The requirement for energy needs some alternative and eco-friendly sources. The use of bioenergy in power generation sectors came to play; since 2000, the primary energy supply of coal has increased by 65%, oil by 22%, and natural gas by 50%, while at the same time, renewables have increased by 48%. In the recent past, the trend has been the same. During 2016–2017, the supply of fossil fuels has risen more than renewable energy. Worldwide biopower capacity increased an estimated 6.5% in 2018 to 130 gigawatts (G.W.), up from 121 GW in 2017. Total bioelectricity generation rose 9%, from 532 terawatt-hours (TWh) in 2017 to 581 TWh in 2018. The European Union remained the most prominent producer by region, with a generation growing 6% in 2018, encouraged by the Renewable Energy Directive. Other trends of preceding years continued: generation grew most rapidly in China—up 14% in 2018—and in the rest of Asia (16%), while generation in North America remained essentially stable. The top five countries in biopower capacity are China, the USA, Brazil, India, and Germany (Fig. 6.5). China is the leading country in terms of biopower capacity in the world. In China, biopower capacity increased by 21% to 17.8 GW (Gigawatts) in 2018. In Asia, India is also doing very well in terms of biopower capacity. Biopower in India increased from 4.95 GW in 2016 to 8.40 GW in 2017–18; India can achieve its target of 10 G.W. Biopower capacity may be in this rather than in 2022. The utilization of Bio Power Generation(TWh)

2019

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2018

520

2017

499

2016

455

Year

2015

424

2014

389

2013

356

2012

328

2011

310

2010

266

2009 0

100

200

300

400

500

600

BioPower (TWh)

Fig. 6.5 Global biopower generation statistics 2009–2019. Data source iea.org, 2019

700

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biomass for power generation is the need of the hour as it solves two significant challenges facing the country—power deficit and waste management. As a country, India produces 150,000 tonnes of municipal solid waste per day. While recycling and segregation can help, they barely scratch the surface. Setting up more biomass power generation remains a feasible option for processing and disposal of waste; the proximity of the problem has necessitated evolving a mix of quick and long-term solutions. In 2019, bioenergy electricity generation increased by over 5%, just below the 6% annual rate needed through 2030 to reach the sustainable development target goals.

6.4 The Growth of the Bioenergy Industry The ongoing global environmental problems arise due to fossil fuels, influencing the world to use eco-friendly and limitless energy sources. The rise in the bioenergy industry results from such a cause; the raw biomass converted into bioenergy by a very complex process that needs proper facilities, research, and support. Its draft Biomass presents many different varieties such as straw, seed waste, manure, paper waste, wood, sawdust, household waste, wastewater, etc. (Soltero et al. 2018). The features of some materials allow them to be used as fuels directly; though, others need a sequence of pre-treatments, which involve different technologies before they can be used.

6.4.1 Industry of Solid Biomass Solid biomass is the fuel resulting from organic materials, such as virgin wood or wood waste. Solid biomass is a renewable and sustainable source of energy used to generate electricity or other forms of power. Solid biomass is generally used in developing countries, primarily for cooking, water heating, and domestic space heating. Bioenergy projects that produce electricity and heat depend on solid fuels sourced locally, such as municipal solid waste, residues from agricultural and forestry works, and purpose-grown energy crops. The powers also can be processed and transported for use where markets are most profitable. For instance, the international trade in biomass pellets is growing to meet requirements for fuels for large-scale heat and power generation and to provide residential heating in markets where the use of shells is supported, notably in Europe and increasingly in Japan and the Republic of Korea. Bagasse and other agricultural residues usually used to produce heat and power in Brazil attract increasing attention elsewhere. In India, major power producer, NTPC, aims to start biomass co-firing at its coal-based thermal power stations, using biomass pellets and briquettes made from scrap timber, forest rubbishes, manure, and the other types of waste residues. In Japan, where support from a generous F.I.T.

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has stimulated rising interest in bioelectricity, establishing large project pipelines, using indigenous resources and imported pellets as fuel.

6.4.2 Industry of Liquid Biomass Liquid biomass is mainly liquid biofuels made by using different biomass. The biomass such as fermenting cellulose, starch, or sugar from which ethyl alcohol is used to produce ethanol, alcohol from vegetable oils, animal fats, or recycled restaurant grease produces biodiesel. The industry of liquid biomass developed with a commencing pace. Many developing countries are also switching to liquid biofuels instead of fossil fuels. Top ethanol producing companies belong to the USA. In Brazil, most ethanol is produced principally by fermentation from sugar cane, the country’s traditional ethanol feedstock. Ethanol production capacity is expanding rapidly in China to meet increasing demand, including a nationwide E10 mandate projected to be in place by 2020. China’s ethanol production capacity summed 3.5 million liters at the end of 2017. New plants capable of producing 8.4 million liters were under construction or going through the approval process in 2018. Global biodiesel production capacity has been growing to meet progressively ambitious blending mandates worldwide, especially in North America. Some advanced biofuels can directly substitute fossil fuels in transport systems, including aviation, and mix in high proportions with conventional fuels in road transport (such as HVO in diesel-fueled vehicles). In 2018, Neste (Finland), the world’s largest HVO producer, proclaimed an investment of EUR 1.4 billion (USD 1.6 billion) to more than double its renewable diesel production capacity in Singapore by adding a further 1.3 million tonnes (1.7 billion liters) of annual capacity. The production of cellulosic ethanol from corn residues, such as kernel fiber, at corn-based ethanol facilities expanded in 2018. The allocation of the plants and facilities can allow for lower-cost production. Among the milestones in 2018, United Airlines operated the longest non-stop transatlantic biofuel journey to date when a bio-jet blend of 30% carinata oilseed and 70% conventional jet fuelpowered a Boeing 787 flight from San Francisco to Zurich. Developments continued in biofuels in aviation, although these fuels replaced only a tiny fraction of aviation fuel in 2018. The future of the liquid biomass industry is highly progressive in terms of new research and developments.

6.4.3 Industry of Gaseous Biomass The gaseous biomass industry is mainly focused on the use of biogas for the generation of electricity. Most of the countries have biogas plants for utilizing biogas to produce electricity. Biogas is a mixture of gases produced from raw materials such as manure, municipal waste, plant material, sewage, green waste, agricultural waste, and food waste. Mainly, it contains methane, carbon dioxide, and a tiny amount of

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water vapors and supplied compounds. The global biogas market size was valued at 55.1 billion USD in 2019 and is expected to grow at a CAGR of 4.48% over the forecast period (REN-21 2020). The market is motivated by increasing greenhouse gas emissions and their damaging impact on the environment. Various governing bodies worldwide invest heavily in producing renewable energy sources to curb carbon emissions and ensure a stable and protected energy supply. The market is mainly categorized into vehicle fuel production, heat generation, and electricity generation. The electricity generation sector is projected to lead the total world share over the projected period. Countries are switching more toward gas-based power plants from coal-based ones due to carbon emissions. Thus, it is anticipated the demand for gas-sourced power plants will drive the market. The utilization of biogas to produce electricity and heat is a progressively common practice, and in 2018, more than 10,000 digesters in Europe and 2200 sites in all 50 US states were creating biogas. Biogas can be advanced to biomethane by eliminating carbon dioxide and impurities, facilitating its injection into natural gas pipelines. In China, where biomethane plants have been rapidly industrialized, some 140 plants were in operation countrywide. Biomethane also is being used as a fuel for marine transport. Norway has supplied biomethane from its biogas facility in Lidkoping for use in a tanker ship. Norway-based cruise operator Hurtigruten announced in 2018 that it plans to finance 742 million euros (849 million USD) to power its ships with biomethane starting in 2021. The production of electricity using biogas is a very effective method for producing electricity than other sources of renewable sources of energy. However, it is applicable only if the evolving heat from the power generator is used ecologically and economically. Since we can always grow trees, crops, and both solid and human waste will always be produced, and there is an infinite amount of biomass available for us to use as energy (Table 6.1). Table 6.1 Occurrence of different types of biomass and their sources Type of biomass Solid biomass

Liquid biomass

Gaseous biomass

Source

Traditional occurrence

Wood

Logs, chips, bark, sawdust

Agricultural waste

Fruit pits, corn cobs, straw

Solid waste

Garbage, food processing waste

Ethanol

Ethyl alcohol from fermenting cellulose, starch, sugar

Biodiesel

Alcohol with vegetable oils, animal fats, recycled restaurant grease

Rot and decay

Dead plants and dead animals

Animal by-products

Fish oil, manure

Human waste

Municipal solid waste, Wastewater treatment sludge

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6.5 Environmental Impact of Bioenergy Use The main concern of today’s world is the degradation of the environment and ecology, hampering humans and other species. Human greed and anthropogenic activities have already harmed the environment to such an extent that many flora and fauna species have become extinct, many others are on the verge of extinction. Every country needs development, but severe problems arise when the resources are overutilized to achieve the development goals. The overuse of fossil fuels in almost every sector in the last 50 years gave rise to these problems. Because of these fundamental problems, the attention now shifted toward green energy since bioenergy sources mainly depend on waste from agriculture, humans, and animals, which means there should be no shortage of biomass to produce bioenergy. The developments in the field of bioenergy are giving new and broad areas for its application. The production of bioenergy and its application also have an impact on our environment. When the wastes from different industries are being utilized, much waste dumping is needed, especially for developed countries. Global yearly biomass generation is more than 140 gigatons—most of the biomass produced in rural parts of developed countries, which is left for self-decomposition. Countries like India, an agro-based economy, deal with stubble burning that causes many environmental issues, mainly air-related pollution. The utilization of this waste can be beneficial in boosting bioenergy production; also, it helps in curbing ecological pollution to some extent.

6.5.1 Impact on Air Quality The use of biomass for the production of bioenergy has both positive and negative impacts on air quality. The traditional method of burning biomass emits gases like carbon mono oxide, nitrogen oxides, sulfur dioxide, lead, and other harmful pollutants that adversely affect air quality. The modern methods of producing bioenergy are now proving more beneficial and have positive effects on air quality. The emissions of nitrogen oxides and total volatile organic compounds lead to the development of ozone in the troposphere, the main component of smog. C.O. is a deadly poison, and the inhalation of delicate particulate matter (PM2.5) is a serious health concern (Peter et al. 2003). Biofuels have many health and environmental benefits, including enhancing air quality dropping pollutant gas emissions compared to fossil fuels. Biofuels such as biodiesel use cuts emissions that contribute to ozone by half, compared to diesel fuel. Presently, second-generation biofuels are projected to reduce carbon emissions by 90%, and by 2040, these could potentially replace up to 40% of all conventional fuels (Krisztina et al. 2010). Ethanol contains 34.7% oxygen by weight. They added oxygen to fuel, resulting in complete fuel combustion, reducing exhaust emission and petroleum use (Huang et al. 2008; Prasad et al. 2007). Ethanol is a high-octane

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fuel, and its use displaces toxic octane boosters such as benzene, a carcinogen. Ethanol is a virtually sulfur-free additive and is biodegradable. Thus, it is easy to see why many states use ethanol to reduce vehicular emissions. Biodiesel is a mono-alkyl ester-based oxygenated fuel made from vegetable oil or animal fats. It has properties comparable to petroleum-based diesel fuel also can be blended into conservative diesel fuel. This interest is based on several properties of biodiesel, non-toxic, and its potential to reduce exhaust emissions (Jha 2009; Knothe et al. 2006). By nature, biodiesel is an oxygenated fuel with an oxygen content of about 10%, increasing combustion and reducing carbon monooxide, soot, and unburnt hydrocarbon. Biodiesel is non-flammable and, in contrast to petrodiesel, it is nonexplosive. There may be some disadvantages of using the traditional method for bioenergy, but the advantages suppress them all. The biogas used as a vehicle fuel, as shown in Fig. 6.6, presents better characteristics than natural gas. Some disturbance still appears for the NOx (nitrogen oxides) emissions, but they stay below the E.U. norms. Concerning CO2 , hydrocarbons, and C.O. emissions, the biogas is far better than the natural gas used for vehicles (N.G.V.) (Traffic and Public Transport Authority 2000). Carbon dioxide emission is approximately 223 g/km on biogas as vehicle fuel, while natural gas and diesel emit 524 g/km and 1053 g/km carbon dioxide, respectively, when used as a vehicle fuel.

6.5.2 Impact on Water Quality and Quantity The crops needed for bioenergy production mainly require more amount of water than other crops. The conversion of land for bioenergy crops may reduce water resources at the watershed level. The primary water quality concern regarding the increasing

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cultivation of bioenergy crops is nutrient pollution resulting from surface runoff and infiltration to groundwater. The practical impact on water quality is the consumption of water by the crops required for bioenergy production. For example, corn crops use more water than wheat and soy crops, mainly used to produce bioethanol. Corn to ethanol conversion is the most mature technology; nearly 40% of total corn grown in the USA is used for ethanol production. The most crucial polluting source of nutrient pollution is nitrate. Increasing the frequency of corn plantation in the corn and soybean rotation system or replacing it with continuous corn would significantly lead to more nitrate in waterways and decrease soil nitrogen content (Wu et al. 2012; Wu and Liu 2012). The choice of land for growing biomass for bioenergy is essential, which should be considered before utilizing the land for production. Water use at a biomass plant ranges between 20 and 50 thousand gallons per megawatt-hour. This water is released back into the source at a higher temperature, disrupting the local ecosystem. Water availability will undoubtedly affect the extent to which bioenergy can contribute to the overall energy mix. Bioenergy crops can impact the water quality in near and long-distance areas, resulting in significance for human needs and biodiversity. The effect on water quality must be considered at a point source and watershed level or collective results. The negative impacts can be avoided by adopting the proper ways, such as assessing the type of land and crops water requirement that can help improve the water quality and the situation by bioenergy development. Indicators to measure water quality refer to the chemical, physical, and biological characteristics of the water. Water pollution can be mitigated, which is caused by feedstock production, by reducing the application of fertilizers and pesticide levels. However, there is substantial potential to raise the presently low productivity of rain-fed agriculture in large parts of the world, particularly in developing countries, through enhanced soil and water conservation, efficient fertilizer use and crop selection (including drought-adapted crops), and use of best practices involving mulching, low tillage, contour plowing, field boundaries, terraces, rainwater harvesting, and crop rotation. Cleaner production approaches focus on maximizing output, minimizing wastage of resources of any kind, and recycling and reusing all by-products. Hence, these approaches can be good for business and the environment. These processes can help improve the water quality and land-use conditions to grow bioenergy crops.

6.5.3 Impact on Soil The crops used for bioenergy need large land areas, but the primary concern is soil erosion and soil degradation. The crops for bioenergy require sizeable agricultural land for production; the impact of biofuels depends on the use of land that can affect the area’s biodiversity. The initial use of land and the number of chemicals used to grow the biomass feedstocks affect the soil. Erosion reduces soil quality and thus decreases the efficiency of natural and agricultural ecosystems. Soil erosion is also triggered in three major pathways—the corn acreage expansion, residue removal, and

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land-use change. Due to the growing demand for ethanol, the corn acreage expansion could have severe adverse significances in soil retention due to its comparative looser planting space. It was projected that the benefits of conservation actions on soil retaining would be weakened further if increased corn cropping occurred on these lands. Cultivating the current corn crops with suitable tillage practices would also decrease soil erosion (Hoekman and Broch 2018). The leftover crops serve as buffer agents for erosive forces like wind and water, increasing soil erosion. Prevention of soil erosion by using proper management techniques is an appropriate option; direct input of organic matter and land-use conversion might aggravate soil erosion and protect soil from being eroded. For instance, when grain crops are converted into perennial grasses, it positively affects water holding and soil due to sods with erect and ridged stems. The switchgrass could decrease the sediment yield in streamflow and soil erosion, upsurge the water use and infiltration irrespective of the climate conditions in the loess gully areas signifying the advantage in soil and water conservation of perennials compared to the traditional crops in such regions (Brown et al. 2000; Cooney et al. 2017). Consequently, growing perennial grasses, especially in erosion-prone areas or slope arable land, has more potential than corn ethanol production.

6.5.4 Green House Gas Emission The traditional use of biomass for fire and heat energy leads to half or unburnt biomass that emits GHG gases to the atmosphere and increases global warming. To reduce GHG emissions, which is the most significant term, is considered in bioenergy generation. Among the GHGs, CO2 , and N2 O are two chief constituents because of their vast quantity and multi-approaches of production (Dunn et al. 2013). Theoretically, net CO2 emissions resulting from the direct use of biofuels are far less than fossil fuels. The studies show that ethanol in gasoline in the USA’s transportation sector can reduce 50–80% emissions. Conversion of land from arable to second-generation bioenergy crops can result in a small decrease in CO2 emissions. The land transformation from natural grassland to first-generation bioenergy crops and short rotation coppice (SRC) presented a marked increase in CO2 emissions. Consequently, it is essential to consider the suitable bioenergy crop types and management practices when considering the mitigation of CO2 emissions. Agriculture is the largest producer of N2 O gas (Williams et al. 2010). Alike CO2 emission, land conversions are the main factors influencing N2 O emissions. Therefore, biomass utilization formed on fringe land for energy could result in a positive environmental effect on national GHG emissions. However, the corn expansion, driven by the demand for ethanol, may also stimulate the N2 O emission. Corn farming requires much more fertilizer than other crops, particularly nitrogen fertilizer, the substrate for the soil denitrification process, provoking N2 O emissions directly. Therefore, the reasonable choice of bioenergy plant type and planting locations is significant in governing the N2 O emission.

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6.6 Sustainable Development with Bioenergy The sustainability of biomass to produce bioenergy depends on the proper and improved use of feedstocks that focus on energy generation and worldwide commercialization of the bioenergy market. Sustainability of second-generation bioenergy has also been driven and supported by European and International directives and certification programs, including the Renewable Energy Directive 2009/28/EC (EURED), International Sustainability and Carbon Certification programs and standards, the Roundtable on Sustainable Biofuels, and the Global Bioenergy Partnership (Scarlat and Dallemand 2011). Countries like Canada, Sweden, and other Asian countries focus on bioenergy, mainly on biofuel production for the transportation sector. Bioenergy signifies a significant type of renewable energy. It is key to supporting the UN Sustainable Development Goals (SDGs) in climate change and energy security. The IPCC 5th Assessment Report summarizes that integrated assessment modeling indicates a high risk of failing to meet long-term climate targets without bioenergy. The importance of bioenergy is that it can improve region-wise energy access and decrease the reliability of fossil fuels for energy requirements. From per commercial point of view, bioenergy can boost agriculture and forest sectors due to the increased use of renewable resources as feedstocks for various industrial methods. It can contribute to our global climate change mitigation goals as well as other social and environmental objectives. However, bioenergy can also have negative impacts if not developed and appropriately organized. Three key worries are food security, risks that land use and land-use change from bioenergy expansion may raise carbon emissions or decrease biodiversity, and challenges in achieving economic competitiveness and providing high quality and affordable energy services. Bioenergy is multi-layered. Specific bioenergy options (such as biofuels produced from edible versus non-edible feedstocks) are not good or bad; sustainability impacts are context-specific and depend on the location and management of feedstock production systems. Luckily, significant knowledge and capability are available to administer bioenergy expansion to harness opportunities and minimize risks of negative impacts.

6.6.1 Sustainable Development Goals and Global Policies There are mainly four goals out of all seventeen sustainable goals on which bioenergy impacts directly. • Goal-2: End hunger, achieve food security and improved nutrition and promote sustainable agriculture, • Goal-7: Ensure access to affordable, reliable, sustainable, and modern energy for all, • Goal-13: Take urgent action to combat climate change and its impacts,

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• Goal-15: Protect, restore, and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss. Policies and measures should be promoted to expand bioenergy markets that support sustainable development goals on a global scale to achieve sustainable development goals. Ensuring safety for regional and international biodiversity, promoting multiple ecosystems, and proper land management is required. Involvement of individual farmers, landowners, policymakers, and other local and national stakeholders is necessary. Information and organization experience in biomass energy should be shared across regions to encourage best practices. This would enable the development of locally adapted management guidelines.

6.6.2 Sustainable Bioenergy Market Expansion Measures To increase the market expansion for bioenergy, some methods can increase the yield and promote multi-purpose land use, meet the demand for food for the rapidly growing population, sufficient food stock for animals, and biomass required for bioenergy generation. Sharing agricultural-based services will help promote modern farming techniques and develop sound management practices at a native level, including agroforestry strategies for growing a mix of high-yielding food and fuel crops in different soils and climates. Land security can give farmers financial incentives to manage their local land for high yields while satisfying soil productivity. To maintain the hassle-free production and transportation of agro products, costeffective approaches for harvesting and transportation can be promoted. The forest and agriculture residue will be utilized appropriately and should become part of higher value, incentives for using agricultural waste, and promoting the guidelines for their sustainable use are some examples that can be helpful. Easy loans for machinery can further support the ramping up of bioenergy systems that utilize residues and waste as feedstock. Another significant issue is food security for the growing population, which can be reduced by using modern harvesting techniques that decrease the losses in food production. Increasing the cold storage facilities, enhancing the transportation infrastructure to safely deliver food to markets, disregarding defective food items to encourage their sale, modifying labels, so food is not cast off prematurely, and enlightening consumers for better food purchases. Governments and practitioners’ guiding principles and support packages exist, demonstrating many valuable ways to sustainably meet food, fodder, and biofuel demand in the coming periods (Fig. 6.7). Global biofuel production will decrease in 2020 because of the pandemic situation across the globe. The forecasted average value for 2025 is somewhere approximately 182 billion liters. Ethanol shares the highest value of 119 billion liters while biodiesel and HVO (hydrotreated vegetable oil, also known as renewable diesel) is 46 and 17 billion liters, respectively, for 2025, as shown in Fig. 6.8.

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6.7 Conclusions and Future Scope The dependence on fossil fuels for so many years proved fatal for the environment and humans. To change the scenario, the sustainable implementation of renewable energy sources is inevitable. The production and utilization of bioenergy in every sector to achieve the natural environment condition are needed today. China is leading in every sector of renewable energy generation and cutting off its dependencies on fossil fuels to a great extent, with a total capacity of 790 GW of renewable power by the end of 2019. The power generation capacity from biomass intensified sharply from 1.4 GW in 2006 to 14.88 GW in 2017. India’s renewable energy capacity is 136 gigawatts (GW), approximately 36% of our total capacity. By 2022, the share of renewable capacity will rise to over 220 GW as per the Indian government; about 32% of India’s total principal energy is from Biomass. About 70% of the country’s population rest on biomass for its energy requirements. The biorefinery concept provides an alternative to industrial processing, keeping in mind that the industrial process generates a significant amount of waste, utilizing that in other industries such as construction uses fly ash and furnace slag from coal-based power plants and steel industries. The worldwide capability of bioenergy plants summed about 140 GW. Bioenergy is one of the significant contributors to renewable energy demand; traditional biomass use in developing countries and more modern uses for biomass by both developed and developing countries in almost all the sectors account for a large part of bioenergy consumption. The Paris climate change agreement is now accepted by many more countries that helps in boosting the bioenergy market at a significant level. Fossil fuels emit many greenhouse gases in the energy sector, while biofuel and biogas GHG emissions are less on comparative analysis. The bioenergy market is approximately 345 billion USD; expecting growth is nearly 627 billion USD by 2017 with an 8% cumulative annual growth rate, an optimistic future hope for both the bioenergy market and environment.

References Biofuels production growth by country/region—Charts, data and statistics—(IEA). Available online at https://www.iea.org/data-and-statistics/charts/biofuels-production-growth-bycountry-region Brennan L, Owende P (2010) Biofuels from microalgae—a review of technologies for production, processing, and extractions of biofuels and co-products. Renew Sustain Energ Rev 14(2):557–77. https://doi.org/10.1016/j.rser.2009.10.009 Brown RA et al (2000) Potential production and environmental effects of switchgrass and traditional crops under current and greenhouse-altered climate in the Central United States: a simulation study. Agric Ecosyst Environ 78(1):31–47. https://doi.org/10.1016/S0167-8809(99)00115-2 Cooney D et al (2017) Switchgrass as a bioenergy crop in the Loess Plateau, China: potential lignocellulosic feedstock production and environmental conservation. J Integr Agric 16(6):1211–26. https://doi.org/10.1016/S2095-3119(16)61587-3 Dunn JB et al (2013) Land-use change and greenhouse gas emissions from corn and cellulosic ethanol. Biotechnol Biofuels 6(1):51. https://doi.org/10.1186/1754-6834-6-51

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Graham PJ et al (2003) Wood-ethanol for climate change mitigation in Canada. Appl Biochem Biotechnol 105(1–3):231–42. https://doi.org/10.1385/ABAB:105:1-3:231 Hiloidhari M et al (2014) Bioenergy potential from crop residue biomass in India. Renew Sustain Energ Rev 32:504–12. https://doi.org/10.1016/j.rser.2014.01.025 Hoekman SK, Broch A (2018) Environmental implications of higher ethanol production and use in the U.S.: a literature review. Part II—Biodiversity, land use change, GHG emissions, and sustainability. Renew Sustain Energ Rev 81:3159–77. https://doi.org/10.1016/j.rser.2017.05.052 IEA Technology Roadmap (2017) IEA Technology Roadmap. Available online at https://www.iea. org/publications/freepublications/ International Energy Outlook (2020). Available online at https://www.eia.gov/outlooks/ieo/ Jiang D, Hao M, Fu J et al (2014) Spatial-temporal variation of marginal land suitable for energy plants from 1990 to 2010 in China. Sci Rep 4:5816. https://doi.org/10.1038/srep05816 Market and Industry Trends—Renewables 2019 global status report (2019). Available online at https://www.ren21.net/gsr-2019/chapters/chapter_03/chapter_03/#sub_1_2 N.S Energy—Top five states for solar power production across India profiled (2021). Available online at https://www.nsenergybusiness.com/features/top-states-solar-power-production-india/ Ozturk M et al (2017) Biomass and bioenergy: an overview of the development potential in Turkey and Malaysia. Renew Sustain Energ Rev 79:1285–302. https://doi.org/10.1016/j.rser. 2017.05.111 Paneque M (2017) Bioenergy—a sustainable and reliable energy source. Agric Res Technol Open Access J 4(4). https://doi.org/10.19080/ARTOAJ.2017.04.555642 Prasad S et al (2007) Ethanol production from sweet sorghum syrup for utilization as automotive fuel in India. Energ Fuels 21(4):2415–20. https://doi.org/10.1021/ef060328z Ragauskas AJ (2006) The path forward for biofuels and biomaterials. Science 311(5760):484–89. https://doi.org/10.1126/science.1114736 Rajaram S, Varma A (1990) Production and characterization of xylanase from Bacillus thermoalkalophilus grown on agricultural wastes. Appl Microbiol Biotechnol 34(1):1990. https://doi.org/ 10.1007/BF00170939 Ramaswami A et al (2011) Two approaches to greenhouse gas emissions foot-printing at the city scale. Environ Sci Technol 45(10):4205–06. https://doi.org/10.1021/es201166n REN21. Renewables 2020 Global Status Report. Available online at https://www.ren21.net/gsr2020 Sánchez ÓJ, Cardona CA (2008) Trends in biotechnological production of fuel ethanol from different feedstocks. Bioresour Technol 99(13):5270–95. https://doi.org/10.1016/j.biortech. 2007.11.013 Scarlat N, Dallemand J-F (2011) Recent developments of biofuels/bioenergy sustainability certification: a global overview. Energ Policy 39(3):1630–46. https://doi.org/10.1016/j.enpol.2010. 12.039 Soltero VM et al (2018) Potential of biomass district heating systems in rural areas. Energy 156:132– 43. https://doi.org/10.1016/j.energy.2018.05.051 Traffic and Public Transport Authority—Technology and biogas use in Sweden, City of Gothenburg. Available online at https://213.229.136.11/bases/ainia_agrobiomet.nsf/0/10AFAFA77AE1EDE CC1257651007BFA83/$FILE/Trendsetter.pdf Williams AG et al (2010) Environmental burdens of producing bread wheat, oilseed rape, and potatoes in England and wales using simulation and system modelling. Int J Life Cycle Assess 15(8):855–68. https://doi.org/10.1007/s11367-010-0212-3 Wu Y, Liu S (2012) Impacts of biofuels production alternatives on water quantity and quality in the Iowa River Basin. Biomass Bioenerg 36:182–91. https://doi.org/10.1016/j.biombioe.2011. 10.030 Wu Y et al (2012) Identifying potential areas for biofuel production and evaluating the environmental effects: a case study of the James River Basin in the Midwestern United States. GCB Bioenerg 4(6):875–88. https://doi.org/10.1111/j.1757-1707.2012.01164.x

Chapter 7

Impact of Emulsified Bio-Fuel on the Environment A. R. Pradeep Kumar, N. Shankar Ganesh, and P. Vignesh

Abstract The emulsified fuels are homogeneous fuel of two immiscible liquids. The primary fuel would be the petroleum fossil fuel, and secondary fuel would be water or wood pyrolysis oil. The emulsified fuels are prepared considering the stringent emission norms and rapid depletion of fossil fuels. The immiscible fluids are prepared as a homogeneous fuel, by adding surfactants (surface active agents). The surface active agents have been chosen, by calculating the Hydrophilic–Liphophilic Balance (HLB) number to determine the type of emulsion. For a basic research to check the suitability of the primary and secondary fuel, 950 ml of petroleum fossil fuel, 50 ml of water, and 1% by volume of surfactants are taken in a beaker and mixed thoroughly at a speed of 5000 rpm in a mixer grinder. The solution obtained will appear like a precipitate, white in color which will be in observation for 24 h to see the separation. If there is a separation, then the surfactants must be changed and quantity may be slightly altered until it becomes a homogeneous solution without separation for 24 h. The fuel then will be tested for the basic properties such as density, viscosity, specific gravity, flash and fire point, and calorific value. A single cylinder naturally aspirated diesel engine will be used for experimental purpose. The engine will be flushed out and operated with petroleum fossil fuel as a primary operation until steady state is obtained. In the steady state condition, the base readings for performance parameters such as brake thermal efficiency and specific fuel consumption will be taken. For combustion characteristics, heat release rate and pressure and crank angle diagram will be plotted. For emission characteristics, Unburnt Hydrocarbon emission, Carbon Monoxide emission, smoke opacity, and oxides of nitrogen emission were tested. The proportion of water would be increased to 10 and 15 ml, and all the characteristics were analyzed, and the readings will be A. R. Pradeep Kumar (B) Department of Mechanical Engineering, Dhanalakshmi College of Engineering, Chennai, India e-mail: [email protected] N. Shankar Ganesh Department of Mechanical Engineering, Kingston College of Engineering, Vellore, India P. Vignesh Department of Mechanical Engineering, Indira Institute of Engineering and Technology, Tiruvallur, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_7

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compiled in a tabular column. In the analysis and discussion section, the reasons for the variation for every property will be analyzed, and justifications will be presented. The experimental study would be taken to further level by adding nano-particles which also will be discussed in the article. Keywords Emulsion · Biodiesel · Performance and characteristics · Emission control

Nomenclature CI NOx HLB DWM W/O O/W D/W N/W ADC CO UBHC

Compression Ignition Oxides of nitrogen Hydrophilic–Liphophilic balance Diesel water emulsion Water in oil emulsion Oil in water emulsion Diesel-water emulsion Nerium-water emulsion Analog to digital converter Carbon monoxide Unburnt hydrocarbon

7.1 Introduction The stringent emission norms across worldwide is the thrust for the researchers to focus more attention toward the emulsified fuels research. Most of the automotive industries are planning to stop the production of Compression Ignition (DI) engines, as it needs complex modifications in their structure to meet these emission norms. Few companies in India have already announced that the production of diesel engines will be stopped soon (https://www.firstpost.com/tech/auto-tech/maruti-suz uki-may-re-launch-diesel-vehicles-by-2021-after-discontinuing-it-in-april-20207803931.html). Later on the company announced that they may re-think about it. All these announcements about diesel engines are mainly because of the emission standards. Entry of battery operated vehicles is another threat for internal combustion engines. Though battery operated vehicles enter the automotive sector, it will not be applicable for all categories, such as heavy load trucks. In earlier decades, the alternative fuels research commenced with vegetable oils from various seeds, which was halted when the cumulative reports revealed few major problems such as clogging of injector, more smoke, and more oxides of nitrogen (NOx ) emission. Biodiesel played a vital role in the next phase of alternative fuel research. Again it is

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the extract of vegetable oil, after the chemical process known as transesterification. The biodiesel took long years of research on various seeds across the world. Almost all the seeds gave concluding remarks that the oxides of nitrogen (NOx ) and smoke emission were found to be more. Of course, few seeds were able to give out efficiency close to petroleum diesel. The reduction of oxides of nitrogen (NOx ) and smoke became a challenge for the researchers, and the research continued with various aspects, such as engine modification, and fuel modification. The researchers in the field of fuel modification arrived at a solution of introducing water in the petroleum diesel and converting it into an emulsified fuel. The emulsified fuel research is not a new one, but already have been under research before three decades. The researchers Valdmanis and Wulfthorst (https://www.firstpost.com/tech/auto-tech/maruti-suzuki-may-re-lau nch-diesel-vehicles-by-2021-after-discontinuing-it-in-april-2020-7803931.html) conducted experiments in a single cylinder direct injection diesel engine by using 20% of water blended with petroleum diesel during 1970 itself. The NOx emission is due to the peak flame temperature produced during combustion, which has to be controlled.

7.2 Literature Review In their experimental work, Bedford et al. (2000) injected water directly into the combustion chamber with the help of an Electronic Control Unit (ECU). However, there was a hydrostatic condition; water with a property of incompressible nature is being used. Ma et al. (2014) adopted fumigation method of introducing water with the intake air, in their experimental work. They have concluded that there was high dense intake mixture which resulted in high volumetric efficiency. They also mentioned that it might be due to the higher cooling effect. In fumigation, the quantity of water injected can be adjusted as per the requirement of the experiment (Gopidesi and Rajaram 2019). Adnan et al. (2012) conducted with CI engine with hydrogen as fuel with water injection. They reported that there was remarkable amount of NOx reduction. But the penalty was difficulty in starting the engine during cool condition. Abu Zaid (2004) conducted experiments with emulsified fuel in a single cylinder CI engine and reported there was improvement in the combustion efficiency. He also mentioned that there was an increase in brake thermal efficiency by 3.5% and decrease in exhaust gas temperature when the water content was increased to 20% by volume. In his previous research (Abu-Zaid 2003), he reported that high pressure steam generated due to the continuous explosion of water particle surrounded by the petroleum diesel. Niko Samec et al. (2002) conducted analytical as well as experimental investigation to study the combustion characteristics of water-in-oil fuel. They have reported that there was an effect on the ignition reaction due to the chemical kinetics.

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Fig. 7.1 Schematic representation of water-in-oil (W/O) emulsion

7.3 Emulsified Fuel 7.3.1 Major Classification of Emulsions There are many classifications of emulsified fuels. However, this paper discusses only the major classification of emulsion. They are water-in-oil (W/O) emulsion and oil-in-water (O/W) emulsion.

7.3.1.1

Water-in-Oil (W/O) Emulsion

In water-in-oil (W/O) emulsion, oil will be in the continuous phase, whereas water will be in dispersed phase. In simple version, the water droplets will be surrounded by the continuous phase of oil (Fig. 7.1).

7.3.1.2

Oil-in-Water (O/W) Emulsion

In oil-in-water (O/W) emulsion, water will be in the continuous phase, whereas oil will be in dispersed phase. In simple version, the droplets of oil will be surrounded by continuous phase of water (Fig. 7.2). Fig. 7.2 Schematic representation of oil-in-water (O/W) emulsion

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7.4 Hydrophilic–Liphophilic Balance (HLB) The petroleum diesel and water are immiscible. Moreover, emulsified fuels are inherently unstable. Hence to make it as a homogeneous fuel, surface active agents are used. There is a possibility of separation of the primary and secondary fuel depending upon the preparatory method. The surface active agents are shortly known as surfactants. These surfactants have a value based on their chemical composition. In an experimental research, Zeng and Lee (2006) mentioned that the surfactants should be selected with a precaution that they should take part in the combustion and get burnt completely without soot formation. Based on which, the Hydrophilic–Liphophilic Balance (HLB) number will be calculated, and the surfactants will be chosen for the preparation of emulsion. The surfactants ensure the dispersion of the water droplets in the continuous phase of oil and vice versa. The most commonly used surfactants are span and tween. The span is known by its chemical name “sorbitan ester” and tween by its chemical name “polyethoxylated sorbitan ester.” In the previous researches by Nadeem et al. (2006), Lif and Holmber (2006), there was an identical statement that the surfactants should not affect the properties of fuel and should burn completely without producing emission gases. Pradeep Kumar et al. (2015) used the Span 80 and Tween 80 as the surfactants by 1% by volume in total quantity. They have reported that there was considerable reduction in NOx as well as smoke. Vellaiyan and Amirthagadeswaran (2016) have also used the Span 80 and Tween 80 with the HLB number of 6.4 and reported that the emulsion was stable. Khan et al. (2014) used the Span 80 and Tween 85 with the HLB number of 6.3 and reported a remarkable results in their research work. The HLB number is the parameter used to determine the category of emulsion. For calculating the HLB number, there is a simple expression as given below.  HLB Number = (Quantity of Surfactant 1) ∗ (HLB number of Surfactant 1)]  (Quantity of Surfactant 2) ∗ (HLB number of Surfactant 2)] + (Quantity of Surfactant 1) + (Quantity of Surfactant 2) Table 7.1 (https://en.wikipedia.org/wiki/Hydrophilic-lipophilic_balance) has given below presents the detail of HLB number of various surfactants. Table 7.1 HLB number of various surfactants

S. No

Name of surfactant

1

Span 20

8.6

2

Span 80

4.3

3

Tween 20

16.7

4

Tween 80

15.6

HLB number

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Fig. 7.3 Diagrammatic representations of micro-explosion phenomena

For producing a W/O emulsion, the HLB number should range from 3 to 6, whereas for producing a O/W emulsion, the HLB number should range from 8 to 16 (https://en.wikipedia.org/wiki/Hydrophilic-lipophilic_balance). In this experiment, Span 80 and Tween 80 surfactants have been used for preparing the W/O emulsion water-in-diesel emulsion.

7.5 The Concept of Micro-explosion Figure 7.3 illustrates the concept of micro-explosion which happens when the W/O emulsion injected into combustion chamber. It happens mainly because of the difference in boiling points of fuel in the continuous phase and water in dispersed phase. In an earlier experiment by Avedisian (1997) during the year 1997, it was observed that the fuel droplets were very small; hence, there is a possibility of complete combustion during the micro-explosion process. In W/O emulsion water in the dispersed phase, and hence it explodes when the combustion started. The water droplets explode, and the secondary atomization takes place which results in a very fine atomized fuel droplets. Anna and Krister (2006) stated there is a possibility of slowing down the micro-explosion process because of degassing the emulsified fuel, as the dissolved may reduce the superheat temperature of water.

7.6 Preparation of Emulsified Fuel 7.6.1 Diesel-Water Emulsion The diesel-water emulsion has been prepared by mixing required quantity of petroleum diesel and varying quantity of water (5, 10, and 15%) by volume, along with the surfactants (0.5% of Span 80 and 0.5% of Tween 80). The speed of rotation of the stirrer should range from 5000 to 10,000 rpm. The process will be continued

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Fig. 7.4 Diesel-water emulsion

Fig. 7.5 Biodiesel-water emulsion

for 10 min. After this process, the sample fuel has been collected in a test tube and kept for visual observation for 24 h to monitor if there is any separation (Fig. 7.4).

7.6.2 Bio-Diesel Water Emulsion The nerium biodiesel has been prepared by transesterification process. The biodieselwater emulsion has been prepared by mixing required quantity of biodiesel and varying quantity of water (5, 10, and 15%) by volume, along with the surfactants (0.5% of Span 80 and 0.5% of Tween 80). The speed of rotation of the stirrer should range from 5000 to 10,000 rpm. The process will be continued for 10 min. After this process, the sample fuel will be collected in a test tube and kept for visual observation for 24 h to monitor if there is any separation (Fig. 7.5).

7.6.3 Comparison of Properties for Emulsified Fuels In the second phase of experiments, the nerium biodiesel is used 20% by volume with petroleum diesel to prepare the emulsion. As the research with biodiesel has reached

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almost a saturation level, a new attempt of emulsion with biodiesel has been done in this experimental work. When any biodiesel is blended with petroleum diesel, the properties of the biodiesel should be compared to check the compatibility. In this regard, the nerium biodiesel has been checked with few other biodiesel fuels and has been shown in Table 7.2. Figures 7.6 and 7.7 represent the flash point test and viscosity test taken to find the properties of reference and test fuels. Table 7.3 compares the essential properties for the diesel-water emulsion and nerium-water emulsion with varying proportions of water. The D/W1, D/W2, and D/W3 have the water content of 5%, 10%, and 15%, respectively. In biodieselwater emulsion, the proportion of biodiesel is kept constant (20% by volume), and the petroleum diesel content has been reduced accordingly. N/W1 has composition of 74% of petroleum diesel, 20% of nerium biodiesel, 1% of surfactants, and 5% of water. N/W2 has the composition of 69% of petroleum diesel, 20% of nerium biodiesel, 1% of surfactants, and 10% of water. The N/W3 has the composition of 64% of petroleum diesel, 20% of nerium biodiesel, and 15% of water. Table 7.2 Comparison of nerium oil with other oils S. No

Property

Petroleum diesel

Nerium oil

Jatropha oil

Pongamia oil

Mahua oil

1

Kinematic viscosity at 40 °C, cSt

3.06

3.53

4.64

4.83

6.2

2

Calorific value, kJ/kg

43,196

42,821

36,693

36,407

34,594

kg/mm3

3

Density at 15 °C,

830

850

876

904

910

4

Flash point, °C

57

71

84

86

90

5

Fire point, °C

63

82

91

95

103

Fig. 7.6 Flash point test

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Fig. 7.7 Viscosity test

Table 7.3 Comparison of essential properties for the diesel-water emulsion and nerium-water emulsion with varying proportions of water Property

Diesel

D/W1

D/W2

D/W3

N/W1

N/W2

N/W3

Calorific value, MJ/kg

43.1

40.61

38.47

36.34

40.52

38.36

36.18

Density, kg/m3

831

832

835

840

837

842

843

Flash point, °C

57

59

61

62

71

72

74

Fire point, °C

63

65

67

69

83

85

87

7.7 Experimental Setup A single cylinder naturally aspirated direct injection diesel engine has been used for this experimental work. The brand name and model of the engine used is Kirloskar SV1. Figure 7.8 shows the schematic diagram of experimental setup. Since two different fuels are going to be tested, two separate fuel tanks have been used. A three-way cock is used to regulate the fuel supply. A probe inserted in the exhaust pipe is connected to smoke meter and gas analyzer. The gas analyzer gives the output of Unburnt Hydrocarbon emission (UBHC), Carbon Monoxide (CO), and oxides of nitrogen (NOx ). The smoke meter gives smoke opacity emission in Hartridge Smoke Units (HSU). A pressure pick-up sensor and crank angle decoder give the feedback to Analog to Digital Converter (ADC). The ADC further feeds the data to a computer which is installed with data acquisition software to plot the in-cylinder pressure and crank angle graphs.

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Fig. 7.8 Schematic diagram of experimental setup

7.8 Experimental Procedure The engine will be flushed out before commencing the each experiment. The engine is tested for its default (manufacturer) settings. All the measuring equipments have been checked for its calibration and accuracy. Before experiment, the engine will be allowed to run till the stable condition is reached. The engine load was adjusted from zero load condition to full load condition. The experimental procedure is further explained by the flowchart given in Fig. 7.9. Figure 7.9 illustrates the experimental procedure. Initially, the baseline readings have been taken with petroleum diesel, which has been considered as reference fuel. Then, the first phase of experiments has been conducted with diesel-water emulsion as test fuel. The second phase experiments have been conducted with bio-diesel water

Fig. 7.9 Flowchart of experimental procedure

7 Impact of Emulsified Bio-Fuel on the Environment Table 7.4 Uncertainty of the equipments

Parameters

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Systematic errors (±)

Speed

1 ± rpm

Load

± 0.1 N

Time

± 0.1 s

Brake power

± 0.6 kW

Temperature

± 1°

Pressure

± 1 bar

NOx

± 10 ppm

CO

± 0.02%

CO2

± 0.02%

HC

± 10 ppm

Smoke

± 1 HSU

emulsion as the test fuel. The performance, combustion, and emission parameters have been studied with both the test fuels. The results have been compared with reference fuel. Table 7.4 describes the uncertainty of the equipments used for this experimental work.

7.9 Results and Discussion This section compares the performance, combustion and emission parameters of petroleum diesel (reference fuel), with test fuels (D/W and N/W emulsions). (a) Performance Parameters (i) Comparison of Brake Thermal Efficiency (BTE) Figure 7.10a, b shows the graphs between the brake thermal efficiency of reference (petroleum diesel) and test (D/W and N/W) fuels. In both the curves, the BTE is maximum at three fourth of load condition for both test and reference fuels. From Fig. 7.10a, it is observed that there was an increase in BTE by 1.21%, 3.08%, and 5.3% with D/W1, D/W2, and D/W3, respectively, when compared with petroleum diesel. The water droplets have been converted into steam which created additional thrust on the piston. This may be attributed to the marginal increase of BTE with D/ W emulsion fuel. In the experimental work by Anna and Krister (2006), they have mentioned that addition of water droplets with diesel fuel, created a positive effect on the piston, which further increased the efficiency during combustion.

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Fig. 7.10 a Brake power versus BTE (D/W). b Brake power versus BTE (N/W)

From Fig. 7.10b, it is observed that there was an increase of 1.12%, 2.78%, and 4.67% of BTE with N/W1, N/W2, and N/W3, respectively. (ii) Comparison of Specific Energy Consumption (SEC) Figure 7.11a, b shows the graph between brake power and Specific Energy Consumption (SEC) of reference and test fuels. From Fig. 7.11a, it is found that there is an increase of SEC, when D/W emulsion fuel is used. The increase in SEC was found to be 11.12%, 12.18, and 12.48 with D/W1, D/W2, and D/W3, respectively. Since water has no calorific value, there is more SEC with D/W fuels when compared with petroleum diesel. It is found from Fig. 7.11b that there was further increase of SEC with N/W fuel, as the calorific value is further decreased due to the blending (20%) of nerium

Fig. 7.11 a Brake power versus SEC (D/W). b Brake power versus SEC (N/W)

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biodiesel fuel with petroleum fuel. Due to higher viscosity of N/W than D/W, the micro-explosion has not given same results as that of D/W. (b) Combustion Parameters (i) In-cylinder Pressure versus Crank Angle The comparison of crank angle versus in-cylinder pressure has been shown in Fig. 7.12a, b. It is observed that there as an increase in peak pressure when the test fuel D/W has been used. The increase was found to be 1.02%, 2.85%, and 4.91%, respectively, when compared with petroleum diesel. Drastic vaporization occurred after the injection of fuel, fragments the fuel droplets which led to the secondary atomization. Also, the water molecules dissociate into hydrogen and oxygen which creates thrust on piston and increases the pressure. Lif and Krister (2006) conducted the experiments with emulsified fuel. They had mentioned that addition of water created an additional torque over complete rpm range. They also stated that there was conversion of water into steam, which created additional pressure. From Fig. 7.12b, it is observed an increase in in-cylinder pressure by 0.93%, 1.80%, and 2.72% for N/W1, N/W2, and N/W3, respectively, when compared with reference fuel. It is also observed that the increase is not as much as like D/W fuel. The reason for this may be attributed to the higher viscosity of biodiesel fuel. (ii) Heat Release Rate (HRR) Heat release rate (HRR) during combustion has been compared for test, and reference has been compared in Fig. 7.13a, b. It is found that the maximum HRR for petroleum diesel is 81.2 J/Deg. CA. It is also observed there is decrease in HRR 1.1 J/Deg. CA, 2.8 J/Deg. CA, and 5.73 J/Deg. CA, respectively. The reason for reduction in HRR with D/W fuel might be attributed to release of water molecules during micro-explosion during combustion. In a previous research by Sachudananthan and Jayachandran (2007), the almost closer results have been reported. They have made

Fig. 7.12 a Crank angle versus in-cylinder pressure (D/W). b Crank angle versus in-cylinder pressure (N/W)

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Fig. 7.13 a Crank angle versus HRR (D/W). b Crank angle versus HRR (N/W)

a trial of 30% of water (by volume) addition and stated that longer ignition delay and hence more quantity of fuel needed to be burned during premixed combustion. The HRR of N/W fuel is found to be slightly higher than D/W fuel. It is also observed an improvement in diffusion combustion as the N/W emulsion has higher viscosity than D/W emulsion as well as reference fuel. Hence, the heavier molecules of N/W emulsion caused a higher HRR than D/W emulsion fuel. The lowest HRR was wound with N/W3 which showed a reading of 78.3 J/Deg. CA. The slower and late burning of heavier molecules would be the reason for it. (c) Emission Parameters (i) Unburnt Hydrocarbon (UBHC) The Unburnt Hydrocarbon (UBHC) of test and reference fuels has been compared in Fig. 7.14a, b. The UBHC with any fuel is due to incomplete combustion of the fuel. The maximum UBHC is found to be 73 ppm for petroleum diesel. From Fig. 7.14a, it is observed that there was reduction in UBHC was found to be 9.45%, 12.16%, and 14.86% with D/W1, D/W2, and D/W3, respectively. There was reduction in UBHC by 8.34, 10.69, and 12.827 ppm for N/W1, N/W2, and N/W3 when compared with petroleum diesel. (ii) Carbon Monoxide (CO) Emission The comparison of Carbon Monoxide (CO) emission has been done in Fig. 7.15a, b for both reference and test fuels. From Fig. 7.15a, it is observed that the maximum CO emission was found to be 0.090% for petroleum diesel, which is reduced by 0.013%, 0.015%, and 0.017% for D/W1, D/W2, and D/W3, respectively. Nithesh (2012) conducted an experimental study and stated that there was reduced CO emission when compared with petroleum diesel and he attributed the reason that secondary atomization caused larger degree of mixing of unburnt mixture. From Fig. 7.15b, it is found that there was decrease in CO emission by 0.14%, 0.16%, and 0.20% for N/ W1, N/W2, and N/W3, respectively. In an earlier research during the year 1976 by

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Fig. 7.14 a Brake power versus UBHC (D/W). b Brake power versus UBHC (N/W)

Muller and Schlader (1976), the similar results have been obtained. The researchers have stated that it might be due to the effect of OH radicals during the formation of Carbon Monoxide. (iii) Smoke Opacity Emission Bernard and Rodica (Muller and Schlader 1976) have defined the smoke as a particle which stuck in the exhaust gas and obstructs, reflects, or refracts the light rays passed through it. Figure 7.16a, b shows the graph between brake power and smoke opacity emission of petroleum diesel and emulsified fuels. A Hartridge smoke meter has been used for measuring the smoke opacity emission; hence, Hartridge Smoke Units (HSUs) will be the measurement for smoke opacity emission, which ranges from 0 to 100. The maximum smoke opacity for petroleum diesel is found to be 53.2 HSU, which is reduced by 2 HSU, 3 HSU, and 5 HSU for D/W1, D/W2, and D/

Fig. 7.15 a Brake power versus CO emission (D/W). b Brake power versus CO emission (N/W)

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Fig. 7.16 a Brake power versus smoke opacity emission (D/W). b Brake power versus smoke opacity emission (N/W)

W3, respectively. In an experimental work by Kandasamy and Marappan (2011), it was observed that there was remarkable reduction in smoke opacity emission. The researchers have mentioned that it might be due to the absorption of heat energy by water when it get vaporized. From Fig. 7.16b, it is observed that there was reduction in smoke opacity emission by 1.46 HSU, 2.48 HSU, and 4.51 HSU for N/W1, N/W2, and N/W3, respectively. There were plenty of earlier researchers by Hsu (1986), Tadadshi et al. (1978), Greeves et al. (1977) and Vichineivsy et al. (1975) with emulsified fuels. All these researchers have reported that the smoke density have decreased 50% when compared with petroleum diesel. They have attributed the reason that due to better mixture formation of fuels. (iv) Oxides of Nitrogen (NOx ) Emission Hasannuddin et al. (2015) in their review paper mentioned paper mentioned that the fuels with the content of higher nitrogen produced more NOx emissions due to the oxidation of nitrogen. The oxides of emission (NOx ) of test fuels and reference fuel have been compared in the bar chart shown in Fig. 7.17a, b. It is observed from Fig. 7.17a that there was decrease in NOx emission by 23.35%, 26.95%, and 29.6%, with DWM1, DWM2, and DWM3, respectively, when compared to petroleum diesel. The same results have been obtained by Roila and Choo (2008). They have concluded that the lower HRR during the premixed combustion might be the reason for this effect. It is also observed from Fig. 7.17b that there was reduction in NOx emission by 9.7%, 12.5%, and 23% with N/W1, N/W2, and N/W3 respectively. Compared with reference fuel. Prakash et al. (2011), in their experimental work, mentioned that blending of water with petroleum diesel reduced the combustion temperature which further led to reduced NOx emission.

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Fig. 7.17 a Brake power versus NOx emission (D/W). b Brake power versus NOx emission (N/ W)

7.10 Conclusion The experimental results with emulsified fuels reveal that it is possible to blend water up to 15% with petroleum diesel as well as biodiesel fuel. It has been also found that simultaneous reduction of smoke and NOx emission is possible with water emulsified fuels. Summary of the experimental results is as detailed below. • There was an increase in brake thermal efficiency both in D/W as well as N/W emulsion fuels. • The SEC was found to be more with emulsified fuels when compared with petroleum diesel because of lower calorific value. • The pressure developed with the emulsified fuels was found to be high when compared to petroleum diesel, because of conversion water molecules into steam, which creates additional thrust on the piston. • The HRR was found to be lesser and diffusion combustion with N/W was found to be more, as it contains heavier molecules than D/W emulsion fuel as well as petroleum diesel. • The emission parameters such as Unburnt Hydrocarbon (UBHC), Carbon Monoxide (CO), smoke opacity, and oxides of nitrogen emission were found to be drastically reduced when compared to petroleum diesel. The reduced emission with water emulsified fuel gives a hope to the researchers to continue the research with various biodiesel fuels.

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7.11 Scope for Future Research In the present experiment, all the tests have been carried out with manufacturer’s settings. Optimizing with various modifications in the engine may give out better results. Blending the nano-additives might enhance the combustion reaction still better. Insulating the combustion chamber may lead to restore the heat produced during combustion. Disclosure Statement No potential conflict of interest was reported by the authors.

References Abu-Zaid M (2003) An experimental study of the evaporation characteristics of emulsified liquid droplets. Heat Mass Transfer 1(1):1–1 Abu-Zaid M (2004) Performance of single cylinder, direct injection diesel engine using water fuel emulsions. Energ Convers Manage 45(5):697–705 Adnan R, Masjuki HH, Mahlia TMI (2012) Performance and emission analysis of hydrogen fueled compression ignition engine with variable water injection timing. Energy 43(1):416–426 Avedisian CT (1997) In: Proceedings of the 4th international microgravity combustion workshop, Cleveland, OH, USA, 19–21 May 1997 Awang R, Yuen C (2008) Water-in-oil emulsion of palm oil biodiesel. J Palm Oil Res 20:571–576 Bedford F, Rutland C, Dittrich P, Raab A, Wirbeleit F (2000) Effects of direct water injection on DI diesel engine combustion, pp 1–10. SAE Pap 2000-01-29 Bernard C, Rodica B (1999) Diesel engine reference book, 2nd edn. Butterworth Heinemann, Oxford Gopidesi RK, Rajaram PS (2019) A review on emulsified fuels and their applications in diesel engine. Int J Ambient Energ. https://doi.org/10.1080/01430750.2019.1667435 Greeves G, Khan IM, Onion G (1977) Effects of water introduction on diesel engine combustion and emissions. Symp (Int.) Combust 16:321–336 Hasannauddin AK, Wira JY, Srithar RY, Sarah S, Ahmad MI, Aizam SA, Aiman MAB, Zahari M, Watanabe S, Azrin MA, Mohd SS (2015) Effect of emulsion fuel on engine emissions—a review. Clean Techn Environ Policy. https://doi.org/10.1007/s10098-015-0986-x Hsu BD (1986) Combustion of water-in-diesel emulsion in an experimental medium speed diesel engine. SAE Paper No. 860300 https://www.firstpost.com/tech/auto-tech/maruti-suzuki-may-re-launch-diesel-vehicles-by-2021after-discontinuing-it-in-april-2020-7803931.html. Last visited 8th June 2021 https://en.wikipedia.org/wiki/Hydrophilic-lipophilic_balance. Last visited 9th June 2021 Kandasamy Kannan T, Gounder MR (2011) Thevetia Peruviana biodiesel emulsion used as a fuel in a single cylinder diesel engine reduces NOx and smoke. Therm Sci 15(4):1185–1191 Khan MY, Abdul Karim ZA, Hagos FY, Aziz ARA, Tan IM (2014) Review article: current trends in water-in-diesels emulsion as a fuel. Sci World J 2014:15 Lif A, Holmberg K (2006) Water-in-diesel emulsions and related systems. Adv Colloid Interface Sci 123–126(1):231–239 Ma X, Zhang F, Han K, Zhu Z, Liu Y (2014) Effects of intake manifold water injection on combustion and emissions of diesel engine. Energ Procedia 61:777–781 Muller DK, Schlader AF (1976) The effect of steam on flame temperature, burning velocity and carbon formation in hydrocarbon flames. Combust Flame 27:205–215

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Nadeem M, Rangkuti C, Anuar K, Haq MRU, Tan IB, Shah SS (2006) Diesel engine performance and emission evaluation using emulsified fuels stabilized by conventional and Gemini surfactants. Fuel 85:2111–2119 Pradeep Kumar AR, Annamalai K, Premkartikkumar SR, Senthur NS (2015) Effect of emulsified fuel on performance and emission characteristics in di diesel engine. J Chem Pharm Sci 7:215– 218 Prakash R, Singh RK, Murugan S (2011) Experimental studies on a diesel engine fueled with wood pyrolysis oil diesel emulsions. Int J Chem Eng Appl 2(6):395–399 Sachuthananthan B, Jeyachandran K (2007) Combustion, performance and emission characteristics of water-biodiesel emulsion as fuel with DEE as ignition improver a DI diesel engine. J Environ Res Dev 2(2):165–172 Sameca N, Kegla B, Dibbleb RW (2002) Numerical and experimental study of water/oil emulsified fuel combustion in a diesel engine. Fuel 81:2035–2044 Singh NK (2012) An experimental investigation of diesel emulsions as fuel in small direct injection compression ignition engines. MIT Int J Mech Eng 2:39–44 Tadashi M, Yasushi M, Minoru T, Noboru M (1978) Experimental reduction of NOx, smoke and BSFC in a diesel engine using uniquely produced water (0–80%) to fuel emulsion. SAE Paper No. 780224 Valdmanis E, Wulfhorst DE (1970) The effects of emulsified fuels and water induction on diesel combustion. SAE Paper No. 700736 Vellaiyan S, Amirthagadeswaran KS (2016) The role of water-in-diesel emulsion and its additives on diesel engine performance and emission levels: a retrospective review. Alex Eng J 55(3):2463– 2472 Vichnievsky R, Murat M, Parois A, Dujeu M (1975) Employment of fuel–water emulsions in compression ignition engines. In: Presented at CIMAC conference, Barcelona, Spain Zeng Y, Lee CF (2006) Modeling droplet breakup processes under micro-explosion conditions. In: Proceedings of the 31st international symposium on combustion, vol 31, pp 2185–2193

Chapter 8

Recent Development of Biomass Energy as a Sustainable Energy Source to Mitigate Environmental Change Simatsidk Haregu, Yigzaw Likna, Degafneh Tadesse, and Chandran Masi

Abstract Recently, there is an upsurge of research on energy production options to meet the global energy demand. For decades, fossil fuels are being used as a dominant energy source which accounts for about 80% of global energy production. The continued exploitation of fossil fuel for energy production potentially harming natural resources, highly impacts the environment, and causes global warming. This becomes a critical issue for the world to maintain the natural ecosystem and necessities research for an alternative eco-friendly energy source. In this endeavor, sustainable energy productions such as biofuel, biogas, and bioenergy have gained great attention to sustain the global energy demand. The recent tremendous research can be the testimony for the advantage of bioenergy which is a promising energy source alternative to fossil fuels. Bioenergy is a renewable form of energy produced from biomass resources such as woods, crops, residues, waste, and algae offer the advantage of reducing dependency on fossil fuels and has a big global role to mitigate the emission of greenhouse gas concentrations and provide the best ecosystem services. Albeit bioenergy productions from biomass become a potential option to reduce the reliance on fossil fuel, and it has some environmental implications on biodiversity such as quality of land and water resources. The write-up in the chapter gears off a discussion on the impact of bioenergy production on the environment and its significant role in climate change. The content is streamlined toward the production of bioenergy from any biological source, its benefit and consequences to the environment, and its contribution to reducing global warming. An attempt is also

S. Haregu · D. Tadesse · C. Masi (B) Department of Biotechnology, College of Biological and Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia e-mail: [email protected] S. Haregu · C. Masi Center of Excellence, Bioprocess and Biotechnology, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia Y. Likna Department of Environmental Engineering, College of Biological and Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_8

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made to highlight the management practice approach to reduce the negative impact of bioenergy on the environment for sustainable development. Keywords Biogas · Eco-friendly · Fossil fuel · Global energy · Global warming · Greenhouse

Abbreviations AD BCR BPFR Ca(OH)2 CaCO3 CH4 CHP CNG CNG CO CO2 FBR GHG GRT H2 O H2 S HCO3 LBG LBM LCA LNG LNG Mg (OH)2 N2 NaOH NH3 PEG VFA

Anaerobic digestion Bubble column reactor Biofilm plug flow reactor Calcium hydroxide Calcium carbonate Methane Combined heat and power Compressed natural gas Compressed natural gas Carbon monoxide Carbon dioxide Fixed bed reactor Greenhouse gas Gas retention time Water Hydrogen sulfide Bicarbonate Liquefied biogas Liquefied biomethane Life cycle assessment Liquid natural gas Liquid natural gas Magnesium hydroxide Nitrogen Sodium hydroxide Ammonia Polyethylene glycol Volatile fatty acids

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8.1 Introduction The world population is increasing from 1.6 billion in 1900 to 7.6 billion today (Ashokkumar et al. 2019). The overtime increasing global population, rapid industrialization, and urbanization have led to rapidly rising global energy demand (Wang et al. 2020). Responding to the energy demand of the ever-increasing population and reducing the alarming global warming are the most severe challenges of the twentyfirst century. Therefore, searching options to produce energy from different sources using sustainable production strategies are needed to sustain energy security. Globally 84% of energy consumption is being generated from non-renewable sources such as coal, natural gas, hydrocarbon, and petroleum (Raza et al. 2019). However, the continued exploitation of conventional energy sources resulted in rapid depletion of the resources, and on the other side, the energy production from fossil fuel is affecting the environment and contributes to global warming, economic crises, and political crises. Moreover, these resources are finite and their reserves worldwide are depleting and in turn raise the price. Therefore, the world is confronted with twin issues such as energy insecurity, climate change that have been a serious threat and uncertainties in using fossil fuel as energy (Mathimani et al. 2017). Convectional emissions particularly, the burning of fossil fuels emit polluting gases at an alarming rate which leads to severe environmental hitches like global warming and as a consequence, a 1.211 °C temperature increase has been observed on the surface since 1880 (Dineshbabu et al. 2016; Mathimani et al. 2017). Therefore, the depletion of limited finite fossil resources is a critical issue that must be overcome by replacing it with green energy for recent periods (Abdalla et al. 2018). Albeit fossil fuel is mainly used for current energy production its limited reserves, increasing waste production and global warming concerns have led to a paradigm shift in research on the production of bioenergy from renewable resources (Tagne et al. 2021). Furthermore, traditional energy sources, such as coal and petroleum, are the first drivers for shifts in climatic patterns and cause to deterioration of the quality of land and water resources (Ale et al. 2019). Other energy sources, such as nuclear energy, pose high environmental and health risks due to potential problems of harmful radiation and disposition of nuclear waste (Ale et al. 2019). Therefore, renewable energy sources have strong potential to replace fossil fuels and meet future energy demands through which global warming; the negative impacts on socioeconomic and environmental can be reduced. Among renewable energy sources, bioenergy could offset substantial amounts of fossil fuels (Correa et al. 2020). Sustainable development is currently one of the most novel concepts in the debate between developed and developing countries who have focused on their economic growth while neglecting the imperatives of environmental protection. With the expression “sustainable development,” it is meant the use of the available resources without jeopardizing the well-being of future generations (Tagne et al. 2021). Therefore, the use of sustainable energies is being promoted as an efficient means of contributing to mitigate GHG emissions and can be considered as the main pillar for climate protection (Demirbas and Demirbas 2007).

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Alternative production chains involving the use of renewable resources are needed to reduce the dependence on petroleum and minimize the adverse effect on the environment. In this aspect, biorefineries are major phenomena as resource conversion systems. So, various technologies are employed to separate biomass resources into their building blocks (carbohydrates, proteins, triglycerides, and others), which can then be converted into biofuels and other high value-added products (Coma et al. 2017; de Sousa et al. 2020). Due to the portfolio of renewable energies, bioenergy is the best element for developing renewable energy sources. Conventionally, the combustion of biomass for heat, light, and power has been used in many parts of the world, and fuelwood is still the main component of bioenergy resources worldwide. Recently, biomass contributes 12.7% of global energy consumption. Due to the development of advanced biomass-to-energy conversion technologies like thermochemical and biochemical processes which gives more convenient energy carriers that are better adapted to the needs at the household, small organization, and industrial scale (Herrmann 2013; de Farias Silva et al. 2019a).

8.2 Current Scenarios of Global Bioenergy Productions Bioenergy production has risen in recent decades as a viable alternative to fossil fuels. Rising fuel prices, rising global energy demand, rising global warming from greenhouse gas emissions, and increased openness to renewable energy resources, as well as introducing clean energy into new markets in the face of uncertain global trade outlooks, have resulted in a paradigm shift to bioenergy production from biological sources, which could significantly reduce the aforementioned issues. According to recent predictions, non-renewable resources will be restricted by 2050, with only 14 percent of oil confirmed reserves, 72% of coal-proven reserves, and 18% of gasproven reserves remaining (Martins et al. 2019). It will vanish if countries continue to rely on fossil fuels as their sole source of energy, prompting a search for alternative energy sources. According to recent studies, renewable energy sources account for barely 14% of global energy production (Bonatto et al. 2020). According to another recent estimate, modern bioenergy accounted for over half of all renewable energy usage in 2017 (Mandley et al. 2020; Wang et al. 2020). Bioenergy currently accounts for 59 percent of all renewable energy used in the European Union, and sustainable bioenergy is gaining popularity, with output expected to increase in the future (Di Fulvio et al. 2019). Fuelwood and animal waste are the most common renewable energy sources in Turkey, which produces 1.5 million tons of biodiesel, 3 million tons of bioethanol, and 2.5–4.0 billion m3 of biogas each year. By 2030, total biomass production in the country is estimated to reach 52.5 Mtoe (Ozturk et al. 2017). Africa leads the world in overall renewable energy generation (48.8%), followed by America and Europe with 12.7% and 10.5%, respectively. Biomass is the most plentiful source of energy in Sub-Saharan Africa, covering over 70% of the continent’s total energy consumption (Hailu and Kumsa 2021). In this regard, Africa is the leading continent in the supply of biomass energy with 95.8% of the total

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energy produced from biomass-based sources (Bonatto et al. 2020). In 2017, Ethiopia became the first country in Africa to build bioenergy (waste to energy) plant in Addis Ababa, which can process 1400 tons of municipal waste and generate 185 gigawatt-hours of power each year (Bioenergy Insight 2017).

8.2.1 Bioenergy Production from Agricultural Biomass Due to its green source, cheap cost, and carbon neutrality, bioenergy produced from alternative biomass feedstocks such as agricultural leftovers, energy crops, and wood is acknowledged as one of the most important alternative energy sources (Hanssen et al. 2020). Chemical compositions of the biomass determine the suitability of the materials for bioenergy production (Yang et al. 2019). It is estimated that by 2035 (Cai et al. 2021), bioenergy will have replaced about half of the world’s gasoline and diesel to achieve the highest significant economic and environmental benefits (Cai et al. 2021). Agricultural and forestry biomass residues are cheap bioenergy substrates with less greenhouse gas (GHG) emissions and suggested that residues could meet 7–50% of bioenergy demands by 2050 and 2–30% by 2100 (Hanssen et al. 2020). The success of bioenergy development is inseparable from the supply of biomass feedstock. Most of the developed countries (Cai et al. 2021), like the USA and Brazil invest a lot of their money to improve the production types of bioenergy feedstock, such as sugarcane and corn (Mao et al. 2018). In September 2020, China pledged at the UN General Assembly to achieve carbon neutrality by 2060 (China Daily 2020). Cassava is regarded as a potent bioenergy feedstock in China due to its capability of drought resistance, easy cultivation, and high starch content (Ye et al. 2017). To get a huge supply of cassava, the Chinese government actively promotes the integration between the farmer and the bioenergy producer. The “company + farmer” integration systems are considered as an effective mechanism to expand the scale of cassava cultivation while ensuring that the bioenergy producers can obtain an excess supply of cassava for the production of bioenergy (Ye et al. 2017). Renewable Fuel Standard (RFS) of producing 136 billion liters of biofuels by 2022 under the Energy Independence and Security. Even though corn has been the major feedstock for ethanol production (Emmanuel et al. 2015), there is growing recognition that relying on corn as the only feedstock for ethanol is not sustainable and profitable because of its negative impacts on the environment and food prices (Khanna et al. 2010). As a result, the RFS mandates those 79 billion liters of biofuels should produce from non-corn feedstocks and at least 61 billion liters from cellulosic feedstocks, such as crop residues, dedicated energy crops, and wood products (Emmanuel et al. 2015). Moreover, these potential energy crops and crop residue must be derived from agricultural land cleared or cultivated before qualifying for sustainable fuel credit under RFS (Abbott et al. 2008). However, conversion of cellulosic biomass to fuel is not yet commercially viable, considerable research is underway on high-yielding feedstock sources that could provide huge biomass for vast scale cellulosic biofuel

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production in the USA and minimize the amount of land that is required to be diverted from food to fuel production (Bioenergy et al. 2010). Vast raw materials are used as feedstocks for a lignocellulosic bio-feedstock obtained from residues derived from forestry or agriculture (Heelan 2015). The current annual consumption of lignocellulosic biomass in bioenergy industries is relatively small when compared with the total biomass currently available. Secondary biomass feedstocks had been predicted as the sustainable nonfood biomass potential at the EU level which had a maximum potential of 476 million tons of lignocellulosic biomass to fulfill the need of all bio-based industries in Europe by 2030 (Heelan 2015. To fulfill this consumption, at least1 a billion tons of lignocellulosic biomass will be produced in Europe on an annual basis by 2030. Therefore, the problem is not only the source of feedstock but rather the logistical problems surrounding the feedstock supply. The lignocellulosic feedstock supply chain may include collection, drying, densification, transport, and storage, and such processes will change depending on biomass type and source (Heelan 2015). Each supply chain stage faces formidable challenges (Hassan et al. 2018). The agricultural residues derived from Livestock and plant residues may be lignocellulose and non-lignocellulose feedstock types, and their detailed description is given in the chart below (Fig. 8.1). Biodiesel production from algae biomass can be considered as a promising alternative renewable energy source for the recent and future energy demand of society. Among algae, cyanobacteria are a potential feedstock source for bioenergy production due to their huge advantages like fast growth, higher lipid contents, and being more amenable for genetic modification compared to the algae. Even though, the expense of algae-based biodiesel production is still high when compared with conventional fuels, which is a major obstacle for industrial biodiesel production (Azizi et al. 2018; Wang et al. 2020). Biogas is valuable renewable energy that can be produced via biodegradation of organic materials and it is mainly composed of 45–70% of methane, 30–40% of

Biomass

Thermochemical

Direct

Liquefaction

Pyrolysis

Biochemicals

Gasification

combustio

Electricity

Anaerobic Digestion

Biodiesel

Char and Biodiesel

Syngas

Biogas

Alcoholic Photobiological Fermentations H2 production

Ethanol

Fig. 8.1 Classification of biomass used as feedstocks for bioenergy

Biohydrogen

Transesterification

Biodiesel

Manure Munucipal biowaste

Livestock Derived Damaged vegetalbles

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NonLignocellulosic Biomass

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Aricultural Residues

Plant derived residues

Barely staw Oat straw

Triticale straw

Rapeseed straw

Lignocellulosic Biomass

Wheat straw

Soya bean straw

Fig. 8.2 Major pathways for conversion of biomass to bioenergy and derived products

carbon dioxide gas, and 1–15% of nitrogen gas less amount of hydrogen sulfide gas with some amount of moisture and siloxanes. The compositions vary based on the source of biogas production approaches such as sewage digester, organic waste digester, and landfill sources (Srivastava 2019) (Fig. 8.2).

8.2.2 Bioenergy Production from Algae and Cyanobacteria 8.2.2.1

Bioenergy Production from Algae

If biofuels are to replace transportation fuels, conventional feedstocks such as oil crops, waste cooking oil, and animal fat will not be able to meet the real demand. Algal biomass biofuels are classified as third-generation biofuels, as opposed to firstgeneration biofuels made from crops and animal fats, and second-generation biofuels derived from lignocellulose biomass. (Dragone et al. 2010; Chu 2017). Oil yield from microalgae is 23 times higher than oil palm and 300 times higher than soya bean per hectare of cultivation (Chu 2017; Taylor and no date). Furthermore, microalgae grown in wastewater and saline water will not compete for the use of clean freshwater for human consumption (Chu 2017). Integration of technologies that involve bio-product industries leveraging environmental protection and waste utilization benefits is the main approach that has attracted intense interest in the production of algal biofuels (Patel et al. 2017; Chu 2017). Several types of renewable fuel can be produced from microalgae (Taylor and no date), including biodiesel derived from microalgal oil, methane produced from anaerobic digestion of the algal biomass, and biohydrogen generated through the photo biological process (Chu 2017).

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Algae are a polyphyletic group of organisms from four different biological kingdoms: Bacteria, Plantae, Chromista, and Protozoa, and around 44,000 species of algae have existed in the world (Ullmann and Grimm 2021). Microalgae are well known for their fast growth with the ability of high carbon fixation rates (6.2 kg m−3 d−1 ) (Hermann and Baier 2009) and concomitant high biomass productivity of up to 40– 80 t dry weight ha-1y-1 (Hermann and Baier 2009; Klassen et al. 2015). Microalgae cultivation is advantageous compared to other crops as they do not require fertile land (arable land), freshwater, herbicides, and pesticides. Microalgae can be easily cultured using various sources of wastewater. The main issues are low-density growth and harvesting of algal biomass (Gorjian et al. 2021). Algae require nitrogen, phosphate, water, CO2 , and sunlight for efficient growth and have greater CO2 sequestration ability from the atmosphere (Arun et al. 2020). Biological components of algal biomass have a greater advantage than other conventional biomass for gaseous and liquid biofuel production with less greenhouse gas emissions (Arun et al. 2020). Moreover, Photosynthetic nature, CO2 sequestration, excessive biomass productiveness, high lipid accumulation, and valuable non-fuel co-products are the notable advantages of microalgae (Choi et al. 2019). Microalgae are a vast group of unicellular, primarily aquatic organisms that have the potential of performing photosynthesis. Because some species are capable of preparing higher lipid contents, such microscopic organisms are considered as a potential source of biofuel (Banskota et al. 2019; Ganesan et al. 2020). As food producer organisms, algae are the initial point of most food webs (Chu 2017) in the marine environment. The biomass potential of most of the algal species is the highest of all terrestrial plants. Moreover, their high content of vitamins, higher fatty acids potential, and additional healthy nutrients have led to increasing consumer demand and commercial interest in algae production during recent times (Ullmann and Grimm 2021). Higher food consumption and energy demand, global climate change, and environmental pollution (Menke 2018) are some of the serious current challenges in the globe. Among other alternative renewable energy sources, Biofuels have great potential to harmonize the food-energy environment trilemma. Photosynthetic organisms such as plants, algae, and cyanobacteria capture solar energy and store it as chemical energy. Most of the time, bioenergy is captured by photosynthetic CO2 fixation. Therefore, carbon-containing biofuels have a varied tendency to be carbon neutral after combustion and their extent of accomplishment depends on the nature of the feedstock, the agricultural practice, and the industrial process. Thus, it might directly contribute to climate change and mitigation. Firstgeneration biofuels were based on edible feedstocks such as corn, soybean, and rapeseed. Consequently, several alternative feedstocks have been proposed to alleviate foodbioenergy competition and land-use change that leads to second-generation or more advanced (Menke 2018) lignocellulosic biofuel feedstocks (corn stover, rice, and wheat straw and organic waste). Moreover, the use of microbial cell factories for bioenergy has regained attention as a result of increasing pressure for higher productivities, novel bioproducts, and environmental protection (Beloqui et al. 2008). Therefore, it is highly appreciated that the microbial world contains the greatest fraction

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of biodiversity in the biosphere and has an innovation potential (Ortiz-marquez et al. 2013). Due to its advantages, there is currently much interest to improve the technology for the use of photosynthetic microorganisms (Ortiz-marquez et al. 2013), such as eukaryotic microalgae or cyanobacteria (Rasala et al. 2013). Although some startup companies are already attempting to commercialize algal fuels their actual potential is still a matter of debate (Menke 2018). Moreover, the use of microalgae (including cyanobacteria) as a food source and food supplement is known for centuries. Microalgae are cultivated for human consumption in many Asian countries, Europe, the USA, and Australia for several decades. Microalgae and cyanobacteria are unicellular marine algal plants that can grow rapidly under natural or artificial light conditions. Large amount microalgal cultivation processes are still under development, favoring growth in raceways or ponds on land. However, there has been some interest in growing microalgae in containers in nearshore waters, likely in conjunction with existing facilities (de Farias Silva et al. 2019a), where designs may consist of open raceway ponds as well as photobioreactors, and hybrids of these two systems designs (Day 2018). Commercial feedstock derived from microalgae and cyanobacteria include products for human and animal nutrition, polyunsaturated fatty acids (Mutanda et al. 2020), antioxidants, coloring substances, fertilizers, soil conditioners, and a variety of specialty products including bio flocculants, biodegradable polymers, cosmetics, pharmaceuticals, polysaccharides (Mutanda et al. 2020), and stable isotopes for research purposes (US Department of Energy 2016). Microalgae are also commercialized in the cosmetics industry or as animal feed (Niccolai et al. 2019). The microalgae business sector is currently very dynamic with several new companies starting every year (Niccolai et al. 2019). Among the microalgal genera largely employed for human consumption, there are Arthrospira, Chlorella, and Aphanizomenon due to their high content in essential nutrients and protein (Niccolai et al. 2019) (Fig. 8.3).

8.2.2.2

Bioenergy Production from Blue-Green Algae/Cyanobacteria

Cyanobacteria, ancient relatives of chloroplasts, are outer membrane-bearing, chlorophyll a-containing, photosynthetic bacteria that carry out photosynthesis much as the pants do (Elfidasari et al. 2020). Cyanobacteria are believed to have been potent organisms to delivered oxygen into the primitive environment of Earth. A small fraction of the cells of certain cyanobacteria may differentiate into heterocysts, in dinitrogen (N2 ) fixation that can take place in an oxygen-containing milieu. Cyanobacteria are capable of growth, and in some cases differentiation, when provided with little more than sunlight, air, and water (Elfidasari et al. 2020). Their growth rate is being improved by the accessibility of genetic nutrients and genomic order (Koksharova 2002). All cyanobacteria carry out oxygenic photosynthesis while some cyanobacterial species can switch to the particular bacterial and oxygenic photosynthesis using sulfide as the electron donor. Under anoxic conditions and during the dark, cyanobacteria carry out fermentation (Abed et al. 2009). Some cyanobacteria form heterocyst and have the ability to fix atmospheric nitrogen (Abed et al. 2009).

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Algae culture

Open pond systems

Hybrid system

Photobioreactor

Drying and dewatering of algae filtration/centrifugation and flocculation Conversion to biofuels

Ferementation

Photo fermentation, Sacharaficacation& fermentation, Hydrolysis & fermentation ABE fermentation

Transesterification

Enzymatic, wet extraction, alcoholysis & acidolysis

Bioethanol Biobuthanol Biomethane

Combustion

Hydrothermal, Supercritical water, Pyrolysis

Biodiesel

Syngas

Hydrogen asited method

Mechanical and Chemical method

Hydrogenation, hydrodeoxygenation

Biochar

Bead beating, Ultrasound, Microwaves, Soxhlet extraction

Bio-oil

Fig. 8.3 Steps and techniques involved in biofuel production using microalgae

Algae-based biodiesel has been considered as a promising alternative renewable energy source for present and future energy demand (Anahas and Muralitharan 2018; Koksharova and Wolk 2020). Among algae, cyanobacteria are excellent feedstock for bioenergy production due to several advantages like fast growth, higher lipid content, and being more amenable for genetic modification compared to the algae (Anahas and Muralitharan 2018). However, the expense of algae-based bioenergy production is still high when compared with conventional fuels. Since there is a major obstacle for industrial bioenergy production (Steinfeld et al. 2012; Anahas and Muralitharan 2019).

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8.2.3 Potential of Genetic Engineering for Bioenergy Crop Production Lignocellulosic biomass is the primary source of bioenergy production. Lignocellulosic bioenergy conversion needs to digest the cell wall components of the biomass (Josekutty et al. 2012; Martin et al. 2021). However, the recalcitrance of the biomass to degradation makes the bioconversion process very expensive for energy production and hence limits the mass production of bioenergy for market competitiveness. Molecular approaches such as genetic engineering are anticipated to play a great role in improving plant biomass for bioenergy conversion. Genetic engineering is applied in bioenergy crops to modify the lignin biosynthesis genes to reduce the lignin content, enhance the biomass yield and improve the digestibility of the biomass. Genetic modification of the plant cell wall by targeting the polymer synthesis gene allows obtaining high biomass yield (Yadav et al. 2018). Xu et al. (2011) have been demonstrated silencing Pv4CL1 gene encoding for a key enzyme for lignin biosynthesis in switchgrass can reduce the lignin content and enhance the digestibility of the biomass. In transgenic Arabidopsis plant, de Farias Silva et al. (2019b) expressed COBL gene, GhCOBL9A a cotton glycosylphosphatidyl inositol-anchored protein-encoding gene, enhance cell growth, thickening, and increased plant biomass. The study showed that overexpression of the GhCOBL9A gene could promote plant growth and development in Arabidopsis plants by upregulating the expression of both CESA genes and cellulose deposition. In the early development stages of the plant, GhCOBL9A gene overexpression enhanced the hypocotyl and root length and in the mature stages, it enhanced stem cell thickening. The finding indicated that manipulating the gene GhCOBL9A in Arabidopsis plants showed a stable phenotype and enhanced biomass production. Sugarcane is one of the best bioenergy crops which have the efficient capability to convert solar energy to chemical energy. Since maize and sugarcane are rich in starch and sugars, they are suitable crops for bioethanol production (Yang et al. 2019). However, the existence of a large number of pentoses in the plant cell wall requires costly pretreatment steps to produce bioethanol. Advance in biotechnology and genetic engineering makes it possible to identify and target the candidate genes to modify the plant cell wall. In sugarcane, the gene encoding for Cinnamyl Alcohol Dehydrogenase (CAD) enzyme for lignin synthesis has been modified to alter the cell wall composition (Raza et al. 2019).

8.3 Impact of Bioenergy on the Environment The benefit of bioenergy is great in the world of facing global warming and today bioenergy contributes about 70% of renewable energy in the world (International Energy Agency 2019). Albeit biomass energy plays a great role to reduce greenhouse gas emissions compared to fossil fuels, bioenergy is not 100% clean (Reid et al. 2020;

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Table 8.1 Biomass generations aimed at bioethanol production S. Common examples Type of feedstock No.

Advantage

Disadvantage

1

First generation, e.g., sugar cane, corn, and beet

• Stable and lower production cost • Uses known technology

• Fuel versus food problems • Geographical limitation • Takes time to harvest

2

Second generation, e.g., Lignocelluloses

• Low or no geographical limitations • Less controversial fuel vs food

• High recalcitrance (Pretreatment problem) • Recent industrial plants • Domestication other cultures

3

Third generations, • Can be used e.g., microalgae anywhere • Needs only and macroalgae water, light, salt and co2

• • • •

4

Fourth generation, • Lower e.g., cyanobacteria environmental impact • Reduced steps to biomass conversion • Composed of two steps (cultivation distillation)

• Emergent technology • Use GMO (genetically modified organisms) • High capital cost • Competitive production values • Little information in the literature

Recent technology High cultivation cost Microalgae demonstration Fermentability of polysaccharides(macroalgae)

Ale et al. 2019). The conversion of crops and feedstock’s into bioenergy is mostly caused raising soil carbon level, utilizing forests would increase GHG emissions and greatly affects land use (Ale et al. 2019). The impact of bioenergy on water resources and biodiversity does not fit with sustainable production. The positive contribution and negative impacts of bioenergy in the environment are presented below (Table 8.1).

8.3.1 Positive Effects 8.3.1.1

Reductions of GHG Emissions

One of the limitations of using fossil fuel as a source of energy is its impact on the environment such as air pollution and greenhouse gas emissions. The increasing concerns of global warming have shifted the world to clean energy such as bioenergy

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which has a great contribution to reduce global GHG emissions (Kang et al. 2018). Liu et al. (2017) figured that the use of switchgrass as a replacement for coal for energy production would reduce greenhouse gas emissions by 29.49 million tons CO2 -eq/year. Albeit the extent of greenhouse gas (GHG) emissions reduction varied among the use of different biomass, using bioethanol as a substitution for gasoline can reduce the GHG emissions by 40–85% (Wu et al. 2018). The wide expansion of forest bioenergy greatly contributes to forest carbon sequestration which can increase by 9.4 billion tons CO2 by 2025 and 15.4 billion tons CO2 by 2095 (Kim et al. 2018). The strong promotion and expansion of forest bioenergy in the globe would derive forest resource investment. For sustainable energy, production attention is given to bioenergy with carbon capture and storage (BECCS) technologies as an anticipating solution to minimize carbon dioxide emissions and reduce the effect of climate change (Creutzig et al. 2021). The integration of bioenergy with carbon capture and storage (i.e., BECCS) technologies permits carbon dioxide removals (CDR) to kick-off CO2 emissions and potentially turn global warming utilizing net negative emissions (Vaughan et al. 2018; Bauer et al. 2020). Albeit the implementation of BECCS could cause water stress its application is an effective option to mitigate the greenhouse gas emission (Hu et al. 2020).

8.3.2 Negative Effects 8.3.2.1

Water Quality and Quantity

The growing interest in the bioenergy sector raised concerns in terms of water resource depletion and quality deterioration in the course of feedstock production and conversion processes (Diaz-Chavez et al. 2011). These are the key factors affecting the sustainable production of bioenergy (Wu et al. 2014). The water consumption differs based on the bioenergy crop used for the conversion process. Some crops like corn consume more water during cultivation and in the corn ethanol production process. Moreover, the water stress caused by the corn ethanol production expansion could greatly affect food security and have consequences in water conservation and soil fertility (Wu et al. 2018). In the selection of bioenergy feedstocks perennial and semi-perennial crops such as sugarcane, grasses like switchgrass, Miscanthus spp., and elephant grass are ideal bioenergy crops with lower water impact but their water consumption is relatively high (Neary 2018). The water resource depletion in response to large-scale bioenergy production has negative consequences and is incompatible with the Sustainable Development Goal (SDG) agenda (Humpenoder et al. 2018). Forest bioenergy systems are suggested which can fit with preserving better quality water supplies in forested structures (Neary 2018).

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Table 8.2 Biochemical reactions in anaerobic digestion Stages

Reaction

Hydrolysis

C6 H10 O6 + H2 O → C6 H12 O6 + H2

Acidogenesis

C6 H12 O6 ↔ 2CH3 CH2 OH + 2CO2 C6 H12 O6 + 2H2 ↔ 2CH3 CH2 COOH + 2H2 O C6 H12 O6 → 3CH3 COOH

Acetogenesis

CH3 CH2 COO- + 2H2 O ↔ 2CH3 COO− + H+ + HCO3 − + 3H2 C6 H12 O6 + 2H2 O ↔ 2CH3 COOH + 2CO2 + 4H2 CH3 CH2 OH + 2H2 O ↔ CH3COO− + 3H2 + H+

Methanogenesis

CH3 CH2 COOH → CH4 + CO2 CO2 + 4H2 → CH4 + 2H2 O 2CH3 CH2 OH + CO2 → CH4 + 2CH3 COOH

8.3.2.2

Biodiversity and Land Use

In the global scenarios, significant damage to biodiversity is increasing over time. By 2050 predictions showed that the potential species loss due to the European Union ecological footprint would rise from 0.75% in 2000 to nearly 1% of global species (Di Fulvio et al. 2019). The increased expansion of bioenergy caused major conversion in land use in the globe and is expected further beyond today (Wu et al. 2018). The land-use changes due to bioenergy differ based on the bioenergy crop types used. Comparing the different biofuel sources, algae-based biofuel requires minimal landuse change while biofuel from first-generation bioenergy crops such as soybean, sugarcane, and corn has resulted in a land-use change (Ale et al. 2019). A landuse change in response to the expansion of bioenergy production becomes a major factor for the biodiversity loss and hence either providing additional agricultural land use or improvement of the current bioenergy production scheme is needed to overcome the impact of biodiversity loss (Dauber and Bolte 2014). Perennial grasses like Miscanthus (Miscanthus x giganteus) can provide a stable habitat for some time and have less impact on biodiversity loss (Wu et al. 2018). In response to biodiversity loss, perennial giant bioenergy grass such as Miscanthus can provide a habitat for wildlife and be used as soil protection and as a source of renewable energy (Petrovan et al. 2017) (Table 8.2).

8.4 Management Practice to Reduce the Negative Impacts Management methods should be established to reduce the aforementioned environmental implications of bioenergy. Bioenergy expansion has severe effects in terms of water use, water quality degradation, and land use. In Brazil, zoning policy is used to reduce the land-use effect in the production of sugarcane biofuel

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(Matemilola et al. 2019). To avoid the risk of world water supplies being depleted, it is critical to employ feedstocks and bioenergy crops that do not deplete water resources. Second-generation bioenergy crops, such as woody tree species, switchgrass (Panicum virgatum), and miscanthus (Miscanthus x giganteus), are currently used feedstocks with lower energy costs and water depletion than traditional feedstocks. (Hu et al. 2020). Global regulations are required for the intelligent use of land and water resources to reduce the negative effects of large-scale bioenergy production and make it compatible with long-term biomass energy production.

8.5 Conclusion and Future Perspectives The use of waste biomass for energy production enhances human lives while also providing significant economic and environmental benefits, all of which contribute to global environmental sustainability. Despite its significance, the current state of affairs revealed that worldwide biomass energy production is not at its peak. Countries around the world should raise awareness of biomass energy, its use, and its environmental impact as compared to fossil-fuel energy. Globally, a boom in research and technology implementation is required to fully boost bioenergy production while limiting the use of fossil fuels. The recalcitrance qualities of the biomass, which are attributable to its complex cell wall structure, should be modified to boost biomass output and digestibility. Even though genetic engineering is employed to change the cell wall structure of plant biomass, off-target effects such as plant growth and mechanical strength have been found. The use of gene-editing technologies such as CRISPR may be the most effective way to precisely target the gene encoding for lignin production. Concerns such as food insecurity, deforestation, water quantity and quality, and biodiversity loss should be considered when producing bioenergy on a big scale, and management practices with policies should be applied. The development of high-yielding bioenergy crops that require less land and water should be prioritized. For long-term growth, a balance between bioenergy increase and water resources, land usage, and biodiversity loss is required.

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Chapter 9

Rice Straw Biomass and Agricultural Residues as Strategic Bioenergy: Effects on the Environment and Economy Path with New Directions Venkatramanan Akshaya, Ilangovan Akila, Raju Murali, Devarajan Raajasubramanian, Narendra Kuppan, and Subramani Srinivasan

Abstract Bioenergy is energy produced from organic material of plant and animal sources, mainly agricultural residues, wood, energy crops, and organic wastes. Bioenergy is the most common renewable energy source globally, accounting for roughly 70% of all critical renewable energy sources. Since biomass is organic, it is one of the most dependable energy sources. Traditional biomass is used by about 2.5 billion people worldwide and about 1.3 million public, specifically children and women, every year prematurely die. Biological resources are agricultural residues, industrial waste, municipal solid waste, and terrestrial and aquatic crops grown only for energy purposes. Agricultural residues are an essential energy source, and rice is a chief crop in several emerging countries, especially Asia. Rice bran and rice straw, which are remnants of this crop, have a high potential for bioenergy production. The source of bioenergy is rice grass, lignocellulosic biomass, lignin, cellulose, and hemicellulose. Rice straw is also used to generate electricity; the fundamental method is a thermochemical one that generates steam via direct combustion of biomaterials. This form, however, is highly undesirable due to the detrimental effects on the environment V. Akshaya · I. Akila · R. Murali · S. Srinivasan (B) Department of Biochemistry, Government Arts College for Women, Krishnagiri, Tamil Nadu 635002, India e-mail: [email protected]; [email protected] R. Murali · S. Srinivasan Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalai Nagar, Cuddalore, Tamil Nadu 608002, India D. Raajasubramanian · N. Kuppan Department of Botany, Faculty of Science, Annamalai University, Annamalai Nagar, Cuddalore, Tamil Nadu 608002, India D. Raajasubramanian Department of Botany, Thiru. A. Govindasamy Government Arts College, Tindivanam, Tamil Nadu 604001, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_9

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caused by the release of carbon dioxide and methane gas. Consequently, it is imperative to progress a method of extracting energy from rice straw to generate electricity. It is an excellent approach to dispose of rice straw and uses heat is helpful for power generation. Eventually, rice straw can be used in high-efficiency, energy production, and affordable agro-biometry to generate electricity and evaluate bioenergy and its impacts in the sense of the particular framework of which it is a part, as well as their direct and broader impacts on the environment and economy. Keywords Agricultural residues · Rice crop · Rice straw · Bioenergy · Power generation · Biomass

9.1 Introduction Bioenergy is renewable energy produced by biochemical and chemical methods used as a liquid biofuel for heating, electricity, or transportation. Bioenergy (including biofuels) and related products can only be produced from waste such as lignocellulose residues from forests, agriculture, food, and solid municipal waste (Nunez-Regueiro et al. 2021). In addition, bioenergy materials may include targeted crops, including algae, virgin lignocellulosic biomass, and oleaginous biomass. Renewable energy technologies based on biological and chemical processes represent a growing and rapid technological field and promise pure technology to reduce reliance on fossil fuels and to produce energy, commodity products, and organic chemicals sustainably from biomass. Biomass resources are abundant and cheap. However, growing plants and processing plants in bioenergy are very labour-intensive and have real drawbacks and disadvantages. Therefore, factors that require sustainable production and economic considerations are important. For this reason, much research is currently underway to develop and evaluate the most favourable and economically viable technology platforms for producing biofuels and efficient and sustainable food storage facilities. These current approaches and technological advances in recent biofuels research focus on the feasibility of potential feedstocks in bioenergy production and explain the significant technical and economic challenges to success (Reid et al. 2020). The biomass is contaminated with animal and plant debris, usually referring to the agricultural residue, which prefers stems, fibres, shells, etc. Carbonaceous waste, food industry waste, municipal garbage, and animal waste all comprise this material. A sewage treatment plant is considered a renewable energy source since replacing old plants with new ones is possible. In terms of generating power, it is far better than coal. In rural India, biomass is commonly utilized for cooking and heating. Despite biomass’s enormous potential, there is still a shortage of information regarding the correct and effective use of biomass, and it also applies in urban areas where solid municipal waste is produced in large quantities but is rarely used (Isaza-Perez et al. 2020). A developing country like India and the amount of waste it creates every day is significant, and the most crucial strategy to waste management and the use

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of waste energy is conserving resources (Shoeb et al. 2014). Other environmental benefits such as power generation and other amenities are also developed.

9.1.1 Biomass Energy in Global Globally one-third of the world’s energy is currently derived from biomass. Rates ranging from 90% in nations like Nepal, Rwanda, Tanzania, and Uganda to 75% in India and 27% from China and Brazil are the broad ranges found in developing countries. Lower standards in industrialized countries include 14% in Austria, 20% in Finland, and 18% in Sweden. Worldwide, biomass accounts for 14% of global energy. Whether two billion or more people now rely on power, biomass will decrease in number in the next century. This biomass dependence will affect growth and future environmental impacts (both local and global) (Zachary James et al. 2021).

9.1.2 Biomass Energy in India India is a rapidly developing country, thus increasing the demand for large amounts of energy, while pollution is also growing at a high rate. This can be easily met by using India’s biomass fuel requirement and aids in waste management and pollution control. India harvests 450–500 million tonnes of biomass annually. Biomass currently accounts for 32% of the country’s primary energy consumption. The Energy Alternatives India (EAI) evaluates that the short-range energy capacity of biomass in India will vary from 16,000 megawatts (MW) when the biomass size is conventionally distinct to 50,000 MW if the scope of the biomass definition can be expanded (Shoeb et al. 2014).

9.1.3 Sources of Cellulosic Biomass Animal and plant waste and natural waste are biomass sources of energy (Fig. 9.1). India is such a vast nation, agricultural waste is generated, and it’s relatively easy to find firewood in India, even in the desert. Sources have been revealed to be divided: Wastes in a forest: Wood, saplings, branches, etc. Wastes from agriculture: All forms of uncooked (uncooked) beans, rice, wheat, weed, fibre, husk, hull, cacao shells, paddy, and grains of cocoa are collected and sent to a crusher after harvest. Decomposition: Deposited animal excrement, scat, fresh excrement, manure weeds like freshwater jacinth, marine jacinth, kelp, seaweed, algae, etc. Other food waste: Municipal waste, industrial waste, and waste generated at the factories.

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Fig. 9.1 Sources of cellulosic biomass

Biomass resources that are renewable and directly used as fuel or converted into another type of energy production are often called “feedstocks.” This chapter will discuss biomass and holistic approaches to agricultural residues and crop residues, rice product availability, and the use of rice straw as fodder and other bioenergy applications.

9.2 Agricultural Residues as Biomass Sources The agricultural residue is a reservoir of energy with tremendous potential. A renewable alternative includes less carbon than fossil fuels while benefiting the community. Carbon-based compounds and diverse agricultural leftovers are all that remain. Rice straw, wheat straw, and corn stover are common residual materials found in the farming industry. To achieve a sustainable approach, crop production resources must be collected and utilized. One of the most energy-intensive farming systems in South Asia is rice-based. Due to depleting natural resources, soil degradation, environmental contamination, and decreasing factor productivity, the sustainability

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of the rice-based cropping system is being challenged today (Nandan et al. 2021). Rice straw, wheatgrass, and cornstalks are agricultural residues. The forest consists of debris, such as twigs, leaves, as well as tree skeletons. Residues obtained from lumber are readily available and affordable sources of lignocellulosic biomass. It consists of 35–55% cellulose, 25% hemicellulose, and 15% linseed extract with minimal protein and ash. The range of agricultural biomass-to-derived energy is between 12 and 20 megajoules per kilogram (MJ/kg), depending on the source of the ash. Ideally, biomass moisture should be reduced by 10% during the pyrolysis process. Very hardwood biomass that does not have “impurities” (leaves and needles) contains less than 2% ash, while agricultural residues such as rice can contain up to 20%. When it comes to the basic structure, wood residues contain slightly more hydrogen than carbon and farming residues (Sushil et al. 2018). Usually, agricultural residues include lignocellulosic wheat, rice straw, corn cobs, bamboo, pineapple, banana leaves, husks, and coconut, depending on the climate needed to grow crops, and this agricultural fibre does not grow in all locations around the world (SerraParareda et al. 2019). Besides cellulose, wheatgrass is one of the most abundant plant residual fibres found in the farming sector.

9.2.1 Agro-residues from Rice Crops Apart from crop grains such as rice, wheat, and maize, residues also serve as an essential resource in processing these grains. These fossils are usually made up of at least 50% of the biomass of mature American plants. Over time, these remains are carved into animal beds, burned, or decomposed in fields. Recent advances in the use of biomass residues for ethanol production or the emergence of power generation for scientific discoveries have raised hopes for a source of both economic and environmental benefits (Kumar et al. 2020). Significantly, by 2030 US agriculture is expected to support 155 million tonnes of bioenergy residues. These residues result from large crops without the need for additional land demand. In the world, rice is among the most extensively consumed grains (Table 9.1). More than any other country, China will eat 149 million metric tonnes of rice in 2020. Following China, India is the second most rice-consuming country, consuming 106.5 million metric tonnes of rice over the same period. In that order, rice consumption in the world’s top ten countries is China, India, and Bangladesh. According to recent data, the world’s rice consumption has been reasonably steady over the last two decades, at roughly 53.9 kg per person each year in 2018–2019 (Farhadi et al. 2021). Energy and petrol are the main energy requirements in developing countries’ industrial, agricultural, transport, and domestic sectors. Almost every major developing country has rice, and the remains of this plant, viz. reed rice and rice straw, have great potential to produce bioenergy, and these materials seek to test the structure’s efficiency by analysing financial technology and emphasizing its effective use in energy production (Jishi et al. 2020). The presentation, symptoms, composition, and processing of rice residues are described in used thermochemical conversion

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and chemical synthesis of rice to demonstrate different sources of biofuels. Finally, studies on the economic development of rice crop bio-based liquid and bio-based liquid polymers using various techniques are presented in the literature of Ding et al. (2019). This assessment demonstrates that crop-based biofuels can be generated profitably since rice husk used for bioenergy is also helpful for these countries’ climate change issues. Table 9.1 World’s major rice cultivated countries

Countries

Rice production in (million tonnes)

China

210.1

India

165.3

Indonesia

74.2

Bangladesh

53.1

Vietnam

44.0

Thailand

33.3

Myanmar

28.3

Philippines

18.6

Brazil

11.9

Japan

10.7

Pakistan

10.3

Cambodia

9.7

USA

9.1

South Korea

5.5

Nepal

5.4

Egypt

6.2

Nigeria

5.3

Madagascar

3.5

Tanzania

3.1

Peru

3.1

Malaysia

3.1

Sri Lanka

3.0

Mali

2.8

Colombia

2.6

Guinea

2.2

Russia

1.1

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9.3 Vital Energy from Rice Crop Residues: Role of Developing the Economy Biomass is making an enormous contribution to renewable energy in the current Scenario. To evaluate the possible use of straw from agricultural products to create the point, it was first necessary to determine the applications. It has been an essential input for energy, economic, and social development in the world’s countries in the initial 1970s. Since 1990, the study of various rice crops and the environment has been completed, applying value-added technology to our low-cost rice crop production (Renata et al. 2019). In 1981, the worldwide push to exploit fossil fuel resources was recognized, and cereal remnants constituted two-thirds of the residues in this global analysis. Of the light livestock’s total energy requirements, 24% are obtained from crop residues. Industrial materials are vital in producing wheat, rice, millet, canna, buckwheat, pulses, and palm oilseeds. From fruits and berries, Asia is a significant grower of oilseed and crop residues. Most dinosaur fossils in North America are produced in the USA from grain, sorghum, and oat. This continent is a primary supplier of wheat, rye, and mixed grain-the remaining part of the Union of Soviet Socialist Republics (FAO 1981). Agriculture has a significant impact on the Indian economy as a whole. While throughout the several agricultural regions throughout India, an extensive array of crops is grown on a large amount of land, and large quantities of crop residue (noneconomic plant parts) are left in the fields after harvest, the practice varies throughout locations. Due to the tremendous amount of crop leftover on the farm, this land has significant economic worth. Off-farm and on-farm production of 141 metric tonnes (Mt) of sugarcane,122 Mt of rice, 110 Mt of wheat, 71 Mt of maize, 26 Mt of millets, 8 Mt of fibre crops produces around 500–550 Mt of crop wastes per year. India is one of the primary food producers, like wheat, corn, soybean, and sugarcane. Leftover residues generated by crops are enormous; they are rising as food production increases. Rice is commonly eaten in countries where it is the main ingredient in the diet, and it is used in some Asian countries to produce energy from rice bran. Rice residue is a more economical option than the use of actual rice. The expanding need for animal feeding and increasing trends in organic agriculture and additional bioenergy cogeneration facilities imply that crop residues present a competitive opportunity in agriculture. Finally, one should remember that using leftover residue is often not mutually exclusive, making it more difficult to estimate its economic value (Shankar et al. 2017).

9.4 Overview of Rice Straw, Availability Rice straw has a unique complex structure, consisting of cellulose fibre, a cell due to its crystalline structure, and trapped lignin and hemicellulose. Rice is a renewable energy source, where we can get energy through chemical conversion processes such

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Fig. 9.2 Pre-treatment column and the post-treatment column of rice straw

Fig. 9.3 Graphical view of straw components in percentage

as pyrolysis, gasification, and combustion. The rice straw contains three fibre layers: lignocellulosic biomass: lignin, cellulose, and hemicellulose. The results shown in Fig. 9.2 can be partitioned into the pre-treatment column and the post-treatment column of rice straw. The straw is made up of lignocellulosic material, mostly of cellulose and hemicellulose (60–80%), lignin (15–20%) but includes water-soluble minerals or ash, and proteins (5–12% in each) shown in Fig. 9.3 (Al-Haj Ibrahim 2018).

9.4.1 Features of Rice Straw The ash composition of rice straw typically weighs 15–18% moisture at 70–80 kg/ m3 of applied pressure. Bulk density, thermal strength, and thermal conductivity are

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physical properties, and the density of rice straw is essential for both its handling and storage. The processes involved in converting biomass into energy rely on thermal and heating properties.

9.4.2 Availability of Rice Straw Rice straw is the basis of around 90% of all rice farming. Chen et al. (2020) estimated 32–38% cellulose, approximately 30–35% mentioned hemicellulose, 13–28% found lignin, and 10–17% perceived in rice straw ash (Table 9.2). Due to the high silica content in the wall, the usage of this compound is not damaging to the environment. Rice straw is produced when paddy rice is harvested, and the entire plant is composed of panicle (hair) roots, stem sheaths, and leaf blades. Cereal crop, next to corn, is the third most communal crop in the globe. Over half of the world’s populace depends on it for both energy and protein. As a result of this production performance, India became the second-holder rice in Asia in July 2017. India, in 2017, will remain the leading exporter of rice for the seventh consecutive year, led by Thailand, Vietnam, and the USA (Nandan et al. 2021). Production of global cereal crops in 2020 is expected to rise by 2.1% more than the estimated 2019 represented in Fig. 9.4. FAO’s initial estimate for world cereal stocks by the close of the 2021 season was down by 2.3% to 805 million tonnes. Now it is estimated to be down by 2.8 million tonnes, a decrease of 2.3%. With the higher revision of 400,000 tonnes, world rice stocks are forecast to reach an on-par level at the end of 2020/21. Bangladesh, China, and Indonesia’s drawdowns will be made up of India, Thailand, and the USA, respectively (FAO 2020). According to Fig. 9.4, international predictions indicate that rice output would total 467 million tonnes in 2020–2021. However, world rice cultivation will only increase by 5.9% over this period. Table 9.1 states that India produced 165 million metric tonnes of rice in 2020–2021. Theoretical ethanol production from the most recent reported composition of those data allows ethanol from a plant-based feedstock to generate 350 million litres of fuel, leading to a considerable change in the worldwide supply of gasoline (Kapoor et al. 2017). Before this, much of the harvested paddy straw was usually used as paper, wood pulp inks, fertilizer, and land. Combination-based collection methods allow it more costly and time-consuming to gather. Only 20% of the rice straw Table 9.2 Major components of rice straw in % (Chen et al. 2020)

Components Cellulose Hemicellulose Lignin Ash

Rice straw (%) 32–38 20–35 13.5–28 10–17

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Fig. 9.4 Global estimate of rice production in 2020–2021

used by farmers in the current year can be expected to be consumed or destroyed during the preparation for the next harvest, implying that only 50% of rice fields are sustainable for the following practice (Mothe and Polisetty 2021). Greenhouse gases and toxicants can be produced when incompletely combusted rice straw is burned, making it hazardous to children and the elderly. Straw burning deprives the soil of nitrogen, phosphorus, and enzymes. At the same time, it destroys many beneficial species that help the ground (approximately 80% of those involved with nitrogen, and enzymes, just 21% with phosphorus remaining). Thus, it is essential to devise new methods for paddy field straw pricing so that farmers can benefit from having the right to collect paddy straw in the fields and, thereby facilitate more significant pollution in the burning it (Jin et al. 2020).

9.4.3 Rice Straw Management for Biomass Conventionally, in southern and south-eastern Asian countries, weeds and rice straw have been treated as waste, dumped in rivers, or burned on the ground, managed using greenhouse gas (GHG) emissions, pollution, and improved methods. Rice residue management options can be separated into off-field and in-field administration as revealed in Fig. 9.5.

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Fig. 9.5 Management of rice straw

9.4.4 Crop Description Rice is a significant crop for human consumption, but 90% is used as animal feed. It accounts for approximately two-thirds of the world’s total wheat production and about two-thirds of its consumption for baking bread (Zhang et al. 2020). Around 17% of the world’s total output gets used as forage. However, this differs widely among countries (Europe and North America, where most wheat is used for feed). Because wheat is the most important grain, we examine other aspects of wheat and rice crops to understand them better. Rice residues are the primary materials used in the rice cultivation industry. The word “grass” refers to everything left after the primary grasses and grain has been harvested, including leaves, straw, and stalks. Collecting reusable pieces of off-field straws is done in bulk or by self-propelled balers. The longer it is left in the sun, the thicker the cover needs to be. Some parts of the field where the grass is burnt, like open-pit roasting, get rid of it quickly. Collecting the grain before cutting the grain significantly influences the amount of grain and grass produced on the farm. There are two main ways in which to harvest grains on the farm: hydraulic and tillage. Manual labour is applied to the crop, and the resulting bundles are then left on the field and placed in packages on the surface. Harvesting is performed using a fixed harvester brought into the area; customized and home-built threshing machines are often used. Due to a large amount of threshing, the grass was heaped near the outlet of the pit where the riches were found. Rice-growing areas worldwide depend on this method for harvesting, which is most often used in rural areas with no mechanical equipment and assessing alternative crop establishment methods with a sustainability lens in rice production systems of Eastern India (Devkota et al. 2020). In manual grain-growing,

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the grain harvest is accomplished by collecting the straw at a centralized facility placed in bales. In the second method, farmers use a self-propelled combine to harvest rice or thresh their grain. Crop threshing involves spreading it across the region, while the mixing process consists of putting the straw on the side. As a result of harvesting by combining, the grass grows behind the machine. If you allow the straw to completely dry, it can be broken up with a manual hammer, which compresses the straw into chunks. Some farms use a grass-cutting machine to speed up harvesting. This type of lawnmower is incredibly effective in places where the grass is not used for other purposes. Many farmers have balers, which produce small square, round bales. Differences in the dimensions and weight of grass bales exist concerning the kind of grass used. However, the packing density remains the same. The standard packing density when dry is between 60 and 100 kg/m3 . The thickness of large bales will increase to 150 kg/m3 to offer more excellent resistance to mould growth.

9.5 Environmental and Socio-economic Evaluation of Rice Straw A wide variety of farming methods are used to produce rice straw. There are essential differences in various types of land planning, planting, and herbicide application for different grass species. In agricultural processes, the life-cycle assessment (LCA) measures environmental burdens, such as climate change. It impacts the presence of ozone and geo-acidification, and marine eutrophication (Nguyen et al. 2020). Burning rice straw on farms is a big challenge for researchers, the government, and farmers in different states. It focuses on clean and environmentally friendly technologies easily applicable to economic and ecologically social grass management. Straw can be achieved with incredible efforts such as biomethane, biohydrogen, pulp, paper making, home enzyme synthesis, biochar, bio-oil production, fodder making, mushroom, and fertilizer production. The proposed technologies can curb stubborn burning at the grassroots level and improve the socio-economic situation of farmers and people living in rural areas. Since most Indian farmers are unaware of the economic and environmental benefits of these advances, many of the methods mentioned above are less exploitative on a commercial scale (Gursharan and Shailendra 2021).

9.6 Utilization of Rice Straw The use of rice straw is determined by its geographies, which can be classified into three groups: 1. Physical characteristics 2. Thermal characteristics

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3. Composition of chemicals. Thermal conductivity, thermal strength, and bulk density are examples of physical properties. When it comes to handling and storing rice straw, density is crucial. When biomass is converted into energy, thermal properties, and heating values are essential. Animal feed and soil fertility are linked to chemical structures such as lignin, cellulose, hemicellulose/carbohydrate, and nutrients. Rice straw has properties that aid in performance calculations and life cycle analysis. The American Society for Testing and Materials (ASTM) and the National Renewable Energy Laboratory (NREL) are two of the most widely used characterization methods for rice grass (ASTM). Rice straw is a readily available, inexpensive, and practical food for nourishing ruminants such as buffalo, cattle, sheep, and goats. In addition to raising crops, livestock rearing is essential to agricultural development. Additionally, livestock provides farmers with revenue and helps produce food for the broader people. The latest scientific and technological farm techniques have been established to boost rice straw’s nutritional and feeding properties and animal performance. Rice straw is considered waste in South and Southeast Asian countries, where they are deposited in large bodies of water or burned in the field. Rice straw combustion results in GHG emissions, waste, and pollution. Rice straw can be processed and used in a variety of ways, thanks to recent technological advancements and Fig. 9.6 illustrates the various application of rice straw. Rice grass management can be divided into in-field management and off-field management. Composting/Manuring: This can be done in one of two ways. To preserve soil fertility, stub soil is mixed with either, as is customary in the rice-growing parts of the country. Typically, new and spoilt grass (animals that have been abandoned, submerged in water, and rendered incapable of feeding) is placed with manure and allowed to create waste, which is subsequently used in the fields for composting.

Fig. 9.6 Manifold applications of rice straw

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Burning: Burning is a straightforward method of removing the remainder of the rice crop. Fodder: In locations where green grass is limited, rice straw is commonly utilized as a base diet food for animals, albeit its low protein and mineral content and high lignocellulose and insoluble ash content are considerations. Wheat straw is preferred over rice straw in states, particularly Uttar Pradesh, Punjab, and Haryana. Green fodder, which doesn’t have to be chaffed, is fed to cows, more labour-intensive than chaffing rice straw. In the energy sector, it can be utilized as off-field management. Either directly or through chemical transformation, rice straw can produce heat or flammable synthetic gas in the energy area (Huang et al. 2020). Roof itch in ricegrowing places is typically treated with rice straw. Rice straw is utilized as bedding for litter-dwelling fowl that are kept cool. Mushroom growing and packing equipment can also be made using rice straw (material used to protect products during transportation from breakage or spoilage). Other items made from rice straw include paper, strawberries, wine, caps, mats, ropes, and baskets (IRRI 2017). Thatching: Rice straw is used extensively in rice-growing villages, especially in eastern Indian states. Poultry droppings: In Eastern Indian states, chaffed rice straw is used as bedding material in deep litter poultry farming. Mushroom farming: Rice straw is used in mushroom cultivation. Packing material: Rice straw, either chaffed or unstaffed, is used to pack goods during transportation to prevent spoilage. Industrial applications: Rice straw is used mechanically to make strawboard, paper, hats, baskets, ropes, mats, and alcohol. Rice straw may be used to produce liquid, gaseous, and solid fuels.

9.7 Productions of Bioenergy from Rice Straw Rice straw is a gorgeous renewable lignocellulosic substance used for bioethanol or biogas production. Additionally, rice straw can also be employed for bio-hydrogen processing, and it is rehabilitated to bio-oil. The bio-oil is converted into gas by pyrolysis, creating both hydrogen and bio-hydrogen. Finally, rice straw is also converted into a chemical pulp and used to make paper in an environmentally responsible, nonpolluting manner, which can be used as a solid fuel or pulped and used to manufacture non-polluting recycled paper (Fig. 9.7).

9.7.1 Bioliquid Fuel Production Rice straw is an appealing substrate for bioethanol processing, but due to its high ash and silica content, the conversion process to ethanol presents several challenges and limitations. After adequate pre-treatment, hydrolysis of grass to acquire hydrolysate

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Fig. 9.7 Schematic presentation consumption of rice straw for energy production

is used in bioethanol production processes, accompanied by anaerobic fermentation. The selection of an effective pre-treatment technique in developing technology to manufacture bioethanol from grass is one of the significant challenges. The method of pre-treatment used has a substantial impact on the enzymatic digestibility and potency of the enzyme sacrifice of grass (as well as the overall economic viability of the process) (Song et al. 2021). The grass is cut or dried and screened for grass powder after removing the damaged leaf and stem. Hold the grass to make grass bricks, then irradiate with an electron beam accelerator before pulverizing and sieving. The grass may be acid-treated, alkali-treated, as a pre-treatment hemicellulose can be efficiently extracted from grass using acid-catalyst vapour blasting or acid pretreatment, resulting in higher yields of fermented sugars. These two pre-treatment methods yielded 46 and 42 g/l of monosaccharides provided by enzymatic hydrolysis of pre-treated grass, respectively. Pre-treatment with ammonium fibre blasting, on the other hand, is distinct from different pre-treatment approaches because it does not significantly dissolve hemicellulose. The yield of monosaccharides produced by enzymatic hydrolysis of pre-treated grass was 37 g/l in this case. The liquefaction process in which a grass powder mixture containing rice, corn, and wheatgrass powder is mixed with phenolic compounds such as phenol, o-chrysol, m-chrysol, and o-chlorophenol will increase the cellulose content of grass (Wang et al. 2020a, b). The resultant mixture is treated with polyethylene glycol, resorcinol, hydroquinone, sulphuric acid, phosphoric acid, formic acid, nitric acid, oxalic acid, acrylic acid, salicylic acid, and organic acid. The acid is rinsed with an organic solvent, neutralized, filtered, and dried to produce a higher cellulose content in the merit. Enzymes are made by combining glucose, ammonium chloride, and water in dried grass powder, sterilizing for 2 h at 121 °C, vaccinating 5% Phanerochaete chrysosporium in a particular medium, and culturing for 30 days at 37–39 °C.

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Xylanase can degrade xylogen, as can MN-dependent peroxide and lactase. After pre-treatment, the grass is given a specific enzyme treatment with cellulose and xylanase; grass powder can be purified. A method for cellulose grass degeneration has been developed using Trichoderma viride. To diminish lignin, grass powder is treated with liquid-state raw enzymes and solid-state culture of P. chrysosporium. Finally, utilizing subcritical and supercritical solvent–water mixes, rice straw can be liquefied in an autoclave. When a 1,4-dioxin-water mixture is being used at 260– 340 °C, the tubular structure of lignocellulose is broken down by deoxidation and decarboxylation processes. The essential products of this process are oil, preasphaltene, and asphaltene fractions, the yield and composition of which are greatly affected by the volume ratio of 1,4-dioxane. Increased dilution of 1,4-dioxane weakens the nucleophilic and hydrolytic capacities of water, resulting in a decrease in the concentration of various phenolic, acid, hydrocarbon, and ester derivatives in the extracted oil and other fractions (Fermanelli et al. 2020). The relative proportion of oxygen in the resulting bio-oil falls when the hydrogen donor solvent is raised (ethanol and 2-propanol). Using solvents, the low boiling point content will be avoided.

9.8 Generation of Solid Fuels Rice straw can be burned as a high-calorie solid fuel or converted into biomass or coal fuels like coke. Rice straw that has been treated with sodium hydroxide can be used to make biomass fuels. Rice straw may be used as linear lumps or processed into high-density pellets by heating, pressing, compression-moulding, or torrefaction, transporting the feedstock over long distances. A high rate of burning and being used as production equipment can be achieved when used in place of coal or natural gas in existing coal and gas plants. Rice straw pellets are made by wetting chopped rice straw with water and inhaling the wet straw by colour, with the water percentage and extraction pressure carefully regulated (Pandey et al. 2021). Rice straw may be crushed and compressed to make solid fuel briquettes, with the piston-moulding process being used for compression. During this phase, the size of the crushed grass, its distribution, and the temperature of the pressure are the limiting elements that considerably affect the compressive strength of the briquettes. Rice, soybean residues, sawdust (e.g. acacia turmeric) mixed with crushed rice straw have been found to augment the caloric value of briquettes, thus lowering the energy needed to make them (Gao et al. 2020). Compression is a term used to describe the process of compression. The effects of the binder are dependent on the form and percentage ratio. A dry mixture of calcium compounds (Ca (OH)2 ) with rice straw, wood sawdust, or bamboo can be rolled out to produce grass briquettes.

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9.8.1 Biogas Production Rice straw is an organic material used to produce biofuels such as bioenergy and biogas in a sustainable manner (approximately 50–75% CH4 and 25–50% CO2 ). Aerobic digestion is the most cost-effective bioreactor process used to convert organic waste into electricity, heat, and compressed natural gas (CNG). Anaerobic digestion can extract biogas from wheat, but as previously mentioned, pre-treatment methods have a significant impact on grass digestion. Aerobic Bacillus and anaerobic Clostridium are indispensable for industrial biogas and bio-hydrogen-producing systems from biomass (Abendroth et al. 2020). One peak of biogas was detected in the technique established by Kovacic et al. (2021), where rice straw cells were employed for anaerobic digestion at room temperature and operated as a substrate for various phosphate levels. This experimental investigation showed that a twostep first-order kinetic model best fit the results. Phosphate levels above a certain threshold have been found to speed up the biogasification process. Rice straw can be converted into biogas using ammonia as a supplementary nitrogen supply in a high-rate anaerobic digestive system. Subsequently the sodium hydroxide treatment, the rice straw is digested in the presence of oxygen in a single step. After large proportions of hemicellulose (36.8%), lignin (28.4%), and cellulose (16.4%) were transformed into readily biodegradable components, a 122.5% increase in the watersoluble matter was observed (Tajmirriahi et al. 2021). Cellulose crystallization after hydroxide treatment was accompanied by an increase in crystallinity. Forming a sizeable three-dimensional lignin structure with a high molecular weight evolves into a smaller, more linear design with a lower molecular weight. A hydrolysis reaction breaks the Easter bonds of lignin-carbohydrate complexes, releasing more cellulose for biogas processing. Compared to untreated rice straw, hydroxide treatment doubles sugar and raises biogas yields by up to 65%. Another technique uses sodium hydroxide, sodium sulphide, and water in a homogenous mixture. The solution is stored at room temperature for 30 days, and then a base mixture made up of hydrochloric acid or sodium hydroxide, and ammonium chloride is added. The absorbent solution absorbed hydrogen sulphide and carbon dioxide from the gas. The gas is first filtered through a molecular sieve constructed of activated carbon to eliminate contaminants and water. When rice straw is gassed, the methane produced may include carbon dioxide, hydrogen, methane, and a blend of carbon monoxide and propane known as “natural gas liquid” (Sabeeh et al. 2020). Alternatively, rice straw can be used to make fuel gas and carbonated semi-coke. The pressure needed to extract coal is utilized to convert water-soluble polymer binders and briquettes. Fourier transforms infrared spectroscopy, and a thermogravimetric analyzer was used in a tube reactor to examine the pyrolysis of rice straw. In light of these observations, the overall pyrolysis rate will increase as the heating rate and temperature grow. The principal pyrolysis gas constituents are water, carbon dioxide, carbon monoxide, formaldehyde, formic acid, methanol, and phenol (De et al. 2020). The highest release of water, carbon dioxide, carbon monoxide, formaldehyde, formic

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acid, methanol, and phenol occurs at 220–400 °C. At approximately 350 °C, the content of ether groups begins to drop while the range of aromatics increases. Biogas is cleaned using water to remove any remaining dust or tar, dried, and then dehydrated using an effective chemical compound that removes sulphur dioxide, carbon dioxide, nitrogen, and oxygen.

9.8.2 Bioethanol Production Rice production, with rich biological resources as a by-product of bioethanol production, is one of the world’s most abundant lignocellulosic wastes. Rice straw can generate 205 billion litres of bioethanol per year or 5% of global consumption. This is the most ever produced from a single biomass source. Rice straw is primarily composed of cellulose (32–47%), hemicellulose (19–27%), lignin (5–24%), and ash (18.8%) (Ashoor and Sukumaran 2020). While pentoses prevail in hemicelluloses containing xylose, arabinose, hexose, and xylose are all necessary sugars in rice straw. Subsequently, glucose 41–43.4%, xylose 14.8–20.2%, arabinose 2.7–4.5%, mannose 1.8%, and galactose 0.4% make up the carbohydrates in rice straw. Bioethanol has emerged as a viable alternative to ethanol fuel. However, bioethanol production from food crops such as cereals (first-generation biofuels) has resulted in unfavourable direct competition with food supplies by switching to more plentiful non-edible plant materials (Wang et al. 2020a, b). Complex carbohydrates, including cellulose and hemicellulose, can be fermented into sugars, making up many plant ingredients. Fermentation of ethanol these sugars can be converted into ethanol by microbes. Bioethanol is produced primarily from sugar and flour, such as sugarcane, corn, and wheat-containing high sugar concentrations. But, as crucial food sources, bioethanol created from these crops can substantially impact food costs and the availability of food worldwide. Cellulose, hemicellulose, and lignin are all contained in rice straw. To maximize the accessibility of the lignocellulosic material for the conversion of cellulose to glucose, it is required to pre-treat the lignocellulosic material. Some of the biological, physical, and chemical processes used to treat lignocellulosic biomass are only a handful of the available technologies, including enzymes, ball milling, steam blasting, acids, alkalis, lime, and wet oxidation (Bajaj and Mahajan 2019). Biologically based pre-treatment processes are inefficient due to their sluggish action and the high cost of ammonia fibre eruption and hot water pre-treatment processes. As a result, it is critical to develop an efficient, cost-effective, and environmentally friendly pre-treatment process. The ability to transform cellulose into glucose was improved by preventing lower enzymatic hydrolysis before fermentation and pre-treating rice straw. The optimum xylanase and cellulase dosages are 23 filter-paper units (FPU) and 62 international units (IU)/g, respectively, for treating pre-treated rice straw at 220 °C and 1.96 megapascals (MPa) (Singh et al. 2021). Using optimal enzyme settings and pre-treatment (15% substrate loading, w/v), we achieved sugar recovery of 0.567 g/g biomass

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(glucose; 0.394 g/g biomass) in 48 h. Rice straw was left untreated (complete sugar recovery: 0.270 g/g biomass; total sugar recovery: 0.270 g/g biomass). After 24 h, Saccharomyces cerevisiae fermentation of hydrolysates yielded 0.172 g ethanol/g untreated biomatter, equal to 80.9% of the theoretical yield depending on the glucose content in the raw material. The chemical composition of the handled rice straw and the control rice straw did not differ significantly. The surface area of treated rice straw, on the other hand, was more than double that of the control. Mafei et al. (2020) exhibited that the popping treatment causes positive changes in the soil, such as augmented surface area and large pores, resulting in decreased hemicellulose, which significantly increases the surface’s enzymatic access to more effective cellulose hydrolysis. Preventing rice grass pre-treatment increases bottom sacrifice and fermentation, both critical for bioethanol output.

9.8.3 Biochar Production Biochar is a carbon-rich substance used as a soil modification to improve soil fertility, enhance carbon preservation, and purify groundwater. It is formed when organic matter or biomass is heated to between 500 and 700 °C without oxygen. Hydrothermal carbonization (HTC) is a newly developed advanced carbonization technique. HTC entirely breaks down the plant cell wall of lignocellulosic biomass, allowing it to be rapidly transformed into a carbon-containing and lignin-like substance (Leng et al. 2021). Rice straw may be used to process biochar; reducing the risks associated with global warming is further aided by biochar’s ability to absorb carbon dioxide. Instead of using fossil fuel offsets, emissions reductions related to biochar use as a soil modifier are used. However, energy is needed for the carbonation of biochar and the transportation of rice straw and biochar products. We still need to research whether making biochar from rice grass positively affects energy balance and financial gain. Alternatively, incomplete gasification of grass and other crop and wood waste will produce straw coal (30–35%), and grass-derived coal is high in nourishments for crops and can treat polluted soil as an adsorbent. Activated charcoal (usually made from rice straw) can be gassed in an enclosed space with a small number of oxidants to create a fuel gas that is mostly carbon monoxide and hydrocarbons. Experimental findings show that as the pyrolysis temperature decreases and the heating rate increases, the gasification reactivity of rice straw char increases (Biswas et al. 2017). Activated carbon is produced from rice straw by processing it into small pieces or fragments, specifically, cane stalk, nutshells, shell waste, dried residue, forest waste, biofuels such as walnut shells, bagasse, nutshells, apricot waste, molasses, bamboo, rubberwood, sawdust, cane stalk, and shell waste (Liu et al. 2020) (Fig. 9.8). The stimulated carbon known as activated charcoal is a porous carbon used to remove impurities or make repairs with a wide surface area. The rising demand for activated coal aligns with environmental requirements and is proportional to new application areas in several countries. The failure to generate activated carbon

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Fig. 9.8 Probable synthesis of bioenergy from rice straw

from primary sources such as hard coal, shells, and wood is the key reason for using other biomaterials, including rice straw, cotton stalks, rice husk, and sugarcane bagasse. The history of activated charcoal production and use dates back thousands of years. Europeans were the first to produce activated charcoal from wood as a raw material. The quickest method for converting biomass to activated coal is to use a heating process such as gasification or pyrolysis, and this costly and multidimensional process produces various materials such as gas, char, and oil (Chen et al. 2018). Another interesting finding by de Carvalho et al. (2020) hypothesized that the required temperature for chemical activation was substantially lower than that required for physical activation, suggesting that the lower temperature employed in chemical activation contributes to the creation of pores.

9.8.4 Generation of Electricity and Power Rice is an everyday staple in many countries, especially in Asia. In response to the increasing population, the number of paddy fields has enhanced dramatically in recent years and is expected to continue to do so in future, and it encourages the use of annual agricultural waste, especially rice straw. Open combustion and soil incorporation are used in some countries to treat agricultural waste. Since it is less costly, open burning is the preferred process; however, because of the adverse effects on the atmosphere caused by carbon dioxide and methane gas release, this process is exceptionally undesirable (Logeswaran et al. 2020). As a result, developing a method of extracting energy from rice straw to produce electricity is critical. To assess rice straw’s potential for power generation, further research on its availability and characteristics, as well as logistics analysis, is needed (Jayabalan et al. 2020).

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Rice straw is appealing as a fuel because it is sustainable and considered carbonneutral. Still, it has yet to be commercially used as a heat and energy feedstock due to a lack of assistance for farmers to harvest rice straw instead of burning it in the field. Straw’s properties are often inferior when compared to coal, which is still the most common solid fuel for electricity and heat generation. The related costs and logistics of harvesting, transporting, handling, and storing rice straw for chemical and energy production are significant roadblocks. Due to the rapid formation of deposits, straw fuels have proven enormously challenging to burn in most combustion furnaces, particularly those built for power generation (Imam et al. 2021). Because of the reduced facility performance, capability, and availability, the cost of generating power from low-quality fuel has increased. Over the last two decades, rice straw as a renewable energy source has piqued people’s interest. On the other hand, rice straw has a low heating value, a low bulk density, and many alkalines and alkaline compounds. This restricts rice straw’s commercial use and makes it difficult to manage, transport, and store. Since residual pre-treatment can boost these properties, the literature is searched for information on some of the basic pre-treatment methods for rice grass, which can be used as an appealing fuel for energy production (Kondaveeti et al. 2019). Sizing, turf washing/leaching, baling, and pelting are all examples of pre-treatment methods. The treatments mentioned above improve rice straw’s physical and chemical properties, improve energy conversion and combustion efficiency, and minimize slag formation in furnaces and grates, among other things. As a result, repairs, transportation, storage costs, and logistics are reduced, promoting commercial use.

9.8.5 Paper Manufacturing Paper is an essential part of many facets of society; every day, 300 million metric tonnes of paper are manufactured worldwide, with 90% of this paper from mature pulpwood. Furthermore, paper demand is projected to rise to about 490 Mt by 2020. Today’s operations need so much paper that it can only do so without it, even with the increased use of electronics. Researchers are looking for additional resources suitable for non-wood materials and agricultural residues to manufacture pulp and paper due to the growing demand for paper and limited timber resources. Scientists also studied many non-wood lingo cellulosic by-products of rural areas agriculture (Jiang et al. 2020). Rice straw, cotton waste, banana fibre, hemp waste, wheatgrass, elephant grass, and other materials are examples. From the resources mentioned above, rice straw tends to be the best material among all the agricultural residues because it is cheap and plentiful, and it is an excellent material for making handmade paper because it is abundant in agro-industries worldwide (Wu et al. 2020). Since the paper industry is dependent on forests and is linked to declining forest cover, it is one of the leading causes of deforestation and environmental degradation. Chemicals detrimental to the environment and human health are used in paper production, whether industrial or handmade. Chlorine,

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chlorine dioxide, sodium hypochlorite, hydrogen peroxide, and peroxy acids are just a few examples. Alternative eco-safe fabrics and manufacturing processes must be used for rice straw handmade paper to gain economic and environmental benefits (Nalubega et al. 2016). Pulp processing from non-wood sources has several advantages, including ease of pulping and excellent fibre for some paper forms. Non-wood materials such as corn straw, bamboo, rice straw, bagasse, reeds, grass, hemp, flax, and pollen and provide 60–80% cellulose fibre in some developing countries (Liu et al. 2018). Rice straw is one of the essential pulp and paper processing materials with its high cellulose content. It has a 33–40% cellulose content, a hemicellulose content of 24– 28%, and a lignin content of 2–25% (Mukherjee et al. 2018). Soda is the oldest and most basic of the pulp-processing methods. Moreover, according to Harun and Geok (2016), non-wood “green” materials include agricultural leftovers and wood from trees such as maples, firs, and hemlocks. Research has examined several rice papermaking techniques: Different cooking settings affect the mechanical qualities of the sheets created by soda–ethanol pulping. Sodium hydroxide content influences rice straw paper’s mechanical and physical attributes and the kinetics of pulping wheat straw with caustic potash-ammonia aqueous solutions (Hassan et al. 2016). Since the papermaking process necessitates recycled waste paper, waste paper consumption continues to rise year after year. This benefit to the protection of virgin natural fibres is essential. The conventional office paper recycling process helps to reduce the amount of waste paper. After washing and polishing, the used form may also be re-pulped. In this experiment, the rice straw was characterized with various sodium hydroxide concentrations before being combined with office waste paper and soda pulping at different temperatures to obtain recycled paper with the desired properties. Delignification is used to determine the effects of sodium hydroxide on rice grass cellulose and lignin content and tensile strength, and water absorption to determine the best operating pulping conditions (Suseno et al. 2019). The proportion of paper mixture used for rice straw varies to equate the physical properties of recycled paper (tensile strength and water absorption) to natural rice straw paper.

9.8.6 Mushroom Cultivation Mushroom cultivation is a profitable agricultural enterprise that uses rice and wheat straw to grow mushrooms. By-product disposal is done without harming the environment. Since the ryegrass mushroom, Volvariella volvacea has a 14 days incubation time, and it is the easiest mushroom to grow. They produce 5–10% mushroom products from rice straw (50–100 kg of mushrooms per tonne of dried grass). On the other hand, the development of oyster mushrooms, Pleurotus spp., offers an onfarm bioconversion method to create healthy food products out of low-quality straw. Mushrooms will grow on this surface naturally because it is very natural. Outdoor and indoor mushroom farms provide similar yields. However, open fields are more subject to weather and higher temperatures, which result in lower harvests. The

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more giant and regular mushrooms produced inside make indoor gardening preferable. Mushrooms are considered adequate food for addressing food and nutrition protection, human health, and climate change adaptation issues (Ishara et al. 2018). Rice straw mushroom, also known as V. volvacea, is a commonly farmed mushroom in East and Southeast Asia. Rice production with rice straw mushrooms adds value and raises income for poor farmers in developing countries (Gao et al. 2020). Rice straw mushroom ranks sixth among edible mushrooms in production, accounting for around 5–6% of global output. Furthermore, rice straw mushroom has potent antimicrobial properties; subsequently, it contains polypeptides, terpenes, steroids, and phenolic compounds like flavonoids, phenolic acids, and tannins, all of which contribute to its potent antimicrobial properties (Chandra and Chaubey 2017).

9.9 Concluding Remarks Rice straw is a low-value agricultural by-product that abundantly exists in nature. Historically, rice straw was regarded as low-value waste material. However, stringent regulations controlling their disposal have prompted scientific investigations into the material’s possible uses. Numerous works and inventions have been made for agricultural operations, energy production, pollution control, building materials, and some critical processes for the benefit of rice straw. Rice straw, when used efficiently, can provide an appropriate feedstock for competitive bioenergy production. The technology for producing bioethanol from lignocellulosic biomass-rice straw is both cost-effective and environmentally friendly. Rice husk looks to be an attractive and practical alternative for bioethanol production due to its vast availability and stunning composition, one of the primary reasons bioethanol production from rice husk is gaining momentum. Rice straw is found globally but is most prevalent in Asia, where > 1 billion tonnes of rice straw are produced. However, since the livestock in this region frequently lack proper feed, and the rest of the ruminant feed is too costly, around half of it is burnt up inefficiently, which causes a significant rise in respiratory diseases and pollution. As a result, new technologies must be developed to use biomass as a feedstock to produce biofuels and bioenergy. Enhancing the value chain of rice straw by-products and implementing sustainable straw management practices are critical for preventing farmers from being fired in the open field and avoiding negative environmental and health consequences. An alternative is to amend the soil with rice straw. However, this should be done with caution to ensure proper decomposition and Greenhouse Gas Emission (GHGE) reduction. Mechanical selection using ballers is critical for the long-term usage of rice straw. Bioenergy: Conduct a review and update the scientific evidence on agricultural residues and rice straw biomass in light of their environmental and economic implications.

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Chapter 10

Weed—An Alternate Energy Source R. Ramya, J. Adur Alaknanda, D. Raajasubramanian, S. Srinivasan, K. Narendra, and M. Manjushree

Abstract Weeds are invasive or unwanted plants that are non-native to the ecosystem grow along with food crops threatening the food security, health, economic development and biodiversity. They are competitive, able to persist and grow under any stressed conditions with high propagating capability. India having temperate to tropical zones possesses rich plant diversity spread across different crop and noncroplands. Weeds grow everywhere consuming the nutrients, soil moisture, space, etc., meant for food crops and thus ultimately affect the crop productivity adversely. Parthenium is a weed that invaded India with imported food grains in the mid-1950s. This weed alone was reported (2001–2007) to invade over 14.5 million hectares of farmland in India (Directorate of Weed Science Research—DWSR). It was also opined that the swift growth of this weed is a threat to environment, biodiversity and country’s economy. Various strategies involving many voluntary organizations, individuals and government agencies in the weed management on a regional scale were R. Ramya Surana College, Peenya, Bangalore, Karnataka, India J. Adur Alaknanda Department of Environmental Science, Surana College, Peenya, Bangalore, Karnataka, India D. Raajasubramanian · K. Narendra Department of Botany, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu, India S. Srinivasan Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu, India D. Raajasubramanian Department of Botany, Thiru. A. Govindasamy Government Arts College, Tindivanam, Tamil Nadu 604307, India S. Srinivasan Department of Biochemistry, Government Arts College for Women, Krishnagiri, Tamil Nadu 635002, India M. Manjushree (B) Faculty of Science, Rotary Educational Society, Mandya, Karnataka, India e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_10

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organized. Though several eradication measures were undertaken in this regard, not a single method is still a choice for the complete eradication of weed. Therefore, the status of weed controlling is envisaged with respect to “large-scale utilization”. Over a century, several studies have been reported that weed can be a potential biomass. Weed can be used as a green manure, biocontrol agent, soil ameliorate, compost which in turn improves physical, chemical and biological composition of the soil and also in the generation of significant quantities of energy. In this age of renewable energy, there is an ever-rising demand for the alternative energy source which calls for exploring and exploiting new sources of energy biomethanation is a process of production of biogas (methane), during which the organic matter is converted into an alternative fuel. Biomethanation offers an effective way to manage the weed biomass in eco-friendly and cost-effective way. Keywords Alternative fuel · Anaerobic digestion · Bioenergy · Biomass · Biomethanation · Weed

10.1 Introduction Weeds are invasive or unwanted plants that are non-native to the ecosystem which grow along with food crops threatening the food security, health or economic development and biodiversity (Bajwa et al. 2016). They are competitive, able to persist and grow under any unfavourable conditions with high reproducing capacity and seed bank quality. India being a temperate country has diverse resources of plants grown in different crop and non-croplands. Weeds grow everywhere consuming the nutrients, soil moisture, space, etc., meant for food crops and thus ultimately affect the crop productivity adversely. Practically, weeds are plants that need to be prevented, controlled or managed to economically benefit an agriculturist. Typically, the principal weed management protocol would be cultural and mechanical in nature, focusing on prevention, crop rotation and cultivation. To have an operative weed management program, one should consider the pest problems, soil quality, capital investment, market, climate, manpower and labour. Understanding the weed control strategies based on all these factors will help in an effective weed management system. Inadequate control of weed is one of the most yield-limiting factors for most of the food crops. As per the report by Bridges in 1992, prominent presence of weed across 196.27 million hectares of cropland and 405 million hectares of range and pasture is seen in the USA. This statistic has irked the worldwide attention of all researchers towards weed management program. One such tropical American weed that majorly caught the attention of the researchers is Parthenium hysterophorus L. (Asteraceae), a whitetop herbaceous weed. The worldwide distribution of P. hysterophorus is shown in Fig. 10.1.

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Fig. 10.1 Global distributions of Parthenium hysterophorus around the world. Red patches depict the invaded countries; blue colour depicts transient populations (present, but establishment is not expected to occur based on technical evaluation) and green represents the countries in native range. Source Shabbir and Javaid (2018)

10.1.1 Impact of Weed on Country’s Economy Apart from their environmental impact, weeds also impose two ways of cost on production, one by reducing the quality and quantity of the agricultural product and other by increasing the input requirements in terms of weed control. Weed competition is the widely studied type of interaction between plants. Competition for light, water, nutrients, etc., always has a deleterious effect on food crops. Moreover, the phytotoxic natural substance produced by weeds makes them a successful competitor for food crops. Weed interaction with food crops also has an indirect impact on the soil microorganisms, which could hinder the food crops at varying degrees. Its interference with livestock contributes to reduce in forage production (Ekwealor et al. 2019), thus contributing to significant losses in crop yields and economic losses in agricultural yields. As per the report published by Bridges in 1992, the average annual financial loss specifically due to weeds grown in the USA was $4.1 Bn, where the status quo remains same even after three decades. It’s $3.3 Bn annually in terms of reduced productivity and weed control expenditures, according to studies conducted by the cooperative research centre for weed management systems. In India, a study by Jabalpur-based Directorate of Weed Science Research—DWSR reported that one single weed like P. hysterophorus had a similar impact. It was in 1956, that the P. hysterophorus weed was first sighted in India, which made its entry along with imported food grains (Fig. 10.2). Later between 2001 and 2007, DWSR reported that the invasive weed has invaded over 14.5 million hectares of farmland

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Fig. 10.2 Overall scheme of anaerobic digestion process

in India. This neotropical invasive weed of both agricultural and urban land of India contributes to serious health hazards due to its allergenic properties (Tefera 2002). The P. hysterophorus weed, which has accelerated its growth as a result of global warming, has become a hazard to the environment and biodiversity, limiting the germination and growth of several food crops. As such, government-administered systems will remain a significant issue in the twenty-first century. Voluntary organizations, individuals and government institutions created a coordinated plan to ensure regional control of Parthenium. There is currently no means of complete elimination of Parthenium. As a result, the Parthenium management is by enlarge viewed on basis of “large-scale Parthenium utilization”.

10.1.2 Sustainable Management of Weeds Through Anaerobic Digestion Weed management with respect to chemical and mechanical control measures raises concerns with them rapidly adapting and thereby diminishing the effects. Hicks et al. (2018) reported the weeds evolve resistance towards herbicides with their intense application. This has led in agricultural landscapes being dominated by a few weed species that are difficult to control (Garnier and Navas 2012). Several studies proposed that weeds can be used as a green manure, biocontrol agent, soil ameliorate (Rashid et al. 2008), compost (Kishor et al. 2010) that may improve biological, chemical and physical properties of the soils and also in the generation of substantial quantities of energy (Gunaseelan, 1994). Ample availability of weeds from the fields contributes significantly as alternative energy source. There are two main processes involved under energy recovery from plant source (biomass), the thermochemical process and biological process (biomethanation process). Thermochemical process is better choice of energy recovery over the biological process due to its cost-effectiveness. But in developing countries like India, a cost-effective thermochemical process of energy recovery is still not a preferred choice due to its low calorific value. This has led to the utilization of the uprooted Parthenium for

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the biomethanation process. Biomethanation is a process of production of biogas (methane). In this process, the organic matter is converted into biogas which is a very useful form of energy.

10.1.3 Overview of Biomethanation Biomethanation being the most sought-after method for weed management was under study for many decades. It offers an effective way to manage the weed biomass in an eco-friendly method. Improper methods of addressing the weed menace have resulted in aesthetically unpleasant patches of land and several other problems. It has been observed that aquatic weeds like water hyacinth (Eichhornia crassipes), Cabomba (Cabomba caroliniana) and Salvinia (Salvinia molesta) and weeds like P. hysterophorus, Lantana camara, Ageratum conyzoides are suitable plant biomass feedstock for biomethanation in generating renewable energy (Biswanath et al. 2020). A plant weed is chosen for the decomposition by anaerobic digestion to yield renewable energy resource—biogas. Renewable energy sources have been widely accepted for energy generation, and with expected fossil fuel limitations in the coming decades, these resources have become a top priority. It is feasible to mitigate some of these concerns by employing a biological process that generates biogas from plant biomass (Daniels 1992; Angelidaki and Ellegaard 2003; Weiland 2003; Yadvika et al. 2004). Biomethanation is a microbial decomposition process that results in the production of methane gas. This anaerobic digestion process is advantageous for recovering valuable resources (Braber and Novem 1995). As a result, an environmentally favourable and economically viable anaerobic digestion process is used to regenerate energy in a sustained manner (International Energy Agency 2004). With a biomethanation system already in place in India, not much research with respect to substantial evidence in using weed as a biomass feedstock; the composition and interactions of a biogas-producing microbial community, as well as the contribution of a particular bacterium to the overall process, are largely reported.

10.1.4 Plants as Biomass Biomass, “any material, excluding fossil fuel, which was a living organism that can be used as a fuel either directly or after conversion process” (ASTM 2002). Worldwide over the past few decades this biomass is gaining importance as to compensate the depleting fossil fuel. Our species has progressed and that has resulted in increased dependency on plant biomass for heat, light, energy and for food preparation (Gowlett 2006). While there are numerous types of plant-derived fuels accessible today, satisfying the growing demand for sustainable energy systems presents a considerable issue. Cellulose, hemicellulose and lignin are all polymers that form

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a complex structure when combined. This complicates its usage as a biomass feedstock. The lignocellulosic residue-derived biomass is resistant to bacterial degradation, needing a pretreatment step. Bioprocess engineering makes use of the term “pretreatment” to refer to the process of converting lignocellulosic biomass from its natural state to one that can be hydrolyzed (Lynd et al. 2002). This indicates that the pretreatment process is critical in the conversion of biomass to a feedstock. The pretreatment processes are classified into three types, namely physical, chemical and biological as per literature (Aftab et al. 2019). However, feedstocks sometimes require a combination of pretreatment for the effective conversion of the biomass into methane. Hamzawi et al. (1998) discovered that alkali pretreatment method significantly increased the biodegradability of a mixture of plant biomass and sewage sludge during co-digestion. Enhancing microbial activity with a range of biological and chemical additives under a variety of operating circumstances has previously been attempted to improve anaerobic digestion. Cattle manures (Dar and Tandon 1987; Alvarez and Liden 2008), crop residues (Braun 2002), weeds, microbial cultures (Weiß et al. 2011), etc., are among the few of the biological additives which were being attempted in the past.

10.1.5 Microbiological Anaerobic Digestion with Respect to Plant Biomass Biogas production increasingly relies on energy crops as a feedstock (Lindorfer et al. 2007). Recently, the growing demand for energy produced from crop biomass, calls for efficient and effective crop digestion systems. There are various parameters that govern the efficient ways of utilizing Parthenium weed as potential feedstock for biomethanation, like inoculum–substrate (I/S) ratio, carbon–nitrogen (C/N) ratio, lignocellulosic content, pH and temperature (Dioha et al. 2013). Among the various parameters, the lignocellulosic biomass and carbon–nitrogen content in the Parthenium play a pivotal role by influencing the methane production. Since it contains the components essential for the production of amino acids, proteins and nucleic acids, and it also has the requisite neutral pH for microbial fermentation, lignocellulosic biomass present in the weed operates as a limiting factor. Cellulose, hemicelluloses and lignin are the three major components of agricultural biomass that acts as a constraint on its use as a feedstock. To produce a Parthenium feedstock, the hemicelluloses found in lignocellulosic biomass must be converted into xylose while maintaining an ideal C/N ratio throughout the process.

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10.1.6 Biochemical Reactions Involved in Anaerobically Digested Biomass Biogas is produced via anaerobic digestion (AD), a process in which organic matter is digested by a microbial consortium in the absence of oxygen. The AD process involves consortium of bacterial groups in carrying out the anaerobic digestion of complex organic matter. Majorly there are four different bacterial groups which contribute to hydrogenesis, acidogenesis, acetogenesis and methanogenesis. The overall biochemical reaction is the conversion of biomass into CH4 , CO2 , H2 , NH3 and H2 S (Evans et al. 2001). The first step of anaerobic digestion is hydrolysis, in which complex compounds are reduced to soluble compounds using extracellular enzymes released by hydrolytic bacteria. The second step is the acidogenesis, wherein the organic monomers of sugars and amino acids released during the hydrolysis are degraded to volatile fatty acids (VFAs) by a group of fermentative bacteria. Propionic, butyric and valeric acids are likewise VFAs, as are acetate, hydrogen and carbon dioxide. The third phase involves the conversion of LCFA and VFA to acetate, CO2 and H2 via the required hydrogen-generating acetogens. The final stage of the four-step process is methanogenesis. Methanogenesis occurs in two ways: One via hydrogenotrophic methanogenesis (producing methane by hydrogenconsuming bacteria utilizing H2 and CO2 in a syntrophic co-culture with obligate hydrogen-producing acetogenic OHPA bacteria); and two by Methanogenic aceticlastic bacteria that produce methane and carbon dioxide when grown on acetate as a substrate. The synergistic process of biomethanation by the consortium of anaerobic microorganisms can generally be classified into four phases: hydrolysis, acidogenesis, acetogenesis and methanogenesis (Fig. 10.3) (Yu and Schanbacher 2010). But, Weiland (2003) divided anaerobic digestion (AD) phases into only two phases as the microorganisms involved in the hydrolysis and acidogenesis are closely related so as the microorganisms involved in the acetogenesis and methanogenesis. The major groups of microorganisms involved in biogas production are anaerobes, which are observed to have a greater degree of metabolic specialization (Nagamani and Ramasamy 2013).

10.1.6.1

Hydrolysis (Chanakya et al. 2006)

In the first stage of hydrolysis, called liquefaction, microorganisms break down complex polymers into monomers. Celluloses, for example, can be converted into sugars or alcohols, proteins to peptides or amino acids and lipids to fatty acids. This is accomplished through the secretion of numerous hydrolytic enzymes by bacteria such as Clostridia and Bacilli, as illustrated in Figs. 10.4 and 10.5.

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Fig. 10.3 Anaerobic breakdown of weed biomass

Fig. 10.4 Methane generation by AD

10.1.6.2

Acidogenesis

Acid formers convert simpler molecules to long-chain fatty acids via fermentation. Hydrolytic and fermentative activities are required for high-quality organic waste treatment and are infrequently limited (Verma 2002). Eubacteria, for example, grow at a faster rate than methanogenic bacteria and acetogenic bacteria (Bhattacharya et al. 1996; Lin and Chen 1997). As a result, hydrolytic and fermentative activities are frequently used to measure the conversion efficiency of a feedstock. Equation 1: Acidogenic fermentation of glucose:

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Fig. 10.5 Hierarchy of technological options in utilizing biodegradable wastes for energy production

C6 H12 O6 → CH3 (CH2 )2 COOH + 2CO2 + 2H2 (Carbon dioxide) (Hydrogen) (Butanoic acid) (d-Glucose) C6 H12 O6 + 2H2 → 2CH3 COOH + 2H2 O (Acetic acid) (Water) (d-Glucose) (Hydrogen) C6 H12 O6 + 2H2 O + 2CO2 → 2CH3 COOH 4H2 (Acetic acid) (Hydrogen) (d-Glucose) (Water) (Carbon dioxide)

10.1.6.3

Acetogenesis

After the formation of numerous complex intermediate and long-chain fatty acids (LCFA), acetogenic bacteria convert LCFA to simple organic acids (formic, acetic and propionic), hydrogen and carbon dioxide. The primary acids produced are acetic acid, propionic acid and butyric acid. Even CO2 and H2 are capable of being used to synthesize acetic acid. Given that approximately two-thirds of the methane produced in a biogas reactor derives from acetate (Gujer and Zehnder 1983), a decrease in the acetate activity that utilizes methanogens has a significant influence on the anaerobic digestion process. Occasionally, acetate can be converted into hydrogen and carbon dioxide only at low pressures, i.e. in the presence of hydrogen-eating microorganisms (Schnürer et al. 1999). The compounds created in this phase are a result of a variety of

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unique microbial species, including a propionate decomposer and Syntrophomonas wolfei, a butyrate decomposer. Equation 2: Acetogenic oxidation reactions: CH3 (CH2 )2 COOH + 2H2 O → CH3 COOH + (Water)

(Butanoic acid)

(Acetic acid)

CH3 CH2 COOH + 2H2 O → CH3 COOH + (Propionic acid)

10.1.6.4

(Water)

(Acetic acid)

CO2 + 3H2 (Carbon dioxide) (Hydrogen)

CO2 + 3H2 (Carbon dioxide) (Hydrogen)

Methanogenesis

Methane is finally formed by a consortium of bacteria termed methanogens like Archaea in two separate pathways: 1. either by cleaving acetic acid molecules to produce CO2 and CH4 2. or by reduction of CO2 by H2 . Equation 3: Methanogenic reactions: CH3 COOH → CH4 + (Acetic acid)

(Methane)

4H2 + CO2 (Hydrogen) (Carbon dioxide)

CO2 (Carbon dioxide)

→ CH4 + 2H2 O (Methane)

(Water)

Methane production is higher when CO2 is reduced, but a lack of hydrogen in the digester causes the acetate reaction, which is the principal pathway for methane generation (Omstead et al. 1980). Hydrolytic bacteria convert large macromolecules into their building blocks, such as amino acids, LCFA and monosugars, in the initial stages of solid-state anaerobic digestion (SS-AD). The remaining microbes are acids and acetogens that further degrade them into acetate, carbon dioxide and hydrogen. Finally, through two aceticlastic and hydrogenotrophic processes, the methanogens convert smaller substrates into methane (Demirel and Scherer 2008; Ferry 2011; Bryan et al. 2011). The microbial consortia that live in the fermenter of a biogas plant provide the foundation for a systematic approach improving the biotechnology process in biogas production. Previously published study in this field indicated that species related to the genus Methanoculleus play a significant role in the methanogenesis process (Schtlüter et al. 2008). Amylolytic microorganisms (Preeti et al. 1993), Phylum Proteobacteria (Stolze et al. 2015), Clostridium straminisolvens (Kato et al. 2004), Phylum Bacteroidetes (Zakrzewski et al. 2012; Stolze et al. 2015), Phylum Firmicutes (Shan-Fei et al. 2016), autotrophic and hydrogenotrophic methanogens (Demirel and Scherer 2008), Phylum Spirochaetes, Acetotrophic methanogens, Methanomicrobiales, Methanosarcinales, Methanobacteriales, hydrogenotrophic methanogens (Klocke

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et al. 2008; Nettmann et al. 2008), Clostridial genomes (Schtlüter et al. 2008), Clostridium stercorarium, Clostridium thermocellum (Zverlov et al. 2010; Koeck et al. 2014), Phylum Actinobacteria, Synergistetes and Euryarchaeota (Zakrzewski et al. 2012), Bacillus thermoamylovorans (Koeck et al. 2014) were among the other microbes identified to have contributed to the AD process. Species related to Clostridial genomes play a significant role in hydrolysis of cellulosic plant biomass in the anaerobic fermenter (Schtlüter et al. 2008). Hydrolysis phase plays a predominant role in determining the ultimate methane yield for a particular substrate (Zaman 2010). Thus, a very complex microbiome is responsible for the efficient production of biogas from a given biomass. Many different groups of microorganisms have to work actively in close consortium for the biomethanation process. Any disturbance to this set-up results in reduced biogas production or at times collapsing the entire process. The consortium and their interactions of the microbial community that produces biogas, as well as the contribution of a particular bacterium to the overall process, are mostly unknown. Thus, a thorough knowledge on microorganisms and their functions is required for the efficient control of the biomethanation. While biogas fermentation from plant biomass is a mature technology, biogas plants’ efficiency and yield can still be boosted. For example, little is known about the underlying biology, and the process’s biological basis is not totally understood. Although in general the scientific contributions to the biogas technology are rapidly increasing, less information is available about microbes within the anaerobic fermenters. Microbiological processes are exceedingly intricate and require much research to be properly understood.

10.1.7 Biogas Technology Biogas technology is becoming a topic of increasing interest among researchers since it accentuates on the biomethanation process for the production of renewable energy source as a substitute for fossil fuel. It has established itself as a technology with great potential to serve as an alternative energy source. Indeed, it has the potential to give many benefits to users and the community, resulting in resource conservation in an environmentally beneficial manner (Yadvika et al. 2004). In today’s world of ever-increasing demand for energy and due to the fast depletion of fossil fuel, this technology has been a boon. Initially, this technology was limited to only cow dung as potential feedstock, very famously called as gobar gas. However, with the recent advances in research, utilization of organic wastes other than cattle dung was considered. There is an ever-increasing demand for alternative energy sources in this age of renewable energy, specifically for the exploration and utilization of new sources of energy. However, weeds have a significant impact on agricultural land. India has been adjusted in the past to meet the requirements of this alternative energy source and to avoid agricultural losses due to weeds (Channappagoudar et al. 1990; Bhan et al. 1997; Kishor et al. 2010; Rajiv et al. 2013).

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The need of the hour would be “improve our environment, enhance our agricultural yield, protect our biodiversity, reduce our dependence on imported energy and deployment of renewable energy resources like available biomass”. All the unwanted plants/weeds have the potential to convert into useful form. Landfills, composting, energy recovery are few conceivable conversion paths for these weeds to recover usable (organic fraction) resources. The majority of countries worldwide use the disposal option for an extended period of time; however, the process pollutes the air and contributes to global warming. These are detailed in detail elsewhere (IEA— International Energy Agency 2004). When biomass is turned into an usable source of energy or compost, certain environmental repercussions are mitigated. Composting is a slow process, so the energy recovery process can be the option of choice. Energy can be recovered by adopting thermochemical technology or by biomethanation. Organic matter is thermally decomposed to produce heat energy, fuel oil or gas in a process termed as thermochemical conversion. The primary technology alternatives in this area are as follows: (i) incineration, (ii) pyrolysis and (iii) gasification. This process is very expensive and not a viable option in developing countries like India, so the better option for managing and recovery of useful resources is the biomethanation or anaerobic digestion or biogas production (Fig. 10.6) (Chanakya et al. 2006). Currently, the strategy is limited to destroying and eradicating weeds. These weeds that have been eradicated can be used directly in the production of biogas. More than 65% of Maharashtra’s biogas facilities are inoperable due to a scarcity of manure (Dhawan et al. 1990). Utilizing these alternative weed by-products in biogas generation can assist in not only resolving the energy issue, but also in preventing environmental degradation. Fig. 10.6 Parthenium hysterophorus in croplands of Hesaraghatta, Bangalore, India

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10.2 Exploring Parthenium hysterophorus as Alternative Energy Source Among the various weeds posing an ecological and economical treat globally, Parthenium has achieved the prominent status in terms of weed management program. Hence, the information pertaining to impact of P. hysterophorus on country’s economy, weed management process, P. hysterophorus as potential feedstock for the anaerobic digestion process, its methane potential, batch anaerobic systems, pretreatments, co-additives, inoculums substrate (I/S) ratio and mainly the metagenomic analysis of the microbiome involved were researched extensively.

10.2.1 Impact of P. hysterophorus P. hysterophorus has established a major weed status in both India (Fig. 10.7) and Australia. Parsons and Cuthbertson (1992) had summarized the weed’s influence on the Indian subcontinent in 1992. In India, the weed P. hysterophorus is alien in origin and extremely difficult to control due to its dominance of both cultivated and uncultivated environments (Evans 1997; Mahadevappa and Patil 1997). Parthenium weed has grown to prominence in the last two decades due to its rapid proliferation in Australia and India, representing substantial environmental hazards in terms of eradication and safe disposal in developing countries.

Fig. 10.7 Weed invasion curve

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Fig. 10.8 Schematic diagram of a gas chromatograph

10.2.2 Parthenium Management Measures in the Past The weed menace is viewed with respect to that of prevention. Prevention is the most essential aspect of the weed management programme. Once a noxious weed establishes, any control measure becomes increasingly more expensive. The basic principles of any weed management program include suppression, prevention, eradication and management (Fig. 10.8). Among the several management programmes proposed, the available methods of control of the weed include chemical (Navie et al. 1996), mechanical and biological (Shrestha 2015). In India, the biological control of P. hysterophorus was contributed by Dhanraj and Mitra (1976), Haseler (1976), Jayanth (1987), Aneja (1991), Pandey et al. (1992), Sreerama (1998). Failure to combat weed incursions would have serious global effects, including the catastrophic destruction of agriculture, forestry and fisheries resources.

10.2.3 Large-Scale Utilization of P. hysterophorus In India, Parthenium has slowly and surely become a serious weed in many agricultural situations; its impact is more rampant in urban areas (Seerjana et al. 2020). In addition to the various eradication methods adapted, Parthenium has also been viewed on the possibility of utilization. Large-scale utilization of weeds can be an economically significant attractive alternative in efficient management of weeds. Though a weed, the plant has been reported to have a number of beneficial pharmacological and medicinal effects along with industrial and other applications (Anita et al. 2014). Its large-scale utilization has been viewed for biogas production (Gitanjali et al. 2009). Generation of substantial quantity of energy from Parthenium was reported by Gunaseelan (1994). The other large-scale utilization of Parthenium biomass was vermicomposting (Biradar and Patil 2001; Yadav and Garg 2011),

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composting (Channappagoudar et al. 2007; Murthy et al. 2010; Kishor et al. 2010; Ambasta and Kumari 2013), green manure (Javaid and Shah 2008; Suryawanshi 2011), paper and pulp industry (Naithani et al. 2008), synthesis of nanoparticles (Parashar et al. 2009), dye degradation (Shinde et al. 2012), corrosion inhibition (Ji et al. 2012) and biochar preparation (Kumar et al. 2013).

10.2.4 Substrate Utilization for Energy Production Various studies on research regarding the utilization of E. crassipes (Chanakya et al. 2006), cheese whey (Wildenauer and Winter 1985; Anna et al. 2010; Najafpour et al. 2010; Aspasia et al. 2012), poultry droppings and cattle dung (Fernando and Dangogo 1986; Machido et al. 1996), L. camara L. (Dhar and Tandon 1987), P. hysterophorus (Gunaseelan 1987), farm wastes (EL-Shinnawi et al. 1989), Ageratum (Kalia and Kanwar 1990), Pistia stratiotes (Abbasi and Nipaney 1991), Eupatorium (Kanwar 1998), rice and wheat straw (Somayaji and Khanna 1994), dairy wastes (Chirag and Datta 1996), fruit and vegetable wastes (Bouallagui et al. 2005), sludge (Rong and Deokjin 2006), kitchen, fruit and vegetable wastes (Ojolo et al. 2007), corn and beet pulp silages, carrot residue, grass silage (Hong et al. 2010), Ipomoea carnea (Deshmukh and Bartakke 2012) as primary resource for energy production have been studied.

10.2.5 Biomethanation Biomethanation is a process that utilizes microbiological action to breakdown organic matter in an oxygen-free environment to produce methane gas. This anaerobic fermentation process is advantageous for recovering valuable resources (Braber and Novem 1995). As a result, anaerobic digestion is used to regenerate energy. This has the potential to make a considerable influence on long-term sustainability (both environmentally and economically) (International Energy Agency 2004). With biomethanation system already existing in India, there is very little research carried out in using plant weed as a biomass feedstock. The utilization of biomass as a source of energy has many alternative aspects (Woods and Hall 1994). Extensive screening has been performed on different crops for their methane potential on various occasions. The plant biomass being looked upon as a potential feedstock for biomethanation was rice straw (Acharya 1958), water hyacinth (Chynoweth et al. 1982; Chanakya et al. 1992; Viswanath et al. 1992; Gunaseelan 1997), tomato plants and tomato stems, Parthenium (Gunaseelan 1987), Banana peel (Gunaseelan 2004), paddy straw (Chanakya et al. 1992), cellulose pulp, maize

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(Raposo et al. 2006), I. carnea (Deshmukh and Bartakke 2012), Zea mays, Cannabis sativa, Beta vulgaris and Helianthus tuberosus (Nges and Björnsson 2012).

10.2.6 Biogas and Its Determination Biogas is referred to be a low-cost technology due to the capacity of the microbial consortia engaged to breakdown a wide variety of feedstocks (Bruni et al. 2010). Biogas is a highly combustible gas that can be used for generation of heat, electricity and mechanical energy. It is a mixture of methane (65–75%), CO2 (30–35%), and NH3 , H2 S, H2 , N2, etc., in trace quantities (Yadava and Hcssc 1981). One of the primary advantages of biogas over other renewable fuels such as ethanol and biodiesel is the fuel’s ability to be derived from a diverse range of substrates or feedstocks. A lot of studies and research activities pertaining with the determination of biogas measurements have been carried out in the last decade (James et al. 1990; Müller et al. 2004; Liu et al. 2004; Walker et al. 2009). As a result, many efforts have been made to define a protocol for the ultimate biogas measurement for a given biomass. The timely measurements of methane gas in a biogas plant are essential to enable the detection of developing problems within the digester, to monitor the optimum operating conditions, gathering practical data so as to compare to the other similar operating plants and to know the economic importance in terms of total methane yield. In many developing countries, the laboratories have very little access to advanced gas measuring equipments, limiting the research aimed at improving the biogas production. The quality of biogas created in fermenters does not remain constant throughout time but fluctuates according to the digestion duration (Khandewal and Mahdi 1986). A common method of biogas collection and measurement is liquid displacement (Singh et al. 2001; Iqbal et al. 2015; Sajeena Beevi et al. 2015). Additionally, the methane ratio is affected by the substrate’s composition, pressure, temperature and pH (Liu and Shen 2004). Manometer techniques, which are widely used for small gas volumes, are a viable alternative to liquid displacement (James et al. 1990). Gasometers are used to measure volume at the general laboratory level since they are inexpensive, simple to install and use, and may operate without maintenance for extended periods of time. They can also be connected to data collection systems (Walker et al. 2009). The speed and total volume of biogas generated during the AD test can be determined in a variety of ways, including by using a lubricated syringe, displacement devices, pressure gauges or transducers, manometer-assisted syringes or low-pressure switch gauges. Gas chromatography (GC) has several advantages, including high resolution, rapidity, sensitivity and quantitative results (Fig. 10.9). It is an excellent choice for determining the concentration of a gas in contact with its liquid phase (Seeley and Aurand 2010). GC is a common method that is used to assess gases in a variety of biological activities (Jaya et al. 2012). A gas chromatographic system is composed of six basic components: flow controllers, injectors, detectors, furnaces, columns and data systems. The injector,

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Fig. 10.9 Effect of delignification on biogas production

detector and oven are frequently integral components of the gas chromatograph, but the column gases and recorders are distinct. In the determination of biomethane concentration, the values obtained using liquid replacement methods (LRM) were comparable to those obtained using GC (Pharm et al. 2013). To be suitable for GC analysis, a molecule must have a high degree of volatility, between 350 and 400 °C. In other words, the entire or a portion of the compound’s molecules must be gaseous or vaporous. Additionally, the substance must withstand high temperatures and rapidly degrade into vapour without deteriorating or reacting with other chemicals. In GC, helium—an inert gas—is used as a carrier gas and nitrogen is used as an unreactive gas. The gases to be investigated interact with the stationary phasecoated column walls. At certain times, depending on the chemical retention duration, this coating eludes the chemicals. Following that, these molecules are examined in further detail in comparison with the GC-calibrated gases. This permits the development of accurate estimates of worldwide standards. Additionally, GC has been associated with a variety of detection techniques, including electron capture, thermal conductivity, fire ionization and mass spectrometry (Grzegorz et al. 2013). Although numerous examples are available in the scientific literature on collection

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and storage (Husted 1994; Kapdi et al. 2004), biogas and methane volume measurements and computations are inadequately described and may contain significant mistakes (Walker et al. 2009).

10.2.7 Pretreatments The type and quantity of fermentative bacteria present in the digester are determined by the composition of the organic material (Zinder 1984). Organic wastes like municipal solid waste, animal manure and food waste have been reported to yield substantial amount of methane from anaerobic digestion process. Lately, due to the abundant availability the lignocellulosic plant biomass has gained much attention. However, lignocellulosic biomass for AD has not been widely adapted because of its complicated cell wall structure which makes it resistant to microbial digestion. Crop biomass contains non-structural carbohydrates (such as glucose, fructose, sucrose and fructans), proteins, lipids and pectins in addition to lignocellulose (McDonald et al. 1991). AD is currently the most cost-effective bioconversion technology for producing heat and compressed natural gas (CNG) from organic waste (Ghosh et al. 2000; Sims 2003). The complex nature of lignocellulosic biomass poses challenges to SS-AD operations by lowering the methane yield. Thus, pretreatment of resistant lignocellulosic biomass is critical for obtaining a high yield of biomass during the AD process (Fig. 10). Physical, chemical and biological pretreatments are used to increase the biodegradability of lignocellulosic biomass for methane production (Liew et al. 2011). Because a single approach of pretreatment does not give effective results due to its low specificity in targeting the lignin that connects hemicelluloses, a combination of one or more pretreatment procedures from the same or other categories is used (Zheng et al. 2014). According to the literature survey, for past few years there have been numerous pretreatment methods developed like mechanical, alkali treatment, acid hydrolysis, steam explosion, biological treatment, chemo-thermal, ultrasonic, ozone treatments, oxidative pretreatment, extrusion, enzymatic, pretreatment with lime, soaking aqueous ammonia (SAA), ammonia recycle percolation (ARP), ammonia fibre/ freeze explosion (AFEX), liquid hot water, organosolv, CO2 explosion, ionic liquid and lactic acid bacteria application (Shashi et al. 2020). Though pretreatments for improving the hydrolysis process have been extensively explored (Sun and Chang 2002; Parveen et al. 2009), there is little literature on the impacts of pre-treating crop biomass for methane production. Dar and Tandon (1987) reported an increased biogas yield with NaOH pretreated Lantana camera. Gunaseelan (1994) discovered that treating Parthenium-based digesters with NaOH increased the amount of gas produced. Alkaline pretreatment significantly improved the biodegradability of a solid waste mixture, according to Hamzawi et al. (1998). The chemo-thermal method of pretreatment has been reported to be the best option by Sarma et al. that maximum lignin was removed by acidic

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delignification process leading to the high methane yield followed by alkaline delignification and thermal pretreatments. Thus, pretreatment of biomass is an appropriate approach for the maximum biogas production. However, more research is needed to address issues such as plant biomass accessibility for AD, anaerobic bacteria adaptation to degrade lignocellulosic feedstock, adaptability of the microbial population on different pretreated substrates, the effect of inhibitors formed during the pretreatment process on AD, and the invention of innovative, low-cost pretreatment techniques for AD (Lucy et al. 2014).

10.2.8 Co-digestion Co-digestion is a process, wherein energy-rich organic materials are added as coadditives to digesters operating with excess capacity for the objective of increasing the net CH4 production potential. The potential outcome of synergistic approach of co-digestion is to improve the nutrient balance, increase the bioavailability of trace metal nutrients, maintain optimal pH balance and improve microbial community. Codigestion also increases specific methanogenic activities and changes the structure of the microbial community involved in the biomethanation process. The co-additives that were reported to have significantly increased the methane yield for the co-digestion process were biological (crop residues, microbial cultures) and chemical additives (Gunaseelan 1987), silkworm waste and oil seed extracts of neem, hybrid beans, guar gum seeds, castor, nirmal seeds, black gram, (Krishnanand 1994), sewage sludge (Sosnowski et al. 2003), heavy metals (Ni2+ and Zn2+ ) (Yadvika et al. 2004), algal sludge (Yen and Brune 2007), cattle manure along with energy crops (Seppälä et al. 2013), grease trap sludge (Luostarinen et al. 2009), food waste along with cattle manure (El-Mashad and Zhang 2010), palm oil mill effluent (POME) as additive in cattle manure fed digester, cattle manure as additive in ornamental plant fed digester (Deshmukh and Bartakke 2012) and commercial additives (zeolite and calcium carbonate) (Kuttner et al. 2015). The high lignin content containing coir pith when co-digested with cattle waste was reported to be a better biodegradation process (Radhika et al. 1983; Deivanai and Kasturi 1995). Aquatic weeds like Salvinia and Ceratopteris, Pistia, Wolfia and Lemna were reported as potential feedstock when added to cow dung-fed digesters (Abbasi and Nipaney 1991; Abbasi and Nipaney 1991; Balasubramanian and Kasturi 1992). The advantages of co-digesting plant materials with animal manure are that the manure provides buffering capacity and a wide range of nutrients, while the high carbon content plant materials improve the C/N ratio of feedstock for the biomethanation process. Crop residues as potential feedstocks for co-digestion with cattle dung to supplement and boost biogas production certainly more exploration.

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10.2.9 Inoculum–Substrate (I/S) Ratio The total methane yield from organic materials depends on the anaerobic microbial activity, the composition and characteristics of the substrate and the number of inhibiting compounds formed during the AD process (Angelidaki and Ahring 1992). The AD process entails a series of intricate biological interactions that are regulated by symbiotic microbial consortiums. The inoculum should come from an active anaerobic reactor, such as a sludge reactor or a manure biogas reactor. The inoculum should have a variety of microbiological components to ensure that the biomethanation process does not adversely affect varied substrates. The microbiological factors that determine the effectiveness of digestive index are critical in biogas production because they establish the embolic conditions for microorganism development (Mao et al. 2015). Likewise, a detailed compositional analysis of the substrate is a key factor in an AD process. The substrates including lignin, cellulose and hemicellulose, which are particularly important for energy crops and agricultural waste, should be emphasized due to lignin’s recalcitrant resistance, which will jeopardize the substrate’s biogas potential. Because determining the biochemical methane potential (BMP) for various organic wastes is required for developing an established AD process, detailed research on the effect of I/S for diverse organic wastes has been studied in recent years. Gunaseelan in 1995 reported a significant relation between I/S ratio to that of methane yield. Additional research is needed to determine the effect of the I/S ratio on methane yields and inoculum activity, as well as the association between microbial activity and substrate and digestate properties.

10.2.9.1

Effect of Substrate Particle Size

The particle size of the substratum is critical for digester content because it impacts gas output. If the feedstock is too large, it will clog the digester and make bacteria work harder to digest it. Smaller particles, on the other hand, give more surface area for substrate adsorption, resulting in enhanced microbial activity and, as a result, enhanced gas generation. Sharma et al. (1988) reported that out of five particle sizes (0.088, 0.40, 1.0, 6.0 and 30.0 mm) of raw materials, a particle size of 0.088 or 0.40 mm produced the maximum yield of biogas. Succulent materials, such as leaves, could be made of large particle size. On the other hand, large particles may obstruct gas production in other materials, such as straws. Physical pre-processing, such as grinding, can greatly lower the necessary digester volume without losing biogas output, according to the findings by Gollakotaand Meher and Moorhead and Nordstedt.

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Analysis of Community-Specific Genetic Problems of Biogas-Producing Microbial Consortia

The diversity and functions of microbiome in an AD process are two important principal aspects. Numerous community analysis methodologies have arisen over the last decade, the majority of which make use of the molecular phylogeny deduced from 16S rRNA comparative sequence analysis. In the past few decades, the applications of genomic tools have drastically expanded the scientific knowledge about microbial world. Rapid microbial community analysis has shown to be a difficult task. This is attributable to the microbial world’s incredible diversity and the great complexity of many microbial communities. A culture-independent technique was used to get a higher resolution of the bacterial population than a culture-based technique. Metagenomic DNA extraction plays a critical role in obtaining high-quality DNA from different environmental samples. Metagenomics is the genomic analysis of microorganisms based on the extracted DNA obtained from the natural environment. It enables a better understanding of the unexplored microbial diversity and to screen the specific functional genes (Mitra et al. 2011). Although many methods about the extraction of metagenomic DNA have been described, they are not suitable for all environmental samples. Therefore, modified methods of metagenomic DNA extraction are still emerging (Lee and Hallam 2009). The terminal restriction fragment length polymorphism (T-RFLP) is a novel technique for measuring variation among homologous amplification product populations. It is a relatively new molecular technique that allows for the detection of minute genetic changes across strains and insight into the structure and function of microbial communities. Due to the technique’s great sensitivity and throughput, it is perfect for conducting comparative comparisons (Marsh et al. 1999). The systematic analysis of microbial diversity in environmental samples is widely used by T-RFLP technique (Thies 2007). T-RFLP has been used in a number of recent research to examine microbial diversity (Lucas et al. 2015). PCR is performed to evaluate the integrity and purity of the extracted DNA sample. Due to the challenges associated with culturally based knowledge of these anaerobes, T-RFLP profiling and 16S rRNA clone data were chosen without cultivation. The polymerase chain reaction (PCR) is used to amplify a specific bacterial gene area expressing 16S rRNA from the population of DNA. The product generated from PCR was digested with restriction enzymes. The terminal restriction fragment was properly measured using an automated DNA sequencer. All bacterial strains can be separated from a model bacterial community using computer-simulated T-RFLP analysis, and the pattern is consistent with the expected outcome. T-RFLP complex bacterial community analysis revealed a high degree of species diversity in activated buckwheat, bioreactor sludge, aquifer sand and termite guts. T-RFLP is an effective tool for analysing a variety of complex bacterial communities and swiftly comparing the community structure and diversity in different conditions. T-RFLP analysis is a highly reproducible and robust technology that produces high-quality fingerprints made up of precision pieces that can theoretically be allocated phylogenetically if the proper base data is obtained after standardization. Many research contributions were

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made with respect to phylogenetic and functional analysis of microbiome (Ariesyady et al. 2007a, b). Metagenomics holds the possibility of providing a new perspective on organisms with various roles, expression systems that contribute to the development of novel enzymes and bioactive compounds that are economically viable (Lorenz et al. 2002). Finally, genomics can shed light on how specific species and strains contribute to the community’s overall activity.

10.3 Conclusion Though there are ample options and abundant availability of organic matter, weed biomass as a substrate for alternative energy source has more ecological and economic viability. Challenges in the utilization of non-available biomass by microbes present in the weeds, are addressed by various pretreatment protocols. A well-established research reports that the weed biomass subjected to such pretreatment process leads to high yield of methane. Application of weeds as potential source of alternative energy has important co-benefits, other than uprooting them for biogas use, replacing them with food crops and native species, reducing floods, improving soil quality, etc. Hence, the primary objective of deploying weeds towards biogas production is to advance the ecological and economical facets globally. Economy is an important determinant of a country’s sustained development. Sustainable energy is a major contributor towards the country’s economy. In order to ensure the access towards reliable affordable energy to the citizens, government, non-government organizations researchers collaboratively have designed various policies and programmes. This would also enable overseas investors to invest in renewable energy market. Hence, the weed management program has opened a whole new avenue in the renewable energy market.

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Chapter 11

Biomethanation for Energy Security and Sustainable Development Kalyanasundaram GeethaThanuja, Divya Thiyagarajan, Desikan Ramesh, and Subburamu Karthikeyan

Abstract In the decade of technology development, evolution in the environment occurs at the faster pace with the excessive and indiscriminate use of natural resources. The pressure on the existing energy reserves puts thirst on alternative, economically viable, environmentally safe, and ecologically efficient basis of energy in fulfilling the world energy demand. The sector of renewable energy plays crucial role in presenting the environmental and economic benefits. Biogas technology serves as a striking tool in conversion of biological waste into energy which improves lives, livelihood, and ecosystem. The biogas produced through anaerobic fermentation of agricultural and allied biomass wastes offers energy from conventional purpose to production of electricity. Biogas constitutes 55–65% of methane, 35–45% of carbon dioxide with the typical calorific value of 21–24 MJ/m3 . However, there are several hurdles in the implementation of biogas technologies, and an appropriate approach of marketing policy, multiprofit model, and business option should be made available to address the market value of biogas. This chapter suggests that biomethanation of crop residues should be demonstrated and promoted for energy security and a sustainable economy. Keywords Anaerobic digestion · Biogas · Biomethane · Biogas upgradation

11.1 Introduction With the wide use of fossil fuel as prime energy source for industrial and domestic purposes, there is a great threat to global energy security assisted with political instability in oil-exporting countries thereby pushing the petroleum prices. The increased K. GeethaThanuja · D. Thiyagarajan · S. Karthikeyan (B) Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Tamil Nadu, Coimbatore 641 003, India e-mail: [email protected] D. Ramesh · S. Karthikeyan Department of Renewable Energy Engineering, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Tamil Nadu, Coimbatore 641 003, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_11

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concerns for energy security, surging oil prices, air quality problems, and greenhouse emission are menacing today’s environmental sustenance. The global energy consumption is predicted to increase threefold by 2050 (Hook and Tang 2013). The continuing crucial challenge on energy demand drives research toward clean energy/ fuels production from organic resources and wastes. A steady increase in the waste production poses severe threat to the environment and public health. Energy recovery from organic wastes serves several purposes, including waste disposal, energy independence, and import substitution. In this regard, renewable energies perform pivotal role to fight against various concerns. Although the energy supply from renewable sources has developed distinctly, its contribution is restricted. Among the renewable technologies, biofuels produced from agricultural residues are environmentally friendly and hold potential to diminish the fuel consumption. Biogas stands out of all the renewable techniques whose importance not only relies on easy storage and electricity production but also on purification and upgradation to grid grade quality or vehicle fuel. Being an alternate to the fossil fuel, biogas has attained attention over the last few years as reflected increased growth in global biogas production. A threefold increase was found from 2005 to 2016 which accounts for the rise from 13.2 billion m3 to 60.8 billion m3 (IEA 2018). The biomethantion technology is used for treating the organic wastes into biogas. The biogas yield can be varied with different organic wastes resources due to its compositions. However, the biogas production potential and methane content of feedstocks are deciding factors for selecting the feedstocks for larger scale biogas production. Biogas is a versatile fuel that could be produced with the broad range of substrates. Feedstocks may be crop residues, animal wastes, organic fraction of municipal solid wastes and agroprocessing industries wastewaters, etc. The cow dung is the most commonly used as feedstock for biogas production in India. Generally, several types of biogas plant/digesters are used in global level and only two types of biogas plants are more popular in India. The Khadi and Village Industries Commission (KVIC) and Deenabandhu model biogas plants are widely adopted in small to larger capacity of biogas production and huge number of these biogas plants installed in different villages across the country. It comprises of methane (CH4 ) and carbon dioxide (CO2 ), along with the traces of hydrogen sulfide (H2 S), ammonia (NH3 ) , water vapor, and siloxanes. The application of biogas is completely depending on plant capacity. For example, the biogas from smaller capacity (upto10 m3 ) biogas plant installed in rural area is used for cooking, lighting, thermal applications, and engine operation, whereas the biogas from larger capacity biogas plant installed in the industries or farms is used for heat or electricity production (on-grid or off-grid mode). Recently, the biogas with higher calorific value has potential to replace the conventional gaseous fuel (i.e., compressed natural gas). For enhancing the calorific value of biogas, CH4 content in biogas has to be increased by biogas processing or upgradation process. The biogas with higher CH4 content (>95%) is referred as biogenic methane or renewable natural gas (RNG) or compressed biogas gas (CBG). Generally, biomethane production involves two steps of process. Firstly, the raw biogas is produced from organic wastes via anaerobic digestion process using consortium of anaerobic microorganisms. Secondly, the raw biogas further upgraded to

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biomethane by removing the unwanted gases (other than CH4 ) in the raw biogas. In other words, the biomethane produced by anaerobic digestion, then biogas upgraded with >97% CH4 , plays crucial role in optimizing the performance of integrated energy systems and serves as appropriate alternate to fossil natural gas. In the emerging era of waste management, biomethanation acts efficiently in converting waste to wide variety of products. The higher energy density due to higher hydrogen content makes biomethane a feasible candidate for even large-scale storage technique. Hence, the biogas production is a viable option for harnessing energy and safe disposal of organic wastes. However, gases other than methane have no calorific value; it is crucial to opt biogas upgradation in energy perspective. The chief benefit is generation of biogas that can be easily employed for either energy generation or heat production. This chapter briefly discusses basics of biogas production, biogas up gradation technologies, biomethane potential, and opportunities for alternate vehicle fuel options for energy security and sustainable development for developing countries.

11.2 Anaerobic Digestion (AD) Besides various technologies, AD is the core process contributing to the changeover from exhausting fossil fuel-based economy to the replenishing renewable energybased circular economy. Biogas production through AD serves as a reliable energy harvesting technique to attain waste into energy. It is microbially catalyzed multistep process comprising of hydrolysis, acidogenesis, acetogenesis, and methanogenesis in which organic matter is mineralized to biogas constituting the most reduced CH4 and most oxidized CO2 form (Kougias and Angelidaki 2018). AD process is intensely scrutinized; several technologies have been refined in course of time and are being in application for treatment of waste and renewable energy production for hundreds of years.

11.3 Biomethanation Biomethanation is achieved by syntrophic interaction between many groups of microorganisms. The production of methane is ubiquitous, defining characteristic of methanogens belonging to archaebacterial domain. Methanogens have been classified, as aceticlastic methanogens that generate methane from acetate (acetotrophic (aceticlastic) pathway), while hydrogenotrophic methanogenic bacteria generates methane from hydrogen and carbon mixture (CO2 reduction pathway) and methylotrophic methanogens convert methyl compounds into methane (methylotrophic pathway) (Boone et al. 1993). The initial stage of methane generation involves the hydrolysis of polymeric organic materials in the biomass feedstock such as carbohydrates, proteins, and lipids, which are digested by hydrolyzing and fermentative bacteria resulting in

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the production of soluble sugars or monosaccharides, simple amino acids, and short chain fatty acids. Numerous aerobic and facultative bacterial groups take part in the hydrolysis stage mainly belonging to phyla Firmicutes and Bacteroidetes. The second stage, namely acidogenesis, involves the converting these monomers, sugars, amino acids, and fatty acids into higher organic acids like propionic and butyric acid and other intermediate products. This acidogenic step is mediated by numerous obligate anaerobes belonging to genus Clostridium, Bacteroides, Butyrivibrio, Peptococcus, and Selenomonas, and as well several facultative anaerobes belonging to Bacillus, Campylobacter, Enterobacter, Lactobacillus, and Streptococcus spp. The next stage, acetogenesis, involves the conversion of intermediate organic acid products of the first stage to acetic acid, H2, and CO2 carried out by acidogenic bacteria, and the final stage, methanogenesis, involves the production of methane using acetate, H2 , CO2, C1 compounds and methyl compounds like methanol, methylamine, and methyl sulfides. It is carried out by three distinct groups of methanogens, namely aceticlastic, hydrogenotrophic, and methylotrophic methanogens. (Patel et al. 2017; Stamatelatou et al. 2014; Weiland 2010). In the first step, CO2 is converted to a formyl group which is linked to methanofuran (MFR), the carrier molecule covalently. Then the subsequent transfer is made to the carrier tetrahydromethanopterin (H4 MPT), which is then dehydrated to produce methenyl-4MPT. A reduction of the methenyl group to a methylene group is followed by further reduction yielding methyl group. Later, this is consequently transferred to the third carrier, sulfhydryl-containing coenzyme M (HS-CoM), that simultaneously exports Na+ through the cell membrane. Finally, the oxidation of HS-CoM along with the coenzyme B produces CH4. Upon hetero-disulfide reduction, HS-CoB and HS-CoM are produced. The substrates go into the process as methyl-S-CoM in methanogenesis from methanol, methylamines, or methyl sulfides. Hydrogen or the oxidation of another methyl-S-CoM to CO2 supplies electrons for the methyl-S-CoM reduction to CH4 by methyl disproportionation. In acetotrophic methanogenesis, the methyl group enters into the pathway as methyl-H4 MPT, and the carboxyl carbon is oxidized to supply electrons required for reduction of methyl group. CO can be transformed to acetyl-CoA, resulting in acetogenic metabolism, or it can be oxidized to CO2 , supplying electrons for final methanogenesis (Costa and Leigh 2014; Patel et al. 2017; Thauer 2012; Zabranska and Pokorna 2018).

11.4 Aceticlastic Methanogens The aceticlastic methanogens belong to the family of Methanosarcinaceae and Methanosaetaceae are known to produce CH4 upon metabolizing acetic acid. In the mass of acetotrophic methanogens, the population of Methanosarcinaceae is supported by high concentrations of acetic acid, thermophilic conditions, and the reactor instability. Furthermore, Methanosaetaceae can thrive in mesophilic environments and form granular sludge at low concentration level of acetic acid in the anaerobic reactors (Costa and Leigh 2014; Kurade et al. 2019).

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11.5 Hydrogenotrophic Methanogens The hydrogenotrophic methanogenic bacteria utilize H2 and convert CO2 to CH4 . Hydrogenic methanogens exhibit largest phylogenetic diversity and divided, namely Class I methanogens that include Methanopyrales, Methanococcales, and Methanobacteriales; the class II methanogens including Methanomicrobiales, Methanocellales, and Methanosarcinales, with the exception of Methanomassiliicoccales. Hydrogenotrophic methanogenesis is another pathway and signify the ancestral form of CH4 generation. Hydrogenotrophs are essential for maintaining a low partial hydrogen pressure in the biogas plants, which supports the growth of syntrophic acetogenic microorganisms which are H2 labile. Further, the CO2 can be reduced to CH4 by several steps with help of hydrogenotrophic methanogens using reductive acetyl-CoA pathway. Electron donors such as hydrogen, formic acid, and alcohols are used to reduce CO2 . The reduction of CO2 to the formyl-MFR, formyl group of methanofuran, with ferredoxin (Fd) as the electron carrier, is the first step in hydrogenotrophic methanogenesis. The formyl group is subsequently transferred to H4 MPT, an electron carrier, and dehydrated to methenyl tetrahydromethanopterin (methenyl-H4 MPT). The formyl group is subsequently transferred to H4 MPT, an electron carrier, and dehydrated to methenyl-H4 MPT. Using alcohol dehydrogenases, hydrogenases, and dehydrogenases, the electron donor reduces the electron carrier F420 to F420 H2 . With F420 H2 as reductant, the reduction of methyleneH4 MPT to methylene-H4 MPTand finally to methyl-H4 MP occurs. The methyl group is subsequently transferred to the next electron carrier, that is, sulfhydryl coenzyme M (HS-CoM), and subsequently reduced to CH4 by oxidizing HS-CoM and HSCoB simultaneously forming CoM-S-S-CoB hetero-disulfide. The ensuing electron bifurcation occurs in the hetero-disulfide reductase complex, which reduces the CoMSS-CoB hetero-disulfide to regenerated HS-CoM and HS-CoB, as well as oxidized forms of Fd ox to Fd red 2-, which is involved in the CO2 reduction in the first step of the cycle. Hydrogenotrophs reduce CO2 to CH4 in six steps viz the reductive acetylCoA pathway. They are essential for maintaining a low partial hydrogen pressure in an anaerobic digester, which supports the growth of syntrophs which are sensitive to higher H2 concentration. (Berghuis et al. 2019; Shima et al. 2020; Wagner et al. 2018).

11.6 Methylotrophic Methanogens Few other groups of methanogens work well on the methyl group (–CH3 ) available substrates to generate CH4 and are termed methylotrophic methanogens. They utilize a variety of substrates such as methanol, methyl sulfides, and methylamines. Generally, based on existence and non-existence of cytochromes, the methylotrophic methanogens are categorized into two groups. The first group comprises of methanogens without cytochromes (Methanosarcinales, Methanobacteriales) and

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requires H2 obligately for their survival and produce CH4 . The second category, which includes Methanomassiliicoccales, produces CH4 while also converting the methyl groups in the substrate into CO2 gas via a membrane electron transport chain (Vanwonterghem et al. 2016).

11.7 Biomethane—Benefits and Risks Methane is produced from biological sources and processes including livestock, waste treatment, and wetlands, which is directly released to atmosphere and results more greenhouse gas (especially CH4 ) emissions. In the case of AD process, biogas from biowastes collected and utilized is in effective way. Furthermore, the biogas can be upgraded as biomethane, and it is an attractive approach for better biogas utilization and offers new clean fuel to transport sector. However, the biomethane production is growing steadily across the globe; it holds its own boon and bane. The environmental benefits of biomethane include decreased need for fossil fuels, reduced water/soil/air pollutions, and minimal intervention into nature. Time and again, biomethane is spotlighted as a sustainable alternate to fossil fuel (Cecchi and Cavinato 2015), reduction of GHG, and exploiting wastes with minimum impact on air quality. Animal and agriculture sources serve as a largest renewable source and cycles through the atmosphere in 12 years. Moreover, biomethanation provides assurance to the energy security; it serves as a host of GHG. The social acceptance on biogas is often obstructed by environmental and health concern. Higher production cost of biomethane gives minimum support to biomethane market in the electricity sector, which is the prime player for biogas plant installations.

11.8 Biomethane Production Biogas is predominantly composed of CH4 at a level of 55–65%, CO2 at a level of 35– 45%, traces amount of few other gases and water vapor (Sahota et al. 2018a, b). The composition of biogas mainly depends upon the nature of the substrate and the reaction conditions used in the anaerobic reactor. Besides CH4 and CO2 , it also contains additional compounds like nitrogen (N2 ) 0–3%, water vapor (H2 O) 5–10%, oxygen (O2 ) 0–1%, hydrogen sulfide (H2 S) 0–10,000 ppmv, ammonia (NH3 ) 0–5 ppmv, hydrocarbons 0–200 mg/m3 , and siloxanes 0–40 mg/m3 (Muñoz et al. 2015)(Kadam and Panwar 2017). Apart from CH4, all other compounds contained in biogas are considered as impurities, which reduce its energy content. In other words, CO2 , N2 and H2 S present in biogas will decrease the calorific value of the biogas. During combustion of raw biogas, water vapor and O2 reacts with other components which release toxic gases such as sulfuric acid and hydrochloric acid, resulting in corrosion of the engine parts. Ammonia is a vital nitrogen source for microbial consortium. However, higher concentration of ammonia inhibits the CH4 production and

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Biomethane production

Biogas cleaning

Humidity removal and drying

Removal of H2S (Desulphurisation)

Biogas upgrading

CO2 removal

Removal of trace components

Fig. 11.1 Steps involved in biogas processing

also forms toxic compounds after combustion. H2 S and other sulfur compounds are extremely corrosive and toxic. Siloxanes even in minor quantities form sticky residues during combustion, which clogs the valves, cylinder heads leading to malfunction (Bragança et al. 2020).In order to overcome from these issues, the biogas needs series of processing techniques (Fig. 11.1) and the treatment of biogas involves two major steps, namely (1) biogas cleaning which aims to remove the toxic and unwanted gases (i.e., other than CH4 and CO2 ); (2) biogas upgrading by removing CO2 and increasing CH4 content to more than 90%. After cleaning and up gradation, the final product is referred as biomethane(95–98% of CH4 content) and used to replace the compressed natural gas (Ryckebosch et al. 2011).

11.9 Biogas Cleaning The biogas must be purified and upgraded to increase its energy content. In order to subdue the ill-effect, several step-wise processes are employed. First water is removed, followed by elimination of toxic impurities like H2 S, NH3 , and O2 (Fig. 11.1). The removal of these impurities assists in achieving the high-qualityCH4 for wide variety of applications (Sahota et al. 2018a, b).

11.10 Removal of Water Vapor The undeviating biogas from the digesters tends to saturated with water vapor (5% at 35 °C), which can react with H2 S crating ionic hydrogen and or sulfuric acid causing corrosion. The process of eliminating water is significant as it also removes oil and the dust particles absorbed with water. Physical separation and chemical drying methods are generally employed for removal of water from biogas.

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11.11 Physical Separation (Condensation) Refrigeration is the easiest way to remove water vapor/droplets from biogas by condensation process. Because of the freezing nature of water droplets on the heat exchanger’s surface, the biogas compresses before cooling to achieve lower dew points and later expanded to desired pressure. Removing water prevents corrosion of equipments like pipelines, compressors, and other parts. Various techniques are being employed to separate the condensed water such as (i) demisters separate the water droplets using a wired mesh (micropore 0.5–2 nm); (ii) cyclone separators remove water droplets by using centrifugal forces, and (iii) the moisture traps condense the water droplets in the biogas and remove the water using water taps fixed at appropriate places in the biogas pipe lines (Ryckebosch et al. 2011).

11.12 Chemical Drying Methods (Absorption and Adsorption) Generally, chemical drying techniques are efficient in water removal from biogas at elevated pressures as compared to either absorption or adsorption techniques operated at atmospheric pressures. In general, the water droplet is absorbed in glycol (drying agent) at low dew point (−5 to −15 °C) and later regenerated it at 200 °C (Persson et al. 2006). Several other chemicals like silica, magnesium oxide, activated carbon, alumina, and hygroscopic salts are also used.

11.13 Removal of H2 S The H2 S content is main toxic gas present in the biogas and ranges from 0.5 to 2%.The presence and corrosive nature of H2 S causes extensive damage to biogas end use components such as pipe lines, motors, and engine parts (Habeeb et al. 2018). It is either removed during digestion or after digestion by physico-chemical (Shah et al. 2017) and biological techniques (Cano et al. 2018). The process of H2 S removed from raw biogas is called desulphurization process. Several methods involved in desulphurization process are furnished in Fig. 11.2.

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Biogas desulphurisation Removal of H2S

In situ desulphurisation

Air/ O 2 dosing

Absorption

Adsorption

Biological desulphurisation

Physical

Physisorption

Chemical

Chemisorption

Biofiltration of H2S

Bioscrubbers (Sulfur oxidising microorganisms)

Fig. 11.2 Methods of H2 S removal from biogas

11.14 Removal of H2 S During Digestion H2 S in the biogas digester can be treated directly by either oxidization or converting sulfide to other form without affecting anaerobic digestion process. The elementary sulfur and insoluble metal sulfide are the end products produced while sulfide get oxidized or reacted with metal ion.

11.14.1 Air/Oxygen Dosing to Biogas System Autotrophic sulfur oxidizing microorganisms such as Thiobacillus cause the biological aerobic oxidation of H2 S to elemental sulfur, and these autotrophs eventually utilize CO2 from biogas for their carbon need. Their presence in the digestate eliminates the need for special inoculation. The mentioned reaction occurs in the biogas: 2H2 S + O2 → 2S + H2 O The oxygen with 2–6% concentration is required for the reaction to occur, which can be introduced into digester viz, air pump. Care should be taken to maintain the anaerobic conditions in the digester. A reduction of H2 S concentrations down to 20–100 cm3 m−3 can be achieved (Hagen et al. 2001; Ryckebosch et al. 2011).

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11.14.2 Addition of Iron Chloride The iron chloride is mixed with biogas feedstock slurry and sent to anaerobic digester. The H2 S in biogas starts to react with iron oxide present in the slurry, thus results in formation of FeS precipitate. The subsequent production of H2 S from the anerobic digestion may be reduced due to iron chloride presence in the digester. The precipitation reaction is as follows: 2Fe3+ + 3S2− → 2FeS + S Fe2+ + S2− → FeS

11.15 Removal of H2 S from Biogas 11.15.1 Adsorption Using Iron Oxide or Hydroxide The purification of biogas is done by removing the H2 S fraction using metal oxides such as iron oxide, iron hydroxide and zinc oxide. During the process, the steel wool or wooden chips impregnated metal oxides act reaction bed, which can react with H2 S gas and produce either iron sulfide or zinc sulfide depending on metal oxides used in the bed. The chemical equation used for the above said reactions is furnished below. Fe2 O3 + 3H2 S → Fe2 S3 + 3H2 O 2Fe(OH)3 + 3H2 S → Fe2 S3 + 6H2 O

11.15.2 Absorption with Liquids The H2 S gas in the biogas can be absorbed in liquids by either physical or chemical methods. In physical absorption, the trace component is dissolved in solvent. For chemical absorption, the component is dissolved, and then subsequently, a chemical reaction of trace component and the solvent takes place. Physical absorption in water or an organic solvent is expedited leading to removal of H2 S. The widely used method is water scrubbing, although it has operational hindrances due to microorganisms’ growth on packing. Huge amount of water and energy is required for absorption process.

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In the case of chemical absorption, chemicals are mixed with water, and the solution is used for absorption process. The main benefits of this method are increased absorption, low quantity of water used, and less energy as compared with physical absorption process. The often-used chemical absorption liquids are diluted NaOHsolution, FeCl2 -solution, and Fe(OH)3 -solution.

11.15.3 Membrane Separation The H2 S fraction in the biogas can be removed upon passing it across a semipermeable membrane, by way of which H2 S and CO2 can pass through the membrane but not CH4 . Additionally, gas–liquid absorption membranes may also be used. In this process, a hydrophobic microporous membrane is important component used to separate the gas and liquid. The molecules in the gas stream can permeate across the membrane where it is absorbed by the liquid that is flowing in the opposite direction to gas stream. NaOH is used as absorbing liquid. The initial 2% level of H2 S in the biogas may be reduced to lower level (97% CH4 ) while also removing organic components such as H2 S, NH3 , HCN, and H2 O. Amine scrubbing system employs two-step approach for biomethane production from biogas. The first and second steps of process are adsorption and stripping or desorption of CO2 with help of aqueous alkylamines viz., diethanolamine, monoethanolamine, and methyl-diethanolamine. The amine fraction of aqueous liquid can react and absorb the biogas impurities such as CO2 and H2 S. During stripping process, the chemical is regenerated by heating to release the CO2 . To avoid chemical toxicity, H2 S is eliminated ahead of time. Inorganic solvent scrubbing is done using carbonates of potassium and sodium; aqueous ammonia, etc. The scrubbing is improved by modification of the solvent and catalysts. (Chen et al. 2015; Ryckebosch et al. 2011; Sahota et al. 2018a, b).

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11.17.2 Adsorption Adsorption process is of four types: (i) pressure swing adsorption (PSA), (ii) vacuum swing adsorption (VSA), (iii) temperature swing adsorption (TSA) and, (iv) electrical swing adsorption (ESA). PSA employs elevated pressure to separate the selected gases in a gas mixture using adsorbents. The role of adsorbents used in biogas upgradation through PSA unit to retain the impurities of biogas mainly CO2 and H2 S gases. The adsorbents used in this process are activated carbon, molecular sieves, or zeolites due to its higher surface area or more porous nature. After adsorption of CO2 and H2 S from biogas, the percentage of CH4 content can be increased to 95–99. When the adsorbent is nearing saturation levels, the adsorbed gases are released by lowering the pressure to aid regeneration. VSA is a distinct type of pressure swing adsorption where the pressure reaches near-vacuum situations for adsorption. In case of TSA, higher temperature is employed for the regeneration of adsorbent material. With regard to ESA, the regeneration is achieved by heating the adsorbent to release the adsorbed gases (Chen et al. 2015; Ryckebosch et al. 2011).

11.17.3 Membrane Separation Membrane separation is built on gas dissolution property and the gas diffusion across the polymer material. When different pressure is exerted on the opposite sides of the polymeric material, gas permeation through the polymer material ensues. The solubility and diffusion co-efficient of the gas membrane system decides the rate of gas permeation across the material. The most commonly used polymer materials are polysulfone, polyimide, and polydimethylsiloxne. High quality biomethane (CH4 > 94%) can be achieved using membrane separation technology. (Chen et al. 2015; Ryckebosch et al. 2011).

11.17.4 Cryogenic Separation Cryogenic separation works by cooling the gas to liquefy and separate them. For biogas upgradation, the biogas is fed into cryogenic separation unit followed by cooling and subsequent compression of biogas takes place. During the process, the gaseous CO2 is liquified and percentage of CH4 in the biogas increased. The liquified CO2 is separated easily from the process. The biomethane (CH4 < 90–99%) can be obtained, and further, it can be used as vehicle fuel or injected to gas grids network for better distribution to consumers (Chen et al., 2015; Ryckebosch et al., 2011). Even though this technology produces good quality biomethane, it has drawbacks such as higher investment and operating costs, energy intensive, and complex process operations (Yousef et al. 2016).

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11.17.5 Biological Methane Enrichment Compared with several biogas upgrading technologies like membrane separation, scrubbing which are considered energy intensive, upgradation of biogas using biological ways (microbes) to convert CO2 , H2 gases into CH4 (Rachbauer et al. 2016) is upcoming. They can be categorized based on the growth and nutrition of the microorganism as chemoautotrophy and phototrophy approaches. Chemoautotrophic method is based in employing hydrogenotrophic methanogens which are capable of utilizing H2 to reduce CO2 to CH4 . Phototrophic biogas upgrading involves phototrophic organisms like algae to capture the CO2 to obtain CH4 rich gas. (Ryckebosch et al. 2011).

11.18 Biomethane and Its Application Biogas upgradation to biomethane has gained interest across the globe. The added advantages of biomethane as fuel are the attractive fuel owing to quick mixing with fossil fuels, their flexibility, and easy storage. Earlier, it was used mainly for the provision of vehicle fuel for cars and trucks for waste collection. The biomethane from biogas is almost similar to the natural gas, and probability is more to replace natural gas in the engines without any modifications (Fig. 11.3). The comparison of the biogas and biomethane with the liquefied petroleum gas is furnished in Table 11.1. The added advantages of biomethane fuel are: (i) used as energy resource due to its higher energy content, (ii) easy to store and safe handling as compared to hydrogen fuel, (iii) use as vehicle fuel without any modification in CNG engine, (iv) distribution via grid network can be possible, (v) reduce oil imports and greenhouse emissions, and (vi) produced from organic wastes, promotes clean environment and circular bioeconomy.

11.18.1 Case Study I: Feasibility of Indian Energy Security Through Biogas Fuel In India, population growth is on the rising trend, with the country’s population expected to reach 1.6 billion by 2050 (IHME 2020). It implies that India’s energy and food requirements will be significantly increased in the future. Due to overpopulation, their standard of living, and limited reserves, there will be a shortage of energy supply in the coming years. It is essential to find alternate sources to ensure the energy security for fuels and electricity generation. Solar and wind energy sources will be dominated resources for electricity production for India. Because of the larger number of cities and its population, the huge quantity of municipal solid wastes will be dumped into the environment, which may result in environmental

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Fig. 11.3 Utilization pathway of biogas and biomethane

Table 11.1 Comparison of significant parameters in biogas, biomethane, and LPG Parameters

Biogas

Content

CH4 , CO2 , CH4 and H2 S and other traces of CO2 impurities

Calorific value ≈30 (MJ/kg)

Biomethane (CBG)

≈52

Liquefied petroleum gas (LPG) Natural gas and refined crude oil

≈46

Energy density 38 MJ/m3 and danger of catching fire is lower

94 MJ/m3 and inflammable

Properties

Heavier than air, tends to settle in ground and accumulate in low-lying areas upon leakage

Lighter than air and disperses quickly

and ground water pollutions, greenhouse gas emissions, and increased probability of public health hazards. On other side, the in situ open yard burning of agricultural residues is being practiced as quick disposal method by farmers. Thus, it results in environmental pollutions and causes health associated issues to the public in nearby areas. The AD technology can offer eco-friendly solution on safe disposal of these feedstocks, which would play vital role in effective waste management in rural and urban levels. It also contributes a significant share to the energy sector, reduction of potential greenhouse gases (GHG) and favors climate change mitigation. In addition

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to that, there will be numerous potential feedstocks available for biogas production in India. The availability of animal wastes is huge quantity as compared to other countries. An estimate shows that India has highest bovine animals in the world and it accounts more than 350 million (USDA, FAS 2006). A simple estimate shows that biogas from 1,11,000 family-type biogas plants can annually save 2,81,498 tons of firewood equivalent. Similarly, digested biogas slurry from these biogas plants is about 30,38,625 tons, which is 10,700 tons of urea equivalent, and it also promotes and helps the organic farming practices (Paikaray and Mishra 2019). The trend of biogas applications in India for the past four decades is shown in Fig. 11.4. Rural energy security The biomass is used as a major cooking fuel in the majority of rural households in India. Generally, the indoor air pollution is common problem faced by rural women. Because of higher exposure time for women in the poor ventilated kitchen room to prepare the foods using traditional biomass cookstoves, incomplete combustion of biomass in the stoves may release harmful gases, smoke, black carbon, and particulate matter. Thus, it results in severe health issues to rural women. The biogas is a clean fuel, which is recommended to replace the less efficient biomass cookstoves and also to provide clean fuel and pollution free environment. Initially, the biogas recommended as cooking fuel in the rural area. Later, thermal heat (cooking) and electricity generation are the two most common uses for biogas produced by small and mediumsized biogas plants in India. The cow dung collected from 3–5 cattle is sufficient to generate 1.5–2 m3 of biogas. However, India produced only 2.07 billion m3 of biogas annually from various feedstocks, compared to a potential of 29–48 billion m3 per year (Mittal et al. 2018). In order to achieve self-sufficiency in energy requirements, the Ministry of New and Renewable Energy (MNRE) in India has several schemes

First generation

Biogas plants (Small, medium & large) & biogas applications

Second generation

Third generation

1. Clean cookingfuel

1. Thermal applications 2. Electricity generation (On/off grid)

1. Thermal applications 2. Electricity generation (On/off grid) 3. Bio-CNG (Vehicle fuel)

Fig. 11.4 Applications of biogas for different purposes for the past four decades in India

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funded through various implementing agencies to promote and intensively implement many biogas programmes. For promoting the biogas programme in India, the nearly 5.03 million family/small size biogas plants were constructed as against the potential 12.3 million biogas plants through National Project on Biogas Development, National Biogas and Manure Management Programme, and the recent New National Biogas and Organic Manure Programme (Fig. 11.5) (MNRE 2019). The biogas installed in the rural areas can ensure clean fuel, clean, hygiene environment and also provide biodigested slurry as fertilizer. The rural energy security can be achieved through biogas as fuel by installing of 12.3 million biogas plants. This could certainly reduce LPG, biomass usage, and also oil imports. National energy security India owns the position of having second largest number of biogas plants contributing to 3800 MW of biopower production (Fig. 11.6). The chief contributing factor to the potential of biogas includes agricultural residues/energy crops, cattle dung and poultry dropping and municipal solid wastes (Table 11.2). The surplus biomass from agricultural residues corresponds to the potential of 28 GW. Further, the country’s sugar mill could generate additional 14 GW provided technical and economic aspects are optimized from the bagasse produced by them. For example, the Kerala Agency for New and Renewable Energy Research and Technology (ANERT) has established 102 large-scale biogas plants using MNRE funds, producing an average of 10 lakh m3 biogas per year. Various biogas feedstocks were used in 105 plants, with 73 numbers based on night soil, 24 numbers based on canteen waste, and 5 numbers based on animal waste. The biogas produced from 500 plants was used for electricity production and heating purposes, respectively (ANERT 2021). Using MNRE biogas programmes, 389 off-grid-biogas-based power plants were installed across the country. Among them, Tamil Nadu is the state with the highest rate of power generation (2853.5 kW) (Table 11.3). 1000000 900000 800000 700000 600000 500000 400000 300000 200000 100000 0

Fig. 11.5 Overview of the biogas plants installed in various states of India (Source MNRE 2019)

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Fig. 11.6 Respective installed capacities in MW across various states, (Source: MNRE 2020) Table 11.2 India’s biogas production potential Source

Availability

Estimated surplus (Metric. Tons)

Arable land

141 M ha

750

Arable land (Monocropping) 50 M ha

150

Cattle dung

300 million cows and buffalos 1000

Poultry droppings

500 million poultry birds

8

MSW

–

>100

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Table 11.3 Biogas-based power generation plants (off-grid) installed through MNRE-funded biogas schemes S. No.

Name of the state

Biogas plants (nos.)

Biogas plant capacity (m3 )

Power generation (kW)

1

Tamil Nadu

52

30,360

2853.5

2

Karnataka

70

15,670

1581.5

3

Maharashtra

68

11,690

1257.5

4

Punjab

41

9980

1035.0

5

Uttar Pradesh

30

4400

591.0

6

Telangana

25

5410

574.0

7

Andhra Pradesh

34

4320

481.0

8

Haryana

3

2540

155.0

9

Uttarakhand

17

1070

124.0

10

Kerala

36

1010

118.0

11

Madhya Pradesh

6

735

70.0

12

West Bengal

1

340

60.0

13

Gujrat

2

285

30.0

14

Rajasthan

2

120

15.0

15

Odisha

2

60

389

87,990

Total

10.0 8951.5

For the year 2040, the minimum and maximum biogas potential of four different wastes (crop residues, animal manure, organic household waste, and sewage wastewater) and different industrial effluents generated in India is predicted to be 0.31 and 0.655 trillion m3 , respectively. In India, the use of biogas has taken on a new dimension, with plans to use it as a vehicle fuel. The biomethane can be compressed in cylinders or supplied to natural gas grid. The Indian government recently launched a scheme called “Sustainable Alternative Towards Affordable Transportation” (SATAT) on August 1, 2018, to generate the compressed biogas (CBG) and biomanure from different biogas feedstocks. The SATAT scheme intends to build 5000 CBG plants by 2023, producing 15 million metric tons of CBG per year to increase the CBG network for ensured fuel supply. The biomethane can be used in gasoline vehicles, which could reduce 676 million tons of GHG emissions per year in the automobile sector in the year 2040 and also reduces air pollution and crude oil import bills (Mittal et al. 2018).

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Case study II: Rainbarrow Farm Poundbury, UK It is UK’s first anaerobic digestion plant to supply biomethane into national gas network. The plant is operated in a joint venture of J V Energen between J V farming ltd. A wide range of feedstocks such as potato wastes, maize silage, grass silage, and food wastes is used. When biogas is produced by AD, it is proceeded to upgradation by H2 S removal and CO2 removal following oxygen injection system and direct membrane transfer, respectively. The produced gas enters the grid unit which is 1500 m apart with the medium pressure of 1.9 bar. The produced gas is purchased by Barrow Shipping ltd. Apart from electricity generation, the plant owns the capacity to produce 23, 000 tons of liquid and 83,000 tons of solid renewable fertilizer a year. The digestate is used by the farmers to replace inorganic fertilizer.

11.19 Future Challenges and Opportunities The biogas/biomethane has potential to replace the conventional fuels in both rural and urban areas. The strong barriers for dissemination of biomethanation technology are technological and implementation challenges, quality feedstock availability, and weak supply chain logistics (Mittal et al. 2018). Biomethane is the piece of puzzle in the replacement of existing conventional energy source. However, there is an extensive awareness with regard to the upgraded biogas, and the mass scale dissemination of technology is unavailable. The present linear model that makes, uses and disposes type is unjustified with large quantities of agro wastes and the urban places that are literally inundated in garbage. The opportunity to create jobs, energy, and resources are quite immense. Circular economies will be the solution for a much stronger recycling economy. The type and capacity of waste to energy facilities will change as the recycling economy is directed toward a circular economy where nothing is wasted. To achieve all these, supply chain management has to be strengthened to vitalize the strategies for collection, segregation and transportation of waste followed by efficient biogas upgrading plants. Except certain countries like Germany, Sweden, and California, the international technical standards and procedures for the application of biomethane, an alternate is lacking, and therefore, it is essential for extensive exercise. The use of biomethane in the transport should ensure several criteria like free of dusts and toxic gases, characteristics smell to detect the leakage, optimum level of oil content, etc. The technical requirements and regulations must be framed for the use of biomethane in required applications. The major challenges faced for implementation of biomethane projects are almost similar to other biofuel projects. Lack of constant availability of biogas feedstocks, cost of biogas production, weak supply chain and logistics for biomethane distribution, supporting biofuel policies for better adoption, and the necessity for government incentives/tax exemptions for successful biomethane project implementation.

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Chapter 12

Recent Technologies for the Production of Biobutanol from Agricultural Residues A. Anuradha, B. Bharathiraja, Muthu Kumar, and R. Praveen Kumar

Abstract Due to increased exploitation of energy resources and environmental issues, there is a need for a fuel which is sustainable and environment friendly in order to meet the world’s future energy needs. Second-generation biofuels can be an attractive option for the society and may encourage them to shift toward the green fuels, also known as advance biofuels. It can be produced from non-food biomass which includes agricultural residues generated as waste during or after processing of agricultural crops without compromising the food security. These agricultural residues comprised of lignocellulosic materials, providing a unique natural resource at a large scale that is renewable and a cost-effective alternative for biobutanol production. Generally, two strategies are followed for the conversion of biomass into biobutanol that enhances the target yield from the raw materials being utilized; first is the thermochemical processing and biochemical processing. This chapter will provide an overview of the technical details being utilized for the conversion of residual biomass into biobutanol that are currently employed. This chapter will also cover the emerging advancements in the two primary conversion techniques, i.e., thermochemical process including gasification, liquefaction, and pyrolysis and biochemical process including fermentative pathways. The review will summarize the integration of biochemical and thermochemical conversion routes for the efficient production of biobutanol also their individual pros and cons will be discussed. Keywords Agricultural waste · Thermochemical · Biochemical · Biofuels

A. Anuradha · M. Kumar (B) Department of Bio-Engineering, Birla Institute of Technology Mesra, Ranchi, Jharkhand 835215, India e-mail: [email protected] B. Bharathiraja Department of Chemical Engineering, Veltech High Tech Rangarajan Dr Sakunthala Engineering Collge, Avadi, Chennai, Tamil Nadu 600032, India R. P. Kumar Department of Biotechnology, Arunai Engineering College, Tiruvannamalai, Tamil Nadu, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_12

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12.1 Introduction The energy crisis and scarcity of resources have created a strong demand for the development of an alternative energy source. Second-generation biofuels, in general, do not jeopardize food security because they are typically made from agricultural leftovers generated as waste during crop processing. As a result, biofuels such as cellulosic bioethanol, biobutanol, and biodiesel are currently attracting the attention of researchers and governments. These agricultural residues are high in lignocellulosic materials, which are typically cheap and locally available. It can be used to produce biofuels in a sustainable manner using a biochemical or thermochemical method (Paulova et al. 2013). Acetone-butanol-ethanol (ABE) fermentation is a biochemical conversion process that produces biobutanol by using more advanced biotechnology to convert fermentable sugars into butanol using a solvent-producing bacterium, specifically Clostridium sp. strains (Chen et al. 2013), whereas thermochemical conversion involves gasification, pyrolysis, and liquefaction. Although carbonaceous materials are commonly gasified, lignocellulosic biomass gasification is still a relatively new technology (Aslanzadeh et al. 2014). As a result, the main purpose of this chapter is to discuss different agricultural biomass that can be used to produce biobutanol.

12.2 Agricultural Residues Non-food biomasses such as agricultural wastes or agricultural residues that are produced as waste during or after crop processing are used to make second-generation biofuels without jeopardizing food security. A large portion of these wastes is dumped or left to rot. These wastes can be transformed into a precious resource by using appropriate bioconversion technology (Ali et al. 2019). These agricultural residues can be utilized for the efficient generation of butanol because of its ease of availability which in turn can also reduce the environmental burden of agricultural wastes. These residues generally have a high percentage of lignocellulose made up of cellulose (30– 50%), hemicellulose (20–38%), lignin (7–21%), and extractives. A high amount of bio-alcohols can be produced if the cellulose and hemicellulose percentage is high (Behera et al. 2019). Cellulose is a linear polymer made of 500–15,000 glucose units connected via 1,4-glycosidic linkages. It is the most important component of a plant’s cell wall. The -1,4-glycosidic linkages build intramolecular and intermolecular hydrogen bonds, making cellulose extremely crystalline, insoluble, and resistant to enzyme degradation, and because of its rigid structure, a compact is required to obtain glucose (López-Contreras et al. 2000). Hemicellulose is a heteropolymer chain comprised of pentose moiety (L-arabinose and D-xylose) and hexose moiety (D-mannose, D-galactose, and D-glucose) with a chain length of 50–200 monomer units. It is less complex and can be converted easily into fermentable sugars (Ali et al. 2019). The third major component is lignin, which accounts for 10–25%. It is

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an aromatic polymer of phenyl propane units. It has a high level of degradability resistance and tightly connected with cellulose and hemicellulose in agricultural biomass (Saini et al. 2014). As a result, delignification of agricultural biomass is required for efficient butanol conversion. A list of lignocellulosic residues that can be utilized to make biobutanol is provided below.

12.2.1 Husks The husk is the outermost layer of seeds like rice, corn, oats, and nuts that are primarily used to produce butanol. Rice husks were gathered from rice processing plants, and these unwanted by-products were often burned which pollutes the environment (Behera et al. 2019). The cell wall of rice husk is made up of polymers such as 21.5% cellulose, 23.1% hemicellulose, and 14.6% lignin, all of which can be degraded and fermented to produce biofuels (Megawati et al. 2011). Various processing technologies can be used to transform it into efficient fuels.

12.2.2 Straw Straw is an agricultural by-product containing dry plant stalks of cereal crops such as oats, rice, rye, and barley, and because of their abundance at the processing site, rice, wheat, and barley are the three main straws that can be used in biochemical conversion technology (Ezeji et al. 2007). Wheat straw has a higher cellulose content, which can support the production of biofuel with an elevated heating value, and barley can be utilized in the same way as wheat straw but has received little attention. Wheat straw is a novel ABE fermentation substrate that can be used as a low-cost biobutanol feedstock with higher yield residues than barley (Qureshi et al. 2010). Among all other agricultural residues, it has a low lignin percentage and a high cellulose content when compared to wood.

12.2.3 Bagasse Bagasse is a pulpy fibrous agricultural waste product usually obtained from sugarcane, sorghum, or cassava which have numerous applications, including the production of enzymes and biofuels. Sugarcane bagasse is a dry pulpy fibrous leftover of cane stalks that is generally discarded as a lignocellulosic agricultural by-product by the sugar industry (Silva et al. 2010). Cassava bagasse is a solid by-product containing 30–50% starch by dry weight, compared to wheat and rice straw have some benefits. Due to its rich organic character and low ash matter, it can serve as an ideal feedstock

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for butanol production. When compared to sugarcane bagasse, it does not need to be pre-treated and can be converted biochemically using microbes (Silva et al. 2007), and when compared to traditional technology, biofuel production from agricultural residues uses sustainable practices that have a negligible environmental impact.

12.3 Conversion of Agricultural Residues to Biobutanol Agricultural residues have high potential because they are readily available in large quantities, inexpensive renewable sources, and polysaccharides found in agricultural residues such as cellulose, hemicellulose, and lignin are of great interest as biobutanol feedstocks. Agricultural residues can be a potent source of renewable energy for meeting the world’s growing energy demands. Currently, there are two routes for converting the lignocellulosic mass into biobutanol: (a) biochemical process and (b) thermochemical process. Biochemical conversion: To convert lignocellulosic biomass into bioethanol, biobutanol, and biomethane, biochemical treatments are commonly used. Generally, microorganisms or their enzymes are used to break down the biomass in the biochemical conversion process and involve a sequence of steps, which includes biomass pretreatment, enzymatic hydrolysis, fermentation, and product recovery (Baruah et al. 2018). The graphical representation of biochemical conversion has been depicted in Fig. 12.1.

Fig. 12.1 Lignocellulosic material is converted to biobutanol through a biochemical process

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12.3.1 Biochemical Routes for Biofuel Production: Important Steps Pre-treatment: Pre-treatment is a crucial technique for converting the lignocellulosebased biomass for biofuel production. An ideal pre-treatment process maximizes sugar yield from pretreated biomass while consuming the least amount of energy (Sindhu et al. 2016). Table 12.1 lists the various pre-treatment processes, which are also discussed further in this chapter. Physical pre-treatment: This method reduces the biomass size into a fine residue which is a basic requirement for biomass processing because it improves enzyme and microbe accessibility during the hydrolysis process. Comminution of lignocellulosic biomass is accomplished using a variety of physical strategies which include Table 12.1 Pre-treatment methods for lignocellulosic biomass Pre-treatment Process

Toxin Advantages release

Disadvantages

Physical

*Milling *Extrusion *Chipping *Shredding *Grinding *Irradiation

Nil

• Highly energy-intensive and unsuitable for industrial use

Chemical

Acid High Pre-treatment: *Sulfuric acid *Hydrochloric acid *Phosphoric acid Alkali Pre-treatment: *Sodium hydroxide *Ammonia Organosolv * Mixture of organic solvents and water Ionic liquids

• Hemicellulose is • Development of hydrolyzed to produce inhibitors xylose and other sugars • For lignin-rich residues, it is less • Lignin structure is effective altered

Biological

*Actinomycetes *Fungi

• Cellulose and hemicellulose depolymerization • There is no development of inhibitors • Low energy consumption

Low

• Surface area of the biomass and the pore size increases • Crystallinity of cellulose decreases

• Slow rate of hydrolysis

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milling such as compression milling, ball milling, wet milling, and dry milling. The crystallinity of cellulose is considerably reduced when residues are reduced in size, which further helps to increase the product yield (Pattanaik et al. 2019). Apart from the size reduction of biomass, pre-treatment with radiations such as ultrasonic and microwave irradiations is also beneficial and is often considered for environmentally sustainable techniques. Microwave irradiation penetrates the biomass matrix and fades the interactions between the components of the lignocellulosic residues (Zhao et al. 2018). In general, mechanical approaches are ineffective when used alone. One major disadvantage is that it consumes a lot of energy. Therefore, to save energy and reduce the cost, it is best used in conjunction with other pre-treatment methods (Hu and Wen 2008). Chemical Pre-treatment: Chemical pre-treatment methods are more commonly used than biological or mechanical treatment procedures because they are more efficient. Acid pre-treatment: Pre-treatment with acid interferes with the bonding patterns of biomass including weak bonds like hydrogen bond, van der Walls force, and also the covalent bonds. This interference results in the solubilization of biomass components (hemicellulose and cellulose) that were earlier held through the abovementioned bonds (Li et al. 2016). There are two types of acid treatments, first, that can be performed at high temperature (80 °C) for a short interval of time, i.e., 1– 5 min, and second, that can be performed at a lower temperature (120 °C) for a long interval, i.e., 30–90 min. However, the concentrated acid pre-treatment can significantly increase the rate of sugar conversion (Kumar and Sharma 2017). According to studies, the most often used acids for pre-treating lignocellulosic biomass are dilute sulfuric acid (H2 SO4 ) and hydrochloric acid (HCl). The production of inhibitory products during acid pre-treatment makes it less desirable. Furfurals, aldehydes, 5hydroxymethylfurfural (HMF), phenols, and organic acids are some of the inhibitors that are generally produced in great quantities during acid pre-treatment. To counteract the effects of these inhibitors, several approaches are available, including chemical and biological detoxification methods (Sassner et al. 2008).

12.3.2 Alkaline Pre-Treatment Aside from acids, a variety of bases are also employed to pre-treat biomass. Alkali treatment needs less pressure, temperature, and ambient conditions than other pretreatment methods, but it takes days and hours to complete the process. Biomass is soaked in alkaline solutions such as sodium, ammonium, calcium, and potassium hydroxide before being mixed for a set period at a suitable temperature (Lee et al. 1994). The structure of lignin is altered, cellulose is partially decrystalized, and hemicellulose is partially dissolved during this process. Alkali pre-treatment is more efficient for biomass with a low lignin percentage, and as the lignin content increases,

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this method becomes less efficient. Hence, the lignin percentage of the biomass influences the efficiency of this pre-treatment. Therefore, alkali pre-treatment is more valuable for biomass with low lignin matter, such as agricultural and herbaceous crops, and less beneficial for hardwoods (Oladi and Aita 2017). In some studies, alkaline pre-treatment was combined with other pre-treatment approaches to efficiently treat high-solid content biomass.

12.3.3 Ionic Liquids (ILs) Ionic liquids with anions or cations are the latest class of solvents with high thermal stability and polarity, a lower melting point, and negligible vapor pressure. Sulfonium, alkylated phosphonium, aliphatic ammonium, pyridinium, and Imidazolium ions are some examples of organic cations, while anions comprise both organic and inorganic ions (Swatloski et al. 2002). In this process, biomass is solubilized in the solvent at 90–130 °C. Interactions between biomass and ionic liquids get exaggerated by anions, cations and temperature, and time of pre-treatment (Zavrel et al. 2009).

12.3.4 Organosolv Organic solvents such as ethylene glycol, methanol, acetone, and ethanol, as well as their mixtures with water, are used to eliminate lignin and hydrolyze hemicellulose in this method, resulting in enhanced cellulose enzymatic degradability. The temperature of pre-treatment is determined by the biomass type and catalyst used, and it can reach 200 °C. During the delignification and solubilization of hemicellulose, the surface area and pore volume of cellulose increase, making enzymatic hydrolysis and saccharification more accessible. Organosolv is a new pre-treatment method that has several benefits, like solvents can be recovered simply via distillation, and solvents can be recycled. However, there are a few significant weaknesses also. Most organic solvents are extremely costly and must be recovered as much as possible, which is a time-consuming and energy-intensive operation (Zhang et al. 2017).

12.3.5 Physiochemical Pre-Treatment Physiochemical treatments such as subcritical water, ammonia fiber explosion (AFEX), supercritical CO2 , and steam explosion have also been found to be effective. The most common and effective pre-treatment method is a steam explosion, and lignocellulosic biomass is typically exposed to a variety of physical forces and chemical effects. High-pressure saturated steam is used to process the lignocellulosic

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biomass, which is then gradually reduced resulting in explosive decompression of the lignocellulosic biomass (Chen et al. 2017). The hydrolysis of hemicellulose into xylose and glucose monomers releases acetic acid, which catalyzes further hemicellulose hydrolysis, and this process is known as autohydrolysis (Singh et al. 2015). The use of carbon dioxide or sulfuric acid in steam explosion pre-treatment reduces time, temperature, and inhibitory product formation while increasing hydrolysis efficiency, resulting in complete hemicellulose removal. When equated to other pre-treatment methods, a steam explosion has several advantages, including a low environmental impact, limited chemical use, high energy efficiency, no recycling costs, and total sugar recovery. The partial destruction of the lignin-carbohydrate matrix, which results in the precipitation and condensation of soluble lignin components, is one of the drawbacks. In the AFEX process, lignocellulosic biomass is heated in a closed vessel with liquid ammonia (in a 1:1 ratio) at 60–100 °C under high pressure for 5–30 min, and then the pressure is suddenly released. The swelling of lignocellulose is triggered by the high pressure and temperature, and the rapid release of pressure disturbs the fibrous structure of biomass, further reduces the crystallinity of cellulose, and thus improves enzyme accessibility. AFEX functions on the same principle as steam explosion (Mathew et al. 2016). Liquid hot water treatment also known as hydrothermal pre-treatment is a method that uses water as a heating medium at a high temperature (typically between 130 and 240 °C) and high pressure to keep water in the liquid phase without the addition of any chemicals. It has been discovered that pretreatment with liquid hot water partially hydrolyzes hemicellulose and disrupts lignin and cellulose structures. Liquid hot water pre-treatment uses a low-cost reaction medium (just water), there is no need for pretreated biomass to be washed or neutralized, and the inhibitor concentration in hydrolyzates is low. The biomass feedstock usually does not need to be preprocessed for size reduction, and reactor materials are inexpensive. However, liquid hot water pre-treatment has significant drawbacks, such as high energy consumption, low hemicellulosic sugar concentration in the pre-treatment hydrolyzate, and a substantial volume of wastewater in downstream processing. sulfite pre-treatment to overcome lignocellulose recalcitrance (SPORL) is a pre-treatment technology for lignocellulosic biomass. SPORL is carried out in two stages. The first step is to remove lignin and hemicellulose fractions from biomass by treating it with magnesium or calcium sulfite. The size of pretreated biomass is reduced in the second stage using a mechanical disk miler. During this method, lowyield inhibitors such as hydroxymethylfurfural (HMF) (0.5%) and furfural (0.1%) were generated.

12.3.6 Biological Pre-Treatment Chemical and physical pre-treatments use conventional ways, costly reagents, and a lot of energy. Biological pre-treatment, on the other hand, is more environmentally sustainable and energy-efficient since it requires the use of live microorganisms for the treatment of lignocellulosic material (Bhatia et al. 2017). Lignin-degrading

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bacteria or fungi are used to pre-treat the biomass in this method, either as whole cells or enzymes. Fungi are the best candidates for such jobs because they can degrade cellulose, hemicelluloses, and lignin. Biological pre-treatment is used to eliminate not only lignin but also specific components such as antimicrobial substances. Though biological pre-treatment does not generate any inhibitors and is an eco-friendly process, some parameters can affect this method such as biomass composition, microorganism, incubation temperature, inoculum concentration, incubation time, and aeration rate. The white-rot fungi frequently employed for the pre-treatment of lignocellulosic biomasses are Pycnoporus cinnarbarinus, Cerrioria lacerate, Phanerochaete chrysosporium, Cyathus stercolerus, and Ceriporiopsis subvermispora. Besides these other species of basidiomycetes were also studied and have been reported for the breakdown of lignocellulosic biomass. Among these, Irpex lacteus, Trametes versicolor, Ganoderma resinaceum, Bjerkandera adusta, and Lepista nuda are well studied. White rot can degrade lignin due to the existence of lignin-degrading enzymes such as peroxidases and laccases. Laccase, which is produced by whiterot fungi, catalyzes the oxidation of phenolic compounds and aromatic amines. Lac enzyme is involved in the degradation and alteration of lignin which advances the yield of both hydrolysis and fermentation processes. In the company of a mediator system, several fungal and bacterial laccases have been used to detoxify numerous agricultural wastes (Rico et al. 2014). Detoxification: For the production of biofuels, particularly bioethanol and biobutanol, detoxification is crucial. The majority of sugar monomers are liberated during pre-treatment of lignocellulosic biomass, along with other inhibitory by-products such as furfural, hydroxymethylfurfural (HMF), phenolics, acetic acids, and salts (Birgen et al. 2019). Formic acid, which is produced during the pre-treatment of lignocellulosic biomass, is another inhibitory compound that can inhibit C. acetobutylicum and the formation of these inhibitory compounds can disturb the fermentation process. It is essential to eliminate them for successful fermentation. Many detoxification methods are used for this purpose, including electrodialysis, dilution, liming, activated charcoal treatment membrane-mediated detoxification, and resin treatment (Chandel et al. 2011). Different detoxification strategies have been discussed in Table 12.2. Table 12.2 Detoxification of different lignocellulosic biomass Biomass used

Treatment

Effect

Sugarcane bagasse

Overliming

Furfurals removal Reduction of reducing sugars

Oakwoods

Activated charcoal

Removal of phenolics

Wheat straw

Ion exchange+ Overliming

Removal of furfurals and phenolics

Spruce wood

Dithionate and sulfite

No major change

Corn stover

Membrane mediated detoxification

Removal of acetic acid

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Although detoxication is for the removal of inhibitors from lignocellulosic hydrolyzates has been shown to improve fermentability, in most cases, only a portion of the inhibitors was removed. As a result, the best detoxification method depends on the type of hydrolyzate to be treated and the efficiency of detoxification on that hydrolyzate, as well as the fermentation microorganisms used in butanol production and the inhibitors that need to be removed.

12.3.7 ABE Fermentation After ethanol fermentation, ABE fermentation is the second-largest fermentation process in the fermentation industry. Clostridium acetobutylicum and Clostridium beijerinckii are the most commonly used microbial strains used for butanol production. Table 12.3 also discusses biobutanol production from various biomasses and microorganisms. ABE fermentation is biphasic; acidogenesis—the initial growth phase of ABE fermentation, produces hydrogen, carbon dioxide, butyrate, and acetate, and lowers the pH of the medium; after that, the culture shifts to the solventogenic phase. For fermentation of pre-treated and hydrolyzed biomass, a variety of different process configurations are applicable. There are a variety of fermentation options such as separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), simultaneous saccharification and co-fermentation (SSCF), and consolidated bioprocessing (CBP). All of these fermentation configurations can be run in batch, fed-batch, or continuous modes, each with its own set of rewards and difficulties. Consolidated bioprocessing (CBP) is an interesting method for creating biobutanol because it employs cellulolytic microorganisms that produce cellulase as well as hydrolysis and fermentation in a single step. In general, detoxification is used for the removal of inhibitors present in the feedstock as described in the detoxification section (Mohd Azhar et al. 2017). Several factors influence the effectiveness of any fermentation such as incubation time, temperature, agitation, media pH, and toxicity. The role of agitation in maintaining the homogeneity of microbes and nutrients in the fermentation broth is critical. Increased agitation speed improves broth homogeneity, reduces temperature gradients, and increases production. However, cell damage occurs when agitation is extremely high, which has a detrimental effect. The pH of media used for fermentation is another factor that has a significant impact on productivity, which has been studied across a wide range and at maximum output. Incubation time, which divides the fermentation pathway into acidogenic and solventogenic phases, is another vital influencing parameter. Acidogenesis begins shortly after inoculation and lasts nearly 30 h for the production of several acids before transitioning to the solventogenesis phase, which usually lasts for 90 h.

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Table 12.3 Biobutanol production from various agricultural residues Biomass used

Microorganism

Pre-treatment

Yield g/L

Rice straw

Clostridium acetobutylicum

Acid hydrolysis

13.5 g/L Ranjan et al. (2013)

Wheat straw

Coculture -Clostridium beijerinckii and Clostridium cellulovorans

Biological treatment

14.2 g/L Valdez-Vazquez et al. (2015)

Pinus rigida wood waste

Clostridium beijerinckii NCIMB 8052

Planetary mill + Enzyme hydrolysis

6.91 ± 0.64 g/L Kwon et al. (2016)

Cauliflower waste

Clostridium acetobutylicum NRRL B 527

Acid hydrolysis + Detoxification

3.06 ± 0.11 g/L Khedkar et al. (2017a)

Corn stover

Clostridium acetobutylicum ATCC 824

Steam explosion + Alkali treatment

63 g/L He and Chen (2013)

Rice straw

Clostridium acetobutylicum MTCC 481

Steam explosion and Acid treatment

0.861 g/L (Steam explosion) 0.803 g/L (Acid treatment) Ranjan and Moholkar (2013)

Peapod waste

C. acetobutylicum B 527 Acid treatment

4.25–5.94 g/L Nimbalkar et al. (2018)

Cassava waste residue

Bacillus coagulans, Clostridium bifermentans

Acid treatment

4.25–5.94 g/L Johnravindar et al. 2017)

Sweet potato vines

Clostridium acetobutylicum

Milling + Enzyme hydrolysis

3.36 g/L He et al. (2017)

Rice straw

Clostridium sporogenes BE01

Acid treatment

6.4 g/L Gottumukkala et al. (2013)

Pineapple peel

Clostridium acetobutylicum B 527

Acid treatment

5.52 g/L Khedkar et al. 2017b)

Rice straw and sugarcane bagasse

Clostridium sp.

Acid treatment

5.23 g/L Cheng et al. (2012)

Rice straw

Coculture—Clostridium beijerinckii and Saccharomyces cerevisiae

Alkaline treatment

Rice straw −0.86 g/L, Sugarcane bagasse—0.61 g/L Wu et al. (2020)

Lettuce residues

Clostridium acetobutylicum DSMZ 792

Thermo-alkaline, diluted acid, and cold NaOH/Urea pre-treatments

10.62 g/L Procentese et al. (2017)

Cornstalks

Clostridium beijerinckii NCIMB 4110

Acid treatment + Enzyme hydrolysis

g /L Tang et al. (2017) (continued)

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Table 12.3 (continued) Biomass used

Microorganism

Pre-treatment

Mango peels

Clostridium acetobutylicum NCIM 2877

Mechanical + enzyme 10.50 g/L hydrolysis Avula et al. (2015)

Yield g/L

12.3.8 Fermentation Modes The most basic fermentation processes are the batch type because it is adaptable to a variety of products, simple to control, and has multiple vessels. The method starts with the addition of substrates, microorganisms, culture medium, and nutrients in a closed system at a specified time under ideal conditions. Only at the end of the fermentation process are the products removed. Various researchers have thoroughly examined batch, fed-batch, and continuous fermentation modes (Kujawska et al. 2015). The continuous method includes continuous introduction of substrates, culture medium, and nutrients to a fermenter with active microbes and continuous recovery of products. Typically, butanol, cells, and residual sugar are obtained. Continuous fermentation has many benefits, including high efficiency, limited fermenter sizes, and low investment and operating costs (Kujawska et al. 2015). A fed-batch system is a hybrid of batch and continuous fermentation processes in which the substrate is charged into the fermenter without the medium being removed. When compared to other fermentation processes, fed-batch fermentation has sufficient oxygen level in the medium, consumes less effort to ferment, and is less toxic to the medium. Although continuous fermentation permits for less sterilization, butanol inhibition, and re-inoculation of microorganisms, researchers have been drawn to batch mode due to its high yield. The fed-batch mode of fermentation can be a good selection for substrate inhibition or catabolite repression. However, it is not the best option due to large solvent accumulation. It is recommended that the fed-batch mode be used in conjunction with a suitable downstream technique. Different modes of fermentation have been depicted in Fig. 12.2.

12.3.9 Techniques for Recovering ABE Fermentation Products by Separation Liquid–liquid extraction, distillation, membrane distillation, vacuum stripping, adsorption, and gas stripping have been suggested as methods for recovering acetone, butanol, and ethanol from ABE fermentation broth. In terms of selectivity, capacity, energy demand, fouling, clogging, scale-up, and ease of operation, each technique has a range of benefits and drawbacks. Table 12.4 lists the numerous separation practices used to recover biobutanol from fermentation broth (Rezaiyan and Cheremisinoff 2005).

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Fig. 12.2 Modes of fermentation: Continues type, fed-batch type, and batch type

12.4 Thermochemical Conversion Thermochemical pathways provide nonbiological biofuel production methods. The economic analysis is carried out by calculating the energy consumed for biofuel production as well as the energy output from the fuels. If the economic viability is found to be cost-effective, thermochemical treatments may be used to manufacture biofuels. Otherwise, crop residue is used as animal feed, organic compost, or soil conditioner, as shown in Fig. 12.3. Thermochemical conversion processes include gasification, combustion, liquefaction, hydrogenation, and pyrolysis. The choice of activities to be used dependent on the nature and quality of the feedstock, the environmental standard, the desired type of fuels, economic conditions, and the various project-specific factors (Marsh et al. 2007). In comparison to the biochemical process, the thermochemical procedure has fewer processing phases and therefore takes less time.

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Table 12.4 Methods for recovering butanol from fermentation broth Methods

Advantages

Disadvantages

Distillation

• Easy to use • A simple two-column distillation system can be used • To separate the mixtures, no additional compound is required

• Expensive investment • Excessive energy consumption • Inadequate selectivity

Adsorption

• High selectivity • Low energy consumption

• Adsorbent regeneration

Gas stripping

• It is simple to use • Not harmful to culture • It can be used continuously

• Low selectivity • The tiny bubbles created by this method produce an excessive amount of foam in the bioreactor • The necessity of antifoam agent

Liquid–liquid • High selectivity and efficient • Forming emulsion extraction • Expensive extractant recovery Protraction

• High selectivity

• Forming emulsion • Membrane fouling

Vacuum stripping

• Simple to use • No negative impact on culture

• Low selectivity

12.4.1 Preparation Stage—Thermochemical Conversion The biomass must be pre-treated before it can be converted thermochemically because biomass can hold lots of moisture. Size reduction and drying are the two most common pre-treatment procedures. Drying is an energy-intensive approach for advancing the overall energy balance of the process and conditions of a gasifier. Size reduction is essential to attain even operation and increases the surface area of the raw material per unit mass.

12.4.2 Gasification Gasification is the method to alter dense raw materials into fuel gas or chemical feedstock gas, which can then be transformed into biofuels via Fischer–Tropsch synthesis. When air or oxygen is used, gasification is akin to combustion, but it is considered a partial combustion practice. In general, combustion is associated with the production of heat. However, gasification is related to the production of important gaseous products that can be burned directly or stored for later use. Furthermore, gasification is thought to be more environmentally friendly. Gasification is a type of pyrolysis that takes place at higher temperatures to produce more gas (Bridgwater 2003). Lower

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Fig. 12.3 Economic analysis of lignocellulosic biomass

CO2 emissions, compact equipment requirements with a small footprint, concise combustion control, and better thermal competence are just a few of the advantages of biomass gasification. Gasification is typically performed at temperatures greater than (727 °C)1000 K. Gasification is classified based on some factors, including gasifier type, temperature of gasification, direct or indirect heating, and gasification agent. The different types of gasifiers, as well as their benefits and drawbacks, are discussed in Table 12.5.

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Table 12.5 Different types of gasifiers for gasification Gasifier type

Advantages

Disadvantages

Fluidized bed

• Large-scale application • Direct or indirect heating • Can generate syngas

• Tar yield is moderate • Increased particle loading

Circulating fluidized bed

• Large-scale application • Can generate syngas

• Tar yield is moderate • Increased particle loading

Entrained flow

• Low tar potential • Can generate syngas

• Particle loading is greater • A large amount of carrier gas

Downdraft

• Small-scale application • Low tar

• Scale limitations • Moisture sensitive

Updraft

• Application on a small scale • Can withstand high moisture levels • There is no carbon in ash

• Tar yield is high • With a heavy gas load, the reaction capability is poor

12.4.3 Syngas Fermentation Gasification of lignocellulosic waste materials produces a gas mixture (syngas) containing methane (CH4 ), carbon dioxide (CO2 ), hydrogen (H2 ), carbon monoxide (CO), water vapor, and short-chain hydrocarbon gases. When compared to saccharification fermentation, which uses only hemicellulose and cellulose, gasification uses all biomass components, counting lignin, which is the main benefit of this procedure. Anaerobic microorganisms, such as Butyribacterium methylotrophicum, Clostridium autoethanogenum, Clostridium ljungdahlii, and Clostridium carboxidivorans can consume syngas as both their carbon and energy sources and creating biofuels such as ethanol and n-butanol illustrated in Fig. 12.4. Even though syngas fermentation has a lot of potential for producing biofuels, there are still a lot of issues to work out in terms of process efficiency. Attention to gas fermentation has grown in tandem with research and patent filings, and numerous companies have emerged to commercialize gas fermentation for the production of biofuels and chemicals (Hang et al. 2010).

12.4.4 Pyrolysis To transform biomass into value-added goods, various thermochemical and biological processes have been used. It is still in the early stages of expansion and must

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Fig. 12.4 Biobutanol production through syngas fermentation

overcome various practical challenges to compete with traditional fossil fuel-based procedures. Pyrolysis is the most practical method since it offers many storage and transportation benefits. Pyrolysis can be defined as the thermal disintegration of lignocellulosic residues in absence of oxygen. The end product of pyrolysis consists of biochar, bio-oil, and gases (hydrogen, methane, carbon monoxide, and carbon dioxide). Pyrolysis has recently gotten a lot of attention from the forestry, municipal, and agricultural sectors because of its ability to convert any type of lignocellulosic residues into commercially feasible biofuels and valued chemical feedstocks for the industrial area (Brown 2009). To achieve the rate of heating in lignocellulosic biomass materials such as stalks, woods, and straws, the size of the particles being heated must be very small (2 mm) and the moisture content should be around 10%. There is a possibility that the process would only produce dust instead of oil if the feedstock contains a lot of moisture. Pyrolysis produces char at low temperatures (450 °C) with a slow heating rate and gases at high temperatures (>800 °C) with a fast heating rate. When heated to very high temperatures, the main product is a liquid bio-oil. In recent years, pyrolysis technology has been used to perform extensive research on the thermochemical conversion of biomass into biofuels (bio-oil, biochar, and biogas). Pyrolysis can be divided into three groups based on their characteristics of reaction temperature and residence time: 1. fast pyrolysis, 2. intermediate pyrolysis, and 3. slow pyrolysis. Fast pyrolysis typically has a very short residence time. In general, shorter reaction times combined with a higher temperature result in a higher yield of liquid product. Slow pyrolysis is the process of heating lignocellulosic biomass in an inert atmosphere for hours to a maximum temperature of 400–500 °C. A variety of catalysts can be used in the pyrolysis of biomass and/or the up-gradation of the vapors formed by thermal pyrolysis. Fast pyrolysis aims to produce liquid fuels from lignocellulosic residues that can be used in any application instead of fuel oil. A variety of specialty and commodity chemicals can be made from the liquid. The fast pyrolysis process must have extremely high heating and heat transfer rates, which often necessitates a finely ground biomass feed. Bio-oil is the chief product of fast pyrolysis, which can yield up to 80 weight percent of dry feed. Fast pyrolysis is an efficient strategy for turning bulky, inhomogeneous biomass into transportable oil with a high volumetric energy density (Bridgwater 2003). The agricultural area

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accounted for 8.6% of total greenhouse gas emissions, which is based on the use of fossil fuels or their products in agriculture. It is essential to consider that the majority of agricultural residues generally crop residues can be transformed into other useful products. Biomass has a complex structure and is usually made up of three natural biomacromolecules: cellulose, hemicellulose, and lignin. Pyrolysis yields condensable vapors, liquids, and gas from cellulose and hemicellulose. Liquid, gas, and solid char are formed as lignin decomposes. More bio-oils can be generated from biomass substrates that contain a higher proportion of lignin derivatives. In this regard, pyrolysis of agricultural residue to produce bio-oil and biochar could be a promising approach. As a result, agricultural biomass has a high potential for pyrolysis-based sustainable production of biofuels and valuable products.

12.4.5 Liquefaction Lignocellulosic residues are generally liquefied at low temperatures and high pressures in water or other suitable solvents; further, biomass is broken down into three components: a bio-oil fraction (the target product), a solid residue fraction (biochar), and a gas fraction. Hydrothermal technology also includes the liquefaction of biomass in water. The main distinction between liquefaction and the other three thermochemical conversion processes (pyrolysis, combustion, and gasification) is that during the liquefaction phase, water or other suitable solvents must be used as the reaction medium. The types of liquefaction solvents can be divided into two groups: water and organic solvents (phenol, ethanol, methanol, acetone, etc.). Organic solvents are used as liquefaction solvents to avoid raising environmental issues. Biomass is combined with water and basic catalysts such as sodium carbonate, and the process is performed at lower temperatures (252–472 °C) but higher pressures (50–150 atm) and for longer periods than pyrolysis (5–30 min.); because of these factors, liquefaction is a more expensive process. The liquid product obtained contains less oxygen (12–14%) than bio-oil generated by pyrolysis and needs less processing. Thermal liquefaction methods for biomass and wastes, both direct and indirect, are currently getting more research than other methods. When biomass components react with smaller molecules like H2 and CO, direct liquefaction occurs. The processing of an intermediate, such as synthesis gas or ethylene, and the chemical conversion of that intermediate to liquid fuels in a sequence of steps is known as indirect liquefaction. Direct liquefaction is similar to pyrolysis in terms of end products (liquid products). They differ, however, in terms of operational conditions (Marsh et al. 2007; Bridgwater 2003). Direct liquefaction, in particular, necessitates lower reaction temperatures but higher pressures than pyrolysis. Furthermore, catalysts are always required for liquefaction, but not as much for pyrolysis. Biomass undergoes depolymerization and decomposition into monomer units at the start of the liquefaction process. These monomer units, on the other hand, have the potential to be repolymerized or condensed into solid chars, which are undesirable.

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Table 12.6 Difference between thermochemical and biochemical conversion Thermochemical

Biochemical

Almost any biomass can be used effectively

Small range of biomass available, bacteria, enzymes, or chemicals are used

The rate of productivity is high

Limited productivity

Biomass is largely used to its full potential

Produces secondary waste

Operated at higher temperatures

Ambient temperatures are ideal

The thermochemical process has fewer processing steps than the biochemical process, resulting in a faster processing time. The final products are compatible with current fossil fuels and could be distributed through the same channels. Thermochemical biomass conversion has several advantages over biological/biochemical biomass conversion which has been discussed in Table 12.6.

12.4.6 Use of Biobutanol in Road Transport Butanol is non-poisonous, less susceptible to water pollution, easily biodegradable, less corrosive, and has a higher energy content than ethanol. Although the physical features of the butanol isomers differ in terms of octane number, viscosity and boiling point, and because of its physicochemical qualities, biobutanol is becoming a viable substitute to bioethanol and gasoline as a transportation fuel in spark-ignition engines. Biobutanol and isobutanol are currently regarded gasoline components that can be combined in larger proportions without causing any modifications to a traditional gasoline engine. Butanol fuel blends can be used in existing cars to replace gasoline without affecting the engine’s requirements. Biobutanol, which can be derived from the same biomass as bioethanol, i.e., lignocellulosic biomass, is another choice for liquid fuels that can replace conventional gasoline in transportation. It also has the ability to be a strong source of renewable energy (Peng et al. 1996).

12.4.7 Physiochemical Properties of Biobutanol The physicochemical qualities of the fuel to be burned in the SI engine indicate its quality. The physical and chemical properties of bioethanol, biobutanol, and gasoline are compared in Table 12.7. When compared to ethanol, biobutanol has numerous rewards when it comes to blending with gasoline. The mixtures have great phase stability, low-temperature properties, oxidation stability during extended storage, distillation features, and volatility in the presence of water. Biobutanol has a slightly higher density than ethanol and gasoline, resulting in improved volumetric fuel economy. Biobutanol has a significantly higher viscosity than gasoline; because

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Table 12.7 Physiochemical properties of butanol are compared to other fuels (Yusoff et al. 2015) Properties

Ethanol

n- butanol

Diesel

Gasoline

Energy density

25

29.2

35.86

32

Octane No

85

96

20–30

80–99

Flash point

14

35

65–88

−45 to −38

Boiling point

78.5

117.7

180–370

25–215

Viscosity

1.2–1.074

2.63

1.9–4.1

0.4–0.8

Flammability

3.3–19

1.4–11.2

1.5–7.6

0.6–8

of the higher flow resistance at lower temperatures, this property can have a negative impact on the fuel injection system (Patakova et al. 2011).

12.5 Conclusion The processing of biobutanol from agricultural residues or wastes has been addressed in this chapter using two routes: biochemical conversion and thermochemical conversion. Both the conversion methods appear promising, but their commercial feasibility is limited. Concerns about energy and the climate have reignited interest in renewable energy sources. Lignocellulosic biomass such as agricultural residues can be a better option for the production of biobutanol because of its cost-effectiveness, renewability, and abundance. ABE fermentation of crop residues to produce biobutanol is a safe and environmentally friendly technology. However, it faces some obstacles, such as low yield and productivity due to inhibitors. These can be overcome using genetic engineering and mutagenesis. Thermochemical conversion of biomass is an increasingly viable way to use agricultural crop residues to full fill energy needs and has several advantages over biochemical conversion that we have already discussed in this chapter. In view of future prospects, the research should be directed toward the efficient use of advanced biotechnology or merging molecular biology with bioprocess engineering techniques for increasing biobutanol yield.

12.6 Competing Interests All the authors declare that they have no competing interests.

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Chapter 13

Microalgal Biomass and Lipid Induction Strategies for Bioenergy Production as a Renewable Resource B. Subha, K. S. Nathiga Nambi, R. Dineshkumar, A. Ahamed Rasheeq, M. Durai Murugan, P. Arun, P. Alaguraj, T. Dharshinipriya, U. Namitha, and P. M. Swetha

Abstract The main objective of the study was to isolate and characterize microalgae from Vellar estuary south coast of India. The isolated eight microalgal species were cultured in CHU 10 broth to find the efficient culture media under laboratory conditions. The growth rate, pH, and biomass for lipid production under different conditions were studied from the eight microalgal species isolated and incubated in different media. On the other hand, the physicochemical properties of sewage water were analyzed, and the suitable environmental condition was adopted for culturing. Microalgae showed good growth, and the biomass was taken for further study among which Nitzschia species was selected based on biomass and lipid production. Further, enhancement was carried out by supplementing media with different carbon (glucose and starch) and nitrogen (urea and yeast) sources. Nitzschia species resulted in a maximum growth rate (2.08) and biomass (0.17 g L−1 ) with glucose as carbon source, while supplemented yeast as nitrogen source yielded a maximum growth rate (1.118) and urea favored the maximum biomass (0.16 g L−1 ). Maximum lipid content about 0.058 and 0.046 g was witnessed when supplementing the glucose and yeast along with the diatom media components (0.025 g). The oil was characterized by FT-IR spectroscopy, and different active functional groups were recorded. In Nitzschia, 98% of different fatty acids were recorded. The present study concluded that the culture B. Subha (B) · R. Dineshkumar Department of Microbiology, Vivekanandha Arts and Science College for Women, Sankagiri, Tamil Nadu, India e-mail: [email protected] K. S. N. Nambi Department of Biology, Gandhigram Rural Deemed to be University, Dindigul, Tamil Nadu, India M. D. Murugan · P. Arun · P. Alaguraj · T. Dharshinipriya · U. Namitha · P. M. Swetha Department of Microbiology, Karpagam Academy of Higher Education, Pollachi Main Road, Eachanari, Coimbatore, Tamil Nadu 641021, India A. A. Rasheeq CAS in Marine Biology, Faculty of Marine Sciences, Annamalai University, Chidambaram, Tamil Nadu, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_13

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conditions, especially the nature of carbon and nitrogen sources, influence the yield on growth, biomass, and lipid production of Nitzschia sp. Keywords Microalgae · Sewage water · Biomass · Nitzschia sp. · Lipid · Media components

13.1 Statement of Novelty Microalgae when compared with other natural sources have a very good potential for biofuel production due to the high aerial productivity, relatively low environmental impact, and low impact on food security. The major shortcoming for commercialization of algal biofuel is the high production costs so strategies are developed to maximize the biomass and lipid production in a viable way. High production costs are the major limitation for commercialization of algal biofuels. Strategies to maximize biomass and lipid production are crucial for improving the economics of using microalgae for biofuels. Selection of suitable algal strains, preferably from indigenous habitats, and further improvement of those ‘platform strains’ using biomass and lipid productions. Conventional approaches to improve biomass and lipid productivity of microalgae mainly involve manipulation of nutritional (e.g., nitrogen and carbon) and environmental (e.g., temperature, light and salinity) factors. Present study throws light on using sewage water as a microalgal cultivation medium and usage of carbon and nitrogen source to increase the lipid production.

13.2 Introduction Microalgae are unicellular photosynthetic microorganisms which live in saline or freshwater environment, having a greater biodiversity than the terrestrial plants. The global energy consumption is dominated by the conventional fossil fuels like petroleum, coal, and natural gas (Liu et al. 2012). Mostly, all the traditional fuels are expensive, highly depletive, and nonrenewable resources (Lie et al. 2012; Cai and Wang 2013). Microalgae act as a very efficient solar energy converters producing a great variety of metabolites, and many species of microalgae can be induced to accumulate substantial quantities of lipid greater than 60% of their dry biomass and exhibit rapid growth and high productivity. Presence of high amount of lipids can be accumulated by diatoms and green algae which makes them most promising species in biotechnological application. Photosynthetic microalgae remove and utilize nitrogen, phosphorus in water, CO2 sequestration in the air, and synthetic lipid converted into biodiesel variety of organisms like plants animals and microbes. Studies of Hosoglu et al. show that high microalgal biomass can be obtained by autotrophic cultivation of microalgae in open

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ponds or closed bioreactor under a natural or artificial source of light. Nevertheless, the light requirement is higher, and culture strategy is low, and in large-scale algal biomass production, these bottlenecks make it hard (Isleten Hosoglu et al. 2013). Microalgae are cultivated in several dozen small to medium scale production system producing few tons to several hundred tons of biomass annually added to human nutritional products. Algae having a unique biomass source for the synthesis of renewable energy as they have several advantages like high lipid oil or starch content and not in need of agricultural land; moreover, freshwater is not essential as nutrients are supplied by waste water and CO2 by the combustion of gas. The total production of Spirulina, Chlorella, Dunaliella, and Haematococcus exceeds about 10,000 tons Zs/year cultivated synthetically. Microalgae serve as an energy resource of next generation having maximum biomass production increased lipid productivity and carbon neutrality. Among the oil producing microalgae, Nannochloropsis is found to be excellent for producing biofuel (Ren et al. 2012). The improvement of lipid productivity and aid large-scale commercial production on selecting suitable fertilizer can be clearly understood by the effect of carbon and nitrogen sources on growth and lipid content (Eizadora et al.). High microalgal growth is found in the municipal wastewater treatment plants, but the usage of chemical fluctuate for removal of algal cells restricts algal biomass and harvesting is not completely practiced. Production of microalgae nutritional products with a few thousand tons of algal biomass with high content of omega 3 fatty acids is carried out commercially by dark fermentation (using starch or sugar rather than light energy and CO2 ) similar to photosynthesis with a few thousand tons of algal biomass and with high content of omega 3 fatty oils (Al-Jabri et al. 2021). The present study was undertaken to isolate, identify, and culture microalgae in a different medium (Chlorella sp., Desmococcus sp., Phormidium sp. in BG11 medium; Nitzchia sp. in diatom medium; Scenedesmus sp., Chroococcus sp. and Synechococcus sp. in nitrogen less BG11 medium and Spirulina sp. in Zarrouk medium) and to compare with sewage. Further, the growth rate, pH, biomass, and lipid production of microalgae were evaluated. Moreover, the physio-chemical properties of the sewage water before and after culture were estimated. The lipid production of microalgae and fatty acid was estimated in different carbon and nitrogen sources treated. Among eight species of microalgae culture in both indoor (in vitro) and outdoor (sewage), Nitzschia sp. shows high lipid content. Hence, Nitzschia sp. could be used for biodiesel production.

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13.3 Materials and Methods 13.3.1 Isolation and Identification of Microalgae The microalgal species were collected from Vellar estuary, South East Coast of India, Cuddalore District, Tamil Nadu, India, and were stored in the Algal culture laboratory, Faculty of Marine Sciences, Annamalai University, India. Different microalgal species were isolated using serial dilution technique, and species identified was done based on the morphological characters (John et al. 2003) with reference to the standard identification manual.

13.3.2 Maintenance of Microalgal Cultures Single pure colonies of microalgal species were isolated, and all the eight species were maintained in culture tubes. Then, subcultures were made at regular intervals, and cultures were deposited in the Algal Culture Laboratory, Faculty of Marine Sciences, Annamalai University, India. The cultures were inoculated in flasks and observed at regular intervals using an optical microscope, inoculated with sterile 50 mL of Chu 10 broth, and were incubated in a rotator shaker for 4000 rpm for 20 min. The algal growth was examined in the flasks using optical microscope, inoculated in sterile 50 mL of Chu 10 broth and incubated on a rotary shaker at 27 °C for 100 rpm under continuous illumination in photo-bioreactors in their respective culture media (i.e., Chlorella sp., Desmococcus sp., Phormidium sp. in BG11 medium; Nitzchia sp. in diatom medium; Scenedesmus sp., Chroococcus sp. and Synechococcus sp. in nitrogen less BG11 medium, and Spirulina sp. in Zarrouk medium) (Andersen 2005).

13.3.3 Cultivation of Microalgae in Laboratory Condition All the eight microalgal pure cultures were isolated and inoculated in 500 mL conical flask with 250 mL of respective medium and kept under continuous 4000 l× illumination. The growth and pH of eight microalgal cultures were observed for a month in four days interval, and finally, the total biomass was harvested on the 30th day.

13.3.4 Collection of Sewage Water The sewage waste water samples were collected from Parangipettai, South East Coast of India, Tamil Nadu (N11°29' 25.86'' , E079°45' 59.73'' ). Ten liters of water samples

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were collected and brought to the laboratory and used as a cultivation medium for the growth of algae.

13.3.5 Cultivation of Microalgae in Media and Sewage Water at Environmental Condition All the eight microalgal cultures were grown in their respective medium and sewage water separately, and the results were compared. 500 mL of defined media for eight algal cultures were taken respectively in eight circular (M1–M8) trays. Biological oxygen demand (BOD), chemical oxygen demand (COD), sodium, calcium, potassium, and nitrogen content of sewage were analyzed. The isolated algal cultures were inoculated separately in eight circular trays (S1–S8), in 500 mL of sewage water sample collected from Parangipettai Coast. Pure algal cells were counted and enumerated by using haemocytometer. Equal number of cells were taken (103 cells mL−1 ) and transferred in all 16 trays (M1–M8 and S1–S8), respectively. All the trays were kept in environmental condition and covered with fine muslin cloth to avoid contamination by dust particles and microbes. The light intensity and temperature were recorded throughout the study period. The average photon value was found to be 90 μE m−2 s−1 and the temperature is 27–30 °C. Manual agitation was provided two times per day. The growth and pH of the algal cultures in the trays (M1–M8 and S1–S8) were observed in 5-day interval for a period of 25 days. Finally, the biomass is harvested from all the 16 trays and centrifuged separately. The total dry biomass of algal cultures in media (M1–M8) and from sewage water (S1–S8) was also determined. The reduction/utilization of BOD and COD, total solids, nitrogen, sodium, calcium, potassium, carbon content, and carbon dioxide fixation by eight algal cultures in sewage (S1–S8) water was also examined.

13.3.6 Influence of Different Carbon and Nitrogen Source on Selected Nitzschia sp. for Biomass and Lipid Production Nitzschia sp. showed less biomass comparing other species, but taking into the account of high lipid production (Nitzschia sp.) was selected and was cultivated in 150 mL of diatom medium for a period of 12 days and used as the mother culture for further analysis. 5 mL of 12 days culture (Nitzschia sp.) was transferred in 12 different flasks of 100 mL capacity, respectively. Concentration of 0.05% of different carbon sources (1-glucose, 2-sucrose, 3-glycerin, 4-starch, and 5-maltose) and influence of 0.05% concentration of different nitrogen sources (6-urea, 7-peptone, 8-sodium nitrate, 9-calcium nitrate, 10-yeast) and the selected Nitzschia were also kept at starved condition, served as control (i.e., diatom medium, 11-without carbon source,

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and 12-without nitrogen source). Nitzschia sp. was studied for a period of 12 days in order to enhance its further growth, biomass, and lipid content production. The growth was determined at two days regular interval, and biomass was calculated. Since these are photoautotrophic, they obtain their energy for food from synthesis from light and are capable of using carbon dioxide as their principal source of carbon. Overall, addition of carbon and nitrogen source in diatom media has evidenced in enhancing the biomass and also the lipid productivity of Nitzschia sp.

13.3.7 Estimation of Growth Factor The growth rate of all eight algae samples was analyzed using spectrophotometer at 560 nm, and the pH was determined using a digital pH meter.

13.3.8 Estimation of Physicochemical Parameters of Sewage Water Various physicochemical parameters like calcium (Natusch and Hopke 1983), potassium (Natusch and Hopke 1983), sodium (Tandon 1993), dissolved oxygen (DO) (APHA 2005), biological oxygen demand (BOD) (APHA 2005), chemical oxygen demand (COD) 9APHA 2005), total solids, nitrogen content (Jones 1991), carbon content, and carbon dioxide fixation rate (Yun et al. 1997) were analyzed according to the given methodology.

13.3.9 Harvesting The microalgal biomasses were harvested by filtration method.

13.3.9.1

Filtration Method

The microalgal filtration was performed using the Whatman GF/G filter paper (0.2 μm in diameter). For each sample, the volume was first measured with a measuring cylinder and is passed through the apparatus (vacuum pump model no: DDA P730-PN) with a suction pressure of less than 0.3 bar. Species like Chlorella vulgaris and Cyclotella with 5–6 μm in diameter are the most appropriate pore size for microfiltration (Edzwald 1993).

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249

Determination of Total Biomass

The weight of the petri dishes was calculated initially to avoid numerical errors. The filtered biomasses were kept in sterile dried petri dishes, and the weight was calculated initially and wet biomasses are calculated as initial weight. Later, the wet biomasses were allowed to dry under shade, and petri dish was weighed (dry weight) with the dry biomass (Mohenimani et al. 2013). The total biomasses were calculated by using the following formula: Total biomass = wet weight (gm) − dry weight (gm).

13.3.10 Determination of Total Lipids Algal cells were dried overnight at 40 °C in a vacuum oven and completely pulverized, using a mortar and pestle for analyzing lipid content. Gravimetrically lipid content was determined using chloroform and methanol mixture solution (Bligh and Dyer 1959).

13.3.11 Lipid Analysis by FTIR Spectroscopy FTIR absorption spectra acquired in transmission mode using PerkinElmer Spectrum Version 10.03.09 was used in confirmation of certain oil compounds. The spectrum was recorded in the ranges between 4000 and 400 cm−1 with a spectral resolution of 4 cm−1 ; for each spectrum, 4 scans were averaged. Typically, IR determines the main methyl ester groups (European Standard EN 14,078).

13.3.12 Algal Fatty Acid Composition of SCO Characterization of biodiesel was used gas chromatography/mass spectrometry (GC– MS) on JEOL GC MATEII at 70 eV (m/z 50–550; source at 230 °C and quadruple at 150 °C) in the EI mode with an HP-5 ms capillary column (30 min). Flow rate of carrier gas, helium was maintained at 1.0 mL min−1 . The temperature was maintained at 300 °C in the inlet and the oven was programmed for 2 min at 150 °C, then increased to 300 °C at 4 °C min−1 , and maintained for 20 min at 300 °C. The injection volume was 1 μL, with a split ratio of 50:1.

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13.4 Results and Discussion Microalgae became the center of attention in the past decades for its ability to act as an efficient renewable source for biofuel production (Razon and Raymond 2011) and other industrial applications (Carlsson et al. 2007). Due to the increasing concern over emission of carbon dioxide, reasonable effects of global warming, coupled with diminishing fossil fuels, microalgae were subjected to severe consideration by industries and policy making agencies that invests millions of dollars for its commercial utilization (Sheehan et al. 1998). Nevertheless, the practicability of this technology to meet the future needs at a global scale necessitates a considerable increase in algal productivity.

13.4.1 The pH, Time Taken for Maximum Growth and Their Biomass of Microalgae Grown in Medium at Laboratory Condition All the eight microalgae were found to be grown in media at laboratory condition. The pH ranged between 8 and 10 inoculated with Chlorella sp., Scenedesmus sp., Chroococcus sp., Desmococcus sp., Synechococcus sp., and Phormidium species. pH between 7–9 for Nitzschia sp., and 9–11 for Spirulina sp. (Table 13.1). Algae relies greatly on medium pH, and it varies based upon the individual species (Liu et al. 2013). The tremendous increase in growth rate was found in Spirulina sp. followed by Chlorella sp., Synechococcus sp., Desmococcus sp., Scenedesmus sp., Chroococcus species. Spirulina sp. (OD 3.29) showed a maximum growth rate till the 28th day, whereas Chlorella Scenedesmus sp., Chroococcus sp., Desmococcus sp., and Synechococcus reached a maximum growth rate at 24th day. The Phormidium sp. gradually rise and attained maximum growth rate at 20th day. In Nitzschia species, the growth rate was increased between 12 and 16th day and then starts decreasing (Fig. 13.1a). Table 13.1 pH of eight microalgae grown in medium at laboratory condition Algae

1st day 4thday 8thday 12th day 16th day 20th day 24th day 28th day

Chlorella

7.8

8.9

10.2

9.8

9.2

9.9

10.2

10.2

Nitzschia

6.7

6.7

6.8

7.6

9.1

8.1

7.9

7.4

Scenedusmus

7.4

8.3

9.6

9.2

9.4

9.6

9.8

9.8

Desmococuus

7.8

9.2

9.5

10.2

10.2

10.2

10.3

9.9

Chroococcus

7.4

9.1

10.0

10.1

9.9

10

10.5

10.3

Synechococcus 7.4

8.8

9.9

9.8

9.9

10

10.3

9.8

Phormidium

7.8

8.4

9.6

9.7

10

10.4

10.9

9.8

Spirulina

7.9

8.8

9.1

9.8

10.1

10.6

10.8

10.9

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Fig. 13.1 a Growth rate of microalgae culture grown in medium at laboratory condition. b Biomass of eight microalgae in laboratory condition

The maximum biomass was obtained in Chlorella sp. (0.224 g L−1 ) followed by Desmococcus sp., Scenedesmus sp., Chroococcus sp., Spirulina sp., and Phormidium sp. Here, Synechococcus sp. showed low biomass (0.076 g L−1 ) followed by Nitzschia sp. (0.092 g L−1 ). The biomass of eight microalgae slightly differed when compared to their growth rate (Fig. 13.1b). Though the Spirulina sp. and Synechococcus sp. showed increase in growth rate, they did not attain maximum biomass and it might be attributed to its cell size and aggregation properties (Dang-Thuan et al. 2013). In general biomass production based on various factors such as nutrient, pH, salinity, temperature and sunlight (Mahdy 2016).

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Table 13.2 pH of eight microalgae culture grown in medium at environmental condition Algae

0th day

5th day

10th day

15th day

20th day

Chlorella sp

7.8

7.4

7.8

7.9

8.8

25th day 8.8

Nitzschia sp

6.7

7.2

7.2

7.3

7.5

7.4

Scenedusmus sp

7.4

7.8

7.6

7.3

7.5

7.4

Desmococuus sp

7.8

7.7

8.1

7.9

8.2

8.8

Chroococcus sp

7.4

7.7

7.6

8.4

8.5

8.5

Synechococcus sp

7.4

7.8

7.8

7.9

8.1

7.9

Phormidium sp

7.8

7.8

7.6

7.8

8.4

8.1

Spirulina sp

7.9

8.9

8.7

9.0

9.6

10.2

13.4.2 The pH, Time Taken for Maximum Growth in Medium at Environmental Condition The pH values were found to be ranged between 8 and 10 for Spirulina sp., 7 and 9 for Chlorella sp., and Desmococcus sp., 7 and 8.5 for Chroococcus sp. and Phormidium sp., 7 and 8 for Scenedesmus sp., and Synechococcus sp., and 6.5 and 7.5 for Nitzschia sp. Optimum pH for most cultured algal species ranges between 7 and 9, with the optimum pH being 8.2–8.7. Compared to pH value of eight microalgae in media at indoor condition, the pH value showed decreased of range at environmental condition in all eight microalgae (Table 13.2). The Chlorella vulgaris maintained their maximum growth rate in a wide range of pH between 6.0 and 9.0, but started to be inhibited from pH 5 (Yun et al. 1997). The growth rate of eight microalgae at environmental conditions in the media is shown in (Fig. 13.2a). The maximum growth rate was obtained in Spirulina sp. (OD 0.494) followed by Chlorella sp. (OD 0.489) and Desmococuus (OD 0.464) on 25th day with no decline phase. They are prokaryotic or eukaryotic photosynthetic microorganisms that can grow rapidly and live in harsh conditions due to their unicellular or simple multicellular structure. The moderate growth rate (OD 0.262) was recorded in Nitzschia sp. and started to decrease after the 20th day. Scenedesmus sp. and Synechococcus sp. did not grow well in media as environmental conditions.

13.4.3 The pH, Time Taken for Maximum Growth in Sewage at Environmental Condition The pH value was found to be ranged between 8 and 10.5 for Spirulina sp., 8 and 10 for Chlorella sp., 7.5 and 9.5 for Desmococcus sp. and Chroococcus sp., 6.5 and 9 for Nitzschia sp., 7.5 and 8.5 for Scenedesmus sp., Synechococcus sp., and Phormidium sp. Compared to pH value in media at environmental condition, slight increases in pH were recorded in all eight microalgae grown in sewage (Table 13.3). The pH

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Fig. 13.2 a Growth rate of microalgae culture grown in medium at environmental condition. b Growth rate of microalgae culture grown in sewage at environmental condition

increases during the daytime up to 10, mainly because of the depletion of the anions NO3– and of CO2 formed in the medium due to the excretion of OH− ions (Saha et al. 2013). The maximum growth rate was recorded in Spirulina sp., (OD 0.509) and Chlorella sp., (OD 0.496) followed by Desmococuus sp., and Chroococcus sp., on 25th day with no decline phase. Most of the algal species that were cultured commercially remain relatively free from contamination by other algae and protozoa (Belay 1997). The moderate growth was obtained in Nitzschia sp., (OD 0.365) followed by Phormidium sp., (OD 0.24). Scenedesmus sp. and Synechococcus sp. did not grow well in sewage, environmental condition (Fig. 13.2b). The pH is another vital factor that governs the properties of microbial surface and flocculation, while such influence may alter the biochemical metabolism (Wong et al. 1990). The pH range of 9 to 11 favored the maximum growth and biomass, Spirulina sp., 7 and 9 for Nitzschia sp., 8 and 10 for another six microalgae species. The isolates preferred near neutral to alkaline pH. The pH value lower or higher than

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Table 13.3 pH of microalgae culture grown in sewage at environmental condition Algae

0th day

5th day

10th day

15th day

20th day

25th day

Chlorella sp.

7.8

8.7

8.6

8.8

9.1

10.1

Nitzschia sp.

6.7

8.8

8.5

8.7

8.6

8.4

Scenedusmus sp.

7.4

8.7

8.6

8.6

8.6

8.5

Desmococuus sp.

7.8

8.6

8.6

9.1

9.2

9.6

Chroococcus sp.

7.4

8.6

8.6

9.1

9.2

9.6

Synechococcus sp.

7.4

8.7

8.5

8.8

8.4

8.5

Phormidium sp.

7.8

8.4

8.6

8.7

8.6

8.5

Spirulina sp.

7.9

8.8

8.8

9.0

9.8

10.6

these values hindered the microalgal growth. The results correlate with the earlier reports by Rai et al. (2014) who revealed that C. turgidus, L. confervoides, and N. commune showed maximum growth at pH 7.5, whereas Nannochloropsis oceanica showed maximum growth at pH 8.4. The limitation of phytoplankton growth and photosynthesis at elevated pH levels was observed by Chen et al. (1994). This could be due to the fact that at high or low pH, the cells might spend maximum energy for maintenance of an internal pH that is necessary for proper cell function (Raven et al. 1985).

13.4.4 Biomass in Medium and Sewage at Environmental Conditions The maximum biomass was obtained in Chlorella sp., (0.134 g L−1 ) followed by Desmococcus sp., (0.130 g L−1 ), Spirulina sp., (0.124 g L−1 )—were maintained in Zarrouk medium), Chroococcus sp., (0.114 g L−1 ), Phormidium sp., (0.076 g L−1 ) and very little trace amount of biomass were found in Nitzschia sp., followed by Scenedesmus sp., and Synechococcus sp. The biomass of eight microalgae was slightly differed when compared to their growth rate (Fig. 13.3). In sewage at environmental condition, the maximum biomass was recorded in the Chlorella sp., (0.201 g L−1 ) followed by Spirulina sp., (0.207 g L−1 ), Desmococcus (0.194 g L−1 ), Chroococcus sp., (0.161 g L−1 ), Nitzschia sp., (0.140 g L−1 ), Scenedesmus sp., (0.08 g L−1 ), Phormidium sp., (0.083 g L−1 ), and Synechococcus sp., (0.071 g L−1 ) (Fig. 13.3). In both media and sewage treatment maintained at environmental condition showed the maximum biomass in Chlorella sp., followed by Spirulina sp., and Desmococus sp., whereas Nitzschia sp. and Chroococcus sp, evidenced moderate biomass in diatom and BG11 medium. Likewise, Scenedesmus sp. and Synechococcus sp. attained low biomass in selective medium. When compared to all the media, all the eight microalgae showed increase in their biomass treated with sewage as environmental conditions. Numerous studies

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Fig. 13.3 Biomass of eight microalgae in environmental condition

evidenced that the municipal and agricultural wastewater acts as a suitable medium for microalgae (Pittman et al. 2011). BG11 and F/2 medium was used in batch reactor culture system and outdoor for culturing Nannochloropsis and Dunaliella salina; their study shows efficient biomass production in photo-bioreactor systems (Rodolfi et al. 2009; Guccione et al. 2014). Among the cultured organisms, there exists a significant variation in growth rate and biomass production that is Spirulina sp. and Chlorella sp. reached a maximum growth rate whereas Chlorella sp. and Desmococcus sp. showed maximum biomass. At environmental condition, Chlorella sp., Desmococcus sp., Spirulina sp., Nitzschia sp., Chroococcus sp. were found to grow well both in the media and sewage. Scenedesmus sp. and Synechococccus sp. did not grow well; it may be due to the inability of these species to utilize the highest level of organic and inorganic pollutants at environmental conditions. In addition, algae can be preferred to treat wastewater as it can be used to eliminate coli form bacteria, decrease BOD and COD, elimination of nitrogen, phosphate or heavy metals to definite extent (Abdel-Raouf et al. 2012; Richmond 1986; Garbisu et al. 1991; Tam et al. 1995). Algae can grow in various environments including marine, brackish, freshwater, wastewaters if and only if it gets adequate amounts of carbon, nitrogen, phosphorus, and other vital trace elements. But based on the species being cultured and composition of waste water, the quantity of growth may vary from scanty to exceptional (Wong and Chan, 1990; Zhou et al. 2011). In our study, the algal species were able to exhibit moderate growth. However, wastewater-based algae cultivation still faced many uncertainties and challenges, including variation of wastewater composition.

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13.4.5 Physicochemical Parameter of Untreated Sewage and Treated Sewage Sample by Microalgae The physicochemical parameters were found to be above the permissible limit in the collected sewage water. This was reduced/utilized by all the eight microalgae inoculated in sewage for a period of 25 days, and hence growth was observed in the studied microalgae. Spirulina sp. was able to remove 91% of the TS, 53.7%, of COD, 88.5% of BOD followed by Chlorella sp., (89.7, 47.3, and 87.6%). During the algae cultivation period, a major part of organic pollutants were consumed. The total nitrogen was highly up taken by Chlorella sp. (82.7%) followed by Spirulina sp., (79.5%). When growing, Chlorella sp. has reduced the BOD up to 87.1% and Scenedesmus sp. removed the mentioned pollutants by 92.1%. Comparing the research data results of other scientists, the present study revealed that the removal capacity of total nitrogen from sewage was achieved better (Wang et al. 2010). Nitzschia sp. removed 98.3% of sodium and 95.8% of calcium, whereas potassium was highly removed from Synechococcus sp., (98.2%). Sulfur, potassium, sodium, iron, magnesium, calcium, and trace elements like boron, copper, manganese, zinc, molybdenum, cobalt, vanadium, and selenium are also important in algal nutrition (Grobbelaar 2004). The several studies have shown that microalgae species have potential to remove heavy metals such as Cu, Fe, Zn, Pb, and Ni when cultured in sewage water (Zerrouki and Henni 2019; Al-Jabri et al. 2021). Among the eight microalgae, Synechococcus sp. and Scenedusmus sp. did not reduce much level of COD, BOD, and TS and indicated their poor growth in sewage water. The inhibition in the growth of microalgae at the initial stage in the wastewater was due to the presence of high nutrient, and the other factors present in sewage as nutrient medium. The results obtained for certain critical parameters which indicate the level of pollution, such as total solids, BOD, COD, total nitrogen, calcium, sodium and potassium, iron, have shown a significant reduction after treatment with the microalgae (Table 13.4). The various water quality parameters were evaluated before and after culturing. The present findings indicated that the Spirulina sp. and Chlorella sp. were found to remove high COD, BOD, and TS. The metal ions were highly removed by Nitzschia sp. and Phormidium sp. The present findings lie in parallel with the report of Mobin and Alam (2014), who stated that the Auxenochlorella protothecoides UMN280 exhibited maximal removal of nitrogen, phosphorus, chemical oxygen demand, and total organic carbon were over 59%, 81%, 88%, and 96%, respectively. Similarly, maximum reduction in COD (99.9%), BOD (100%), NO3 (99.98%), PO4 (99.96%), and TC (100%) was observed in ponds containing C. vulgaris (Ahmad et al. 2013). Deviram et al. (2011) noticed that the free cells of Chlorella sp., without any additional nutrients resulted in 50% of reduction in COD and BOD after 96 h, whereas other two strains could reduce up to 49.5 and 48.3 (Ulva sp) and 43.5 and 42.2 (Cladophora sp) for COD and BOD, respectively.

42.1 13.4

2800

40.6

74.8

96.1

60.7

38.4

45.5

Total solids

Total nitrogen

COD

BOD

Sodium

Calcium

Potassium

1.33

2.10

5.64

14.6

321

Des

1.30

1.61

1.02

15.7

44.6

12.8

396

Nit

1.70

2.65

9.77

21.2

48.2

12.6

448

Sce

1.17

2.27

7.69

18.9

45.0

14.0

334

Chroo

1.28

1.88

4.86

11.9

39.4

7.0

287

Chlo

0.80

4.02

7.87

23.9

49.6

12.6

491

Syn

1.39

2.40

7.79

20.1

47.1

19.6

411

Phor

Final concentration in treated sewage sample by microalgae (mg/L)

Initial concentration in collected untreated sewage sample (mg/L)

Parameters

Table 13.4 Physicochemical parameter of untreated sewage and treated sewage sample by microalgae

1.38

2.05

1.92

11.0

34.6

8.3

249

Spi

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Table 13.5 Carbon content and carbon dioxide fixation by microalgal biomass in medium ((outdoor) environmental condition) Parameter

Des

Nit

Sce

Chro

Chlo

Syn

Phor

Spi

Carbon content (mg g−1 )

18.108

54.326

15.521

16.715

22.874

10.347

4.434

19.367

0.066

0.019

0.056

0.061

0.083

0.037

0.016

0.070

Co2 fixation (g mL−1 d−1 )

13.4.6 Carbon Content and Carbon Dioxide Fixation by Microalgal Biomass in Medium (Environmental Condition) The biomass of Nitzschia sp. contains maximum carbon content (54.326 mg g−1 ) followed by Chlorella sp., (22.874 mg g−1 ). Among the eight microalgae, Chlorella sp., (0.083 g mL−1 d−1 ) and Spirulina sp., (0.070 g mL−1 d−1 ) fixed highest level of CO2 , whereas Phormidium sp. fixed low level of CO2 (0.016 g mL−1 d−1 ) (Table 13.5). Highly CO2 tolerant microalgae and cyanobacteria that are suitable for biological fixation of CO2 are Anacystis, Botryococcus, Chlamydomonas, Chlorella, Emiliania, Monoraphidium, Rhodobacter, Scenedusmus, Spirulina, and Synechococcus (Sawayama et al. 1995; Sung et al. 1999).

13.4.7 Carbon Content and Carbon Dioxide Fixation by Microalgal Biomass in Sewage (Environmental Condition) The carbon content was found to be absent in Desmococuus sp., Scenecoccus sp., Synechococcus sp., and Phormidium sp. Hence, CO2 fixation by these microalgae could not be recorded. Apart from the above microalgae, the biomass of Nitzschia sp. contains highest carbon content (36.217 mg g−1 ) but found to be fixed low level of CO2 . Chlorella sp., (0.088 g mL−1 d−1 ) and Chroococcus sp., (0.079 g mL−1 d−1 ) fixed highest level of CO2 from sewage indicated that these organisms could be suggested as best microalgae for CO2 sequestration (Table 13.6). In wastewater treatment ponds, the algae produces oxygen from water as a by-product of photosynthesis that is used by the bacteria and their biooxidize the organic compounds in the wastewater. An end product, carbon dioxide is fixed into cell carbon by the algae during photosynthesis (Wang et al. 2010).

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Table 13.6 Carbon content and carbon dioxide fixation by microalgal biomass in sewage [(outdoor) environmental condition] Parameter Carbon content (mg

g−1 )

Co2 fixation (g mL−1 d−1 )

Des

Nit

Sce

Chro

Chlo

– –

36.217

–

24.154

21.7305

0.013

–

0.079

0.088

Syn

Phor

Spi

–

–

15.521

–

–

0.056

13.4.8 Selection of Microalgae for Lipid Production The microalgae grown in laboratory condition exhibited maximum biomass, when compared with medium and sewage in environmental conditions. So, eight laboratory cultivated microalgae were subjected for further analysis viz., lipid production. Screening as well as a selection of microalgae that produces increased quantities of neutral lipids is very essential for its successive commercial production of algaebased biofuel. Among the wide array of microalgae exists very few were identified for successful commercial application (Norton et al. 1996). Microalgae under mass cultivation in photo-bioreactors indicated that Nitzschia sp., produced highest lipid content (47.4%) followed by Chlorella sp., and Scenedusmus sp., Chlorella sp., Spirulina sp., and Desmococcus sp., attained maximum biomass in media in indoor as well as in media and sewage at environmental condition. Quite a few microalgal species such as Chlorella sp., (Griffiths and Harrison, 2009; Ding et al. 2015), Dunaliella sp., (Francisco et al. 1998; Mutsumi et al. 2006), Isochrysis sp., Phaeodactylum tricornutum, Oocystis minuta, and Nannochloris sp., (Takagi Mutsumi et al. 2006; Gouveia Luisa and Ana 2009) possess 20–30% of oil content. The total lipid production within algal strains varies depending on the algal metabolism and environmental conditions. Nitzschia sp. was able to uptake highest level of sodium and calcium and also moderate level of BOD, COD, TS, and TN. Among the eight microalgae, Nitzschia sp. produced highest lipid content.

13.4.9 Total Lipid Content of Eight Microalgae Grown in Medium at Laboratory Condition Nitzschia sp. attained highest lipid content of 47.4 g dry weight among the eight microalgae. Lipid content (5–20%) in microalgae under optimal conditions is reported to increase up to 20–50% under unfavorable conditions (Hu et al. 2008). Higher lipid is found in Nitzschia sp., followed by Chlorella sp., (28.2 g), Scenedesmus sp., (26.1 g), and Desmococcus sp., (24.6 g) and showed moderate lipid content. Hu et al. (2008) reported that Chlorella sp., revealed higher total lipid content (7.8 g) than other isolated strains followed by S. incrassatulus (6.5 g) and S. dimorphus (4.5 g), while Chroococcus coherens showed the lowest lipid content. Spirulina sp. (9.8 g) and Synechococcus sp. (9.2 g) produced low lipid content (Fig. 13.4). This is similar to the findings of Ehimen et al. (2010) who reported that the Spirulina

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Fig. 13.4 Lipid content of eight microalgae under mass cultivation in laboratory condition

platensis samples were determined to have a total lipid content of (10.95 g) of their biomass. The biomass oil content of the used microalgae strain is highly dependent on the specific growth conditions not only influenced by the microalgae species. Based on the results obtained, Nitzschia sp. alone selected, and it was supplemented with different carbon and nitrogen sources for further enhancement of biomass and lipid production in medium at laboratory condition.

13.4.10 The pH, Growth Rate and Biomass of Nitzschia sp. Under Different Carbon Source The pH value of Nitzschia sp. was found to be ranged between 8 and 9 under glucose; 7.5 and 9 under starch. The pH values were started decreasing from 8 to 7 and 6 under sucrose, glycerin, and maltose (Table 13.7). William (2008) had studied that not only the organic carbon or substrate (a carbon source such as sugars, proteins and fats), vitamins, salts, and other nutrients (nitrogen and phosphorous) are vital for algal growth but also equilibrium between operational parameters viz. oxygen, CO2 , pH, temperature, light intensity, product, and by-product removal. Nitzschia sp. reached maximum growth rate (OD 2.08) under glucose at 10th day followed by starch (OD 1.7) at 8th day (Fig. 13.5a). The growth of Nitzschia sp. was found even in diatom medium without carbon source (i.e., control). The growth was very low in media containing maltose carbon sources. These results were in agreement with glucose-grown Chlorella vulgaris UAM101 cells (Martinez and Orus 1991). The similar result as that growth rate was reported in biomass of Nitzschia sp.; compared to control (0.080 g), the maximum biomass was obtained in Nitzschia sp., under glucose (0.174 g) followed by starch (0.097 g) and low biomass under maltose (Fig. 13.5b). Liu et al. (2008) studied that Phaeodactylum triconutum could

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Table 13.7 pH value of Nitzschia sp. under different carbon source No. of. days

Glucose

Sucrose

Glycerin

Maltose

Starch

2nd day

8.0

8.1

7.7

7.9

7.5

4nd day

8.4

8.0

8.1

8.3

7.9

6th day

8.4

8.1

8.0

8.1

8.3

8th day

8.6

8.3

8.0

8.1

8.6

10th day

8.7

7.8

7.6

7.9

8.2

12th day

8.9

7.9

7.6

6.2

8.8

grow mixtrotrophically, and moreover, glycerol, acetate, or glucose all significantly enhanced specific growth rate and biomass. In order to further enhance the growth and biomass of Nitzschia sp., different C and N sources were supplied separately. The C source (glucose and starch) and N

Fig. 13.5 a Growth rate of Nitzschia sp. under different carbon source. b Biomass of Nitzschia sp. under different carbon source

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source (urea and yeast) enhanced the growth and biomass of Nitzschia sp. Glucose as carbon source and yeast as a nitrogen source provide maximum lipid content. The first studies on heterotrophic algal growth, with 10 g L−1 glucose supply, reported an increase in lipid content of Chlorella protothecoides from 15 to 55% (Miao et al. 2006). Under three organic carbon sources, including glucose (1% w/v), acetate (1% w/v), and glycerol (1% w/v), C. vulgaris achieved biomass productivity of 254 mg Ld−1 and lipid productivity of 54 mg Ld−1 on glucose with light (mixotrophic) which was 19 folds and 14 folds higher than biomass and lipid productivities obtained in the same culture with merely air bubbling into the medium, respectively (Liang et al. 2009). Another study by Hong et al. (2013) reported that the glucose was the best substrate with the maximum biomass concentration (3.46 g L−1 ), specific growth rate (0.819 d−1 ), and highest total lipid content (43.4%). Similar reports were also observed by some other microalgae species like Chromochloris zofingiensis (Sun et al. 2008; Liu et al. 2010).

13.4.11 The pH, Growth Rate and Biomass of Nitzschia sp. Under Different Nitrogen Source The pH value of Nitzschia sp. was found to be ranged between 7.5 and 8.5 under urea and yeast; 6 and 7 calcium nitrates. The pH value started decreasing from 8 to 7.5 under peptone and sodium nitrate (Table 13.8). A drop in pH can be observed when ammonia is used as the only source of N, especially during active growth owing to the release of H+ ions. An increase in pH is observed when nitrate is used as the only N source (Grobbelaar 2004). Nitzschia sp. reached maximum growth (OD 1.16) under urea followed by yeast (OD 1.118) at 12th day (Fig. 13.6a). Here, the growth was very low at control (without nitrogen source) and under sodium nitrate. A wide variety of nitrogen sources, such as ammonia, nitrate, nitrite and urea, can be used for growing microalgae (Becker and Baddiley 1994). Nitrogen is mostly supplied as nitrate, but often ammonia and urea are used, both displaying similar growth rates (Kaplan et al. 1986). Kim et al. (2016) used nine different nitrogen sources, including NaNO3 , KNO3 , NH4 NO3 , NH4 HCO3 , Table 13.8 pH value of Nitzschia sp. under different nitrogen source Days

Urea

Peptone

Sodium nitrate

Calcium nitrate

Yeast

2nd day

7.9

8.1

7.9

6.3

7.8

4nd day

7.6

8.0

8.2

6.6

8.2

6th day

7.8

8.0

8.2

6.2

8.1

8th day

8.0

8.1

8.4

6.1

8.0

10th day

8.2

7.9

7.9

7.0

8.4

12th day

8.4

7.6

7.5

7.2

8.6

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NH4 Cl, CH3 COONH4 , urea, glycine, and yeast extract which were compared at the given concentration of 8.82 mM. Higher biomass concentration was achieved under organic nitrogen sources, such as yeast extract (2.23 g L−1 ) and glycine (1.62 g L−1 ), compared to nitrate- (1.45 g L−1 ) or ammonium-N (0.98 g L−1 ). Ren et al. (2013) investigated the effect of two different nitrogen sources, sodium nitrate (NaNO3 ), and urea (CH4 N2 O), on the growth, lipid yield, and fatty acid composition of N. oceanica IMET1. Similar to growth rate, the maximum biomass was recorded in Nitzschia sp., under urea (0.164 g) followed by yeast (0.094) and low at control (0.076) (Fig. 13.6b). The urea molecule contains a carbon atom as well as two nitrogen atoms. This carbon atom is released as CO2 when urea is utilized and, presumably, it is available for photosynthetic assimilation. Therefore, urea has the potential of providing both the nitrogen and 1.5 to 10% of the carbon requirement (Neenan et al. 1986). The carbon

Fig. 13.6 a Growth rate of Nitzschia sp. under different nitrogen source. b Biomass of Nitzschia sp. under different nitrogen source

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and nitrogen source enhancing maximum growth and biomass of Nitzschia sp. were selected, and its biomass was taken for lipid extraction. Nitrogen is a vital ingredient for cell protein and protoplasm for its growth and influences the productivity. Microalgae utilize various dissolved forms of organic and inorganic nitrogen sources. The essential criteria for mass production of microalgae vary from species to species; it is based on selection of the suitable nitrogen source. Several varieties of nitrogen sources, including yeast extract, nitrate, ammonia, and urea were used for growing microalgae. In this study, yeast extract acted as a superior nitrogen source and this was similar to that of in marine microalga Tetraselmis sp. This efficiently used yeast when compared to that of glycine, urea, and nitrate (Kim et al. 2016). Yeast was the fastest consumed nitrogen source; it could achieve highest cell growth rate may be not solely due to the nitrogen, since the yeast also contains various other compounds such as amino acids, peptides, vitamins, and carbohydrate that favors the microalgal growth. This technique was focused to improve the biomass as well as lipid production. On the other hand, lipid productivity is a more indicative index of total lipid production than lipid content from the commercial standpoint (Griffiths and Harrison 2009).

13.4.12 The Lipid Content of Nitzschia sp. Under Efficient Carbon and Nitrogen Source Compared to control, the highest lipid content was recorded in Nitzschia sp., under yeast as nitrogen source (0.058 g) followed by glucose as carbon source (0.046 g), and low lipid content was obtained under urea as a nitrogen source (0.015 g) (Fig. 13.7). The result was dissimilar to (Supriya et al. 2012) who found high lipid content of Nitzschia sp., (1.29 g L−1 for sodium nitrate and 1.09 g L−1 for urea) in the stationary phase of culture in the both cases. Hence, glucose as carbon source and yeast as nitrogen source can be selected as suitable C and N source for enhancing both biomass and lipid production of selected efficient Nitzschia sp., for low-cost biodiesel production. The cellular lipid accumulation was quite low at low levels of glucose concentration and then showed an increase when glucose concentration was increased. Lipid production of Chlorella sp. KKU-S2 reached the maximum of 6.25 g L−1 with 47.8% CDW at 50 g L−1 glucose which was obtained (Ratanaporn and Supaporn 2011). The lipid content was found to be around 39.5–44.8% dry weight in Nannochloropsis sp. (Doan et al. 2011). Similarly, Dunaliella salina exhibits 34–44% dry weight of lipid content as reported (Weldy and Huesemann 2007).

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Fig. 13.7 Lipid content of Nitzschia sp. under efficient carbon and nitrogen source enhancing biomass

13.4.13 Selection of Efficient Microalgae for Lipid Production All of the eight microalgal species were found to be growing in suitable media at indoor conditions. Meanwhile, in the account of environmental conditions, the maximum growth rate and biomass were obtained in Chlorella sp., Spirulina sp., and Desmococcus sp. In sewage at environmental condition, Chlorella sp., Spirulina sp., Desmococcus sp., Chroococcus sp., and Nitzschia sp. were able to grow and also reduced the pollutants quantity and fixed CO2 . On the final day, the cells in all eight trays containing sewage were observed under light microscopy, where Chroococcus sp., Scenedesmus sp., and Synechococcus sp. were found to be contaminated and did not fix much level of CO2 . Among all eight microalgae, Nitzschia sp. produced highest lipid content of 47.4 g dry weight. De La Pena et al. (2007) proved the change in lipid content from 26.4 to 81.5% DW in diatom Amphora sp., due to changes in media composition. Though Chlorella sp., and Desmococcus sp. showed their maximum growth and biomass in both indoor and environmental conditions, reduced organic and inorganic pollutants, and also fixed high level of CO2, they did not possess optimum lipid content of biodiesel production. Compared to other microalgae (Chrococcus sp., Phormidium sp., Scenedesmus sp. and Synechococcus sp.), Nitzschia sp. was able to grow and produce moderate biomass at both indoor and environmental conditions, which also produce more oil. Hence, Nitzschia sp. was selected, and its growth and lipid content were further enhanced by optimizing C and N sources in order to select potential microalgae for low-cost biodiesel production. Generally, diatoms have the largest proportion of their body, about 70% of their dry weight. The diatom lipids have been suggested as a potential diesel with emphasis on the neutral lipids due to their lower degree of unsaturation and their accumulation

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in algal cells at the end of the growth stage. Both polar (neutral) lipids are found in diatoms (Round et al. 1990).

13.4.14 FT-IR Determination of SCO The FTIR analysis of SCO IR graphs results is given in Fig. 13.8. There was the observance of significant peaks between 1743.60 and 1462.45 cm−1 , C=O: Carbonylic compounds (aldehydes, acids, etc.) are the strong C=O stretching absorption band, and it confirms the presence of carbonyl groups Fig. 13.8. C–H: absorption bands characteristic of the vibrations of C–H bonds. There were peaks between 2853.32 and 2922.93 cm−1 which corresponds to the asymmetric and symmetric vibrational modes of methyl groups, and it confirms the asymmetric and symmetric vibrational modes of methylene groups. The peak from 3395.65 to 3011.35 cm−1 is ascribed to the band of the amine groups. The band at 1372.20 cm−1 was due to the alcohols. The absorption peak at 1147.48 and 1097.25 cm−1 attributed to the C–O–H in secondary and tertiary alcohols and CH2 in alcohols. The band observed at 720.79 cm−1 was due to the Alkenes Cis-R-RCH=CHR. The FTIR analysis carried out and indicates the presence of biodiesel for Leptolyngbya sp., (Belle Mare) and Nodularia harveyana (Albion) lipids only peaks at 1738.30 cm−1 for C=O and 1171.49 and 1249.31 cm−1 for –C–O were obtained for the Leptolyngbya sp., (Belle Mare). As a Nodularia harveyana peak at 1737.84 cm−1 for C=O and 1189.43 cm−1 for C–O were obtained (Knothe 2006). Since the biodiesel was mainly mono alkyl ester, the intense (C=O) stretching bond of alcohol appears at 1053.13 cm−1 C–O obtained (Knothe 2006). Due to the dominant volume of biodiesel was present in the mixture, these spectra look similar to commercial. The

Fig. 13.8 FTIR analysis of the SCO product from Nitzchia sp.

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intense stretching bonds of O–H at 3247 cm−1 confirm the presence of biodiesel, besides the other absorbance peaks also show the existence of ethanol, carboxylic acid, alkenes, and alcohol.

13.4.15 Characterization of Fatty Acid Properties in SCO Quantitative differences in various SCO and individual acids were found in the fatty acids which are given in Table 13.9. Major fatty acid compositions are recorded in SCO, which includes palmitic acid (C16:0), oleic acid (C18:1), stearic acid (C18:0), linoleic acid (C18:2), and linolenic acid (C18:3) very much related to that of vegetable oil. Nearly, 98% of the fatty acids were identified in the SCO, in which saturated fatty acids are higher followed by monosaturated and polyunsaturated fatty acids. Most abundant fatty acids in SCO are palmiitic C16:0 (23.6), stearic acid C18:0 (7.3%), oleic acid C18:1 (47.52%), linoleic acid C18:2 (10.3%), and linolenic acid C18:3 (0.38%). Cheng et al. (2005) reported the highest activation energy of 46.68 kJ mol L−1 and the maximum solid residue of 25.81% were obtained in the pyrolysis of biodiesel made from C. gracilis cells, which were cultured with 0.5 mmol L−1 nitrogen (no silicon) and accumulated the minimum polyunsaturated fatty acid (C20:5). Microalgae lipid production can be divided into two groups: nonpolar lipids like triacylglycerol and polar lipids like glycerophospholipids, polyunsaturated fatty acid, eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA). Porphyridium cruentum has ability to accumulate the polyunsaturated in triacylglycerol (Cohen et al. 1988). In another study, Parietochloris incisa have the potential to produce omega -6 polyunsaturated fatty acid (Bigogno et al. 2002; Khozin-Goldberg et al. 2002). Some other species such as Pavlova lutheri, Nannochloropsis oculata, Talassiosira pseudonana, and Phaeodactylum tricornutum can be able to produce TAGs at a lower level (Berge et al. 1995; Eizadora et al. 2009).

13.5 Conclusion The present study shows the huge potential of microalgae in the marine environment. Sewage effluents proved to be a better low-cost media source for microalgal growth. Spirulina and chlorella yielded good biomass in the sewage media treatment. The study has proved the influence of carbon and nitrogen sources on the lipid production of Nitzchia sp. The findings can further lead the research community in biodiesel production from marine microalgae.

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Table 13.9 Fatty acid composition of SCO produced from Nitzchia sp. Fatty acid

No. of carbon chain

Percentage by volume in the SCO (%)

Capric acid

C10:0

ND

Undecylic acid

C11:0

1.09

Lauric acid

C12:0

0.2

Tri decylic acid

C13:0

0.37

Myristic acid

C14:0

1.64

Penta decylic acid

C15:0

0.2

Palmitic acid

C16:0

23.6

Cis-5-palmitoleic acid

C16:1ω-5

0.5

Margaric acid

C17:0

ND

Cis-7-heptadecenoic acid

C17:1 ω-7

ND

Stearic acid

C18:0

7.3

Oleic acid

C18:1

47.52

Vaccenic acid

C18:2

10.3

Linoleic acid

C18:3

0.38

Nonadecyclic acid

C19:1

0.1

Arachidic acid

C20:0

1.1

Eicodadienoic acid

C20:2

1.06

Arachidonic acid

C20:3

1

Heneicosanoic acid

C21:0

ND

Pehenic acid

C22:0

0.3

Lignoceric acid

C:24

0.01

Cis-5-eicosapentaenoic acid

C20:5ω

0.1

Docosa pentaenoic acid

C22:3 ω

0.7

Total

97.17

∑ of SFAs

84.03

∑ of MUFAs

11.28

∑ of PUFAs

1.86

ND not detectable

Conflict of Interest The authors declare that they have no conflict of interest.

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Chapter 14

Recent Trends in Microbial Fuel Cell S. Sivaprakash, Prabhavathy Sivaprakash, and V. Saraswathy

Abstract Microbial fuel cell (MFC), a bioelectrochemical system, helps to generate electricity at atmospheric temperature conditions with/without existence of intermediator using bacteria or microorganism. This technology is very important for future sustainable technology for biodegradable materials using microorganism. In microbial fuel cell, microbes undergo catabolism reaction for easy energy generation. Energy produced is relatively of low intensity due to its nature of mimicking bacterial interactions. However, as per Carnot cycle, efficiency of energy level in MFC is relatively more than 50%. Views on various aspects of MFC will be explained from different resources in terms of their electrochemical performance using their morphology, catalyst arrangement, and activation of microorganism including cathode, anode, and separator along with catalyst. The MFC system assembly consists of a cathode and anode along with biocatalyst which is separated by an ionic porous separator in presence of an electrolyte medium. In real condition, this porous separator is polymeric/ceramic in nature which allows flow of ions thereby electron move in the external circuit. Porous cathode material helps to induce reduction process and anode material undergo oxidation without any external/ internal obstruction during operation of MFC will be explained from reported literature. Various factors such as pH, Temperature range, etc. may influence electrochemical redox reaction during MFC working process. This can give a clear idea and simultaneously leads to improvement of the system performance indirectly, which also will be validated from reported documents. Design of MFC module for optimal performance with energy output and other factors influencing MFC performance with application potential will be considered in various aspects. In addition to this, bioenergy harvesting will also be discussed from reported literature.

S. Sivaprakash (B) CSIR—Central Electrochemical Research Institute, Mandapam, India e-mail: [email protected]; [email protected] P. Sivaprakash CSIR—Central Mechanical Engineering Research Institute, Durgapur, India V. Saraswathy CSIR—Central Electrochemical Research Institute, Karaikudi, India © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023 P. K. Ramanujam et al. (eds.), Bioenergy, Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-99-3002-9_14

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14.1 Introduction Microbial fuel cells (MFCs), a source of sustainable energy, are devices that convert chemical energy from organic wastes into electrical energy by using catalytic activity of microbes. In future, energy generation will be much cleaner and more sustainable than today. Reduced secondary pollution along with cost-effective operation under ambient environmental conditions is observed in MFC when compared to other bioenergy conversion processes like anaerobic digestion, gasification, and fermentation (Chouler et al. 2016; Park and Zeikus 2003; Angelaalincy et al. 2018). MFC comprises of anode and cathode chambers that are submerged in aqueous solution that are separated by an ion exchange membrane which helps in cation exchange like Nafion and Poly (tetrafluoroethylene) (PTFE) (Tharali et al. 2016; Choudhury et al. 2017; Mathuriya and Yakhmi 2016). For fundamental concept, understanding schematic representation of a two chamber MFC is shown in Fig. 14.1. In recent times, MFC energy generation is one amongst several new alternative energy sources. The energy generation takes place due to presence of microbial activity as MFC system primarily depends on living biocatalysts (microbes) to facilitate the movement of electrons. These active biocatalysts that are present in anode oxidize the organic substrate (fuel) to produce electrons and protons. Thus, anode material appreciably impacts biofilm formation which works as a catalyst and subsequently degrades the substrate anaerobically to release electrons, i.e. an external electrical circuit helps to transfer electron from anode to cathode. At the cathode, the generated protons flow through the permeable exchange membrane and react with oxygen, forming water, and convert chemical energy into electrical energy.

Fig. 14.1 Schematic representation of two chamber MFC. Adapted from Ref. (Flimban et al. 2019)

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Kalathil et al. (2018) clearly explain on the ability of MFC to generate electricity from any biodegradable substrate and describe the reaction kinetics that occurs in MFC by considering acetate (electron donor) and oxygen (terminal electron acceptor) (Kalathil et al. 2018). Anode reaction: CH3 COOH + 2H2 O → 2CO2 + 8e− + 8H+ Cathode reaction: 2O2 + 8e− + 8H+ → 4H2 O Overall: CH3 COOH + 2O2 → 2H2 O + 2CO2 + Biomass + Electricity Transport of Electrons to Electrodes The electrons are transported to electrodes, which takes place through the following modes. A. Direct electron transfer—transfer of electrons without deviation to the electrode surface. B. Direct electron transfer through nanowires—with the assistance of nanowires, electron transfer takes place. C. Electron transfer through mediators—mediators or electron shuttles are used to move electrons from bacteria’s outer membrane to electrodes (Mustakeem 2015). Biochemical cell reactions MFCs transform chemical energy to electrical energy by decomposition of organic molecules, and the resulting emf (electromotive force) that is produced can be calculated as follows: E emf = E cathode −E anode −η The half-cell potentials at cathode, anode, and loss term (loss term deals with Ohmic losses, activation losses, and mass transfer losses) are E cathode , E anode , and the loss term, respectively. The half-cell potential may be computed using the Nernst equation: E halfcell = E 0 −

RT lnQ nF

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where E halfcell is the half-cell reduction potential at the temperature of interest, E 0 is the standard half-cell reduction potential, R is the universal gas constant: R = 8.31446261815324 J K−1 mol−1 , T is the temperature in kelvins, n is the number of electrons transferred in the cell reaction or half-reaction, F is the Faraday constant, the number of coulombs per mole of electrons: F = 96,485.3321233100184 C mol−1 , and Qr is the reaction quotient of the cell reaction [Source: Wikipedia, (Jain 2015)] The Gibbs free energy equation can be used to calculate the amount of energy generated by an electrochemical system: G = −nFEemf The number of electrons is n, the Faraday constant is F, and the standard cell potential is E cell . Using the Gibb’s free energy equation, energy is generated in MFC for a thermodynamically favoured overall reaction (Mustakeem 2015; Jain 2015).

14.2 Anode Materials An anode electrode functions as a solid electron acceptor, and the materials used in an anode electrode must have a number of specialized features to facilitate interaction between the electrochemically active biofilm and the surface of the material. Natural polymers (high molecular weight) are secreted by microorganisms also called extracellular polymeric substances (EPS) which help to create functional and structural stability of biofilm that initiates physiochemical property of a biofilm. Microbes not only cause corrosion, but they can also hinder or protect it, which is referred to as microbiologically influenced corrosion (Rollefson et al. 2011; Choudhury et al. 2017; Angelaalincy et al. 2018). Microbes within MFCs utilize catalysts to transform chemical energy in organic compounds to electrical energy (Chaudhuri and Lovley 2003). Effectiveness of anodic biofilm formation enhances the extracellular electron transfer in absence of mediators. Maximum power density generated by MFC is proportional to the logarithm of the surface area of the anode. MFC research work in recent times (5 years) mainly focuses on increasing anode material performance (Cai et al. 2020). As of reported literature by Santoro et al. (2017), different arrangements of carbon such as carbon brush, carbon cloth, carbon rod, carbon mesh, carbon veil, carbon paper, carbon foam, carbon felt, granular activated carbon, granular graphite, carbonized cardboard, graphite plate, reticulated vitreous carbon, and carbon fibres can be used as an anode material in MFCs, and metal electrodes like stainless steel plate, stainless steel mesh, stainless steel scrubber, silver sheet, nickel sheet, copper sheet, gold sheet, and titanium plate are used in commercial electrodes. For effective electrode performance materials consisting of diverse carbon morphologies like 1D, 2D and 3D structures are being attempted by recent researchers as surface area of anode plays a key role for energy generation purpose in MFC. Anode electrodes with excellent electrical conductivity, corrosion

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Fig. 14.2 Digital photograph of carbon cloth (a), carbon brush (b), carbon rod (c), carbon mesh (d), carbon veil (e), carbon paper (f), carbon felt (g), granular activated carbon (h), granular graphite (i), carbonized cardboard (j), graphite plate (k), reticulated vitreous carbon (l), stainless steel plate (m), stainless steel mesh (n), stainless steel scrubber (o), silver sheet (p), nickel sheet (q), copper sheet (r), gold sheet (s). Images adapted from Ref: (Santoro et al. 2017) Creative Common CC BY licence

resistance, high mechanical strength, and biocompatibility are key requirements for robust MFC operation (Santoro et al. 2017) (Fig. 14.2).

14.3 Cathode Materials In the cathode electrode, proton along with electron and oxygen combines to form water. Most anode material can also be used as a cathode material for electrode, but the following criteria should be acquired; hence, MFC cathode electrodes should have excellent mechanical strength, electronic and ionic conductivity, and catalytic properties, etc. Normally catalyst is required to reduce activation energy barrier to increase rate of redox reaction. Oxygen reduction reaction (ORR) undergoes two pathways to

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form water (four electron pathways) and hydrogen peroxide (two electron pathways) in which, on comparison, the previous case is more favourable. Oxygen reduction reaction is mostly deficient for any simple cathode electrode. To balance this state, it is necessary to coat the cathode surface with active catalyst layer. Generally, platinum is used as a successful catalyst for ORR due to its high surface area and low over potential nature. The high cost factor and occurrence of side reactions of platinum catalyst limit it use for commercial applications. Transition-metal oxide catalyst such as MnO2 , palladium, and lead oxide (PbO2 ) can be considered for suitability in near future for better ORR performance (Mustakeem 2015).

14.4 Membrane Materials An ideal membrane used in MFC influences the performance of MFC system in terms of cost effectiveness by using suitable dense membrane material with high mechanical strength, increased biofouling resistance, high proton conductivity as a result of lower membrane resistance, good segregation properties, stable thermal and chemical properties, electronically resistive, hydrophilic nature of membrane is increased by the use of nanocomposite membrane. This requires homogeneous dispersion of nanoparticle in nanocomposite membrane materials (Tharali et al. 2016; Leong et al. 2013). Common membranes used in MFC are cation exchange membranes are (Nafion, Hyflon, Zirfon, and Ultrex CMI7000), anion exchange membranes (RALEXX AEM), membrane-less MFC and polymer/composite membrane (SPEEK membrane and BPSH membrane), and porous membrane (ceramic coated, glass wool, microfiltration membrane) (Leong et al. 2013).

14.5 Microorganisms Nowadays, suitable waste disposal methods are extremely expensive due to lack of space availability and deleterious odour that occurs with delayed clearance time. On the other hand, this situation can be handled by taking efforts to efficiently utilize the power of microorganisms for decomposing biodegradable waste materials (substrate) to usable products together with energy generation gives us an opportunity to work on MFC technology (Flimban et al. 2019). This might help us to deal with waste disposal as well as clean contaminated soil and water. As explained earlier, different microorganisms have the ability to transmit electrons to the anode produced from the metabolism of biodegradable organic materials. A wide variety of microorganisms are used for energy generation in MFC. According to Du et al. (2007), marine sediment, soil, wastewater, fresh water sediment, and activated sludge are all excellent sources for these microorganisms (Niessen et al. 2006; Zhang et al. 2006). MFC output also depends on the type of microorganism

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used. Initially, Potter (1911) employed Saccharomyces cerevisae and bacteria such as Escherichia coli for energy generation in MFC (Potter and Waller 1911). Geobacter SPP, G. Sulfurreducens, Shewanella oneidensis, Shewanella putrefaciens, Escherichia coli, Gluconobacter oxydans, Geothrix fermentas, Chlorella vugaris, Dunaliealla tertiolecta, Scenedesmus obliquus, Chlorella pyrenoidosa, Corilous versicolor, Agaricus meleagris, Streptococcus lactis, Erwinia dissolven, Lactobacillus plantarum, Paracoccus denitrificans, etc. are different microorganisms that are used in MFC by various studies.

14.6 Substrate In MFC, the substrate concentrations influence MFC performance. A wide range of organic materials can be used as substrate for microbes. The microbes decompose the substrate in the anode chamber to form electron and proton. The substrate being an electron donor plays a very essential role in establishing electricity generation. The electrons transfer from anode to cathode by an external circuit using copper wire connected to both of these electrodes for redox reaction, and at the same time, the protons move to the cathode through membrane. Various organic substrates can be used as potential fuels for MFCs (Ullah and Zeshan 2019). From literature, variety of substrates are being used in MFC ranging from pure compounds to complex mixtures of organic matter which includes compounds like acetate, glucose, cellulose particles (Rezaei et al. 2009), corn stover biomass (Zuo et al. 2006), ethanol (Kim et al. 2007), lactate (Manohar and Mansfeld 2009), landfill leachate (Greenman et al. 2009), phenol (Luo et al. 2009), starch (Niessen et al. 2004), and sucrose (Behera and Ghangrekar 2009). Complex mixtures like brewery wastewater (Feng et al. 2008), paper recycling wastewater (Huang and Logan 2008), swine wastewater (Min et al. 2005), chocolate industry wastewater (Patil et al. 2009), and many more are used (Chhazed et al. 2019).

14.7 Design of MFC The design of a MFC mainly depends on requirement, number of chambers, mode of operation, size and scalability factors, etc. Based on assembly, the MFC types can be classified into single-chamber MFC, dual chamber MFC, and stacked MFC. Basic MFC module construction usually contains single or dual chamber with anode and cathode chamber assembled by using different materials like glass, polycarbonate, as well as plexiglass which are separated by ion porous membranes and filled with variety of substrates and microorganism (Rhoads et al. 2005).

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14.7.1 Single-Chamber MFC The single-chamber MFC involves an anodic chamber coupled with air–cathode where protons are transferred from anolyte to air–cathode in various designs as per functional requirement like rectangular (Park and Zeikus 2003), cylindrical, tubular, flat plate, and concentric modules. The scale up is simple in this single-chamber MFC because air is used as oxygen source and a lesser amount of material utilization with reduced overall cost and higher energy output (Juan 2014; Tharali et al. 2016).

14.7.2 Dual Chamber MFC Dual chamber MFC is commonly used for testing and performing experimental studies in laboratory scale (batch mode and continuous mode). In dual chamber MFC, it consists of two compartments with anode and cathode separated by an ion exchange membrane (Du et al. 2007, Juan 2014). At present, there are also facilities to handle large feed volumes. The regular design of dual chamber MFC usually consists of a simple H-shaped arrangement with a proton-exchange membrane between the anode and cathode, assists proton diffusion, and limits substrate and oxygen crossover (Flimban et al. 2019). The major benefit in dual chamber MFC facilitates effective recovery of nutrients from municipal wastewater (Ye et al. 2019) (Fig. 14.3).

Fig. 14.3 a Schematic of typical single-chamber microbial fuel cell. b Schematic of typical dual chamber microbial fuel cell. Adapted from Ref. (A) (Mustakeem 2015) and (B) (Flimban et al. 2019)

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Fig. 14.4 Schematic representation of the electrical circuit connection in the 6-stacked MFCs. a individual, b in parallel, c in series, and d mixed (parallel series). Adapted from Ref. (VilajeliuPons et al. 2017) Creative Commons Attribution 3.0 Unported Licence

14.7.3 Stacked MFC In stacked MFC arrangement, single MFCs are stacked in series or parallel or together (series-parallel) to enhance energy output. This kind of construction increases the yield of overall system. However, some operational factors may influence and either increase or decrease the overall output performance in this case (Fig. 14.4).

14.8 Types of MFCs 14.8.1 Mediator-Less MFC Mediator-less MFC system does not necessitate any additional mediator in the system for electron transfer from microbes (valid for certain microbes) to the electrode. Few microbes reported in literature like Aeromonas hydrophila, Geobacter metallireducens, Geobacter sulfurreducens, Rhodoferax ferrireducens and Shewanella putrfaciens are used in mediator-less MFCs (Juan 2014).Optimal operational parameters for mediator-less MFCs include neutral pH, lower resistance, and increased rate of aeration (dissolved O2 concentration) in cathode compartment for efficient performance.

14.8.2 Membrane-Less MFC Membrane-less MFC does not involve expensive proton-exchange membranes, and its performance greatly depends on the growth of electrogenic bacteria present.

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Fouling behaviour is not seen in membrane-less MFC as membrane is absent in this case. Important advantages of membrane-less MFCs are high proton transfer rate, reduction of membrane cost, etc. During continuous working of MFC, there is sharp decline in MFC performance because of high oxygen transfer from cathode to the anode and substrate crossover rate (Leong et al. 2013; Tharali et al. 2016).

14.9 Factor Affecting the Performance of MFCs Lot of attention has been given for designing MFC and proper working of its internal components which includes anode and cathode compartments containing respective electrodes, membrane, and operational condition.

14.9.1 Electrode Material The electrode materials must have certain specific characteristics which had been clearly described in the anode and cathode materials section. High surface area electrode materials are highly preferred as it increases the MFC performance considerably (Zhang et al. 2012; Alatraktchi et al. 2014; Kumar et al. 2017). Nowadays, nanomaterials are used in place of the electrode materials to increase surface area which helps to deliver very good performance than the normal electrode. The nanomaterials or catalyst insertion to the electrode increases the electron transfer rates of anode electrode resulting in increased power output.

14.9.2 Membrane (Porous Interface Layer) A membrane surface area is very much important for efficient system output. Membrane fouling can occur during MFC operation due to anolyte diffusion over the membrane to catholyte. In addition to this, catholyte transfer to anolyte will affect the performance of the microorganisms. This concentration polarization on the membrane surface and effect on microorganisms will affect total system electrochemical performance, and it can be clearly observed in the power output.

14.9.3 Operational Condition In MFCs for significant results, the operational parameters like pH, temperature, feed rate, and shear stress should be maintained at optimum conditions. During implementation, it is discovered that the utilization of MFC energy production for

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practical applications at the lab size is considerably low. MFCs typically operate at room temperature, at atmospheric pressure, and at a pH of 7. Rate of feeding is not considered in this review. Lack of feeding, temperature factor, and pH variations affects energy generation during continuous operation so for respective applications, it is beneficial to study, optimize these parameters to improve MFC performance.

14.9.3.1

Effect of pH

Electrochemical / thermodynamic shortcomings usually occur when there is a pH concentration gradient across MFCs anode and cathode chambers influencing MFC performance. Restricted and slow movement of proton via membrane increases the proton concentration in the anolyte of anode chamber that occurs after continuous operation of MFCs for long time duration. So, acidic nature in the anode chamber limits microbe growth (affecting biofilm formation), and for this reason, neutral pH condition should be retained as it favours active growth of microbes (Venkata Mohan et al. 2014). Similarly, the reduction reaction is affected by proton deficiency because the cathode chamber becomes too alkaline (He et al. 2006) and thereby reduces energy generation. To achieve more energy yield from MFCs, it is important to sustain oxygen reduction at the cathode chamber of the system with low operating pH as per Nernst equation. According to studies, a pH range of 6 to 9 is ideal for microbe growth in order to achieve better power output (Kumar et al. 2017).

14.9.3.2

Effect of Temperature

The kinetics of MFC system is influenced by temperature variations as microbial reactions begin to cease at temperatures below 20 °C (Shantaram et al. 2005). This condition greatly affects MFCs performance. Generally, MFCs operate at room temperature (25–30 °C). However, Jafry et al. (2013) state that MFCs show good results in terms of COD reduction and enhanced power density at higher temperatures owing to enhancement in microbe metabolism and membrane permeability (Jafary et al. 2013). As microbial activity is accelerated at slightly elevated temperatures (30–37 °C), chemical and biological reaction takes place in MFC efficiently. Increase in temperature is directly proportional to increased microbial activity thereby enhanced power output. This accelerates initial formation of biofilm at the anode surface and advance MFC operation (Phung et al. 2004; Kumar et al. 2017). After stable biofilm formation at the anode, if little temperature variations occur, the microbes can accordingly regulate their metabolism (Liu et al. 2005).

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14.10 Energy Harvesting Technologies Energy produced from MFCs is comparatively very low in nature. Furthermore, it cannot be used as such in electronic devices because MFCs are low power systems with thermodynamic limitation. So, researcher in this regard needs to review energy harvesting strategies by shaping it to a usable form and move towards energy harvesting in MFCs with help of fundamental understanding of basic concept, knowledge of flow patterns, power electronics, circuitry, and programming, etc. (Wang et al. 2015). As mentioned early, MFCs produce very low energy, and this generated energy on the other hand is not adequate for practical applications. In MFCs energy harvesting technique at optimal conditions, energy output generated is consumed by electronic devices and executed through power management system (PMS). PMS circuit comprises of capacitor-based systems, charge pump-based systems, boost converter-based systems (Wang et al. 2015).

14.10.1 Capacitor-Based Systems A capacitor consists of two conducting electrodes separated by a dielectric which helps to store energy, and it can be retrieved later without energy loss. Average power generated by a capacitor in MFCs (Pavg ) and its energy storage calculation is clearly mentioned below. A capacitor is charged from discharged voltage V d (V), to charged voltage V c (V), with capacitance C (F), and then amount of energy W (J), stored in the capacitor is calculated using equation given below. W =

 1  2 C Vc − Vd2 2

Considering a single charging cycle in MFCs, the average power (Pavg ) generation is calculated by dividing the total stored energy W, in the capacitor by the time taken for charging using equation given below. Pavg

  W 1 C Vc2 − Vd2 = = tc − td 2 tc − td

where charging time (tc − td ) stands for the difference in charging time (tc ) and discharging time (t d ) of the capacitor. Maximum power density is calculated by dividing the total power generated (PTotal ) by the anode surface area, A (m2 ) (Dewan et al. 2009; Dewan et al. 2010; Wang et al. 2015). When scaling up from lab experiments, it is clear that the maximum power density is related to the logarithm of the anode surface area. In MFCs, rate of microbial reaction limits power generation as this influence conversion of chemical energy into electrical energy. There are two modes of energy

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harvesting, namely continuous energy harvesting and intermittent energy harvesting. In continuous mode (low power consuming devices), there is continuous passing of current through electrical load, and in case of intermittent energy harvesting (high power consuming devices), energy is first stored in capacitor and then discharged through the electrical load. It is more efficient and beneficial to harvest energy intermittently since the maximum power generated is very much higher compared to the energy harvested by continuous mode (Dewan et al. 2009).

14.10.2 Charge Pump-Based Systems MFC technology utilizes biodegradable materials to harvest electricity where energy production has been verified using charge pumps which are low-cost devices having simple circuit topologies. The charge pump is a DC/DC converter (inductor-less) that functions to either step up or down the voltage using capacitor to store energy and its transfer. A typical operating voltage supply of 3.3 V is required by most of the electronic devices but charge pump based systems can raise the voltage from 0.3 V to around 1.8–2.4 V. This voltage produced from charge pump is comparatively low; therefore, charged capacitors can be connected in different combinations (series/parallel) to achieve desired voltage levels for different applications as per load requirement.

14.10.3 Boost Converter-Based Systems In MFC research, energy harvesting using a boost converter system is required to improve the voltage of an MFC to the voltage level of the load since a charge pumpbased system cannot increase the cell voltage to operating voltage of 3.3 V. Power management system composed of a direct current (DC/DC) boost converter is devised as it is vital to boost the output voltage to a higher value where commercially usable voltage can be delivered to operate regular electronic devices. Both semiconductors (diodes and transistors) and energy storage components (capacitors and inductors) are used in the boost converter circuit, that has a more extensive design. Proper optimization can help in increasing MFC performance in terms of energy.

14.11 Mathematical Modelling In MFC during optimization, the combinations of factors occurring in the system in terms of electrochemical, physical, and biological aspects should also be considered and taken into account. Mathematical models are developed using reaction kinetics, nature of microbial growth, mass balance of components, and charge generation.

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During modelling, the reaction area needs to be considered in case of continuous flow MFC modules. Commercial modelling and simulation software tools are available for fuel cell purpose. However, the same procedure is not applicable for MFC function. For accurate and reliable results, researches need to adapt the following techniques. In 1942, an empirical model proposed by Monod introduced the concept of growth limiting substrate. In recent studies, mathematical modelling using Monod-type equations (Oliveira et al. 2013) describes the substrate consumption for growth of microorganisms, and in the same way, the rates of the processes that take place in MFC are estimated using a mix of the electrochemical kinetics equation (Battler–Volmer) and Monod-type equations. (Zeng et al. 2010; Sirinutsomboon 2014). Vasilenko et al. (2020) presented that both model and experimental data correspond the results of component concentration distribution estimates over the thickness of the active layer and over time. Also, he explains that the models account for component concentration dynamics in different areas of the MFC as a consequence of diffusion, migration, consumption, and generation as a result of reactions, among other things (Vasilenko et al. 2020).

14.12 Application Biodegradable waste and sewage are utilized to create electricity using MFC technology. In the meanwhile, it can facilitate wastewater treatment and bioremediation. Similarly in lab scale, MFC also finds application in water softening, heavy metal recovery, dye decolouration, biosensing, remote sensing, robotics, biosensors, BOD monitoring, chemical toxicants monitoring, and hydrogen production.

14.12.1 Electricity Generation Microbial fuel cells are used to supply energy for low power devices and its performance is often measured in terms of power output. This power output is calculated using polarization curves which follows a basic kinetic law for any electrochemical reaction. The polarization curve shows the voltage output for a given current density loading which are typically attained with a potentiostat/galvanostat electrochemical testing system where data acquired for the anode, cathode, or MFC as a whole. As current demand increases, polarization curve shows how well MFCs maintains its voltage. Maximum voltage observed at zero current intensity signifies open-circuit voltage (OCV). On extracting continuous constant current from the system, the MFC voltage drops down to zero and finally stops current draw out (Uría Moltó 2012). For any traditional fuel cells or MFCs, the power density curve also referred to as power curve is very much helpful for determining the point of maximum power transfer (Fig. 14.5).

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Fig. 14.5 Representation of different characteristics regions of a polarization curve, also called IV curve. Adapted from Ref. (Uría Moltó 2012)

MFC Overpotentials: In the MFC system, the electron donor must have a redox potential lower than electron acceptor for spontaneous redox reaction to occur. System energy generated is difference in electrode potentials. In anode, potential is determined by respiratory enzymes of the bacteria, and in cathode, potential is determined by catholyte and oxygen. While in realistic occurrence, the actual output voltage of MFC is less than expected thermodynamic ideal voltage because of irreversible losses that arise as overpotentials which is described earlier. Overpotential is influenced by the physical components of MFC which include anode, cathode, and membrane plus other parameters involved in MFC operation and design (Uría Moltó 2012) (Fig. 14.6). Microcomputer powered using MFC: From literature (Walter et al. 2020), a brief example displays self-stratifying membrane-less MFC modules (S-MFCs) with an irregular feeding rate of 1.8 L urine that is pumped once every 3 h to a single MFC module. Total displacement volume of 6.9 L is observed for each module with hydraulic retention time of ~ 11.5 h. According to Walter et al. (2020), the microcomputer Game Boy Color (GBC) may be powered instantly and continually by MFCs without the use of any power management equipment. Minimum power requirement for microcomputer using MFC cascade is given. But a lot of effort is needed to calibrate this application for specific needs as per requirement (Table 14.1). The MFC system can power a microcomputer directly and continuously while scaling up for end-user applications. There is a great need to explore and investigate the system stability and PMS circuits while used for extensive constant operation (Fig. 14.7).

14.12.2 Wastewater Treatment MFCs used in wastewater treatment can be simultaneously utilized for energy harvesting in a competent approach. Thus, MFC for wastewater management facilitates removal of organic pollutants and energy recovery at the same time. MFCs might potentially be used to evaluate how much biodegradable material is remaining

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Fig. 14.6 Potentials of different oxidation/reduction process occurring in the anode and cathode. Adapted from Ref. (Uría Moltó 2012)

Table 14.1 Stacked MFC performance for microcomputer

Module (MFC cascade)

Voltage (V)

Ampere (mA)

Power (mW)

3

~ 1.832

~ 82

150

4

~ 2.55

~ 61

130

Fig. 14.7 a Picture of the four modules directly powering a GBC. b Electrical output of the system comprising a single cascade of four S-MFC modules directly connected to a Game Boy Color. All four modules were electrically connected in series. Current is the amount drawn by the GBC, while the voltage is the measured value of each module and of the cascade. The power was calculated using the drawn current and the cascade voltage. * stands for the interruption during which a cascade comprising only the three first modules was connected to the GBC. Adapted from Ref. (Walter et al. 2020)

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in wastewater streams. Such activities might be accomplished by MFC-based self-powered devices.

14.13 Summary MFC technology gained popularity due to both energy generating ability and waste treatment efficiency. Advantages in terms of MFC operation are ability to self-regenerate microorganisms and strong resistance to environmental stress with reduced sludge disposal, low carbon footprint, etc. Economically, it helps microorganisms connected to electrodes break down wastes and toxic substances during energy recovery and beneficial nutritional by-products. Energy generation generally takes place due to presence of microbial activity. MFC system mostly depends on living biocatalysts. Work on scaling up MFC system from 1 to 1000 L on lab scale to pilot plant investigations is being carried out. During MFC operation while handling large feed volumes, scale up studies put forward challenges and limitations on various MFC components. A greater emphasis on gaining a deeper knowledge of the microbial processes in the MFC system is very much needed as in real-word practical application, there are lot of complication to overcome while designing MFC modules from laboratory to pilot scale and beyond.

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