Zero-Carbon Energy Kyoto 2010: Proceedings of the Second International Symposium of Global COE Program “Energy Science in the Age of Global Warming—Toward CO2 Zero-emission Energy System” [1 ed.] 4431539093, 9784431539094

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Green Energy and Technology

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Takeshi Yao Editor

Zero-Carbon Energy Kyoto 2010 Proceedings of the Second International Symposium of Global COE Program “Energy Science in the Age of Global Warming—Toward CO2 Zero-emission Energy System”

Editor Takeshi Yao Program Leader Professor of the Graduate School of Energy Science Kyoto University Steering Committee of GCOE Unit for Energy Science Education Yoshida-honmachi, Sakyo-ku Kyoto 606-8501, Japan [email protected]

ISSN 1865-3529 e-ISSN 1865-3537 ISBN 978-4-431-53909-4 e-ISBN 978-4-431-53910-0 DOI 10.1007/978-4-431-53910-0 Springer Tokyo Berlin Heidelberg New York Library of Congress Control Number: 2011920681 © Springer 2011 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. The use of general descriptive na mes, registered names, trademarks, 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. Cover design: WMXDesign, Heidelberg, Germany Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com)

Preface

Since 2008, four departments of Kyoto University, Japan—the Graduate School of Energy Science, the Institute of Advanced Energy, the Department of Nuclear Engineering, and the Research Reactor Institute—along with the Institute of Economic Research have been engaged in a Global Center of Excellence (COE) Program entitled “Energy Science in the Age of Global Warming—Toward a CO2 Zero-emission Energy System”. (Here, we have abbreviated all greenhouse gases including carbon dioxide to “CO2.”) This Global COE Program is being carried out under the auspices of the Ministry of Education, Culture, Sports, Science and Technology of Japan with the support of Kyoto University. The aim is to establish an international education and research platform to foster educators, researchers, and policymakers who can develop technologies and propose policies for establishing a scenario toward a CO2 zero-emission society no longer dependent on fossil fuels by the year 2100. Last year, the Global COE held its First International Symposium, Zero-Carbon Energy, Kyoto 2009, at the Kyoto University Clock Tower and published the proceedings in a book by the same title. This year, the Second International Symposium of the Global COE was held at Kyoto University’s Oubaku Plaza. The many excellent lectures and discussions by invited speakers and members of the Global COE and the interesting presentations by students of the GCOE Unit for Energy Science Education reflect the progress achieved by the program. This book is a compilation of those lectures and presentations. As part of the further agenda of the Global COE, the Scenario Planning Group is setting out a CO2 zero-emission technology roadmap and drawing up a CO2 zero-emission scenario based on analyses of social values and human behavior. The Advanced Research Cluster is promoting a socioeconomic study of energy, a study of new technologies for renewable energies, and research on advanced nuclear energy by following the roadmap established by the Scenario Planning Group. At the GCOE Unit for Energy Science Education, students are planning and conducting interdisciplinary group research of their own, combining social and human sciences with natural science and working toward CO2 zero emission. By participating in the scenario planning and through interaction with researchers from other fields, students will acquire the ability to survey the whole energy system and to apply the experience to their own research. The Global COE is striving to foster v

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young researchers who will be able to employ their skills and knowledge with a broad international perspective and expertise in their field of study in order to respond to the needs of society in terms of various energy and environmental problems. The Global COE is publicly promoting the achievements of the platform by making information available on the website of the Global COE; by publishing annual reports, quarterly newsletters, books, and self-inspection and -evaluation reports; by hosting domestic and international symposia and activity report meetings; by hosting the industry–government–academia collaborative symposia and citizen lectures; and by co-hosting related meetings both domestically and internationally. For securing energy and conservation of the environment, which are the most important issues for the sustainable development of human beings, the Global COE continues to take action for the establishment of “low-carbon energy science” as an interdisciplinary field integrating social science and human science with the natural sciences. Takeshi Yao Program Leader Global COE “Energy Science in the Age of Global Warming –– Toward a CO2 Zero-emission Energy System”

Contents

Part I Scenario Planning and Socio-economic Energy Research (i)

Invited Paper

Singapore’s Perspective on Energy and Future Cities................................. Seeram Ramakrishna (ii)

Contributed Papers

Long-Term Scenario Analysis of a Future Zero-Carbon Electricity Generation System in Japan Based on an Integrated Model ...................... Qi Zhang, Benjamin Mclellan, Nuki Agya Utama, Tetsuo Tezuka, and Keiichi N. Ishihara Evaluation of Carbon Dioxide Absorption by Forest in Japan .................. Yoshiyuki Watanabe, Satoshi Konishi, Keiichi Ishihara, and Tetsuo Tezuka 2050 ASEAN Electricity Demand: Case Study in Indonesia and Cambodia ................................................................................................. Nuki Agya Utama, Keiichi N. Ishihara, Qi Zhang, and Tetsuo Tezuka (iii)

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Session Papers

Proposal of a Method for Promotion of Pro Environmental Behavior with Loose Social Network ............................................................ Saizo Aoyagi, Tomoaki Okamura, Hirotake Ishii, and Hiroshi Shimoda

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Performance Analysis Between Well-Being, Energy and Environmental Indicators Using Data Envelopment Analysis.................... Jordi Cravioto, Eiji Yamasue, Hideki Okumura, and Keiichi N. Ishihara

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Municipal Solid Waste Management with Citizen Participation: An Alternative Solution to Waste Problems in Jakarta, Indonesia .......................................................................................................... Aretha Aprilia, Tetsuo Tezuka, and Gert Spaargaren The Influence of the Electrification in Erdos Grassland in Inner Mongolia, China ............................................................................... Wuyunga and Tetsuo Tezuka

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Part II Renewable Energy Research and CO2 Reduction Research (i)

Invited Papers

The Potential of Biodiesel with Improved Properties to an Alternative Energy Mix......................................................................... Gerhard Knothe

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Net Energy Calculations for Production of Biodiesel and Biogas from Haematococcus pluvialis and Nannochloropsis sp. ............................. Luis F. Razon

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(ii)

Contributed Papers

Characterization of Oligosaccharides with MALDI-TOF/MS Derived from Japanese Beech Cellulose as Treated by Hot-Compressed Water ............................................................................. Kazuchika Yamauchi and Shiro Saka

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Microwave/Infrared-Laser Processing of Material for Solar Energy ........ 100 Taro Sonobe, Kyohei Yoshida, Kan Hachiya, Toshiteru Kii, and Hideaki Ohgaki (iii)

Session Papers

Pongamia pinnata as Potential Biodiesel Feedstock ..................................... 111 Fadjar Goembira and Shiro Saka Construction of a Novel Strictly NADPH-Dependent Pichia stipitis Xylose Reductase by Site-Directed Mutagenesis for Effective Bioethanol Production .................................................................................... 117 Sadat Mohammad Rezq Khattab, Seiya Watanabe, Masayuki Saimura, Magdi Mohamed Afifi, Abdel-Nasser Ahmad Zohri, Usama Mohamed Abdul-Raouf, and Tsutomu Kodaki

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Evaluation of Different Methods to Determine Monosaccharides in Biomass ........................................................................................................ 123 Harifara Rabemanolontsoa, Sumiko Ayada, and Shiro Saka Pyrolysis and Secondary Reaction Mechanisms of Softwood and Hardwood Lignins at the Molecular Level............................................ 129 Mohd Asmadi, Haruo Kawamoto, and Shiro Saka Fractionation of Japanese Cedar and Its Characterization as Treated by Supercritical Water ................................................................. 136 Mahendra Varman and Shiro Saka Two-Step Hydrolysis of Japanese Cedar as Treated by Semi-Flow Hot-Compressed Water with Acetic Acid ............................ 142 Natthanon Phaiboonsilpa and Shiro Saka Liquefaction Behaviors of Japanese Beech as Treated in Subcritical Phenol ....................................................................................... 147 Gaurav Mishra and Shiro Saka Glycerol to Value-Added Glycerol Carbonate in the Two-Step Non-Catalytic Supercritical Dimethyl Carbonate Method ......................... 153 Zul Ilham and Shiro Saka Prospect of Nipa Sap for Bioethanol Production ......................................... 159 Pramila Tamunaidu, Takahito Kakihira, Hitoshi Miyasaka, and Shiro Saka Dissolution of Cerium Oxide in Sulfuric Acid.............................................. 165 Namil Um, Masao Miyake, and Tetsuji Hirato Utilization of Magnetic Field for Photocatalytic Decomposition of Organic Dye with ZnO Powders................................................................ 171 Supawan Joonwichien, Eiji Yamasue, Hideyuki Okumura, and Keiichi N. Ishihara Hybrid Offshore Wind and Tidal Turbine Power System to Compensate for Fluctuation (HOTCF)..................................................... 177 Mohammad Lutfur Rahman, Shunsuke Oka, and Yasuyuki Shirai Beam Stabilization by Using BPM in KU-FEL ............................................ 187 Yong-Woon Choi, Heishun Zen, Keiichi Ishida, Naoki Kimura, Satoshi Ueda, Kyohei Yoshida, Masato Takasaki, Ryota Kinjo, Mahmoud Bakr, Taro Sonobe, Kai Masuda, Toshiteru Kii, and Hideaki Ohgaki

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Analysis of Transient Response of RF Gun Cavity Due to Back-Bombardment Effect in KU-FEL.................................................... 193 Mahmoud Bakr, Heishun Zen, Kyohei Yoshida, Satoshi Ueda, Masato Takasaki, Keiichi Ishida, Naoki Kimura, Ryota Kinjo, Yong-Woon Choi, Taro Sonobe, Toshiteru Kii, Kai Masuda, and Hideaki Ohgaki Part III (i)

Advanced Nuclear Energy Research

Contributed Papers

Nuclear Characteristics Transition Depend on the Position of External Source on the Accelerator-Driven System Using KUCA and FFAG Accelerator ....................................................................... 205 Jae-Yong Lim, Cheolho Pyeon, Tsuyoshi Misawa, and Ken Nakajima High Performance Computing of MHD Turbulent Flows with High-Pr Heat Transfer ........................................................................... 214 Yoshinobu Yamamoto and Tomoaki Kunugi (ii)

Session Papers

Comparison Between Microbubble Drag Reduction and Viscoelastic Drag Reduction .......................................................................... 225 Li-Fang Jiao, Tomoaki Kunugi, and Feng-Chen Li Numerical Study on Bubble Growth Process in Subcooled Pool Boiling ...................................................................................................... 233 Yasuo Ose and Tomoaki Kunugi Towards Gyrokinetic Simulations of Multi-Scale Micro-Turbulence in Tokamaks: Simulation Code Development .............. 239 Paul P. Hilscher, Kenji Imadera, Jiquan Li, and Yasuaki Kishimoto Study of a Particle Confinement in Helical Type Reactor by GNET Code ................................................................................................ 245 Yoshitada Masaoka and Sadayoshi Murakami Study of the Mechanisms Leading to the Nonlinear Explosive Growth of Double Tearing Instabilities in Fusion Plasmas ......................... 252 Miho Janvier, Yasuaki Kishimoto, and Jiquan Li Remote Collaboration System Based on the Monitoring of Large Scale Simulation “SIMON”: A New Approach Enhancing Collaboration ............................................................................... 258 Akihiro Sugahara and Yasuaki Kishimoto

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Target Design of High Heat and Particle Load Test Equipment for Development of Divertor Component ..................................................... 264 Do-Hyoung Kim, Kazuyuki Noborio, Yasushi Yamamoto, and Satoshi Konishi Experimental Investigation on Contact Angles of Molten Lead–Lithium on Silicon Carbide Surface ................................................... 271 Yoshitaka Ueki, Tomoaki Kunugi, Keiichi Nagai, Masaru Hirabayashi, Kuniaki Ara, Yukihiro Yonemoto, and Tatsuya Hinoki Comparison of Operation Characteristic in Radiation Detectors Made of InSb Crystals Grown by Various Methods .................................... 278 Yuki Sato, Tomoyuki Harai, and Ikuo Kanno Specimen Size Effects on Fracture Toughness of F82H Steel for Fusion Blanket Structural Material ........................................................ 286 Byung Jun Kim, Ryuta Kasada, Akihiko Kimura, and Hiroyasu Tanigawa Tensile Behavior of Transient Liquid Phase Bonded ODS Ferritic Steel Joint ........................................................................................... 292 Sanghoon Noh, Ryuta Kasada, and Akihiko Kimura Helium Ion Irradiation Effects in ODS and Non-ODS Ferritic Steels ................................................................................................... 300 Ryuta Kasada, Hiromasa Takahashi, Kentaro Yutani, Hirotatsu Kishimoto, and Akihiko Kimura Thermal Conductivity of SiCf /SiC Composites at Elevated Temperature .................................................................................................... 306 Youngju Lee, Yihyun Park, and Tatsuya Hinoki Development of the Crack Detection Technique for NITE SiC/SiC Composite Applied to Fusion Blanket ............................................ 311 Kazuoki Toyoshima, Tomoaki Hino, and Tatsuya Hinoki Author Index.................................................................................................... 317 Keyword Index ................................................................................................ 319

Part I Scenario Planning and Socio-economic Energy Research

Singapore’s Perspective on Energy and Future Cities Seeram Ramakrishna

Abstract With physical constraints of land size and with no natural energy resources, Singapore has to harness the human and intellectual capital of the nation to have sustainable economic growth in an urban setting. Many cities of the future have similar constraints like Singapore. With UN estimating that about 60% of the world’s population is expected to be living in urban cities by 2030, we have to develop new energy models urgently. Singapore had taken a whole-of-government approach that engaged the global, regional and local talent, industries, academicians and the citizens to develop long term strategic plans to address the challenges of energy sustainability in a holistic manner. The strategic objective is to build a distinctive global city which is liveable and lively into the future. Singapore has no natural energy resources of coal, oil gas, hydro, geothermal and biomass power. The prevailing wind speed is not high enough to be tapped with the current technology. The tidal wave is not strong enough to be tapped. Singapore has limited options and is highly dependent on fossil-based energy source. Between fuel oil and natural gas, it has gradually move to natural gas as it emits 40% less CO2 than fuel oil. The other energy options are to increase waste to energy, consider option of biofuels, promote solar energy and studying the feasibility and option of nuclear power. Enhancing energy efficiencies in all sectors of electricity generation, industries, transportation and housing are key strategies to reduce carbon footprint of future city. Increasing electrification of urban mobility and increasing connectivity in the various transportation of walking, cycling, cars, buses and trains will make city travel more energy efficient. For the built environment, zero-energy building and green building certification will encourage the use of more climate-neutral energy sources. With the strategic location that Singapore is just 1° north of the equator, solar energy is expected to provide 10–15% of the primary energy source for Singapore. Keywords Climate฀change฀•฀CO2฀emissions฀•฀Energy฀•฀Future฀cities

S. Ramakrishna (*) Office of Deputy President (Research and Technology), National University of Singapore, 21 Lower Kent Ridge Road, Singapore 119077, Singapore e-mail: [email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_1, © Springer 2011

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Introduction

Rapid economic development, urbanization and consumerism have led to soaring demand for energy. The global energy crisis is at the forefront of current events. According to the United Nations, 60% of the earth’s population (4.9 billion people) will live in cities by 2030. The number of megacities, which metropolises with a population of more than ten million, will increase from 22 today to 26 by 2015. There are more than 300 cities with over a million inhabitants. Today, about half of the world’s population lives in cities. Cities consume about 75% of the world’s energy. They emit 80% of the world’s green-house gases. The urban population is expected to increase. As such, if urbanization continues on the same scale, there will be an increasing demand by city dwellers to access to energy, water, mobility and efficient, affordable healthcare (Fig. 1). City planners and developers will need to rapidly scale up their urban infrastructure to provide for the city dwellers, who will need good access to energy, water, mobility and affordable housing. Cities, by virtue of their high human density and economic growth, are the hotspots of climate-changing practices such as high energy consumption, pollution and deforestation.

Fig. 1 Urban and rural population of the world, 1950–2050. Source: World Urbanization Prospects, The 2009 Revision

Singapore’s Perspective on Energy and Future Cities

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Singapore

Singapore is a small city, densely populated, with few natural resources and an open economy. Global problems, from the financial crisis to the threat of climate change, cast a large shadow on our small island nation. We are a city-state of 5.08 million people1 on a small island with no natural hinterland. We import much of what we consume. All the elements of a functioning state – our homes and offices, factories and power plants, roads, reservoirs, airports – have to be located within the 700 km2. At the same time, we need to ensure that our people have a clean, green and comfortable environment to live in. Singapore’s overall goal is to grow in an efficient, clean and green way. The strategic objective is to build a distinctive global city which is liveable and lively into the future. Singapore’s economy had grown from labour intensive to knowledge and innovation intensive economy in less than 50 years. Like most countries that do not have natural energy resources, the key challenges are sustainable economic growth and safeguarding our energy security and natural environment (Fig. 2).

Fig. 2 Singapore economic development journey. Source: Singapore Department of Statistics 1 Statistics Singapore www.singstat.gov.sg Singapore’s total population was 5.08 million as at end June 2010. There are 3.77 million residents, of which 3.23 million were Singapore citizens and 0.54 million were permanent residents.

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Fig. 3 Drivers for change

With Singapore physical constraint of land size and with no natural energy resources of coal, oil, gas, hydro, wind, tidal, geothermal and biomass power and the need to mitigate climate change, Singapore is driven to find new ways for sustained economic growth while safeguarding our energy security and natural environment (Fig. 3). Under the leadership of the Prime Minister, the country took a whole-of-government approach and appointed international advisory panels of top minds, form interministerial committees, engaged the academics and industrials in local panels and using web-based platform to engage the public in consultation and feedback to tackle the challenges. The four key areas of focus include: look at all available energy options, for short term will increase fuel mix to use more natural gas, built more waste incineration plants for electricity generation, deploy more solar panel applications, work on biofuels and undertake feasibility of nuclear option. Energy Efficiencies are immediate actions can be taken for all sectors. Increase electrification of urban mobility. And use more climate-neutral energy sources for built environment. Climate change and energy issues are complex and cut across different sectors and industries, and involve policies from different ministries and agencies. The Energy Policy Group (EPG) was set up in 2006 with four working groups on Economic Competitiveness, Energy Security, Climate Change and the Environment, and Energy Industry Development, headed by the different agencies as shown in Fig. 4. The clean energy movement in Singapore gained momentum in 2007, when Prime Minister Lee Hsien Loong announced that Singapore will be developing the clean energy industry as a key growth area, generating a potential $1.7 billion in revenue and 7,000 jobs by 2015 [1]. The National Energy Policy Report developed by the Ministry of Trade and Industry (MTI) and released in November 2007 outlines six strategies for Singapore

Singapore’s Perspective on Energy and Future Cities

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Fig. 4 Energy Policy Group

to strengthen its economic competitiveness, enhance energy security and improve environmental sustainability [2]. The six key strategies are: 1. 2. 3. 4. 5. 6.

Promote Competitive Markets Diversify Energy Supplies Improve Energy Efficiency Build Energy Industry and Invest in Energy R&D Step Up International Development Develop Whole-of-Government Approach

In April 2009, the Singapore Government unveiled an S$1 billion (US$730 billion) Sustainable Development Blueprint which contains strategies and initiatives developed towards achieving both economic growth and a good living environment for Singapore over the next two decades [3]. The blueprint is based on a four-pronged strategy: boosting our resource efficiency, enhancing our urban environment, building our capabilities, and fostering community action. Some of the aggressive targets set include: 1. To achieve a 35% reduction in energy intensity (consumption per dollar GDP from 2005 levels by 2030. 2. To raise overall recycling rate to 70% by 2030. 3. To improve air quality by reducing ambient PM 2.5 (fine particles) levels to an annual mean of 12 mg/m3 by 2020, and maintain the same levels up to 2030. 4. To build Singapore into an international knowledge hub in sustainable development solutions. 5. To achieve a community in Singapore where environmental responsibility is a part of our people and business culture.

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The government has taken actions to catalyze collaborative innovation. For instance, to encourage energy-efficient building technologies, the Building and Construction Authority (BCA) has set aside a $5 million fund to encourage local developers to partner experts worldwide to develop prototype building designs that can achieve at least 50% improvement in energy efficiency [4]. Besides new buildings, the Government has also established a $100 million fund to help building owners upgrade and improve the energy performance of their existing buildings. At the same time, the Housing and Development Board (HDB) has embarked on the largest solar test-bed in Singapore to understand and adapt solar technology to our local conditions. Through the Housing Development Board public housing programme implemented over the last 50 years, over 80% of Singaporeans live in 900,000 HDB flats across the island, with 95% of them owning their homes. As the largest housing developer in Singapore, HDB plays a key role in spearheading sustainable development practices. In Singapore, we have a Green Mark Scheme under the BCA. This is a green building rating system, promoting and adoption of green building design and technologies. Under this scheme, buildings are assessed on factors including energy and water efficiency, indoor environmental quality and environmental protection. We have set a target of at least 80% of buildings in Singapore should attain Green Mark certification by 2030.2 NUS has achieved the Green Mark awards for its University Town, University Town’s Education Resource Centre, the Mochtar Riady Building at the NUS Business School and the T-Lab. The Singapore Government is taking the lead in embracing the green mark standards for all public sector buildings. For its part, the HDB is aiming for the Green Mark Platinum standard, the highest green mark rating, for some important public housing projects. HDB is also developing its first Eco-Precinct, named the Treelodge@Punggol. Punggol is a coastal town located at Singapore’s northeast.3 With its eco-friendly features that capitalize on nature and the use of green technologies, the precinct will create a green living environment and raise popular awareness of environment sustainability. Punggol will serve as a ‘living laboratory’ to test new ideas and technologies in sustainable development, integrating urban solutions to create a green living environment. R&D studies will be conducted to address the diverse expectations and changing aspirations of residents. Urban solutions in the areas of energy, waste and water management will be explored. Eventually, HDB hopes to lower the implementation cost of these solutions and to replicate them across other towns.

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Economic Development Board (EDB). Housing and Development Board (HDB).

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Going forward, Singapore seeks to serve as a “Living Laboratory” where new ideas and technologies in sustainable development can be tested (Fig. 5). It invites companies to partner our government agencies, local companies and research institutes for a diversity of R&D activities. Singapore will be a “Living Laboratory” to test new concepts, develop and commercialize cutting-edge urban solutions, capitalizing on Singapore’s experience in systems-level integration across six focus areas (See footnote 2) (Fig. 6). One key area is in promoting of energy efficiency. Energy efficiency reduces the carbon footprint in our city and also saves costs for businesses and consumers.

Fig. 5 Singapore as a Living Laboratory

Fig. 6 Urban solutions focus areas

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In addition, Singapore forms global partnerships with other countries to develop innovative prototypes for the sustainable cities of tomorrow. One good example is the Tianjin Eco-city in China [5]. The Governments of Singapore and China are jointly developing the 30 km2 city into an environmentally friendly, socially harmonious and resource efficient city. This project involves putting in place key infrastructure to support sustainable development, such as a light-rail transit line to link the Eco-city to Tianjin City and surrounding districts, a pneumatic waste collection system, a new wastewater treatment plant, and major rehabilitation works for existing water bodies. In July 2010, a ground-breaking ceremony was held at Jurong Island where Singapore will build the world largest Experimental Power Grid of 1 MW [6]. This S$38 million (US$27.5 million) facility will be ready by second half of 2011. This Experimental Power Grid Centre (EPGC) will perform research on “intelligent grids” and distributed energy resources. This power grid will allow power from solar, fuel cells, and electric/hybrid vehicles to feed energy back into the system. NUS performs high-quality research over a broad range of disciplinary and crossdisciplinary areas. It has a wide energy and environment cluster as shown below (Fig. 7). The Solar Energy Research Institute of Singapore (SERIS) is Singapore’s national institute for applied solar energy research, jointly set up by NUS and the Economic Development Board (EDB). It performs quality research and work closely with the industry in solar photovoltaic devices as well as innovative materials for solar and energy-efficient buildings. It has a research funding of S$130 million over 5 years. The Energy Studies Institute (ESI) is established by the Singapore Government and hosted by NUS. As Southeast Asia’s first think-tank on energy issues, ESI play an important role in the development of energy policies in the region on three key areas – Energy Economics, Energy Security, and Energy and the Environment. The NUS Global Asia Institute (GAI) is an initiative of NUS President Tan Chorh Chuan on research and scholarship directed at topics pivotal to Asia’s future. The institute will bring together existing expertise from NUS and other universities, particularly those with expertise in India and China, in its quest for solutions that will solve the critical issues within Asia [6]. In the area of nuclear energy, subject to the Singapore Government’s support, NUS is prepared to undertake the following high impact research in areas such as: 1. 2. 3. 4. 5. 6. 7.

Nuclear Forensics and Detection Radio Chemistry and Nuclear Defense Reactor Engineering Nuclear Medicine Material Sciences Environmental Sciences Life Sciences

Singapore’s Perspective on Energy and Future Cities

Fig. 7 NUS energy and environment cluster (color figure online)

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Conclusion

Cities today face many similar challenges arising from pressures such as urbanization, climate change, and energy constraints. No one city is able to solve all the problems it faces. Only by collaborating with one another through sharing of ideas and expertise, cities of the world can learn from one another as they grow and develop sustainably.

References 1. The Straits Times, 27 March 2007 “S’pore aims to be key player in green energy push” 2. Ministry of Trade and Industry (MTI). http://www.mti.gov.sg/. Accessed 13 Sept 2010 3. Ministry of the Environment and Water Resources (MEWR). http://app.mewr.gov.sg/. Accessed 13 Sept 2010 4. Building and Construction Authority (BCA). http://www.bca.gov.sg/. Accessed 13 Sept 2010 5. Sino-Singapore Tianjin Eco-city. http://www.tianjinecocity.gov.sg/. Accessed 13 Sept 2010 6. The Straits Times, 17 July 2010 “Power grids of the future” – The world’s largest experimental energy grid, and the first in South-east Asia, is being developed on Jurong Island

Long-Term Scenario Analysis of a Future Zero-Carbon Electricity Generation System in Japan Based on an Integrated Model Qi Zhang, Benjamin Mclellan, Nuki Agya Utama, Tetsuo Tezuka, and Keiichi N. Ishihara

Abstract The realization of a zero-carbon electricity system is of vital importance to a future zero-carbon energy system and society. Nuclear power and renewable energy are expected to contribute significantly to this in the future in Japan. Therefore, in the present study, their roles in future zero-carbon electricity system was examined using long-term scenario analysis from 2005 to 2100 based on an integrated analysis model. The analysis is conducted in three steps to (1) estimate electricity demand and load pattern based on lifestyle and industrial structure in the future using a bottom-up simulation sub-model; (2) plan the optimized power generation mix to satisfied obtained electrical demand and load subject to various constraints including natural resources, economic, environmental, geographic, natural conditions, etc. using an optimization sub-model (3) confirm the reliability of the obtained best mix power generation system by using an hour by hour simulation sub-model. The results give the schedule of nuclear and renewable energy development from 2005 to 2100 and show that they will contribute 60% and 40% respectively in terms of electricity production by 2100. Finally, the whole system is proven as technically feasible with the help of EV (Electric Vehicle) batteries and hydrogen for daily and seasonal electric storage respectively, operated based on smart control technologies. Keywords Electricity฀generation฀system฀•฀EV฀•฀Nuclear฀power฀•฀PV฀•฀Zero-carbon

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Introduction

In an examination of potential zero-carbon energy futures for Japan, it was considered that the CO2 emission reductions required could be achieved mainly in three different ways: by a reduction in energy demand, an expansion in nuclear power or

Q.฀Zhang฀(*), B. Mclellan, N.A. Utama, T. Tezuka, and K.N. Ishihara Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan e-mail:฀[email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_2, © Springer 2011

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the increase in renewable energy production. Several studies also show that this reduction could be achieved by increasing the share of electricity utilization on the end-user side [1, 2], which is considered to be the most effective way to reduce demand through technology substitution and energy saving, and increase the penetration of nuclear power and renewable energy simultaneously. The philosophy adopted in this study agrees with these studies and considers that society is becoming more reliant on electricity, which further highlights the need to move to a zerocarbon electricity system based on zero-carbon power sources including nuclear power฀and฀renewable฀energy฀(Photovoltaic฀(PV),฀wind,฀biomass,฀etc.). Although some future zero-carbon energy system scenarios based on renewable energy (solar, wind, wave, etc.) have been proposed both for individual countries or globally [3, 4], the most common criticism is that renewable energy produces electricity too intermittently and is too costly. Thus, nuclear power is expected to contribute as a low-carbon energy source much more in the future in Japan [1, 5]. On the other hand, in the future, renewable energy is likely to become cheaper and cheaper, but nuclear power may become more and more expensive due to the price rise of nuclear fuel. Furthermore, too much nuclear power without effective nuclear waste treatment will convert the CO2 problem to a nuclear waste problem. Therefore, in the present study, long-term planning of a scenario for a zero-carbon electricity generation system with maximum renewable energy from 2005 to 2100 is conducted using a developed integrated model.

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Scenario Analysis for Electricity Generation System and Proposal for an Integrated Model

The basic idea of the present study is to conduct the scenario in three steps to (1) estimate electricity demand and load pattern based on lifestyle and industrial structure in future; (2) plan the optimized power generation mix to satisfy electrical demand and load subject to various constraints including natural resources, economic, environmental, geographic, natural conditions, etc. (3) study the reliability of the obtained best mix power generation system using an hour by hour simulation. Therefore an integrated model has been proposed including (1) a bottom-up simulation model, (2) an optimization model (3) an hour by hour simulation model. As shown in Fig. 1, three sub-models are connected with each other through data flow.

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Estimating Future Electricity Demand

The final total electrical demand and load is obtained using the bottom-up simulation model as shown in Fig. 1 based on framework comprised of residential, commercial, industrial and transportation sectors and their several sub-sectors. The simulation is

Long-Term฀Scenario฀Analysis฀of฀a฀Future฀Zero-Carbon฀Electricity฀Generation฀System฀

Efficiency Improvement

Technology Substitution

Estimating electricity demand

1 Annual Electricity Demand

Bottom-Up Simulation Model Life Style

Electric Annual Load Duration Curve

Population, GDP, Macro Economy

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Physical, natural and system constrains

Long-term Electricity Mix Planning Model

2

Environment and economy constrains Hourly Electric Load Data

Hourly Demand-Supply Electricity Storage (Battery, Hydrogen)

Hour by Hour Simulation Model

Reliability examination of electricity system

Optimization planning of electricity mix

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Best Mix Of Electricity System

Operation Pattern of Power Plants

Fig. 1 Proposed฀Integrated฀Scenario฀Analysis฀model฀for฀Zero-Carbon฀Electricity฀system฀(ZCEISAM)

Final Energy Consumption(1015J) (Left) and Electrification(%)(Right) 16000.00

electricity heat oil coal

14000.00

80.00%

biomass hydrogen gas Electrification ratio

70.00% 60.00%

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10000.00

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Electricity

6000.00 4000.00

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Oil

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Biomass 20.00%

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0.00

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2005 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060 2065 2070 2075 2080 2085 2090 2095 2100

Fig. 2 Obtained final energy demand by using the bottom-up simulation model

conducted in several steps based on the base year data, assuming parameters such as efficiency, share design according to socio-economic and technology parameters such as lifestyle, macro economy, technology improvement and technology shift. The simulation results are shown in Fig. 2, in which the electricity demand is shown to increase from 1,000 TWh to 1,500 TWh from 2005 to 2100 [6].

Q.฀Zhang฀et฀al.

20

4

Long-Term Optimization Planning of Electricity Generation

The detailed long-term optimization planning model in the proposed integrated model is shown in Fig. 3. The model aims to find the least total CO2 emission solution to meet the electrical demand obtained in the previous step, subject to various constraints including physical space, replace schedule, generation grid technology, environmental, economic, resource availability, and so on. The proposed optimization method is quite different to many models proposed in past studies such as MARKAL฀and฀AIM฀(Asia-Pacific฀Integrated฀Model),฀which฀aim฀to฀find฀the฀least฀ cost solution. The philosophy is that the external costs that will arise from the negative environmental impacts of fossil fuel burning and climate change are not considered in the existing least cost analysis models, meaning that these results cannot be accepted as realistic. Therefore, if humanity is really serious about the climate change issue, the least total amount of CO2 accumulation in the atmosphere should be the goal pursued, which means a least total CO2 emissions path for a final zerocarbon energy system should be pursued. The obtained optimization results (subject to the main constraints listed in (Table 1) are shown in Fig. 4. The results indicate that to realize a zero-carbon electricity generation system by 2100, Japan will still be dependent 60% on nuclear power, with 35% on all renewable energy and 5% on energy storage.

Capacity constraints Fuel Consumption Cost Constraints

Electricity Demand Electrical Load Pattern

Initial Install Capacity New Equipment Constraints

Least Accumulated CO2 Long-term Planning Optimization Model Construction Cost OM Cost Fuel Cost

Install Capacity, Electricity production Cost, Fuel Consumption CO2 Emission Power Output Pattern Utilization Ratio

Efficiency Load Factor Constraints Electrical Storage Constraints

Fig. 3 Long-term optimization planning model for electricity generation mix

Long-Term฀Scenario฀Analysis฀of฀a฀Future฀Zero-Carbon฀Electricity฀Generation฀System฀ Table 1 Main constraints for the optimization planning [7–10] Max capacity Replacement strategy Annual CF Min 60% Coal Replace 50% (of current capacity) by 2050, and no Max 85% replacement after 2050 Oil No replacement (of current Min 30% capacity) Max 60% Min 40% Gas Replace 100% (of current capacity) by 2050, and no Max 70% replacement after 2050 Hydro 30 GWe Max construction capacity: 40% 1 GW/year Nuclear 185 GWe Max construction capacity: 80–90% 3 GW/year PV 100 GWp 2030: 54 GW 12% Wind

50 GWe

Biomass 30 GWe

2050: 25 GW

20%

Max construction capacity: 1 GW/year

60–80%

21

Hourly CF Min 50% Max 90% Min 0 Max 100% Min 0 Max 100% 40%

Min 0 Max 70% Min 0 Max 100% Min 0 Max 100%

CF Capacity factor Power Generation (100 GWh) 18000.00 Battery Wind Gas

16000.00 14000.00

PV Nuclear Oil

Biomass Coal Hydro PV

Battery

12000.00 Wind

Biomass

10000.00 8000.00 Nuclear

6000.00 4000.00 2000.00 0.00

Coal Oil

Gas Hydro

2005 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060 2065 2070 2075 2080 2085 2090 2095 2100

Year

Fig. 4 Obtained electricity generation mix for zero-carbon electricity system in Japan

5

Hour by Hour Simulation Model for Reliability Analysis

For the case of zero-carbon power sources, the output electricity of nuclear power stations cannot be adjusted, due to safety and economic constraints, and the output electricity of renewable power from solar, wind and wave highly depends on weather conditions such as intensity of sunlight, strengths of wind and waves which are highly unpredictable. Therefore, the existence of adequate electricity storage facilities is a key part of zero-carbon electricity systems to level electric loads and absorb the output fluctuations of renewable power sources. Therefore, batteries in electric vehicles (EV) [11–14] and hydrogen [15–17] are selected for daily and

Q.฀Zhang฀et฀al.

22

seasonal electricity storage, the whole electricity system and detailed hour by hour simulation model are shown in Figs. 5 and 6 respectively, by which the hour by hour electricity supply-demand balance and electricity storage information can be obtained. The input hourly electrical load data and electricity mix were obtained in the first two steps. The hourly power generation is obtained according to nuclear operation conditions, solar irradiation and wind speed, etc. The simulation starts by reading the hourly electric loads from the data record. Then it checks if the amount of power generation at one point in time is greater than the load demand. If so, the system will use its spare capacity to either recharge the batteries (providing that they are not full) or generate hydrogen. However, if the amount of power generated is lower than the electricity demands, then the system will first attempt to use the electricity stored in batteries, and then when these are empty it will generate electricity from the stored hydrogen. The hourly electrical supply-demand balance relationship and electricity storage operation information were obtained by using the developed computer software

Hydrogen-Based Electricity Storage PEM Electrolyzer

Grid Power Source

Storage

Fuel Cell

E2H H2E

Electrical Load

Smart Control G2V V2G

Electric Vehicle (EV)

Electricity/Hydrogen Information Communication

Battery-Based Electricity Storage

Fig. 5 Schematic diagram of a zero-carbon electricity system based on electric storage and smart control technologies

Hourly Available Capacities of Hydrogen Production and Electricity Supply from Fuel Cells

Hourly Electrical Load Data

Hourly Short-term, Long-term, Comprehensive Electric Storage Strategy

Hour by Hour Demand-Supply Computer Simulation

Hourly Available Charge/Discharge Capacity of Batteries in EVs

Hourly Power Generation

Hourly Moving Pattern and Charge/Discharge Pattern of EVs

Hourly Demand-Supply Hourly Electricity Storage (Battery, Hydrogen)

Operation Pattern of Power Plants, solar irradiation, wind speed

Fig. 6 Hour by hour simulation model for confirming demand-supply balance in electricity system

Long-Term฀Scenario฀Analysis฀of฀a฀Future฀Zero-Carbon฀Electricity฀Generation฀System฀

23

Fig. 7 Hour by hour simulation result obtained by using a developed computer code

code as shown in Fig. 7. The results show that during the spring and autumn periods, and some week-long Japanese holidays such as the New Year Festival (beginning of Jan.), Golden Week (beginning of May) and Bon Festival (middle of August.), surplus electricity generated from nuclear power is converted to hydrogen through water electrolysis when the EV batteries are in a “full” state. On the other hand, electricity is generated from hydrogen fuel cells in winter and summer when many electrical load peaks appear due to the heating and air conditioning demands, respectively. Hence during this period the hydrogen generated during the other periods must be converted back into electricity.

6

Conclusion

A zero-carbon electricity generation system is of vital importance to the achievement of a zero-carbon emissions energy system in future, with the society becoming reliant on electricity more and more. An integrated model has been proposed to conduct long-term scenario analysis for zero-carbon electricity generation system in Japan from 2005–2100. The electricity demand is expected to increase from 1,000 TWh to 1,500 TWh from 2005 to 2100, and Japan will be dependent 60% on nuclear power, with 35% for all renewable energy and 5% for energy storage. The obtained electricity generation system is proven to be technically feasible and reliable with the help of EV batteries and hydrogen for daily and seasonal electric storage respectively, operated based on smart control technologies.

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Q.฀Zhang฀et฀al.

Acknowledgements The authors wish to thank all members in the GCOE scenario planning committee, scenario-advanced technology joint meeting and scenario strategy meeting in Graduate School of Energy Science, Kyoto University for helpful comments and support.

References 1. JAEA (2009) 2100 nuclear vision (in Japanese) 2. Ministry of Economy (2005) Trade and industry, super long-term strategic technology roadmap, energy technology vision 2100. Ministry of Economy, Japan (in Japanese) 3. Lund H, Mathiesen BV (2009) Energy system analysis of 100% renewable energy systems – the case of Denmark in years 2030 and 2050. Energy 34:524–531 ฀ 4.฀ Jacobson฀MZ,฀Delucchi฀MA฀(2009)฀A฀path฀to฀sustainable฀energy฀by฀2030.฀Sci฀Am฀301(5):38–45 5. Uchiyama Y (2008) Global warming and future nuclear power industry. Trans At Energy Soc Jpn 50(4):2–3 (in Japanese) ฀ 6.฀ Zhang฀ Q,฀ Tezuka฀ T,฀ Ishihara฀ KN,฀ Esteban฀ M,฀ Utama฀ NA฀ (2009)฀ Study฀ on฀ a฀ zero-carbon฀ electricity฀system฀in฀Japan฀using฀a฀proposed฀optimization฀model.฀Proceedings฀of฀international฀ symposium฀ on฀ sustainable฀ energy฀ and฀ environmental฀ protection฀ (ISSEEP),฀ Yogyakarta,฀ Indonesia, 23–26 November 2009 7. World Nuclear Association (2009) Nuclear power in France. http://www.world-nuclear.org/ info/inf40.html. Updated Oct 2009, Accessed Dec 2009 ฀ 8.฀ Tokyo฀Electric฀Power฀Company฀(2009)฀Nuclear฀power฀monthly฀capacity฀factor฀data.฀http:// www.tepco.co.jp/nu/index-j.html. Accessed Dec 2009 [16] ฀ 9.฀ The฀ Homepage฀ of฀ Kansai฀ Electric฀ Power฀ Cooperation฀ (2009)฀ http://www.kepco.co.jp/ localinfo/live/n_unten/teikaku/teikaku.htm. Accessed Dec 2009 ฀10.฀ Zhang฀ Q฀ (2010)฀ Study฀ on฀ the฀ potential฀ of฀ nuclear฀ power฀ and฀ renewable฀ energy฀ in฀ Japan.฀ GCOE scenario strategy meeting, May 2010 (in Japanese) 11. Yoda S, Ishihara K (1997) Global energy prospects in the 21st century: a battery-based society. J฀Power฀Sources฀68(1):3–7 12. Kariatsumari H, Shimizu N, and Nozawa A(2009) Smart grid ON! – Next generation electricity gird based on battery and sensor, Nikkei Electronics, 2009.10.19:30–52 (in Japanese) 13. Guille C, Gross G (2009) A conceptual framework for the vehicle-to-grid (V2G) implementation.฀Energy฀Policy฀37(11):4379–4390 ฀14.฀ Kempton฀W,฀Kubo฀T฀(2000)฀Electric-drive฀vehicles฀for฀peak฀power฀in฀Japan.฀Energy฀Policy฀ 28(1):9–18 ฀15.฀ Hall฀PJ,฀Bain฀EJ฀(2008)฀Energy-storage฀technologies฀and฀electricity฀generation.฀Energy฀policy฀ 36(12):4352–4355 16. Gutierrez-Martın F, Garcıa-De Marı JM, Baıri A, Laraqi N (2009) Management strategies for surplus electricity loads using electrolytic hydrogen. Int J Hydrogen Energy 34:8468–8475 17. Honma T, Ed. (2006) Handbook of hydrogen and fuel cell, Ohmsha (in Japanese)

Evaluation of Carbon Dioxide Absorption by Forest in Japan Yoshiyuki Watanabe, Satoshi Konishi, Keiichi Ishihara, and Tetsuo Tezuka

Abstract In order to investigate regional absorption of carbon dioxide (CO2) by forests in Japan, first, focusing on an experimentally obtained relation between photosynthetic rate of a tree and atmospheric CO2 concentration around the tree, the atmospheric CO2 concentration dependence of CO2 absorption rate of forests has been described by a Michaelis–Menten type function. Secondly, from the viewpoint of local region for operating area of electric power companies, CO2 absorption by forests has been investigated for different three cases with a simple model in which the atmospheric CO2 concentration around artificial forests are artificially increased up to 1,000 ppm. The resultant CO2 absorption by forests much depends on the atmospheric CO2 concentration, and will be effectively promoted by an easy artificial treatment. Those results might be useful to design a biomass energy carbon capture storage system toward a sustainable society. Keywords Absorption฀•฀Atmospheric฀CO2฀concentration฀•฀Carbon฀dioxide฀(CO2) •฀Forest฀•฀Photosynthesis

1

Introduction

In recent years, emission of greenhouse gasses typified by carbon dioxide (CO2) drastically has increased with drastic increasing energy demand on global scale; consequently, global warming and various environmental issues grow into serious problems. In Japan, total artificial CO2฀ emissions฀ as฀ of฀ FY฀ 2008฀ is฀ about฀

Y. Watanabe (*), K. Ishihara, and T. Tezuka Graduate School of Energy Science, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan e-mail: [email protected] S. Konishi Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_3, © Springer 2011

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1,214 million tonnes [1], where the CO2 emissions mostly are classified into the following three main sectors: (a) Energy industries sector typified by heat power generation, (b) Manufacturing industries and Construction sector typified by ion-, steel- and cement-making, and (c) Transport sector typified by automobiles. On the other hand, removals (absorption) of CO2 at continental areas in Japan is mostly classified฀into฀the฀land฀use,฀land-use฀change฀and฀forestry฀(LULUCF)฀sector,฀and฀the฀ value฀as฀of฀FY฀2008฀is฀about฀79฀million฀tonnes฀[1], and in which CO2 absorption by forest land is about 80 million tonnes that corresponds to about 7% of the total artificial CO2 emissions (1,214 million tonnes). This means that forest is an important natural sink to remove and storage CO2. In the present study, the emission and absorption of CO2 in Japan are discussed focusing on the heat power generation and forest land. For฀the฀heat฀power฀generation฀in฀Japan,฀there฀are฀ten฀big฀electric฀power฀companies฀ (Hokkaido-, Tohoku-, Tokyo-, Chubu-, Hokuriku-, Kansai-, Chugoku-, Shikoku-, Kyushu-, and Okinawa-electric power Co., Inc.). Figure฀ 1a฀ shows฀ the฀ electric฀ production฀ by฀ the฀ ten฀ companies฀ in฀ FY฀ 2005–2009฀ (avg.) [2]. The operating region of each company is also shown in the figure. The electric production by Tokyo and Chubu are much higher than those by the other companies because of large amount of population and industrial establishments. The total electric production by the all companies is about 490 billion kW h with CO2 emissions of about 340 million tonnes which is estimated by the CO2 emission factor 0.69 kg-CO2/kW h for heat power generations. As฀ to฀ forest฀ land฀ in฀ Japan,฀ total฀ forest฀ land฀ area฀ as฀ of฀ FY฀ 2008฀ is฀ about฀ 25.0฀ million ha which covers about 70% of Japan’s total land area (37.8 million ha). About 60% and 40% of the total forest land area mainly are covered by natural forests (native forest) and artificial forests (intensively managed forests), respectively. The natural forests consist of broadleaf trees such as cherry, maple and oak, while the artificial forests consist of needle leaf trees such as Larix kaempferi, cedar and฀cypress.฀Figure฀1b฀shows฀the฀forest฀land฀area฀as฀of฀FY฀2007฀[3] in the operating region of each electric power company. Notice that each number in the figure corresponds฀that฀in฀Fig.฀1a. The north land (Hokkaido and Tohoku) has relatively much forest. In addition, both natural forests and artificial forests exist in a relatively large amount at any operating regions except Okinawa. Here, consider the photosynthesis in plants. The photosynthesis is a chemical reaction inside a plant, and is between H2O and CO2 absorbed by the plant, leading to production of dioxide (O2)฀and฀storage฀of฀carbon.฀Figure฀2 represents an experimentally obtained relation between photosynthetic rate and CO2 concentration in the atmosphere for Larix kaempferi seedlings [4]. The photosynthetic rate much depends on the atmospheric CO2 concentration. This indicates that when the atmospheric CO2 concentration around forests can be increased by artificial or some means, the forests will absorb much more CO2. From฀those฀arguments฀described฀above,฀in฀the฀present฀study,฀focusing฀on฀the฀relation between photosynthetic rate of forests and the atmospheric CO2 concentration, CO2 absorption by forests at the operating region of each electric power company was numerically investigated, in which the atmospheric CO2 concentration around forests was increased by an artificial means as described in the next section.

Evaluation฀of฀Carbon฀Dioxide฀Absorption฀by฀Forest฀in฀Japan

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200

Tohoku

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Hokuriku

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Natural forests

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60%

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Artificial forests 2

0

Operating region of each electric power company Fig. 1 (a)฀Electric฀production฀by฀the฀ten฀big฀electric฀power฀companies฀in฀FY฀2005–2009฀(avg.)฀ and (b)฀forest฀land฀area฀in฀the฀operating฀region฀of฀each฀electric฀power฀company฀in฀FY฀2007

2

Procedure

The฀present฀study฀was฀conducted฀through฀the฀following฀two฀steps:฀(a)฀Focusing฀on฀ the relation between photosynthetic rate of a tree and atmospheric CO2 concentration, the atmospheric CO2 concentration dependence of CO2 absorption by forests was described using a numerical formula, in which that the Larix kaempferi as one of฀needle฀leaf฀trees฀was฀chosen;฀(b)฀From฀the฀view฀point฀of฀the฀operating฀region฀of฀ each electric power company, CO2 absorption by forests was investigated using a

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Y. Watanabe et al. 8

Exp.

Photosynthetic rate, v (µmolm−2 s−1)

Larix kaempferi 6

4

2

0

−2

0

200

400

600

800

1000

Concentration of CO2 in the atmosphere, x (ppm) Fig. 2 Experimentally obtained relation between photosynthetic rate and CO2 concentration in the atmosphere for Larix kaempferi seedlings

CO2

Power plant

Pipeline

Forests

Fig. 3 Simplified schematic of transportation of CO2 emitted form a heat power plant into forests by pipeline

simple model in which the atmospheric CO2 concentration around artificial forests was฀artificially฀increased฀as฀represented฀in฀Fig.฀3. As shown in the figure, CO2 emitted from a heat power plant is directly transported and spread into forests using pipeline, where the concentration of atmospheric CO2 spread inside forests is maintained with 1,000 ppm which is much higher than the average (equilibrium) atmospheric CO2 concentration of around 385 ppm. Notice that this artificial treatment is done for only artificial forest. Namely, the atmospheric CO2 concentration around artificial forests is set to 1,000 ppm, while that around natural forests is set to the average value (385 ppm). By the way, the atmospheric CO2 concentration inside forests cannot be increased over 1,000 ppm because the limit for animals not to die (get pale) is around 1,000 ppm.

Evaluation฀of฀Carbon฀Dioxide฀Absorption฀by฀Forest฀in฀Japan

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29

Results and Discussion

First,฀by฀fitting฀of฀the฀tendency฀for฀Larix kaempferi฀in฀Fig.฀2 to a Michaelis–Menten type function, the relation between photosynthetic rate of a tree and atmospheric CO2 concentration around the tree was described by n(x) = 11.49x/(624.48+x)−1.02, where x is the atmospheric CO2 concentration. The photosynthetic rate increases with increasing the atmospheric CO2 concentration, and becomes progressively saturated over 1,000 ppm. When the atmospheric CO2 concentration is around 1,000 ppm, the photosynthetic rate increases more than twice of that at around the average CO2 concentration (385 ppm). And then, the description of relation between CO2 absorption rate of forests and atmospheric CO2 concentration around forests was attempt using the following two assumptions: (a) The tendency of relation between CO2 absorption rate of forests and atmospheric CO2 concentration is similar to that between the photosynthetic rate of a tree and atmospheric CO2 concentration; (b) Most of current forest land in Japan is soaked at around 385 ppm of the average CO2 concentration, and the total CO2 absorption by forests is approximated by the 80 million tonnes mentioned in the previous section. The resultant equation with the two assumptions is given by K(x) = an(x) in the unit (ton-CO2/ha), where a is the constant number of 0.99. The CO2 absorption rate of forests is an increasing function of atmospheric CO2 concentration, and the absorption rate at around 1,000 ppm is more than twice of that at around 385 ppm. Through the use of K(x), CO2 absorption by forests at a variety of atmospheric CO2 concentration can be estimated. Next, from the view point of the operating region of each electric power company, CO2 absorption by forests was investigated for the following three cases: (a) Current forest฀land,฀(b)฀Forest฀land฀with฀twice฀artificial฀forest฀land฀area,฀and฀(c)฀Forest฀land฀ with฀new฀species฀of฀artificial฀forests.฀Figure฀4 shows the annual CO2 emission and absorption by heat power plants and forests for the three cases: (a), (b) and (c). In the case of (a), the CO2 absorption by forests is 111 million tonnes. This value is increase of 39% over the current one (80 million tonnes), and is correspond to 33% of CO2 emission฀amount฀(340฀million฀tonnes)฀from฀the฀heat฀power฀plants.฀For฀the฀case฀of฀(b),฀ the CO2 absorption by forests is 137 million tonnes which is increase of 70% over the current one, and is correspond to 40% of CO2 emission amount from the heat power plants. As to the case of (c), the CO2 absorption rate of the new species is assumed to be twice of that of the current one, and the CO2 absorption by forests is 218 million tonnes which is increase of 170% over the current one, and is correspond to 64% of CO2 emission amount from the heat power plants.

4

Summary

In order to investigate regional absorption of CO2 by forests in Japan, first, focusing on the relation between photosynthetic rate of a tree and atmospheric CO2 concentration around the tree, the atmospheric CO2 concentration dependence of CO2

Y. Watanabe et al. CO2 emission and absorption (million tonnes)

30 150

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50

CO2 emission : 340 million tonnes

0 CO2 absorption:

−50

Forests 218 million tonnes

Operating region of each electric power company

Fig. 4 Annual CO2 emission and absorption by heat power plants and forests for the three cases (a), (b) and (c)

Evaluation฀of฀Carbon฀Dioxide฀Absorption฀by฀Forest฀in฀Japan

31

absorption rate of forests was described using a Michaelis–Menten type function. The CO2 absorption rate is an increasing function of atmospheric CO2 concentration, and becomes progressively saturated over 1,000 ppm. In addition, the absorption rate at around 1,000 ppm is more than twice of that at around 385 ppm. Secondly, using the described function, CO2 absorption by forests in the operating region of each electric power company was investigated with a simple model in which the atmospheric CO2 concentration around artificial forests was artificially increased up to 1,000 ppm, and the investigation was done for the following three cases:฀(a)฀Current฀forest฀land,฀(b)฀Forest฀land฀with฀twice฀artificial฀forest฀land฀area฀ and฀(c)฀Forest฀land฀with฀new฀species฀of฀artificial฀forests.฀In฀the฀case฀of฀(a),฀the฀CO2 absorption by forests is 111 million tonnes that is increase of 39% over the current one (80 million tonnes). As to the case of (b), the CO2 absorption by forests is 137 million tonnes that is increase of 70% over the current one. And then, for the case of (c), the CO2 absorption by forests is 218 million tonnes that is increase of 170% over the current one. It follows from these arguments that the CO2 absorption by forests much depends on the atmospheric CO2 concentration around the forests, and will be effectively promoted by an easy artificial treatment. Those results here might be useful to design a biomass energy carbon capture storage system toward a sustainable society.

References 1. National Greenhouse Gas Inventory Report of Japan, Center for Global Environmental Research (CGER) and National Institute for Environmental Studies (NIES), April 2010 2. Monthly report on electric power statics, Japan Electric Association, 2004–2009 3.฀Monthly฀ statics฀ of฀ agriculture,฀ forestry฀ and฀ fisheries,฀ Ministry฀ of฀ Agriculture,฀ Forestry฀ and฀ Fisheries฀of฀Japan,฀2007 4.฀Yazaki฀K฀et฀al฀(2004)฀Tree฀Physiol฀24:941–994

2050 ASEAN Electricity Demand: Case Study in Indonesia and Cambodia Nuki Agya Utama, Keiichi N. Ishihara, Qi Zhang, and Tetsuo Tezuka

Abstract ASEAN (Association of South-East Asian Nations) member countries are predicted to become a net importer of oil in the next 15–20 years. Therefore it is important to predict the future electricity demand in the region. However, predicting future electricity demand entail various issues and, one of them is its uncertainty. This study serves to reduce the uncertainties of predicting future electricity demand in the least and developing countries under ASEAN. Introducing the time-series relationship between economic and energy as an input in key parameters and GDP parameters on causality runs from economic to electricity and bi-directional economic and electricity. The result is then applied to predict the future electricity demand trend and is used as reference scenario. Policy, household size, power generation cost, etc are used as key assumption. Granger-causality test proves to be useful in order to predict the future electricity demand trend in Cambodia with the errors during 2005–2008 periods merely 5–7% compares to the actual data. While in Indonesia the error for 2000–2008 predictions compare to the actual demand which is accounted 8% in average. Keywords Cambodia฀•฀Electricity฀•฀Indonesia฀•฀Supply–demand฀scenario

1

Introduction

Although having more than 28,000 billion barrels of oil reserve, ASEAN (Association of South-East Asian Nations) member countries is predicted to become a net importer of oil in the next 15–20 years. Oil price boom in 2007–2008

N.A. Utama (*), K.N. Ishihara, Q. Zhang, and T. Tezuka Graduate School Energy Science, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan e-mail: [email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_4, © Springer 2011

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2050 ASEAN Electricity Demand: Case Study in Indonesia and Cambodia

33

was a crucial moment for the policy maker in ASEAN member countries, to consider how to swift its dependency from fossil fuel to other alternatives fuel. Moreover, according to the prediction by Asian Center of Energy (ACE) [1], the share of generation mix in the region will move towards non-oil fuels. In 2020, almost 45% of the fuel for mix generation in ASEAN will be coal, followed by 40% in natural gas and 1.5% is oil. The rest of the primary will be either renewable energy or nuclear. Thus, it is important to show a possible future energy scenario independent of fossil fuel in the member countries. The purpose of this study is predicting electricity demand and developing scenarios for ASEAN countries, the reference scenario development by utilizing the causality test on the time series of electricity demand and economical growth. Scenario planning frequently consists of three typical growth scenarios, high, low and medium (moderate); these types of scenarios sometimes are dangerous since most of the people thinks that the moderate one is most likely happens [2]. Moreover, to a great extent, forecast errors are led by wrong growth rate expectations, which have materially caused big forecast errors [3]. Yoo, emphasized that even there is a strong relationship between electricity consumption and economic growth it does not necessarily imply a causal relationship. The causal relationship may very well run from electricity to economic and/or economic to electricity [4].

2

Methodology

In order to reduce the uncertainty and burden on the predicting the future using key assumption, some measures were used, such as Granger-causality test (describes below) and data gathering on the related organization. The diagram explaining the methodology of the study is shown in Fig. 1.

Fig. 1 Methodology graph on the predicting the future electricity demand

34

2.1

N.A. Utama et al.

Data Collection on GDP, Population and Electricity Consumption

To test the causality relationship, the historical data in the countries, such as GDP, income per capita and electricity consumption are collected. The data were taken from the statistical sources such as Asian Development Bank (ADB) [5], World Bank [6], United Nation [7], and International Energy Agency [8]. Other micro parameters such as diffusion of home appliances and the yearly electricity consumption, data on electricity power generation such as reserve planning, load, fuel mix electricity generation, capacity etc. were also taken into account. Moreover, the Indonesian data was taken from [9] and [10].

2.2

Granger-Causality Test and LEAP

Granger-causality test was performed to detect any presence of a causal relationship between electricity use and income (GDP per capita). Many evidences proved that the uni-directional causality does not always run from energy to economics. In case of Cambodia and Indonesia [11–14], energy demand are driven by their economic growths. Therefore the test can be used to check whether the electricity demand can be predicted by using the country’s economic trends. LEAP (Long-range Energy Alternative Planning) is a scenario-based energy-environment modeling tool. Its scenarios are based on comprehensive accounting of how energy is consumed, converted and produced in a given region [15]. In the development of the scenario LEAP is used, to predict the future electricity demand based on the current input on GDP (for uni-direction, I → E and E → I causality). The yearly growth for input such as the population and electricity demand is predicted. The growth prediction is crucial point in LEAP since the tools only calculate based on the input parameters. For the development of electricity demand scenarios the electricity consumption growth for appliances was also predicted.

3 3.1

Result and Discussion Granger Causality Relationship Between Electricity Consumption and Income Growth (Represent by GDP Per Capita)

The relationship between electricity consumption and economic growth in the region is calculated, such as uni-directional causality between electricity and economic growth (causality runs either way between both parameters; represent by ‘→’ sign),

2050 ASEAN Electricity Demand: Case Study in Indonesia and Cambodia

35

bi-directional causality (causality exist for both parameters; represent by ‘↔’ sign) as well as no causality at all (no influence between both parameters), which is summarized in Table 1 with reported values. The missing findings and unbalance result are filled by own calculation. There are a number of evidences to support bi-directional or uni-directional causality between electricity consumption and income (GDP per capita). The evidence shows for most of the least developing countries such as Myanmar, Cambodia and Lao PDR has the similar causality; income causes the increase of electricity consumption. Table 1 shows that electricity and income is bi-directional causality (means both have significant influence to effecting one to another [14]). Most of the evidence for Indonesia shows that the income is also influencing the electricity consumption except [16] and [17]. The share of the residential sector in the electricity consumption for Cambodia, Lao PDR and Indonesia is 47%, [8] 40% [18] and 42% respectively [9]. However in Myanmar, the empirical evidence proves that not literally income leads to electricity consumption even the residential electricity consumption share reach almost 40% [8]. The industrial share also plays important factors to predict

Table 1 Empirical result summary of the ASEAN member countries (E = Electricity/Energy; I = Income)

Brunei Darusalam [14] This study Cambodia This study Indonesia [11] [12] [17] [19] [13], [14]

Indu strial com merc ial

I

50 55 60 65 70 75 80 85 90 95 00 05

El. Share [%] resid entia l

I E

E

Sources

E

Countries

Causality

I

Study period (1950-2005)

13

19

68

47

16

37

42

40

18

This study [14] [13] [11]

40

39

10

20

50

30

[11] This study The Philippines [20] [12] [17] [19] [14] This study [11] Singapore [21] [13] This study Thailand [20] [22] [17] [19]

39

42

19

35

35

30

20

38

41

21

46

32

42

47

9

This study Lao PDR Malaysia

Myanmar

Viet Nam

[13] [14] This study

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N.A. Utama et al.

the causality from energy to income as Myanmar share of electricity in industry reach 42% in total, therefore the relationship can be both ways (bi-directional). On the other hand, the most developed countries in the region (Brunei and Singapore) show the bi-directional cause [13, 14, 19]. It means that both parameters are influencing one to another, this is due to the high share of non-residential (industrial and commercial) electricity consumption in Singapore and Brunei 79 and 87% respectively [8] (Table 1). In some countries in the developing category such as Thailand, The Philippines and Malaysia the relationship on causality through empirical evidence is mostly bi-direction (energy and income are cause related each other), except [4] in Thailand (I → E) and [20] (E → I), [14, 21] in The Philippines (E → I), [20] (E → I) and [14] in Malaysia (I → E). The trend for bi-directional causality is attributable to the high share of industrial sector more than 30% and the low residential sector share less than 35%.

3.2

Case Study on Demand Scenarios; Cambodia

The national GDP is predicted by ADB in average of 7% per year up to year 2020 and assuming to be steady 5.5% in the following years up to 2050. The percentage share of electricity in the base year (2006) is residential sector (more than 45% share) follows by commercial in 35% and the remaining is industrial sector. Cambodia’s current GDP reaches 16.39 billion US$, while the population in the same year reaches 13.28 million and creates the GDP per capita, 1,234 US$. With the average household size 5.25, the number of Cambodian household was about 2.53 million. The annual population growth accounts 1.7% and reduces up to 1.5% in year 2050 with the 14% household share in urban and the remaining 86% in rural. The electrification ratio in urban is higher than rural areas, 75% urban household get access to the electricity, while only 9% in rural have access. The use of electricity in urban areas is vary from air conditioning (AC) up to microwave, cooling fan has the biggest percentage share of the electricity consumption in the household follows with the lighting and AC [22]. In commercial sector the AC has the biggest share of electricity consumption and followed by lighting. Moreover, for the un-electrified areas, the biggest share of primary energy is kerosene use for lighting, whereas wood biomass and charcoal use for cooking. Same study shows the highest number of appliances use in household is cooling fan follows by entertainment appliances (TV, radio and computers). The AC reaches 2,571 kW h/household (HH)/year followed by lighting (1,110 kW h/HH/y) and cooling fan (833 kW h/HH/y). The efficiency scenario for lighting suggests to use fluorescent light bulb (currently accounted 5%) to replace incandescent bulb (currently accounted 95%), includes lighting management and automation in commercial and industrial sectors. The cooling scenario supports active and passive system for reducing cooling electricity consumption through; (1) green labeling appliances, (2) building codes; envelopes form and materials and interior improvement.

2050 ASEAN Electricity Demand: Case Study in Indonesia and Cambodia

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Fig. 2 (a) Cost comparison on electricity demand scenarios in 2050 in Cambodia and (b) energy cost estimation for Indonesian supply scenarios in 2050

The result on cost estimation (Fig. 2a) in 2050 shows by improving building codes, utilizing green labeling for cooling appliances and implementing passive cooling for non air conditioned building will save 11 trillion US$ accumulatively up to 2050. In the same period by combining both scenarios the accumulated amount of money can be saved approximately 15 trillion US$.

3.3

Case Study on Supply Scenarios; Indonesia

The future electricity demand growth is estimated using trend from economic growth in average of 6.84% up to 2050. Other key assumptions are used for the base year, such as 205 million populations with 1.12% growth, 52 million household, 79% living in urban by the end year estimation (United Nations). The base year electricity consumption on residential, commercial and industrial sectors is taken from IEA [8]. Current capacity is accounted to 21 GW and assumes to be increase up to 415.6 GW in 2050 (in line with the demand measurement). The transformation and distribution loses accounted 11.5% [9] and will reduce to 9% in 2050. The medium target of electricity generation mix from the Indonesian government is used as a reference up to 2025 [10], the electrification currently is 65% and will reach 100% in 2050, with assumption of 86% grid connection and 14% off grid. Current reserve margin accounts 9% and will increase (as the PLN target) up to 30% in 2050. The reference scenario was developed by utilizing the electricity mix and capacity based on the government energy roadmap in 2008. Moreover, the other scenarios are categorized as follows: (1) Coal scenario, uses mainly coal which assume that the percentage of coal power generation reach 80–90%. (2) Nuclear scenario, where 50–60% of electricity will be covered by nuclear power generation follows by 30% share of coal based power plant in and keep maintaining the percentage of renewable energy based power plant on 2025 roadmap. (3) Renewable energy

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scenario, by optimizing the renewable energy (RE) potential on 20% hydro and 32% (solar, biomass, geothermal and wind combined) and rely the remaining percentage with natural gas (NG) and coal (29% and 18% respectively). (4) Best cost scenario, by maximizing the RE potential (reducing solar potential to 10% compare to 15% in RE scenario) and utilizing more natural gas (40%) and reduce nuclear to 0%. As seen in Fig. 2b the best cost scenario has higher expenses (especially during investment cost) in the first 8 years in around 3.8 billion US$. However, the scenario will save approximately 24.7 billion US$ in total.

4

Conclusion

Due to its economic development, increases of population and household in Cambodia leads to the high share of electricity demand comparing to commercials and industrial sectors; Moreover, low electricity consumption in industrial sector causes from high percentage of share for industry with low electricity intensity (agro and garment industry). Demand scenarios on lighting and cooling shows efficient to reduce the cost of electricity in the future. However, it needs huge investment to replace the current appliances as well as capacity building to introduce building codes in the country. In Indonesian case, the actual consumption and prediction (this study) (2000– 2008) shows 8% errors in average. The maximum utilization of RE potential proves to have relatively low cost; however its capacity could not fulfill the need of electricity demand in 2050. Comparing to the reference scenario, the best cost scenario results US$ 24.7 billion in total reduction, by increasing the share of NG and reducing the share of coal (from the RE scenario). The development of small to medium power generation is more beneficial rather than huge investment in one or two big power generation. Increasing the capacity for coal and NG based power plant can increase the potential for small to medium power generation with low cost investment. NG and coal based power plants are good option for long term plan option in the country, with the consideration of small capacity. For Nuclear, in order to reduce the cost the country should have its technology know how (particularly human resources) rather than ‘cradle to the grave’ imported human resources and technology.

References 1. ASEAN Center for Energy (ACE) (2005) Electricity and development in ASEAN. ASEAN Energy Bull 9:3–4 2. Soontornrangson W, Evans DG, Fuller RJ, Stewart DF (2003) Scenario planning for electricity supply. Energy Policy 31:1647–1659 3. Linderoth H (2002) Forecast errors in IEA-countries’ energy consumption. Energy Policy 30:53–61

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4. Yoo SH (2006) The causal relationship between electricity consumption and economic growth in the ASEAN countries. Energy Policy 34:3573–3582 5. Asian Development Bank (ADB) (2009) Cambodia: enhancing governance for sustainable development. Available at http://www.adb.org 6. World Bank Database (2009) Economy watch, data on GDP Available at http://www.economywatch.com/world_economy/. Accessed June 2009 7. The United Nations Statistics Division (UNSD) of the Department of Economic and Social Affairs (DESA) (2009) Data on population, electricity consumption and GDP. Available at http://data.un.org/ 8. International Energy Agency (IEA) (2008) Energy statistic of non-OECD countries, IEA Statistic 9. Stated Owned Electricity Company (PLN) (2009) Statistics. Available at http://www.pln. co.id 10. Ministry of Energy and Mineral (2009) National energy policy, Directorate General of Electricity and Energy Utilization, Ministry of Energy and Mineral Resources 11. Murry DA, Nan GD (1996) A definition of the gross domestic product – electrification interrelationship. J Energy Dev 19–2:275–283 12. Masih AMM, Masih R (1996) Electricity consumption, real income and temporal causality: results from a multicounty study based on co integration and error correction modeling techniques. Energy Econ 18:165–183 13. Yoo SH (2006) Electricity generation and economic growth in Indonesia. Energy 31:2890–2899 14. Chontanawat J, Hunt LC, Pierse R (2008) Does energy consumption cause economic growth?: evidence from a systematic study. J Policy Model 30:209–220 15. Long-range Energy Alternatives Planning System (LEAP) (2006) User guide, Stockholm Environment Institute, March 2006 16. Asafu-Adjaye J (2000) The relationship between energy consumption, energy prices and economic growth: time series evidence from Asian developing countries. Energy Econ 22:615–625 17. Fatai K, Oxley L, Scrimgeour FG (2004) Modeling the causal relationship between energy consumption and GDP in New Zealand, Australia, India, Indonesia, the Philippines and Thailand. Math Comput in Simul 64:431–445 18. Ministry of Energy and Mines LAO PDR (2006) Overview of energy subsector activities in the Lao PDR, Sub regional energy forum-2 HoChiMinh, Viet Nam, 22 November 2008 19. Glasure YU, Lee AR (1998) Cointegration, error-correction, and the relationship between GDP and electricity: the case of South Korea and Singapore. Resource Energy Econ 20:17–25 20. Masih AMM, Masih R (1998) A multivariate cointegrated modeling approach in testing temporal causality between energy consumption, real income and prices with an application to two Asian LDCs. Appl Econ 30–10:1287–1298 21. Yu SH, Choi JY (1985) The causal relationship between energy and GNP: an international comparison. J Energy Dev 10:249–272 22. Sovanndara N (2002) Household electricity use analysis and forecasting: the case of Phnom Penh, Cambodia. Unpublished Master Thesis, The Joint Graduate School of Energy and Environment (JGSEE), Thailand

Proposal of a Method for Promotion of Pro Environmental Behavior with Loose Social Network Saizo Aoyagi, Tomoaki Okamura, Hirotake Ishii, and Hiroshi Shimoda

Abstract Recently, environmental and energy problems, which are typified by global warming, have grown into serious problems. In Japan, CO2 emission of residential sector however is relatively at high level. Consequently, decrease of CO2 emission by Pro Environmental Behavior (PEB) in households is necessary. The purpose of this study is proposal of a method for promotion of PEB in households, which consists of (1) presentation of appropriate PEB depending on place and time and (2) loose social network of PEB footprint communication using portable devices (iPhone). The proposed method was practiced in a Japanese home with a participant. From the result, we confirmed that the proposed method promote PEB through the experiment. Other experiments with several participants and long periods are planned now because the experiment had only one participant and the period of the experiment was too short to confirm continuance. Keywords Awareness฀•฀Cellular฀phone฀•฀Loose฀social฀networks฀•฀Pro฀Environmental฀ Behavior (PEB)

1

Introduction

Recently, environmental and energy problems, which are typified by climate change, have grown into serious problems and CO2 emissions have to be decreased in various sectors in order to solve the problems [1]. In Japan, CO2 emission of industrial sector has been decreased, that of residential sector however is relatively at high level [2]. Consequently, decrease of CO2 emission by Pro Environmental Behavior (PEB) in households will contribute to solving environmental and energy problems greatly.

S. Aoyagi (*), T. Okamura, H. Ishii, and H. Shimoda Graduate School of Energy Science, Kyoto University, Yoshida-honnmachi, Kyoto 606-8501, Japan e-mail: [email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_5, © Springer 2011

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There are some studies about promotion of PEB of people. Conventionally, such studies regard people’s environmental attitude or consciousness as a key factor to promote their PEB [3]. Nevertheless, recent studies revealed that cultivation or change of environmental attitude of people is not sufficient for promotion of their PEB [4, 5], and new approaches are necessary. Purpose of this study is proposal of a method for promotion of PEB, which is characterized by presentation of available PEB depending on place and time, and footprint communication in loose social network.

2

2.1

Proposal of a Method for Promoting Pro Environmental Behavior Existing Studies of Promotion of PEB in Households

There are some studies about what are needed for promotion of PEB in addition to cultivation of environmental attitude or concern. Blake [5] pointed out that there are three barriers between environmental concern and PEB, named individuality such as laziness or lack of interest, responsibility to PEB, and practicality such as lack of information. Based on the study of Blake, Yi proposed an approach of promote PEB of people and examples of the system as implementation of the approach, which consists of two parts [6]. First, the approach employs some computing devices which provide information to people in order to break barriers of responsibility and practicality. For example, the provided information is about energy consumption of people, which shows how much energy can be saved by PEB. Next, the approach employs social networking sites and online community such as Facebook (http://www. facebook.com) which is an area of exchange of information of PEB or mutual reporting of PEB experience of users in order to break the barrier of individuality through psychological bandwagon effect. Bandwagon effect is similar to conformity [7], and the fact that other people do PEB can work as the reason why people do PEB by the effect. The approach of Yi is considered to be effective for promotion of PEB. Nevertheless, there are some problems in the approach. First, these two parts, computing devices for energy information and online community are not integrated, users of these system therefore have to get information from the computing devices, and put the information to online community by themselves in addition to PEB. These behaviors bother people, and it may decrease people’s intention to do PEB rather than promote PEB. So integration of two parts, such as automatic information sending, is required as mentioned by Yi himself [7]. Second, we consider that information, which is given to people by devices are insufficient. These are just information about energy consumption, and are not information about what, how and when to do PEB. Therefore, users of the system have to determine their behavior by themselves.

Proposal of a Method for Promotion of Pro Environmental Behavior

45

Components of the method

Purpose Promotion of PEB

Awaking available PEB Band wagon effect

Presentation of appropriate PEB depending on place and time Using portable devise Loose social network of PEB foot print communication

Fig. 1 An overview of the proposed method

2.2

The Proposed Method for Promotion of PEB

Based on the above discussion, we propose a method for promotion of PEB, which includes two components as shown in Fig. 1. The first component is presentation of appropriate PEB depending on place and time using portable device such as iPhone. Using the system, an appropriate PEB is presented to users of the system in appropriate timing by a mobile device. For example, when a user starts to cook with gas stove, a mobile device of the user presents a PEB about saving gas. The information which is presented by the proposed method is so rich that users can know what, how and when to do PEB. The second component is loose social network of PEB footprint communication. PEB footprint means the fact a user did a PEB, which is communicated to other users฀ in฀ our฀ definition.฀ Loose฀ social฀ network฀ means฀ a฀ kind฀ of฀ social฀ networking฀ system, which is characterized by dealing with only a few information such as twitter (http://www.twitter.com) in our definition. Therefore, loose social network of PEB footprint communication means a kind of social network where users communicate the fact they did PEB to other users. The social network will invoke bandwagon effect, which promote PEB of people. In addition, these two components of the proposed method are completely integrated. As mentioned above, presentation of appropriate PEB is conducted by a mobile device, loose social network is also accessed using a mobile device. Moreover, presentation of PEB and access to the loose social network can be integrated in dedicated client software which can tell the fact he/she do PEB to other users who use the system with just a single touch a button.

2.3

Implementation of the Method and System Configuration

We implemented the proposed method as an integrated system as shown in Fig. 2. First, the system included an iPhone for each user, and dedicated client software is installed into the iPhone. Users take along iPhone in his/her home. Next, Bluetooth station stations are placed in places where PEB are available, such as sink, toilet or refrigerator in users’ home. Moreover, Wi-Fi station is set in user’s home for connecting

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Portable devise(iPhone) User’s home(example)

User

Web server

Toilet refrigerator Bluetooth stations Sink

Wi-Fi station

Fig. 2 An overview of system configuration

iPhone and web server with Wi-Fi network, and the system employs a web server which have dedicated server software with database of a list of PEB and its appropriate place and time, place information of Bluetooth stations, and log of user’s behavior. When the system presents an appropriate PEB to users, it works as follows: 1. A user comes close and enter into an area of a Bluetooth station in daily life. 2. When iPhone recognizes entering, asks web server about what PEB is available in this place and this time. 3. Web server returns a PEB to iPhone, and iPhone present a PEB to the user. Next, the system provides loose social network of PEB footprint communication as follows: 1. Many users concurrently use the system (for example, 1,000 users). 2. When a user do PEB, he/she can put a PEB footprint with just a single touch a button. Users can add some comments to a PEB footprint. 3. PEB footprints are shown to other users as timeline like twitter. PEB footprints are just declarations of PEB to all users, and there are no obligations to reply or “deep” communication.

3 3.1

Field Practice of the Proposed Method Purpose and Method

Purpose of the practice is to confirm that the proposed method promote PEB. We define “promotion of PEB” as “a participant starts to PEB or increases frequency of PEB through the practice” in this study. The period of practice was about a week

Proposal of a Method for Promotion of Pro Environmental Behavior 100%

1

1

90% 80%

16

70% 60% 50% 40%

10% 0%

no answer

6

had no occasions

8

Not do at all

10

Less likely do

4

Sometimes do

30% 20%

1 2 7

47

15

29 Often do Always do

5 Pre questionnaire

Post questionnaire

Fig. 3 Comparison of frequencies of 53 PEBs between pre questionnaire and post questionnaire

from 2010 August 3th to August 10th. Participant is a Japanese woman and ten confederate participants were played by one of the authors in the loose social network of the system. The system of the proposed method was set in her home and 53 PEBs were presented to the participant. Pre questionnaire and post questionnaire were conducted to reveal frequency of participants’ PEB. In addition, participant’s PEB footprints were recorded in order to confirm their actual PEB history.

3.2

Results and Discussion

Figure 3 shows Frequencies of 53 PEBs between pre questionnaire and post questionnaire of the participant. We can find that the frequency increased through the practice. In particular, the number of PEBs that were answered as “always do” increased greatly and that of “Not do at all” dramatically decreased from 16 to 2. Figure 4 shows the number of PEB footprints of the participant in the experimental period. We can find sudden decrease in August 7th. This is because participant misunderstood how to use PEB footprint, before 7th. She put footprints without doing PEB. We therefore improved sentences for explanation of how to use PEB footprints in the system in order to avoid misunderstanding in 7th. After that, about ten footprints were recorded in a day.

4

Conclusion

In this study, we proposed the method for promotion of PEB with loose social network and practiced with a participant in actual Japanese home. From the result, we confirmed that the proposed method promote PEB through the experiment.

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the number of PEB footprints 100 90 80 70 60 50 40 30 20 10 0

8/3

4

5

6

7

8

9

10

Date

Fig. 4 The number of PEB footprints in the experimental period

Other experiments with several participants and long periods are planned now because the experiment had only one participant and the period of the experiment was too short to confirm continuance.

References 1. IPCC (2007) IPCC fourth assessment report: climate change 2007 2. METI (2008) 2007 Annual energy report 3. Nishino S, Sumida K (2004) Scaling for measurement of attitude toward environmental education. J Home Econ Jpn 55(10):815–822 4. Hirose Y (1994) Determinants of environment-conscious behavior. Res Soc Psychol 10(1):44–55 5. Blake J (1999) Overcoming the ‘value-action gap’ in environmental policy: tensions between national฀policy฀and฀local฀experience.฀Local฀Environ฀4(3):257–278 6. Yi B (2009) Persuasive technology in motivating household energy conservation, Business aspects of the internet of things seminar of advanced topics FS 2009, 52–58 7.฀Latane฀B฀(1981)฀The฀psychology฀of฀social฀impact.฀Am฀Psychol฀3–4:343–356

Performance Analysis Between Well-Being, Energy and Environmental Indicators Using Data Envelopment Analysis Jordi Cravioto, Eiji Yamasue, Hideki Okumura, and Keiichi N. Ishihara

Abstract Data Envelopment Analysis (DEA) has been applied to know the performance of 40 countries in terms of energy, environmental and well-being related indicators. The method used is a basic Charnes, Cooper and Rhodes (CCR) DEA model applied to countries treated as Decision Making Units (DMUs) with two energy related indicators as inputs and one well-being indicator as output. The variables were selected based on correlations between seven energy-environmental indicators, and eight well-being indexes. From the correlations, two DEA models were constructed and compared. The first one, named “Production” DEA model, using electricity consumption per capita and CO2 emissions per capita as inputs and GDP per capita as output. The second one, “Development” DEA model using the same inputs but Human Development Index (HDI) as output. Results show that most developed countries compared to the others have low efficiency in the production model and even lower results in the development one. Among the “best” performing countries were Costa Rica, Ghana and the Philippines for the production model, and Tanzania and Nigeria for the development one. Keywords CO2฀emissions฀•฀DEA฀•฀Electricity฀consumption฀•฀Well-being฀indicators

1

Introduction

During the past 25 years, alternative measures have been proposed to substitute GDP as a proxy to measure well-being. The theoretical idea behind some is that the link to limited amount of resources and environmental degradation is not accounted

J. Cravioto, E. Yamasue, H. Okumura, and K.N. Ishihara (*) Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto, 606-8501, Japan e-mail: [email protected]; [email protected]; [email protected]; [email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_6, © Springer 2011

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within the production measurements. Others believe that the level of well-being cannot be measured through production proposing alternative indexes more related to variables involved with development (HDI) or direct surveying quality of life or satisfaction (LSI). In any case, current societies utilise resources and energy as supply for the production of goods necessary for daily life, and these goods have an effect on the level of well-being of the individuals and their community. The relationship between these well-being indexes and energy consumption is therefore complex and not straightforward, and the assessment of performance from communities is a difficult task to undertake. In recent years, however, a mathematical programming technique called Data Envelopment Analysis (DEA) has proved to be useful to compare performance among similar decision making units (DMU) based on efficiency relationships of correlated inputs and outputs. It has been applied in a range of studies exploring the efficiency of energy provision [1], consumption [2] or environmental performance [3], but fewer works have explored socio-economic performance [4] or well-being performance in terms of energy resources use. This research is therefore intended to provide a performance comparison among a set of countries in terms of energy consumption and CO2 emissions to production and well-being levels.

2 2.1

Method Sample and Index Selection

The selection of the sample included 40 countries representative of the five continents. This sample is intended to be symbolical in terms of cultural and size differences. Table 1 shows the selected countries. From several economical indicators and well-being indexes, Table 2 shows those selected based on data availability for the sample. Energy related indicators are also included in the table.

2.2

Correlation Analysis

A correlation analysis applied to the sample with data for 2007 showed that the strongest correlations were found for production and energy supply: GDP with energy related indicators. However, some correlations were also found among HDI, GINI and QLI with electricity consumption per capita (Electricity/pop) and CO2 emissions per capita (CO2 /pop). Table 3 shows an outline of selected correlations coefficients. For this paper, two relations have been selected. The first one, GDP/pop with Electricity/pop and CO2 /pop forming what will be described later as the “Production” DEA model. And second, HDI with Electricity/pop and CO2 /pop forming the “development” DEA model.

Performance฀Analysis฀Between฀Well-Being,฀Energy฀and฀Environmental฀Indicators Table 1 Countries in sample Asia/Oceania Europe Uzbekistan Spain India Russia Indonesia Poland China Greece Japan Bulgaria Korea Turkey Malaysia Germany Philippines France Thailand UK Australia Italy New Zealand Sweden Norway

Africa/Middle East Morocco Nigeria Tanzania South Africa Ghana Iran Saudi Arabia Israel

51

Americas United States Mexico Canada Brazil Argentina Venezuela Chile Jamaica Costa Rica

Table 2 Well-being,฀environmental฀and฀energy฀indexes฀and฀indicators Energy related Environment related Well-being฀related฀ indicators/indexes [6] indicators/indexes [6] indicators/indexes [5] Total Primary Energy CO2 emissions Gross Domestic Product (GDP) Supply (TPES) GDP per capita (GDP/pop) Electricity consumption CO2 emissions per capita (CO2 /pop) Human Development Index (HDI) [7] Electricity consumption per CO2 emissions per GDP capita (Electricity/pop) (CO2 intensity) CO2 emissions per TPES Satisfaction with Life Index (LSI) [8] Energy Depletion Index (EDI) [5] Quality of Life Index (QLI) [9] Happy Planet Index (HPI) [10] GINI Index

Table 3 Correlation coefficients between selected indexes and indicators HDI QLI GINI LSI 0.67 0.69 −0.56 0.42 Electricity/pop CO2 /pop 0.66 0.49 −0.39 0.32

2.3

GDP/pop 0.87 0.72

Data Envelopment Analysis Models

Data Envelopment Analysis (DEA) is the mathematical tool used in this paper to evaluate the performance of countries in terms of how they use inputs to generate an output. By creating a linear programming model from efficiency relations of the inputs and the output, the relative efficiency can be calculated for each country. The ground concept is the efficiency factor where each output is related to the input as shown in (1) [11].

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max(Em ) =

∑v j =1

jm

y jm

I

∑u i =1

x

im im

subject to J

0≤

∑v j =1

jm

y jn

I

∑ uim xin

≤ 1; n = 1,2...N

i =1

v jm , uim ≥ 0; i = 1,2...I ; j = 1,2...J ;1 ≤ m ≤ n

(1)

Where฀Em is the efficiency of the mth country, yjm the jth output of the mth country, vjm is the weight of that output, xim is ith input of the mth country, uim is the weight of that input, yjn and xin the jth output and ith input respectively of the nth country and N฀the฀total฀number฀of฀countries.฀When฀evaluating฀the฀problem฀the฀efficiency฀of฀the฀ mth฀country฀can฀be฀obtained.฀When฀some฀outputs฀are฀undesired฀in฀the฀performance,฀ like the case of pollution or emissions, the simplest case is to treat them as an input as described by Cooper et al. [12] and valuate performance. This approach is adopted in this paper to deal with emissions as a product of electricity production.

2.3.1

Production DEA Model

If for each country, electricity consumption per capita and CO2 emissions per capita are treated as inputs and GDP per capita as the only output, as an example (2) shows the mathematical expression for country A. max E A =

3.79vGDP , A 13.6uElect ., A + 19.10uCO2 , A

subject to 0≤ 0≤ 0≤ 0≤

37.9vGDP , A 1.36uElect ., A + 19.10uCO2 , A 11.1vGDP , A 0.2uElect ., A + 4.14uCO2 , A

≤1

31.7vGDP , A 1.69uElect , A + 17.37uCO2 , A 7.6 vGDP , A 0.23uElect , A + 4.57uCO2 , A

… n = 40

≤1

≤1 ≤1 (2)

Performance฀Analysis฀Between฀Well-Being,฀Energy฀and฀Environmental฀Indicators

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Where฀EA is the efficiency of country A, 37.9 the output (GDP/pop) in thousands of USdls per capita, 1.36 input No.1 (Electricity/pop)฀in฀MW฀h฀per฀capita,฀19.10฀input฀ No.2 (CO2 /pop) in tons of CO2 per capita, vGDP,A the weight of the output, uElect,A the weight of input No.1 and uCO ,A the weight of input No.2. The aim of the 2 problem is to find vGDP,A, uElect,A, uCO ,A such that EA is maximum subjected to the 2 constraints of efficiencies of the other 40 countries (n=40). To obtain the efficiency of each of the other countries the same linear programming model is used until the valuation of the 40th country (when m=n). Results are named “production” performance.

2.3.2

Development DEA Model

In this model, HDI takes the place of the country’s output while electricity consumption per capita and CO2 emissions per capita remain as inputs. The mathematical expression for country A does not change from (2) except for the factors used in the numerator for each country. The output is 0.955 (HDIA) for country A, 0.849 (HDIB) for country B, etc. The performance results are named “development” results.

2.3.3

Assumptions in the Model

The general assumption when using a DEA model is that if one DMU is the most efficient to obtain outputs from inputs, the others should be able to do it in the same way. Therefore, this comparison between countries assumes that all are equally capable of obtaining their production outputs or development achievements using their inputs. Other assumptions are those implied when using the basic CCR model.

3

Results and Discussion

Figure 1 shows a graph with performance results from both DEA models. In the graph except for Sweden, Norway and France most developed countries have efficiencies below 60% in the production model and lower in the development one perhaps associated with lower CO2 emissions and electricity consumption of these countries. Only two countries had performance over 70% in both models (Nigeria, Tanzania) which means their electricity consumption and CO2 emission is the smallest compared to their achievements in economic growth and development. This effect not only suggests that electricity consumption and emissions in all low efficiency countries are less significant for production, but also less meaningful to their development as measured with HDI. Future policy measures therefore should aim at reducing inputs to attain a better performance in both models.

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Development DEA Performance [%]

Tanzania Uzebekistan Jamaica Russia Bulgaria S. Africa Venezuela Canada Australia USA Malaysia

80

60

40

Korea China Iran Polonia New Zealand Chile Thailand Japan Greece Germany

Spain Turkey UK Italy Mexico Argentina

Nigeria

Ghana Indonesia India

20

Morocco France

0 0

20

40

60

Philippines Brazil Norway 80

Costa Rica Sweden 100

Production DEA Performance [%]

Fig. 1 Development to production performance in country sample

4

Conclusion

The best performing countries in the production model were Costa Rica, Ghana and the Philippines whereas Tanzania and Nigeria were for the development one. Other countries show lower efficiency performance in both DEA models meaning less significant impact of electricity and CO2 emissions to wealth or development achievements. Acknowledgement The authors would thank Japan’s MEXT and Kyoto University Global COE Program฀“Energy฀Science฀in฀the฀Age฀of฀Global฀Warming”฀for฀their฀financial฀support.

References ฀ 1.฀ Hu฀J-L,฀Wang฀S-C฀(2006)฀Total-factor฀energy฀efficiency฀of฀regions฀in฀China.฀Energy฀Policy฀ 34:3206–3217, Elsevier 2. T-l Yeh, T-y Chen, P-y Lai (2010) A comparative study of energy utilization efficiency between Taiwan and China. Energy Policy 38:2386–2394, Elsevier ฀ 3.฀ Zhou฀ P,฀ Ang฀ BW,฀ Poh฀ KL฀ (2008)฀ Measuring฀ environmental฀ performance฀ under฀ different฀ environmental DEA technologies. Energy Economics 30:1–14, Elsevier 4. Golany B, Thore S (1997) Restricted best practice selection in DEA: an overview with a case study evaluating the socio-economic performance of nations. Ann Oper Res 73:117–140, J.C. Baltzer AG, Science Publishers ฀ 5.฀ The฀World฀Bank฀(2009)฀World฀development฀indicators฀2009.฀CD-Rom

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6. IEA (2009) Energy statistics of OECD and non-OECD countries 2009. IEA Publications 7. United Nations Development Programme (2009) Human Development Report 2009. Overcoming barriers: human mobility and development. ISBN 978-0-230-23904-3, UNDP ฀ 8.฀ White฀A฀(2007)฀A฀global฀projection฀of฀subjective฀well-being:฀a฀challenge฀to฀positive฀psychology?฀Psychtalk฀56:17–20,฀The฀data฀on฀SWB฀and฀SWLS฀were฀extracted฀from฀a฀meta-analysis฀ by Marks, Abdallah, Simms and Thompson ฀ 9.฀ Economist฀Intelligence฀Unit฀(2005)฀Quality฀of฀life฀index.฀The฀World฀in฀2005,฀The฀Economist฀ Newspaper Ltd 10. Marks N, Abdallah S, Simms A, Thompson S et al (2006) The Happy Planet Index 1.0. New Economics Foundation 11. Ramanathan R (2003) An introduction to data envelopment analysis, a tool for performance measurement. Sage, Thousand Oaks. ISBN 0-7619-9761-X 12.฀ Cooper฀WW,฀Seiford฀LM,฀Tone฀K฀(2007)฀Data฀envelopment฀analysis:฀a฀comprehensive฀text฀ with models, applications, references. Springer ISBN 978387452814

Municipal Solid Waste Management with Citizen Participation: An Alternative Solution to Waste Problems in Jakarta, Indonesia Aretha Aprilia, Tetsuo Tezuka, and Gert Spaargaren

Abstract The verity that ascertains waste as one of the contributors to CO2 emission leads the discourse to enter the limelight. Formulating suitable waste management scheme for developing countries such as Indonesia would require careful considerations that take into account the specific local context. This paper argues that in view of decentralization planning in Indonesia, the roles of local government and citizens in waste management are more imperative than ever. It provides an overview of current practices in waste management that takes the perspectives of the citizens as the end-users and the government as the regulator. The practices of solid waste management in Jakarta are observed at the municipality and community level in order to suggest further approaches to enable the initiative as a sustainable long-term solution. Keywords Community฀ •฀ Indonesia฀ •฀ Municipal฀ solid฀ waste฀ •฀ Public฀ participation฀ •฀Waste฀management

1

Introduction

Waste฀is฀one฀of฀the฀sources฀of฀greenhouse฀gas฀emissions฀that฀contributes฀1.4฀Gt฀or฀ 3% of the total CO2 emissions [1]. Although minor levels of emissions are released through waste treatment and disposal, the prevention and recovery of wastes avoids emissions in all other sectors of the economy [2]. Developing country

A. Aprilia (*) and T. Tezuka Department of Energy Science, Graduate School of Energy Science, Kyoto University, Kyoto, Japan e-mail: [email protected] G. Spaargaren Department฀of฀Environmental฀Policy,฀Wageningen฀University,฀ Wageningen,฀The฀Netherlands e-mail: [email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_7, © Springer 2011

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governments฀are฀facing฀various฀constraints฀in฀MSW฀management,฀therefore฀active฀ public participation to support the household waste management is prerequisite. Currently there are 94 areas in Jakarta that already operate waste management with ‘3R program’. These areas can reduce waste of up to 485 t per day, which is around 7% of the total waste generation [3]. Among the areas that already undertake 3R program, there are several communities that are actively supporting the neighborhood-based waste management, such as Rawajati community. The purpose of this paper is to provide an overview of the current existing condition of municipal solid waste management with the particular focus on household wastes. For the purpose of this research, the three main actors behind the community-supported neighborhood based waste management in Rawajati were interviewed and the waste management practices at the community level are observed.

2

Operational System of Community Waste Management in Rawajati

Rawajati฀ ward฀ is฀ located฀ in฀ Pancoran฀ district,฀ South฀ Jakarta.฀ The฀ ward฀ has฀ been฀ successful in motivating the community to implement the autonomous community waste management program [4]. The organic wastes that are produced by the ten neighborhood units within one neighborhood clusters in which 686 households reside at Rawajati ward that are involved in the community-based waste management scheme is around 2.67 kg/ household. It consists of 60% organic waste, 28% inorganic waste, 2% hazardous waste, and 10% paper waste [5]. Based on field observation and discussion with the main actors of waste management in the community level, the operational flow of waste management in Rawajati is presented in Fig. 1 below.

Home Transfer station

Organic Communal

Inorganic

Hazardous & chemical

Final disposal site

Waste residues

Recycled

Collection bin

Collected by Cleansing Department

Fig. 1 Household waste management flow in Rawajati community (Source: Analysis)

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3

3.1

A. Aprilia et al.

Barriers of Community-Supported Neighborhood Based Waste Management Barriers on Policy

Citizen participation is an increasingly important factor in planning and development policies following the decentralization legislation in Indonesia. The capacity of citizens to plan and deliver services have immediate relevance as the country moves฀to฀a฀decentralized฀planning฀model฀following฀Law฀No.฀22฀and฀Law฀No.฀25,฀ passed฀in฀1999,฀which฀were฀followed฀up฀with฀Law฀No.฀32฀year฀2004฀on฀Regional฀ Governance. The enactment of these laws has changed Indonesia from a highly centralized state, with governance, planning, and fiscal management partially ‘de-concentrated’ to provincial government offices, to a decentralized state with autonomous power over these responsibilities ‘devolved’ to lower levels of government. From a policy perspective, successful decentralization rests on the assumption that citizens through their participation in civil society organizations will undertake many planning and service-delivery functions previously the responsibility of various levels of government [6]. The฀same฀notion฀of฀decentralization฀applies฀to฀MSW฀management฀in฀Indonesia,฀ in which the laws that are devised by the state government are to be followed by regional regulations as guidelines for the technical implementation. Currently, the implementation฀of฀MSW฀management฀in฀Indonesia฀does฀not฀refer฀to฀any฀specific฀ guidelines or require any regulations compliance since the policy formulation is still at early stage. The follow up of the laws that should be translated into regional policies are still underway, which are expected to provide effective baseline for devising regional policy that largely depends on specific regional context. According to the Government Regulation no. 03 year 2001, the regional government has the main authority to manage the wastes in their respective jurisdiction area [7]. The master plan of waste management in Jakarta is mainly based on two major฀ laws:฀ Law฀ No.฀ 18฀ year฀ 2008฀ and฀ the฀ Medium฀ Term฀ Development฀ Plan฀ Jakarta฀Province฀year฀2007–2012. In฀ 2006,฀ The฀ Minister฀ of฀ Public฀ Works฀ issued฀ a฀ National฀ Regulation฀ no.฀ 21/ PRT/M/2006฀on฀the฀National฀Policy฀and฀Strategies฀for฀the฀Development฀of฀Waste฀ Management฀System.฀This฀regulation฀addressed฀that฀the฀communities฀are฀potential฀ to be involved in the waste management; however it is not yet systematically developed. Under this regulation, there are several policies that were devised; among others are the minimization of wastes optimally from the source and improvement of active roles of the society and private sectors as waste management partners. Further฀to฀this,฀the฀President฀of฀Republic฀of฀Indonesia฀enacted฀the฀Law฀No.฀18฀year฀ 2008฀on฀Waste฀Management,฀which฀defines฀wastes฀as฀the฀remaining฀of฀daily฀human฀ activities and/or natural process in solid formation. This law was established considering the waste management to date that is not yet according to the methods and techniques of sustainable waste management, therefore resulted in negative impacts

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upon public and environmental health. It is stated in the law that waste has been a national issue so that the management should be done comprehensively and in integrated manner in order to give benefits economically, health benefits for the public, and environmentally safe, as well as to enable behavioral shift in the society. Article 3 of the law specifically mentions that waste management is conducted based on various principles, including sustainability, benefits, togetherness, awareness, and฀economic฀values.฀With฀regard฀to฀sorting,฀it฀is฀regulated฀under฀article฀13,฀which฀ states that the managers of residential areas, among others, must provide facilities for waste sorting. The Government Regulation that serves as the regulation for implementation of waste฀management,฀which฀is฀to฀be฀issued฀following฀the฀Law฀No.฀18/2008฀on฀waste฀ management, is not yet released. Due to the unavailability of regulation, the municipalities continue to operate waste management scheme without proper mechanism or guidance. There are no stringent measures or law that regulates the sanctions against illegal dumping, improper treatment and disposal of waste. According฀to฀Law฀No.฀18/2008,฀waste฀generation฀must฀be฀minimized฀from฀the฀ source to reduce the burden of waste transport and disposal. The law also highlighted the importance of community in undertaking measures for waste reduction to minimize the burden of management and treatment. However, as these initiatives are still voluntary, not many communities are willing to apply the initiative. Financing฀ the฀ municipal฀ solid฀ waste฀ management฀ (SWM)฀ operation฀ would฀ require hefty funds; however the government failed to impose retribution for waste management฀ from฀ the฀ households.฀ The฀ financing฀ of฀ SWM฀ largely฀ relies฀ on฀ the฀ Regional Budgets and based on the Regional Budget of Jakarta in 2010, the allocated funds for Cleansing Department is only 2.9% of the total Budget [8]. The communities are reluctant to pay retribution as they have already pay the monthly community waste management fee. There is little awareness on the role of Cleansing฀Department฀in฀MSW฀management.

3.2

Barriers on Technical Operations

Cleansing Department encounters problems with regard to infrastructure, such as lack of waste trucks and 40% of the existing trucks are obsolete [9]. This condition results in the service cover that cannot reach all Jakarta residents. Another constraints encountered by the department is the lack of available financing for promotion of 3R and community waste management for the reduction of waste generation. The people of Jakarta have little or no awareness on the existing problems on waste, and as the case of any mega-urban, the population relies heavily on disposable goods for convenience purposes. In the case of Rawajati, due to rapid urbanization some of the residents are what is termed as ‘seasonal residents’ or temporary residents. The residents’ mobility is therefore high, which leads to the urgent need to frequent socialization of the community waste management initiative. The initiative to promote the activities would

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also require the commitment and willingness of the community, especially the community leaders, to approach the new residents to participate. However based on the interview with the leaders, the decreasing commitment is encountered, which hinders the attempts to sustain the initiative. This condition is partly due to the fact that their involvements are voluntary; therefore no incentives are available to reward their activities. Another aspect that hinders the operation of this initiative is due to some of the householders that are not willing to participate. The majority of households that are not participants are mostly those who are working full-time and claim for not having the luxury of time and energy to sort and recover their wastes for composting and recycling. It is also observed that due to the small reward for undertaking such initiative, householders with good socio-economic status tend to resent the invitation to participate. At the same time, the rest of the householders that are already participate in the initiative also faces reluctance to continue such practice due to the little incentives obtained from producing compost and recycled handicrafts. The production of goods are not rewarded with compensation that commensurate their time and energy to produce them. The women group also faces problems with regard to the marketing of handicrafts. The society still has reluctance on using recycled products due to esthetical reasons. Therefore there is a very limited niche market for selling such products in Indonesia. In regards to composting, there is also an issue due to the seasonal needs of compost, which is mostly during nursery or planting period. That said, composts are not always marketable all-year round, and there is the need to have storage facilities during non-planting period.

3.3

Prospects for Sustainability of Initiative

The success and sustainability of community waste management largely depend on the commitment and dedication of the community leaders and members. The underlying reasons for householders to be involved in the initiative are comprised of several pull and push factors. The pull factors for the proactive involvement of the community leaders and members to manage their wastes, in addition to environmental concerns, is also compensation or incentives to commensurate their involvement. The sales of compost and recycled products generate revenues to the householders although the amount is relatively small. Additionally, the push factors are including the conditions of environment that is threatened by the improper treatment of wastes. The community has been facing several problems in the past due to the improper waste management. The burning of waste and the use of incinerators within the premises created major air pollution that reaped complaints from concerned citizens. Based on the observation, the commitment and involvement of community leaders and members is decreasing subsequent to the relatively successful operation since 2001. One of the solutions to address this issue is to enable successors to step in and lead the operations for a certain period of time. There is also the need to raise the awareness of the society on the current waste crisis faced by Jakarta in order to

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encourage voluntary measures on the reduction of waste at households. Several measures to ensure the sustainability of initiative may include the creation of incentives to be incorporated in the Regional Regulation, which could be direct such as additional income, or indirect incentives such as the provision of waste sorting bins, waste shredders, etc. To address the issue on the limited market availability, government and private sectors may take part in marketing of recycled goods. For instance is to establish regulation for manufacturers to take back packaging of their produced goods and to assist in exporting the recycled handicrafts.

4

Conclusions

This research emphasizes on the importance of community support in the current waste management scheme in order to ease the burden of high volume of waste to be disposed at the landfill. Indonesia has applied decentralization planning model that signifies the major roles of local governments and citizen participation in the planning and delivery of public services. In terms of municipal waste management, the development of policy remains in its take-off stage. The state government already devised the national law that is yet to be translated into local regulations that serve as implementation guidelines on municipal waste management. The current implementation of waste management is lacking clear guidelines and is based on self-regulating mechanisms within the neighborhood units. Retribution from the citizens cannot be imposed due to unawareness on the roles of government in terms of฀waste฀management฀as฀the฀self-provisioning฀scheme฀occurs.฀Moreover,฀retribution฀ is yet to be incorporated in the law and is not treated as a regulatory instrument. As such, the government relies heavily on Regional Budgets as the source of financing. Given the constraints of the government to provide full service to all aspects of the waste flows, the current mechanism to involve citizen participation is prerequisite and needs to be improved. The community waste management practices has demonstrated the possibility of active involvement of the community in reducing waste generation฀through฀various฀schemes.฀While฀collective฀citizen-participation฀evolves฀ in the typically low-to-medium income community, it cannot prevail without the existence of market mechanism and appealing stimulus. Acknowledgments The authors are grateful to the Global Centre of Excellence (GCOE) Program฀of฀Kyoto฀University’s฀Graduate฀School฀of฀Energy฀Science฀for฀the฀financial฀support฀of฀this฀ research.

References 1.฀Stern฀N฀(2006)฀Stern฀Review:฀The฀Economics฀of฀Climate฀Change,฀UK฀Treasury 2.฀UNEP฀IETC฀(2010)฀Waste฀and฀Climate฀Change:฀Global฀trends฀and฀strategy฀framework,฀Osaka/ Shiga

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3. Cleansing Department (2010) 3R programme at neighbourhood and regional scales 4.฀Department฀of฀Public฀Works฀(2008)฀Best฀practices฀of฀solid฀waste฀management฀in฀Indonesia 5.฀Waste฀ Management฀ Task฀ Force฀ (2008)฀ Integrated฀ waste฀ management฀ in฀ Rawajati฀ ward,฀ Pancoran,฀South฀Jakarta 6. Beard V (2005) Individual determinants of participation in community development in Indonesia.฀Environ฀Plann฀C฀Gov฀Policy฀23:21–39 7.฀Jakarta฀Regional฀Government฀(2010)฀Regulation฀of฀the฀Jakarta฀Regional฀Government฀No.฀03฀ Year 2001 8.฀Jakarta฀Provincial฀Government฀(2010)฀Regional฀Budget.฀Available฀online:฀http://www.jakarta. go.id/jakv1/apbd/browse/2010#browse 9.฀Cleansing฀Department฀(2010)฀Master฀plan฀of฀waste฀management฀in฀Jakarta

The Influence of the Electrification in Erdos Grassland in Inner Mongolia, China Wuyunga and Tetsuo Tezuka

Abstract This paper is based on the questionnaire and interview of the nomadic family in Erdos Grassland of Inner Mongolia. This survey analyzes the change in nomadic lifestyle and culture by comparing daily activities and ethnic cultures between electrification and non-electrification families. Although a variety of activities in life have changed after electrification, the basic nomadic sense of value seems to have been preserved. Keywords Electrification฀•฀Erdos฀grassland฀•฀Lifestyle฀change฀•฀Nomadic฀family

1

Introduction

Inner Mongolia is in the north of China mainland. It is known as the largest pasture area in China. The dispersed residence peculiar to the nomadism in this large area has kept 75,000 people in non-electrified lifestyle [1]. Due to the disperse lifestyle and the volume of the renewable energy in local area, the local government started to introduce the independent power plant such as WHS (wind power home system) and SHS (solar energy home system) in order to improve the nomadic life by electrification in 1980 [1]. Thus, the electrical appliances such as radio, television, washing machine, refrigerator, rice cooker have become available for nomadic family. The use of the electrical appliance has not only improved their lives but also had a profound influence on the society and culture in various perspectives. Especially the information and communication appliances such as radio, television, computer and cell phone have changed the ethnic culture drastically with the information flow from modern society.

Wuyunga (*) and T. Tezuka Graduate School of Energy Science, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan e-mail: [email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_8, © Springer 2011

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Wuyunga and T. Tezuka

This paper investigates the change in lifestyle, society structure and ethnic culture in Erdos grassland with the electrification mainly based on the results of the survey about the way of living and thinking of the local people during two periods; one is from August 4 to 14 and the other is from August 17 to 25 in 2009. The samples of the survey are 40 nomadic families. Half of the samples are located 10 km or more away from the village. Since the family leader answered the questionnaire, the age of the sample in the questionnaire means the age of the leader. The survey also includes interviews for the local government in the period of August 17 to 19 in 2009.

2

The Possession of Electrical Appliance

Table 1 shows the possession of electrical appliance. The battery-powered radio has also been applied in non-electrification area. It is verified that the television, light bulb and cell phone are possessed by all of the electrified families. The rice cooker is possessed by all families with the grid power or WHS of 300 W, while the washing machine prevails in all of the families with grid power. Young families of 20s, 30s are apt to possess every type of electrical appliances.

3

Changes in Lifestyle

In order to clarify the changes in nomadic lifestyle, activities and ethnic culture, six non-electrification samples have been removed, and the number of available samples is 34.

3.1

Changes with the Introduction of the Television

All answerers indicate that they have got more opportunities to get new information after electrification. The answer, “quite much more information”, accounts for 73.5% and the answer, “much more”, accounts for 26.5%. They get the information mainly from television or radio. Young families of 20s or 30s get most of their information from television while the elder families of 50s rely on the radio. Generally speaking, however, questionnaire results say that the radio is most important appliance for the families with or without electrification to get information. Nomadic฀people฀consider฀watching฀TV฀as฀a฀common฀activity฀in฀their฀daily฀life฀ after฀the฀electrification.฀The฀average฀time฀of฀watching฀TV฀is฀around฀4฀h฀in฀summer,฀ while 3 h in winter. The answer to the question about new information and knowledge฀ obtained฀ by฀ TV฀ says฀ that฀ 80%฀ of฀ samples฀ choose฀ “Learning฀ Chinese”.฀ Questionnaire results conclude that Chinese language has prevailed in nomadic area by the introduction of the television, that is, by electrification (See Table 2).

Table 1 Possession rate of home electric appliance (multiple-answer style, total samples: 40) Unit: % Electrification type Age structure Grid WHSWHSOverall Nonelectric electricity 100 W 300 W 20s 30s 40s Lamp 85.0 0.0 100.0 100.0 100.0 100.0 100.0 93.3 TV 85.0 0.0 100.0 100.0 100.0 100.0 100.0 93.3 Radio 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Washing 60.0 0.0 100.0 27.3 83.3 100.0 100.0 66.7 machine Refrigerator 32.5 0.0 63.6 9.1 41.7 100.0 50.0 33.3 Rice cooker 77.5 0.0 100.0 72.7 100.0 100.0 100.0 86.7 Cell phone 85.0 0.0 100.0 100.0 100.0 100.0 100.0 93.3 Computer 10.0 0.0 27.3 0.0 8.3 33.3 33.3 6.7

Over 60s 50.0 50.0 100.0 16.7 0.0 16.7 50.0 0.0

50s 80.0 80.0 100.0 40.0 20.0 80.0 80.0 0.0

The Influence of the Electrification in Erdos Grassland in Inner Mongolia, China 65

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Table 2 Information฀and฀knowledge฀obtained฀by฀TV฀(multiple-answer฀style,฀the฀number฀of฀ samples: 34)

Item

Unit: families Age structure Overall 20s 30s 40s

50s

Over 60s

Chinese language study Government policy Professional know-how on live-stock raising Health knowledge Information of overseas societies Others

27 13 18 12 21 2

3 2 2 2 1 0

1 0 0 1 0 0

3 1 2 3 3 0

6 2 3 2 5 1

14 8 11 4 12 1

Table 3 Roles of lighting (multiple-answer style, the number of samples: 34) Unit: families Age structure Item Overall 20s 30s 40s 50s Extending study hours 30 3 6 14 6 Facilitating moonlighting such as handiwork 22 1 4 11 5 Extending recreation hours 21 3 6 9 3 Facilitating cares for live-stock delivery 28 3 4 12 7 Others 2 1 0 0 1

Over 60s 1 1 0 2 0

Table 4 Income of the average live-stock farmer [2] Sales of livestock Sales of Kashmir Moonlighting Share in overall household income (1982) 24.2% 73.8% 0.8% Share in overall household income (2007) 20.0% 76.4% 3.4%

3.2

Changes with Residential Lamp

All families who answered the questionnaire say that the use of electric lamps is the most useful for improving their nomadic life. Time of using lamp in a day is around 4 h in summer and 3 h in winter. The answer to the question “which is the most important function of the residential lamp?” is shown in Table 3. Since the residential lamp can increase time for studying by 2 or 3 h in the evening, it is considered as an important factor for improving the children’s life. The use of lamp has made it฀ possible฀ for฀ the฀ Nomadic฀ people฀ to฀ help฀ the฀ delivery฀ of฀ the฀ livestock฀ even฀ at฀ night. The birth rate of livestock has increased after electrification. Women have had more time to make dairy products and, therefore, they could purchase more residential lamps (See Table 4).

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Table 5 Consumption of major foods per capita of live-stock farmer in Inner Mongolia [3] Unit: kg 1978 1998 2007 Actual Actual Actual consumption % consumption % consumption Item % Wheat 77.67 44.0 79.08 34.5 81.97 32.9 Rice 21.10 11.9 42.34 18.5 49.06 19.7 Fresh vegetable 41.00 23.2 57.01 24.9 55.35 22.2 Meat 23.84 13.5 36.11 15.8 44.48 17.8 Poultry 0.00 0.0 0.17 0.0 1.21 0.5 Animal fat 2.22 1.3 0.30 0.0 0.24 0.0 Vegetable฀oil 0.00 0.0 2.61 1.1 2.79 1.1 Egg 0.49 0.2 0.54 0.2 1.13 0.5 Milk and processed 10.40 5.9 11.08 5.0 13.25 5.3 products

3.3

Changes with Rice Cooker and Refrigerator

The possession rate of the rice cooker is 77.5% and that of refrigerator is 32.5%. Young families of 20s, 30s are the main users of both rice cooker and refrigerator. Over 80% of the answers indicate that they become able to eat rice in daily life with the rice cooker while 60% think they become able to eat vegetables with the refrigerator. Table 5 shows the ratios of principal food consumption in 1978, 1998 and 2007. It is shown that the food has been diversified since the rice cooker and the refrigerator began to prevail, that is, electrification started.

4

Comparison of the Ethnic Culture of Electrified Area with that of Non-Electrified Area

Sense of values about daily life shapes the lifestyle and determines daily activities. The sense of value can be a mixture of changeable one and stable basic one that does not easily change with the effect of environment of life. In this study both senses are investigated through interviews to local people (See Table 6). ฀(a)฀ From฀the฀results฀of฀the฀items฀from฀No.฀10฀to฀12,฀it฀is฀considered฀that฀the฀market฀ economy has much influence on “values of money” of the local people. Thus, it is concluded that “values of money” has been easily changed with the electrification. ฀(b)฀ From฀the฀results฀of฀the฀items,฀No.฀7฀and฀8,฀the฀ways฀of฀education฀of฀the฀local฀ people has been changing from the experience-based education in grazing life to the modernized education style. It is also the results of the electrification.

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Table 6 Questionnaire on sense of values in daily life [4] Unit: % Question items Q1 Inner Mongolia is the place of residence of Before Mongolian After Q2 Mongolian is nomadic ethnicity Before After Q3 Grazing is the best lifestyle in prairie Before After Q4 Water should be carefully and efficiently Before utilized After Q5 Horses are important friends for Before Mongolians After Q6 Desertification is the penalty handed down Before by God After Q7 Children must help in housework Before After Q8 Children must take care of infant liveBefore stocks After Q9 Children are expected to succeed Before After Q10 Income in the form of money is desired Before After Q11 Shopping is preferred to saving money Before After Q12 If salary is promising, working in cities is Before attractive After

Agree 100.0 100.0 100.0 100.0 83.3 94.1 100.0 100.0 66.7 88.2 66.7 88.2 66.7 58.8 66.7 44.1 50.0 88.2 33.3 94.1 16.7 94.1 0.0 52.9

Neither฀agree฀ Disagree nor disagree 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 16.7 0.0 5.9 0.0 0.0 0.0 0.0 0.0 33.3 0.0 5.9 5.9 33.3 0.0 3.0 8.8 16.7 16.7 5.9 35.3 0.0 33.3 8.8 47.1 50.0 0.0 5.9 5.9 33.3 33.3 0.0 5.9 16.7 66.7 0.0 5.9 0.0 100.0 0.0 47.1

The use of electric appliances has improved their quality of life and then the number of answers to want their children to succeed the stockbreeding in Erdos. This means that the way of thinking about education has also been changed by the electrification. ฀(c)฀ From฀the฀results฀of฀the฀items,฀No.฀5฀and฀6,฀the฀awe฀of฀“animal”฀and฀“god”฀also฀ has changed and diversified a little. However, most of the answers about “animal” and “god” with both of electrification and non-electrification show that the awe of “animal” and “god” has been kept in the nomadic life. ฀(d)฀ From฀the฀results฀of฀the฀items฀from฀No.฀1฀to฀4,฀the฀sense฀of฀value฀about฀“the฀ grassland and animals” and about Mongolians’ lives in Inner Mongolia” changes only a little and has been kept in the nomadic life.

5

Conclusion

This paper shows the results of the comparative study of the nomadic lifestyles and sense of values about daily life between the electrified and non-electrified families in Erdos. The results show that obvious changes have occurred in some daily

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activities and some sense of value about daily life after the electrification. The comparative study, however, shows also that nature-oriented way of thinking has been kept in nomadic people. Thus, more attention should be paid to taking advantage of the tradition nature-oriented lifestyle in order to expand the renewable energy system in the electrification process.

References 1.฀GEF฀ and฀ United฀ Nations฀ Development฀ Programme฀ (2009)฀ Renewable฀ energy฀ based฀ chinese฀ un-electrified region electrification 25:29 2.฀National฀ Bureau฀ of฀ Statistics฀ of฀ Erdos,฀ China฀ (2008)฀ Erdos฀ statistical฀ yearbook.฀ China฀ Statistics, Beijing 3.฀National฀ Bureau฀ of฀ Statistics฀ in฀ Inner฀ Mongolian,฀ China฀ (2008)฀ Inner฀ Mongolian฀ statistical฀ yearbook. China Statistics, Beijing 4.฀Gao฀L,฀Taoketao฀(2007)฀Grassland฀culture฀and฀modern฀civilization.฀Inner฀Mongolia฀Education฀ Press, pp 43–70

Part II

Renewable Energy Research and CO2 Reduction Research

The Potential of Biodiesel with Improved Properties to an Alternative Energy Mix Gerhard Knothe

Abstract Fuels derived from renewable biological sources (biomass) are prominent among the sustainable energy sources. Biodiesel, the mono-alkyl esters of vegetable oils or animal fats, is one of the significant biomass-derived fuels. It is obtained from vegetable oils or other triacylglycerol feedstocks by transesterification with an alcohol giving glycerol as co-product. While biodiesel is technically competitive with petrodiesel fuel, problems that have beset biodiesel include poor cold flow and oxidative stability. These problems are to a great extent due to most biodiesel fuels containing mainly the same five C16 and C18 fatty acid esters. Five methods, including fatty acid profile modifications, exist for overcoming these problems. Properties of neat esters show that enriching acids such as decanoic or palmitoleic acids in feedstocks may improve biodiesel properties. The alcohol also plays a role with esters other than methyl imparting more favorable properties to biodiesel. The technical problems of biodiesel also afflict feedstocks, perhaps more severely, with claimed high production potential. Thus, algae-based biodiesel fuels would likely possess worse cold flow and oxidative stability than most vegetable oil-based biodiesel. Hydrodeoxygenation of vegetable oil feedstocks yields renewable diesel, whose composition thus resembles petrodiesel. Properties, including mass and energy balance of biodiesel and renewable diesel are compared as are potential uses. Biodiesel has a favorable balance compared to other biomass-derived fuels, also when including co-products. For fuels such as biodiesel and others to be more competitive, fuel properties as well as economics and production potential need to be improved. Keywords Biodiesel฀•฀Energy฀balance฀•฀Feedstocks฀•฀Fuel฀properties฀•฀Renewable฀ diesel example

G. Knothe (*) U.S. Department of Agriculture, National Center for Agricultural Utilization฀Research,฀Peoria,฀IL฀61604,฀USA e-mail: [email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_9, © Springer 2011

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Introduction

Continuing and increasing world-wide concerns regarding the availability of petroleum and other “conventional” sources of energy have sparked the search for฀sustainable฀sources฀of฀energy.฀Liquid฀fuels฀obtained฀from฀biological฀sources฀ (biomass) such have found considerable in this connection and several have been commercialized. Biodiesel [1, 2], defined as the mono-alkyl esters of vegetable oils or animal fats or other triacylglycerol feedstocks, is among these fuels. Standards have been developed for biodiesel, notably the American standard ASTM D6751 [3] and the European standard EN 14214 [4]. This fuel is technically competitive with conventional petroleum-derived diesel fuel (petrodiesel). Advantages of biodiesel include domestic origin, renewability of most carbon atoms, compatibility with the existing fuel distribution infrastructure, reduction of most regulated exhaust emissions, low or no sulfur and aromatics content, biodegradability, safer handling due to high flash point, inherent lubricity, and a positive energy balance (>4:1). Problems associated with biodiesel include oxidative stability due to its content of unsaturated fatty acid chains, poor cold flow and a slight increase of nitrogen oxides (NOx) exhaust emissions in many emissions tests, although this problem may fade with time as increasing market penetration of new exhaust emissions technologies alleviates this effect. Therefore, the issue of improving biodiesel fuel properties, especially oxidative stability and cold flow is of great significance. Specific fatty acids, especially decanoic or palmitoleic acids, may be targets for enrichment in triacylglycerol feedstocks in order to improve biodiesel properties [5, 6]. Overall, five approaches to these problems exist [6]. Renewable฀diesel฀[7, 8] is another fuel that can be obtained from triacylglycerolbased feedstocks, albeit through a different process, namely hydrodeoxygenation instead of transesterification as in the case of biodiesel. This fuel more closely resembles the composition of petrodiesel as alkane-type hydrocarbons are its primary constituents. Thus its properties also more closely resemble that of petrodiesel of the (ultra-)low sulfur type. Both฀ biodiesel฀ and฀ renewable฀ diesel฀ are฀ thus฀ prime฀ examples฀ of฀ liquid฀ fuels฀ derived from biological sources and contribute to the mix of alternative energy sources that now exit. This article briefly discusses, with an emphasis on biodiesel, this contribution.

2 2.1

Discussion Overview of Biodiesel Properties

The major components of biodiesel are the esters of fatty acids, usually methyl esters, as methanol is the most common alcohol used to prepare biodiesel. The most common fatty acid methyl esters found in biodiesel are methyl palmitate (hexadecanoate;

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C16:0), methyl stearate (octadecanoate; C18:0), methyl oleate (octadecenoate; C18:1 D9), methyl linoleate (octadecadienoate; C18:2 D9, D12) and methyl linolenate (octadecatrienoate; C18:3 D9, D12, D15). The unbranched long-chain nature of fatty esters is the reason why biodiesel can be used in a diesel engine. They resemble the long-chain hydrocarbons, i.e. alkanes, that “ideally” constitute petrodiesel. For example,฀ hexadecane฀ is฀ the฀ high-quality฀ reference฀ compound฀ on฀ the฀ cetane฀ scale฀ (cetane฀number฀=฀100)฀used฀for฀diesel฀fuel฀ignition฀quality.฀Especially฀the฀saturated฀ fatty acid methyl (or other) esters C16:0 and C18:0 have high cetane numbers comparable to those of hexadecane or other long-chain alkanes. Cetane number decreases with increasing unsaturation and decreasing chain length [9]. Thus the cetane number of methyl oleate is around 55–58, that of methyl linoleate around 40–42 and that of methyl linolenate around 25 [10]. Minimum cetane numbers prescribed in biodiesel standards are 47 in the American biodiesel standard ASTM D6751 [3] and 51 in the European biodiesel standard EN 14214 [4]. The low temperature properties of biodiesel are affected by compound structure in a similar fashion. The melting points of fatty esters increase with increasing chain length and increasing saturation. The melting point of methyl stearate is 37.7°C, that of methyl palmitate 28.5°C, that of methyl oleate −20°C, methyl linoleate −43°C and methyl linolenate around −45°C [11]. The high melting points of the saturated esters affect the cloud point, the temperature at which the first solids form when cooling a fuel, and pour point, the temperature at which the fuel no longer flows, of biodiesel. For example, the cloud point of methyl soyate, which contains about 10–11% C16:0 methyl ester and 4–5% C18:0 methyl ester is around 0°C [12]. The cloud point of biodiesel from a feedstock containing even greater amounts of saturated esters, for example methyl esters of palm oil (>40% C16:0 methyl esters) is considerable higher. The cloud and pour point are affected by the amount and nature of the saturated esters with the nature of the lower-melting unsaturated esters not playing a role [13]. Minor constituents of biodiesel such as monoacylglycerols [14] (from the production process) and sterol glucosides [15] also affect cold flow. Similarly, oxidative stability, i.e., the tendency to react with oxygen in air, is also affected by compound structure. The saturated fatty esters are oxidatively stable. Increasing฀ unsaturation฀ leads฀ to฀ decreasing฀ oxidative฀ stability.฀ Relative฀ reaction฀ rates of oxidation when assigning methyl oleate a relative rate of 1 are 41 for methyl linoleate and 98 for methyl linolenate [16]. Thus the C18:2 and C18:3 esters are฀oxidatively฀very฀unstable.฀The฀so-called฀Rancimat฀test฀is฀prescribed฀in฀biodiesel฀ standards to assess oxidative stability. The minimum induction time using this test is 3 h in the ATSM D6751 and 6 h in EN 14214. However, even methyl oleate in the฀neat฀form฀does฀not฀meet฀the฀3฀h฀requirement฀[4]. This means that antioxidant additives฀will฀always฀be฀necessary฀to฀meet฀the฀oxidative฀stability฀requirements฀in฀ biodiesel standards. Kinematic viscosity is another fuel property affected by the fatty ester components. This property increases with increasing chain length and increasing saturation [17]. However, most biodiesel fuels meet the viscosity ranges prescribed in biodiesel standards which are 1.9–6.0 mm2/s in ASTM D6751 and 3.5–5.0 mm2/s in EN 14214.

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Decreasing kinematic viscosity is the major reason for the production of biodiesel from triacylglycerol feedstocks as the high viscosity of vegetable oils leads to engine deposits and other problems when using them as fuels. Other important properties and performance issues not addressed in biodiesel standards are lubricity and exhaust emissions, the latter being dealt with by a variety of regulations. For sake of brevity they are not discussed here.

2.2

Improvement of Biodiesel Properties

The brief discussion above shows that the task of improving biodiesel properties faces difficult obstacles. Improving cold flow by reducing saturated fatty esters reduces oxidative stability, improving oxidative stability by reducing unsaturated fatty esters worsens the cold flow behavior. Cetane number (and emissions) is affected negatively by reducing the amount of saturated esters. Five methods have been identified for improving the fuel properties of biodiesel [6]. These are: (a) the use of additives, (b) producing esters other than methyl, (c) changing the fatty acid profile through physical procedures, (d) the use of feedstocks with an inherently different fatty acid profile (e) or modifying the fatty acid profile of existing feedstocks through, say, genetic modification. The use of additives is straightforward. Issues to consider are additive compatibility if additives serving different purpose are used, influence of additives on other properties (for an example, See [18]), additive cost and the observation that many additives may not be as effective as claimed. Esters other than methyl appear to have advantageous properties. For example, ethyl esters generally have lower melting points than methyl esters [11] while not affecting oxidative stability or cetane number [10]. Branched esters such as isopropyl esters have been shown to possess lower crystallization temperatures (for example, isopropyl soyate crystallized at temperatures 7–11°C lower than methyl soyate, See [19]) while again not affecting oxidative stability or cetane number. The major disadvantage to this approach is that alcohols other than methanol are usually considerably more expensive and that changes to the transesterification reaction yielding biodiesel may be necessary. Physical procedures for modifying the fatty acid profile are based on winterization, i.e., repetitive application of cooling cycles with removal of higher melting components [20]. The effect on the fatty acid profile is to enrich the lower-melting polyunsaturated fatty acid chains. While this procedure improves the low-temperature properties, oxidative stability and cetane number are lowered. An interesting issue is to define biodiesel components that exhibit lower melting points and acceptable oxidative stability simultaneously while not comprising properties such as cetane number and kinematic viscosity. It has been discussed that palmitoleic acid (9(Z)-hexadecenoic acid; C16:1) and, when considering saturated chains, decanoic acid, are candidates fatty acid for enrichment in the fatty acid

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profiles of vegetable oils. The prime advantage is that their methyl esters possess lower melting points (approximately −34°C for methyl palmitoleate and −13°C for methyl decanoate [11]) while offering acceptable cetane numbers (51 to 56 for methyl palmitoleate and 51.6 for methyl decanoate [5]) and oxidative stability, although in the case of methyl palmitoleate no advantage over methyl oleate exists in this respect. Indeed, methyl esters produced from an oil, cuphea oil, enriched in decanoic acid (approximately 65%) showed improved cold flow properties (cloud point −9 to −10°C) with a cetane number around 55−56 and oxidative stability฀per฀Rancimat฀of฀approximately฀3−3.5฀h฀[21]. On the other hand, an oil moderately enriched in palmitoleic acid (15−20%) did not lead to a biodiesel fuel with improved properties, likely due to the presence of small amounts of highmelting esters of C20 and C22 saturated fatty acids [22]. It may be noted that the potential exhaust emissions of biodiesel from such oils were extrapolated from other studies [23, 24] and no disadvantages are likely, rather, exhaust emissions are likely more favorable than in the case of biodiesel fuels with more conventional fatty acid profiles. Oils obtained from algae have been finding increasing attention as potential biodiesel feedstocks (for example, See [25]), although critical voices have also been raised (for example, See [26]). The composition of numerous algal oils as compiled in some literature [27], however, raises concern that properties of biodiesel from these feedstocks may possess poor cold flow and oxidative stability simultaneously as may such oils exhibit high amounts of saturated and polyunsaturated fatty acids. It may be noted that biodiesel derived from other, inedible oils such as jatropha [28] does not offer any advantages in terms of fuel properties as many of these oils consist of the same C16 and C18 fatty acid as the conventional commodity oils. Feedstocks consisting largely of materials other than triacylglycerols may also pose a potential source of biodiesel [29–32]. The conversion (by microbiological procedures) to fatty acids may be tailored to enrich the fatty acid profile in acids with advantageous properties.

2.3

Renewable Diesel

As mentioned above, petrodiesel ideally consists of long-chain unbranched hydrocarbons,฀i.e.฀alkanes.฀Recently,฀procedures฀to฀produce฀such฀compounds฀from฀triacylglycerol feedstocks have found attention [7, 8]. The resulting product is best termed renewable diesel [8]. It has been stated that the procedure can be tailored to yield renewable diesel with different properties to, for example, with different cold flow properties. Thus this process is of interest for turbine ( jet) fuels as they are used฀for฀aviation฀purposes.฀Renewable฀diesel,฀its฀composition฀simulating฀petrodiesel,฀ therefore has properties similar to petrodiesel.

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Comparison of Biodiesel and Renewable Diesel

Regarding฀fuel฀properties,฀the฀observations฀made฀above฀for฀biodiesel฀vs.฀petrodiesel฀ largely hold for the comparison of biodiesel vs. renewable diesel due to the similarity of the latter with petrodiesel. The processes used to prepare biodiesel and renewable diesel vary considerably. This also leads to varying mass balances. This is illustrated in Fig. 1 using neat triolein, the triacylglycerol of oleic acid, as feedstock. When using triolein as feedstock, methyl oleate is the product of transesterification and heptadecane is the product of hydrodeoxygenation. Glycerol is the co-product of biodiesel production and propane a co-product of renewable diesel production. As both CO2 and propane are liberated during renewable diesel production, while during biodiesel production the glycerol ester moiety is “replaced” by the methyl ester moiety from methanol, the mass balance of renewable biodiesel production is lower than that of biodiesel. However, some of the energy used to produce renewable diesel is stored in the hydrocarbon product, leading to a higher energy content of the renewable diesel on a molar basis. The production of biodiesel from the triacylglycerol feedstock and alcohol generally is conducted at 60–65°C for 1 h at ambient pressure with a catalyst such as sodium methoxide while renewable diesel production฀requires฀more฀drastic฀conditions฀such฀as฀elevated฀temperature฀(around฀ 300°C) and pressure in the presence of hydrogen and a catalyst (typically sulfided NiMo/g-Al2O3 or CoMo/g-Al2O3). The more unsaturated the feedstock, the greater the hydrogen฀requirement฀is฀for฀producing฀renewable฀diesel.฀While฀the฀energy฀balance฀ of overall biodiesel production is known to be positive, that of renewable diesel production has not been definitively established, but is likely less favorable due to the฀more฀severe฀conditions฀required฀for฀its฀production.฀Another฀issue฀to฀consider฀ in this connection is that glycerol, a common commodity compound, is obtained “free” when producing biodiesel, eliminating the petrochemical route using propene as starting material. Otherwise, when using the same feedstocks, the other factors influencing the energy balance are the same. Biodiesel - Methyl oleate from triolein: C57H104O6 + 3 CH3OH MW 885.453

3 C19H36O2 + C3H8O3 3 x 296.495 = 889.458 = 100.5% mass app. 40000 kJ/kg = 39547 kJ/L

Renewable Diesel - Heptadecane from triolein: C57H104O6 + 6 H2 MW 885.453

3 C17 H36 + 3 CO2 + C3H8 3 x 240.475= 721.425= 81.5% mass app. 47500 kJ/kg =41310 kJ/L

Fig. 1 Production and mass balance of biodiesel and renewable diesel production as shown for triolein

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Thus, a possibility seems to be to use biodiesel and renewable in the applications where each offers the most benefits. For biodiesel these would be ground applications taking advantage of its better environmental properties and safer handling while for renewable diesel this would be aviation applications due to the possibility of producing a fuel with improved cold flow properties.

3

Outlook

Developing฀alternative฀fuels฀for฀liquid฀fuels฀to฀power฀compression-ignition฀engines,฀ including turbine (jet) engines, as well as burners and heaters is essential in light of the problems associated with dwindling petroleum reserves. Both biodiesel and renewable diesel are interesting alternatives, each with its one advantageous applications. Both fuels, and other biomass-derived fuels not discussed here, are affected by the issue of feedstock availability and supply. In the case of biodiesel, in order to enhance its contribution to an alternative energy mix, improvement of fuel properties, especially cold flow and oxidative stability is important. Modifying the fatty acid profile of the feedstocks to give inherently better properties is a long-term but promising approach to achieving this goal.

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฀12.฀ Dunn฀RO,฀Bagby฀MO฀(1995)฀Low-temperature฀properties฀of฀triglyceride-based฀diesel฀fuels:฀ transesterified methyl ester and petroleum middle distillate/ester blends. J Am Oil Chem Soc 72:895–904 13. Imahara H, Minami E, Saka S (2006) Thermodynamic study on cloud point of biodiesel with its fatty acid omposition. Fuel 85(12–13):1666–1670 ฀14.฀ Yu฀ L,฀ Lee฀ I,฀ Hammond฀ EG,฀ Johnson฀ LA,฀ Van฀ Gerpen฀ JH฀ (1998)฀ The฀ influence฀ of฀ trace฀ components on the melting point of methyl soyate. J Am Oil Chem Soc 75:1821–1824 ฀15.฀ Moreau฀RA,฀Scott฀KM,฀Haas฀MJ฀(2008)฀The฀identification฀of฀steryl฀glucosides฀in฀precipitates฀ from commercial biodiesel. J Am Oil Chem Soc 85:761–770 ฀16.฀ Frankel฀ EN฀ (2005)฀ Lipid฀ oxidation,฀ 2nd฀ edn.฀ The฀ Oily฀ Press,฀ PJ฀ Barnes฀ and฀ Associates,฀ Bridgwater ฀17.฀ Knothe฀G,฀Steidley฀KR฀(2005)฀Kinematic฀viscosity฀of฀biodiesel฀fuel฀components฀and฀related฀ compounds. Influence of compound structure and comparison to petrodiesel fuel components. Fuel 84:1059–1065 18. Schober S, Mittelbach M (2005) Influence of diesel particulate filter additives on biodiesel quality.฀Eur฀J฀Lipid฀Sci฀Technol฀107(4):268–271 ฀19.฀ Lee฀I,฀Johnson฀LA,฀Hammond฀EG฀(1995)฀Use฀of฀branched-chain฀esters฀to฀reduce฀the฀crystallization temperature of biodiesel. J Am Oil Chem Soc 72:1155–1160 ฀20.฀ Dunn฀RO,฀Shockley฀MW,฀Bagby฀MO฀(1997)฀Winterized฀methyl฀esters฀from฀soybean฀oil:฀an฀ alternative diesel fuel with improved low-temperature flow properties. SAE (Society of Automotive Engineers) Technical Paper Series 971682 ฀21.฀ Knothe฀ G,฀ Cermak฀ SC,฀ Evangelista฀ RL฀ (2009)฀ Cuphea฀ oil฀ as฀ source฀ of฀ biodiesel฀ with฀ improved fuel properties caused by high content of methyl decanoate. Energy Fuels 23:1743–1747 22. Knothe G (2010) Biodiesel derived from a model oil enriched in palmitoleic acid, macadamia nut oil. Energy Fuels 24:2098–2103 ฀23.฀ McCormick฀RL,฀Graboski฀MS,฀Alleman฀TL,฀Herring฀AM฀(2001)฀Impact฀of฀biodiesel฀source฀ material and chemical structure on emissions of criteria pollutants from a heavy-duty engine. Environ Sci Technol 35:1742–1747 ฀24.฀ Knothe฀G,฀Sharp฀CA,฀Ryan฀TW฀III฀(2006)฀Exhaust฀emissions฀of฀biodiesel,฀petrodiesel,฀neat฀ methyl esters, and alkanes in a new technology engine. Energy Fuels 20:403–408 25. Chisti Y (2007) Biodiesel from microalgae. Biotechnol Adv 25(3):294–306 26. van Beilen JB (2010) Why microalgal biofuels won’t save the internal combustion machine. Biofpr 91:41–52 27. Hu Q, Sommerfeld M, Jarvis E, Ghirardi M, Posewitz M, Seibert M, Darzins A (2008) Microalgal triacylglycerols as feedstocks for biofuel production: perspectives and advances. Plant J 54(4):621–639 28. Foidl N, Foidl G, Sanchez M, Mittelbach M, Hackel S (1996) Jatropha curcas฀L.฀as฀a฀source฀ for the production of biofuel in Nicaragua. Bioresour Technol 58:77–82 ฀29.฀ Kalscheuer฀R,฀Stölting฀T,฀Steinbüchel฀A฀(2006)฀Microdiesel:฀Escherichia coli engineered for fuel production. Microbiology 152:2529–2536 ฀30.฀ Keasling฀JD,฀Hu฀Z,฀Somerville฀C,฀Church฀G,฀Berry฀D,฀Friedman฀L,฀Schirmer฀A,฀Brubaker฀S,฀ del Cardayré SB (2007) Production of fatty acids and derivatives thereof, WO/2007/136762, November 29, 2007. http://www.wipo.int/pctdb/en/wo.jsp?WO = 2007136762 ฀31.฀ Wackett฀ LP฀ (2008)฀ Biomass฀ to฀ fuels฀ via฀ microbial฀ transformations.฀ Curr฀ Opin฀ Chem฀ Biol฀ 12:187–193 ฀32.฀ Stöveken฀T,฀Steinbüchel฀A฀(2008)฀Bacterial฀acyltransferases฀as฀an฀alternative฀for฀lipase-catalyzed฀ acylation for the production of oleochemicals and fuels. Angew Chem Int Ed 47:3688–3694

Net Energy Calculations for Production of Biodiesel and Biogas from Haematococcus pluvialis and Nannochloropsis sp. Luis F. Razon

Abstract Microalgae have been proposed as possible alternative feedstock for the production of biodiesel because of their high photosynthetic efficiency. However, the high energy input required for microalgal culture and oil extraction may negate this advantage. There is a need to determine whether microalgal biodiesel can deliver more energy than is required to produce it. Using the Cumulative Energy Demand method in Simapro®, net energy calculations were done on systems to produce biodiesel and biogas from two microalgae species: Haematococcus pluvialis and Nannochloropsis sp. In spite of very optimistic assumptions, the results show a large energy deficit for both systems. Largest contributions came from the energy required to culture the microalgae and the energy required to either dry the microalgae or to disrupt the cell wall. Recommendations are made to develop wet extraction and transesterification technology to make microalgal biodiesel systems viable from an energy standpoint. Keywords Biodiesel฀ •฀ Energy฀ balance฀ •฀ Haematococcus pluvialis฀ •฀ Microalgae •฀Nannochloropsis

1

Introduction

Biodiesel, the accepted name for fatty acid methyl esters derived from the oils of living things, has emerged as an immediately available, environmentally friendly alternative to petroleum-derived diesel fuel. However, some simple calculations would show that even if all of the vegetable oil in the world were converted to

L.F. Razon (*) Department of Chemical Engineering, De La Salle University, 2401 Taft Avenue, Manila, Philippines e-mail: [email protected]

T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_10, © Springer 2011

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biodiesel, the resulting production would fill only 18% of transport diesel fuel demand [1]. Hence, there is a need to develop alternative sources for biodiesel feedstock. Microalgae have a higher photosynthetic efficiency than terrestrial plants and would need less land to fill demand [2]. On the other hand, harvest and conversion of the algal oils to biodiesel is more complicated and expensive since the algal culture has inherently greater water removal requirements since the algal biomass concentration is only in the order of g L−1. While the microalgae are photosynthetic, algal culturing systems like photobioreactors and raceway ponds continuously use energy for agitation and supply of carbon dioxide. Because of this, Reijnders [3] suggested that energy gain from using photosynthetic microalgae for biodiesel might be less than energy demand. This was refuted by Chisti [4], however. In this study, we apply the Cumulative Energy Demand method from Simapro® 7.2.2 for two scenarios for obtaining biodiesel and biogas from microalgae. The data for key inputs like electricity and chemicals were obtained from the ecoinvent® database. Previous studies have made similar but not identical analyses [5–10].

2

Haematococcus pluvialis

Haematococcus pluvialis is a fresh-water, photosynthetic microalga that has been mentioned as a potential source of lipids for conversion into biodiesel [11] or for CO2 sequestration [12]. Figure 1 shows the proposed process flow diagram.

Fig. 1 Process flow diagram for the production of methyl esters and biogas from H. pluvialis

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85

To control alien species, a photobioreactor is used to periodically feed an axenic slurry into the raceway pond [12]. A flat-plate photobioreactor consumes 50–70 W m−3 [13]. The hydraulic power requirement for the raceway pond is estimated using the following equation [14]: P=

r QD d 102e

(1)

where P = power (kW), Q = the quantity of water in motion (m3 s−1), r = the specific weight of water (kg m−3), e = the efficiency of the paddle wheel and Dd is the head loss in m. For a channel with a rectangular cross-section, Q = w • v • d where w = width, d = depth and v is the velocity of the water. In this paper, the dimensions of the pond in [12] are used: w = 5.5 m and d = 0.12 m. Typical values for the water velocity, efficiency and head loss are v = 0.25 m s−1, e = 0.17 and Dd = 0.06 m, respectively [14]. These numbers result in a power estimate of 0.57 kW which is rounded up to 0.60 kW. For biomass productivity, the highest observed biomass concentration was 432 g m−3 and a fat content of 25% [12] were used. CO2 and nitrogen requirements were estimated using an elemental composition of H. pluvialis reported in [15]: 45.6% C, 8.2% H, 6% N, 0.58% S, 39.6% O (assumed, by balance). Nitrogen requirements are to be supplied by potassium nitrate. Phosphorus requirements from single superphosphate are estimated with the Redfield N:P ratio of 16 [16]. Energy for pumping CO2 into the pond was estimated by assuming 80% absorption of the CO2 into the water and a compressor head and efficiency of 58 cm and 30%, respectively. Electricity is provided by a nearby natural-gas fired combined heat and power (CHP) plant and the allocations are distributed according to the energy content of the heat and electricity. This source of electricity is used for all electrical power. The algal slurry from the pond is concentrated by via two stages: gravitational settling and microfiltration. The gravitational settling is accomplished without the use of flocculants because of the large size of H. pluvialis (19–29 um) [17]. Power requirements for thickeners are negligible [18]. The algal concentration in the underflow and the overflow are assumed to be ten times the original concentration and 0.2 times the original concentration respectively. The overflow is used as a feed to the biogas process. The power requirements to concentrate an algal slurry using a cross-flow microfilter by a factor of 48 is about 1.37 MJ m−3 [19]. The retentate is fed into a cracking bead mill to release the oil from H. pluvialis cysts [20, 21]. The bead mill requires 10.15 MJ • (kg dry weight)−1 [22]. Eighty percent recovery of oil in biomass was assumed. The cracked slurry is fed into a decanter, which is assumed to consume a negligibly small amount of power and recovers 80% of the oil. Process inputs for transesterification are taken to be similar to soybean biodiesel [23]. The theoretical biogas yield from the thickener overflow and the depleted algal slurry was computed using the elemental composition in [15] and the following equation [24]: a b   n a b  n a b Cn H a Ob +  n − −  H 2 O →  + −  CH 4 +  − +  CO2   2 8 4  2 8 4 4 2

(2)

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Sixty percent conversion was assumed, which is indicated in [24] as a reasonable assumption for more particulate substrates. Elemental nitrogen is also assumed to be 60% converted to ammonia compounds which can be recovered in a biofilter and used to augment pond fertilizer. Allocations are done on a dry solids basis and are indicated in Fig. 1. Three displacements were done: (1) filtrate from the microfilter displaces fresh water; (2) glycerin from transesterification displaces glycerin from palm oil and (3) the ammonium compounds from biogas displaces NH4NO3. Net energy calculations show that 1 kg of methyl esters from H. pluvialis oil, accompanied by 2.6 m3 of biogas at standard temperature and pressure (STP), requires 222 MJ of primary energy input (4 MJ for methyl esters and 218 MJ for the biogas). Since the energy derived from the biodiesel and the corresponding biogas are 37 and 51 MJ, respectively, the total energy output from the process is 88 MJ. There is an energy deficit. This conclusion is obtained despite optimistic assumptions throughout the analysis. The direct process contributions to produce the biodiesel and the biogas are summarized in Table 1. The three largest contributors are: (1) the electricity for the bead mill (70 MJ, 32%); (2) the electricity required for the photobioreactor (57 MJ, 26%) and (3) fertilizer (39 MJ, 18%). Another possible tactic for a more favorable energy balance is to recycle the thickener overflow to the raceway pond, thus minimizing or eliminating the need for the initial photobioreactor. Both of these alternatives (wastewater and thickener overflow) are insufficient however to eliminate the energy deficit.

3

Nannochloropsis sp.

Other microalgae that have been proposed as feedstock for biodiesel are those of the genus Nannochloropsis because of their high oil content and high biomass productivity [7]. The genus grows in salt water. While this means that specialized pumps and fittings need to be used because of the higher corrosivity of the salt water, this may be an advantage because fresh water use will be minimized. Figure 2 shows the proposed process. The dimensions and energy requirements of the raceway pond are assumed to be the same as the pond for H. pluvialis. Biomass yield is computed from an areal productivity of 16 g (dry weight) • m−2 d−1 [25] and a cell concentration of 0.35 g (dry weight) • L−1 [26]. The proximate composition is taken as: protein = 30.1%, fat = 30.2%, carbohydrate = 9.7%, moisture = 3.1% and ash = 26.9% [27, 28]. Elemental composition is taken from the empirical formula of carbohydrates, protein and fat which are C6H10O5, C5H7NO2 and C57H104O6 respectively [24]. From these data, oil yield, CO2 and fertilizer requirements are computed. Power requirements for CO2 injection and pond agitation are computed in a manner similar to that of the H. pluvialis case. Control of other species is achieved by chlorination with 4 ppm of sodium hypochlorite [25]. Electricity for the energy needs are provided by a natural-gas fired CHP plant with the energy burden allocated according to the amount of energy

Net Energy Calculations for Production of Biodiesel and Biogas Table 1 Direct process contributions to of biogas at STP from H. pluvialis Process Photobioreactor KNO3 P2O5 Electricity Raceway pond KNO3 P2O5 Electricity Microfilter Allocation for thickener underflow Electricity from CHP plant Credit for “fresh” water Bead mill Electricity Transesterification Allocation for oil Methanol NaOH NaOCH3 Electricity from CHP plant Heat from CHP plant Credit for glycerin Total for methyl esters Biogas generation Allocation for depleted algal cake Allocation for thickener overflow Electricity from CHP plant Treatment (sewage) Credit for ammonium compounds Total for biogas

87

produce 1 kg of methyl esters and 2.6 m3 Amount

Energy equivalent (MJ)

0.032 kg 0.018 kg

2.9 0.9 57

0.34 kg 0.10 kg

30 4.7 27

1,200 kg

100 2.2 −6.0

−1,100 kg

70

0.2 kg 0.002 kg 0.01 kg

−0.2 kg

28 kg 13,000 kg 13 m3 −0.013 kg

5.7 15 0.2 1.3 0.1 2.8 −21 4.0 160 22 3.3 33 −0.7 218

provided as electricity and heat. The algal slurry is concentrated using a gravity thickener to recover 90% of the biomass. Al2(SO4)3 flocculant is necessary because of the small size of Nannochloropsis (2–4 um) [7]. The thickened slurry is dried to a cake (90% solids) using a sewage sludge belt drier, which consumes 3.35 MJ kg−1 of evaporated water [29]. The oils are extracted at 96% efficiency by leaching with hexane and transesterified using processes similar to soybean [23]. Biogas conversion of the depleted algal cake is assumed to proceed in the same manner as the one for H. pluvialis. The same allocation and displacement practices as that for the H. pluvialis case are adopted. Energy demand calculations for the process show that the primary energy input to produce 1 kg of methyl esters from algal oil and 1.5 m3 of biogas at standard temperature and pressure is 290 MJ, which is allocated as 66 MJ for the methyl

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Fig. 2 Process flow diagram for the production of methyl esters and biogas from Nannochloropsis

esters and 224 MJ for the biogas. The net energy output that may be expected from the 1 kg of methyl esters and the corresponding 1.5 m3 of biogas at STP are 37 and 25 MJ respectively. A net energy deficit again results. The direct process contributions to produce the biodiesel and the biogas are summarized in Table 2. The largest contributors to the energy usage are: (1) heat from the CHP plant for the dryer (120 MJ, 42%) and (2) sewage treatment for the biogas residue (72 MJ, 25%).

4

Conclusions

Neither of the systems would be practicable as purely energy generation systems; i.e., systems to take advantage of photosynthesis to produce more energy. Detailed full-chain energy analysis of methyl esters from jatropha [30] and palm oil [31] showed very favorable energy balances. The results from this paper do not the possibility that these systems would be desirable from a GHG-reduction viewpoint as concluded by Campbell et al. [6]. It is also possible that the energy products may be considered as by-products for more valuable products, as is the case for astaxanthin from H. pluvialis [12]. For the reasons discussed in the Introduction, fuel from algal biomass may still be the most viable long term source of renewable fuel. However, Zemke et al. [32] states that the theoretical thermodynamic limit of microalgal lipid production is only 14.5 kg m−2 a−1. In this study, the microalgal production rates used correspond to 13.3 kg m−2 a−1 for H. pluvialis and 5.8 kg m−2 a−1 for Nannochloropsis. It seems that very little improvement can be expected in this direction. Perhaps, the search for species to cultivate can de directed towards finding species that have thin cell walls and require minimal energy for disruption. Postharvest dewatering technology must be improved or perhaps eliminated altogether. A direct transesterification of fungal lipids using acid catalysts has been reported recently [33]. Such approaches would most likely be the ones to help microalgal biodiesel become viable.

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Table 2 Direct process contributions to produce 1 kg of methyl esters and 1.5 m3 of biogas at STP from Nannochloropsis Process Amount Energy equivalent (MJ) Raceway pond KNO3 0.05 kg 5.9 P2O5 0.04 kg 1.8 NaOCl 0.09 kg 1.6 Electricity 15 Thickener Al2(SO4)3 1.5 kg 13.9 HCl (15%) nil nil Algal biomass dryer Allocation for underflow 30 kg 35 Heat from CHP plant 120 Oil extraction Hexane 2.7 g 0.2 Electricity from CHP plant 20 Transesterification Allocation for oil 1 kg 67 Methanol 0.2 kg 15 NaOH 0.02 kg 0.2 NaOCH 3 0.01 kg 1.3 Electricity from CHP plant 0.5 Heat from CHP plant 2.8 Credit for glycerin −0.2 kg −20.9 Total for methyl esters 66.0 Biogas generation Allocation for depleted algal cake Allocation for thickener overflow Electricity from CHP plant Treatment (sewage) Credit for ammonium compounds Total for biogas

2.8 kg 10,600 kg 29 m 3 −0.2 kg

157 3.9 1.9 72 −11 224.0

Acknowledgements The advice and assistance of Dr Raymond Tan, Dr John Benneman and Mr. Long The Nam Doan is gratefully acknowledged. The University Research Coordination Office and College of Engineering of De La Salle University are thanked for the grant of a sabbatical leave. Lastly, the grant of a free license for Simapro® by Pre’ Consultants bv is most highly appreciated.

References 1. Razon L (2009) Alternative crops for biodiesel feedstock. CAB Rev Perspect Agric Vet Sci Nutr Nat Resour 4:056 2. Schenk PM, Thomas-Hall SR, Stephens E, Marx UC, Mussgnug JH, Posten C, Kruse O et al (2008) Second generation biofuels: high-efficiency microalgae for biodiesel production. Bioenergy Res 1:20–43

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3. Reijnders L (2008) Do biofuels from microalgae beat biofuels from terrestrial plants? Trends Biotechnol 26:349–350 4. Chisti Y (2008) Response to Reijnders: do biofuels from microalgae beat biofuels from terrestrial plants? Trends Biotechnol 26:341–352 5. Kadam K (2002) Environmental implications of power generation via coal microalgae cofiring. Energy 27:905–922 6. Campbell PK, Beer T, Batten D (2011) Life cycle assessment of biodiesel production from microalgae in ponds. Bioresour Technol 102:50–56 7. Jorquera O, Kiperstok A, Sales EA, Embiruçu M, Ghirardi ML (2010) Comparative energy life-cycle analyses of microalgal biomass production in open ponds and photobioreactors. Bioresour Technol 101:1406–1413 8. Clarens AF, Resureccion EP, White MA, Colosi LM (2010) Environmental life cycle comparison of algae to other bioenergy feedstocks. Environ Sci Technol 44:1813–1819 9. Lardon L, Helias A, Sialve B, Steyer J-P, Bernard O (2009) Life-cycle assessment of biodiesel production from microalgae. Environ Sci Technol 43:6475–6481 10. Sander K, Murthy GS (2010) Life cycle analysis of algae biodiesel. Int J Life Cycle Assess 15:704–714 11. Damiani MC, Popovich CA, Constenla D, Leonardi PI (2010) Lipid analysis in Haematococcus pluvialis to assess its potential use as a biodiesel feedstock. Bioresour Technol 101:3801–3807 12. Huntley ME, Redalje DG (2007) CO2 mitigation and renewable oil from photosynthetic microbes: a new appraisal. Mitig Adapt Strateg Glob Change 12:573–608 13. Lehr F, Posten C (2009) Closed photo-bioreactors as tools for biofuel production. Curr Opin Biotechnol 20:280–285 14. Borowitzka M (2005) Chapter 14: Culturing microalgae in outdoor ponds. In: Andersen RA (ed) Algal culturing techniques. Elsevier Academic, San Diego, CA, pp 205–217 15. García-Malea MC, Acién FG, Fernández JM, Cerón MC, Molina E (2006) Continuous production of green cells of Haematococcus pluvialis: modeling of the irradiance effect. Enzyme Microb Technol 38:981–989 16. Geider RJ, La Roche J (2002) Redfield revisited: variability of C:N:P in marine microalgae and its biochemical basis. Eur J Phycol 37:1–17 17. López MCG, Sánchez EDR, Casas López JL, Fernández FGA, Sevilla JMF, Rivas J et al (2006) Comparative analysis of the outdoor culture of Haematococcus pluvialis in tubular and bubble column photobioreactors. J Biotechnol 123:329–342 18. Genck WJ, Dickey DS, Baczek FA, Bedell DC, Brown K, Chen W et al (2008) Liquid–solid operations and equipment. In: Perry’s chemical engineers handbook, 8th edn. 19. Danquah MK, Gladman B, Moheimani N, Forde GM (2009) Microalgal growth characteristics and subsequent influence on dewatering efficiency. Chem Eng J 151:73–78 20. Mendes-Pinto MM, Raposo MFJ, Bowen J, Young AJ, Morais R (2001) Evaluation of different cell disruption processes on encysted cells of Haematococcus pluvialis: effects on astaxanthin recovery and implications for bio-availability. J Appl Phycol 13:19–24 21. Lorenz RT, Cysewski GR (2000) Commercial potential for Haematococcus microalgae as a natural source of astaxanthin. Trends Biotechnol 18:160–167 22. Doucha J, Lívanský K (2008) Influence of processing parameters on disintegration of chlorella cells in various types of homogenizers. Appl Microbiol Biotechnol 81:431–440 23. Huo H, Wang M, Bloyd C, Putsche V (2008) Life-cycle assessment of energy and greenhouse gas effects of soybean-derived biodiesel and renewable fuels. Argonne National Laboratory, Argonne, IL. http://www.transportation.anl.gov/pdfs/AF/467.pdf. Accessed December 2009 24. Angelidaki I, Sanders W (2004) Assessment of the anaerobic biodegradability of macropollutants. Rev Environ Sci Biotechnol 3:117–129 25. Zmora O, Richmond A (2004) Microalgae production for aquaculture. In: Richmond A (ed) Handbook of microalgal culture. Blackwell, Oxford, pp 365–379 26. Richmond A (2004) Biological principles of mass cultivation. In: Richmond A (ed) Handbook of microalgal culture. Blackwell, Oxford, pp 125–177

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27. Sukenik A, Zmora O, Carmeli Y (1993) Biochemical quality of marine unicellular algae with special emphasis on lipid composition. II. Nannochloropsis sp. Aquaculture 117:313–326 28. Rebolloso-Fuentes MM, Navarro-Pérez A, García-Camacho F, Ramos-Miras JJ, GuilGuerrero JL (2001) Biomass nutrient profiles of the microalga Nannochloropsis. J Agric Food Chem 49:2966–2972 29. SIEMENS (2008) Sludge dryers (company brochure EPS-SLUDGEDRY-USA-BR-0908). http://www.water.siemens.com/SiteCollectionDocuments/Product_Lines/Dewatering_ Systems/Brochures/EPS-SLUDGEDRY-USA-BR-1008.pdf Accessed 8 July 2010 30. Prueksakorn K, Gheewala SH, Malakul P, Bonnet S (2010) Energy analysis of Jatropha plantation systems for biodiesel production in Thailand. Energy Sustain Develop 14:1–5 31. Pleanjai S, Gheewala SH (2009) Full chain energy analysis of biodiesel production from palm oil in Thailand. Appl Energy 86:S209–S214 32. Zemke PE, Wood BD, Dye DJ (2010) Considerations for the maximum production rates of triacylglycerol from microalgae. Biomass Bioenergy 34:145–151 33. Vicente G, Bautista LF, Gutiérrez FJ, Rodríguez R, Martínez V, Rodríguez-Frómeta RA, Ruiz-Vázquez RM, Torres-Martínez S, Garre V (2010) Direct transformation of fungal biomass from submerged cultures into biodiesel. Energy Fuels 24:3173–3178

Characterization of Oligosaccharides with MALDI-TOF/MS Derived from Japanese Beech Cellulose as Treated by Hot-Compressed Water Kazuchika Yamauchi and Shiro Saka

Abstract Japanese beech was treated with two-step hot compressed water (first step, 230°C/10 MP/15 min: second step; 270°C/10 MP/15 min) and obtained various cellulose-derived compounds in the second step with relatively high molecular weights were characterized by MALDI-TOF/MS. As a result, cellulose-derived products such as cello-triose, cello-tetraose, cello-pentaose, cello-hexaose, celloheptaose, cello-octaose, and cello-nonaose, and their dehydrated compounds were identified. In spite of the fact that for these cellulose-derived products, supercritical water treatment in our previous study resulted in the dehydration and fragmentation reactions at the reducing end, two-step hot-compressed water treatment resulted only in dehydration reaction. This suggests that hot-compressed water treatment would be milder than that of supercritical water. These results indicate further that the MALDI-TOF/MS is a powerful tool to analyze the molecular structures of hydrolyzed oligosaccharides and evaluate decomposition pathway of lignocellulosics as treated with hot-compressed water. Keywords Cello-oligosaccharides฀ •฀ Hot-compressed฀ water฀ •฀ Japanese฀ beech฀ •฀ MALDI-TOF/MS

1

Introduction

Bioethanol from lignocellulosics has recently been attracted as an alternative liquid fuel for gasoline engine. Since lignocellulosics is the most abundant biomass resource on the earth, bioethanol from lignocellulosics can play an important role

K. Yamauchi (*) and S. Saka Graduate school of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan e-mail: [email protected]; [email protected]

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in mitigating the greenhouse gas emission [1, 2] and developing the sustainable society for the future [3]. Lignocellulosics is a composite material of cellulose, hemicellulose encrusted with lignin [4] which can be converted into fermentable sugars for ethanol production. Cellulose, however, is a crystalline polysaccharide composed of glucose linked together by (1 → 4)-glycosidic bonds making up about 40–50% of the dry wood mass. Acid hydrolysis with sulfuric acid has been used most frequently for saccharification of lignocellulosics to ferment for ethanol production [5–8]. In this process, water-soluble฀ sugars฀ are฀ separated฀ from฀ lignin.฀ However,฀ conventional฀ yeast฀ fermentation is able to convert hexoses such as glucose and mannose etc to ethanol, but neither pentoses such as xylose and arabinose, nor oligo-/polysaccharides. Therefore, it is necessary efficiently to hydrolyze lignocellulosics into hexoses. In our previous study, a new process of bio-ethanol production from lignocellulosics, by hot-compressed water treatment followed by acetic acid fermentation and hydrogenolysis has been developed [9]. The first stage of this process is based on two-step semi-flow hot-compressed water treatment. This stage can hydrolyze and decompose hemicellulose and cellulose separately without any catalysts used. The second stage is based on acetic acid fermentation in which not only hexoses and pentoses, but also uronic acids, oligosaccharides, dehydrated and fragmented products from saccharides were found out to be all converted to acetic acid by Clostridium thermoaceticum and Clostridium thermocellum. The final stage of this process is hydrogenolysis of the obtained acetic acid to ethanol. In this paper, cellulose-derived oligosaccharides from Japanese beech obtained by two-step semi-flow hot-compressed water treatment were analyzed with Matrix assisted laser desorption ionization combined with time-of-flight mass spectrometry (MALDI-TOF/MS) to characterize for its molecular structures, and elucidate decomposition pathway of lignocellulosics as treated with hot-compressed water. The elucidated pathway will be useful to study the potential of the following acetic acid fermentation in the new ethanol production process.

2 2.1

Materials and Methods Two-Step Hot-Compressed Water Treatment

Japanese beech (Fagus crenata) wood flour (18 mesh-passed) was used for hotcompressed water treatment. The wood flour was, therefore, extracted with ethanol– benzene (1:2 v/v) mixture by using Soxhlet apparatus, and dried at 105°C for 24 h before use. The conditions of the two-step semi-flow hot-compressed water treatment were 230°C/10 MPa/15 min for the first step and 270°C/10 MPa/15 min for the second step as reported in the previous paper [10]. In this study, however, the hot-compressed water-soluble portion collected at the second step mainly composing of the cellulose-derived oligosaccharides was analyzed with MALDI-TOF/MS.

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MALDI-TOF/MS Analysis

The obtained water-soluble portion was then studied by using MALDI-TOF/MS (Axima Performance, Shimadzu, Japan) equipped with a nitrogen laser (337 nm) after฀being฀mixed฀with฀matrix฀(DHB;฀2,5-dihydroxy฀benzoic฀acid)฀solution,฀applied฀ to a stainless steel sample slide and dried under vacuum. The obtained data is an average of 20 laser shot analyses. Cello-triose (Glc3), cello-tetraose (Glc4), cellopentaose (Glc5) and cello-hexaose (Glc6) (SEIKAGAKU CORPORATION, Japan) were used as standards of oligosaccharides. Mass spectrum is shown by m/z (mass to charge ratio). It calculates from mass number (m) of ion, and the number of its elementary charge (z). In case of the singly charged ion, the z value equals to one, and the m/z value shows directly mass number. Since saccharide ions have a high affinity with alkali metal ions, sodium ion (Na+: m/z 23) and potassium ion (K+: m/z 39) in the matrix reagent are associated with these saccharide ions during ionization [11].

3

Results and Discussion

In our previous study, the decomposition behavior of Japanese beech was studied in two-step semi-flow hot-compressed water treatment (first step: 230°C/10 MPa/ 15 min, second step: 270°C/10 MPa/15 min) [10]. As a result, hemicellulose and cellulose were, respectively, decomposed at the first and second stages. In the first step, xylo-oligosaccharides and xylose, glucuronic acid and acetic acid derived from a major hemicellulose of the hardwood, O-acetyl-4-O-methylglucuronoxylan were found. In addition, monomeric and dimeric lignin derived products were also found in the first step. While in the second step, various hydrolyzed and decomposed products, such as glucose, mannose as isomerized product of glucose, cellooligosaccharides, levoglucosan, were obtained from cellulose. Monosaccharides and other low-molecular weight compounds were able to be characterized [10].฀However,฀ it is difficult by these technologies to analyze high molecular weight products, such as oligosaccharides and polysaccharides. Therefore in this study, MALDI-TOF/MS was utilized for characterization of these oligosaccharides and polysaccharides. Figure 1a shows MALDI-TOF/MS spectra of the standard mixture of cellooligosaccharides such as cello-triose (Glc3), cello-tetraose (Glc4), cello-pentaose (Glc5), and cello-hexaose (Glc6). Molecular weights of these compounds are 506, 668, 830 and 992, respectively. Because of the Addison of sodium ion (Na+: m/z 23) in the matrix reagent, corresponding four peaks that show m/z 529.1 (506 + 23), 691.1 (668 + 23), 853.1 (830 + 23), and 1014.9 (992 + 23) were identified. In addition, potassium ion (K+: 39) is also associated with these saccharide ions instead of sodium ion (arrows in Fig. 1a). Figure 1b shows MALDI-TOF/MS spectra of hot-compressed water-soluble portion. The cello-triose (Glc3; m/z 529.2) cello-tetraose (Glc4; 691.3), cello-pentaose

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(Glc5; 853.3), cello-hexaose (Glc6; 1015.2), cello-heptaose (Glc7; 1177.1), cellooctaose (Glc8; 1338.9), and cello-nonaose (Glc9; 1500.7) were identified. Moreover, potassium ion (K+: m/z 23) associated cello-oligosaccharide (Glc3, Glc4, Glc5, Glc6 and Glc7) were also identified as corresponding peaks at m/z 545.2 (506 + 39), 707.3 (668 + 39), 869.2 (830 + 39), 1031.2 (992 + 39) and 1193.1 (1,154 + 39). In addition, additional peaks were appeared as shown by asterisks in Fig. 1b. These peaks must be corresponding to dehydrated cello-oligosaccharides such as cello-tricyl-levoglucosan, cello-tetracyl-levoglucosan, and cello-pentacyl-levoglucosan at m/z 673.3 [691.3 − 18.0], 835.3 [853.3 − 18.0] and 997.2 [1015.2 − 18.0]. Ehara et al., however, demonstrated that the glucose at the reducing end of cellooligosaccharide decompose to levoglucosan by dehydration, erythrose, and glycolaldehyde by fragmentation as treated with supercritical water under the condition of 380°C/40 MP/0.24 s [12]. Such fragmentation reaction did not take place in this hot-compressed water treatment. Therefore, hot-compressed water treatment must be milder than that of supercritical water. Detected peaks in MALDI-TOF/MS analysis derived from oligosaccharides show their parent peaks without any fragmentation. Therefore, the molecular weights of these peaks indicate the intact hydrolyzed compounds themselves by hot-compressed water. Through these lines of evidence on hydrolyzed and dehydrated

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compounds, decomposition pathway of cellulose as treated by the hot-compressed water can be elucidated and the molecular structures of hydrolyzed oligosaccharides can be identified. Such information would be useful to study the potential of the following acetic acid fermentation in the new ethanol production process. These results clearly indicate that the MALDI-TOF/MS is a powerful tool to analyze the molecular structures of hydrolyzed oligosaccharides and decomposition pathway of lignocellulosics as treated with hot-compressed water.

References ฀ 1.฀ Yuan฀JS,฀Tiller฀KH,฀Al-Ahmad฀H,฀Stewart฀NR,฀Stewart฀CN฀(2008)฀Plants฀to฀power:฀bioenergy฀ to fuel the future. Trends Plant Sci 13(8):421–429 ฀ 2.฀ Farrell฀AE,฀Plevin฀RJ,฀Turner฀BT,฀Jones฀AD,฀O’Hare฀M,฀Kammen฀DM฀(2006)฀Ethanol฀can฀ contribute to energy and environmental goals. Science 311:506–508 ฀ 3.฀ Hoogwijk฀ H,฀ Faaij฀ A,฀ van฀ den฀ Broek฀ R,฀ Berndes฀ G,฀ Gielen฀ D,฀ Turkenburg฀ W฀ (2003)฀ Exploration of the ranges of the global potential of biomass for energy. Biomass Bioenergy 25:119–133 ฀ 4.฀ Saka฀S฀(2000)฀Chemical฀composition฀and฀distribution.฀In:฀Hon฀DNS,฀Shiraishi฀N฀(eds)฀Wood฀ and cellulosic chemistry, 2nd edn. Marcel Dekker, New York, pp 51–81 5. Wyman CE (1994) Ethanol from lignocellulosic biomass: technology, economics, and opportunities. Bioresour Technol 50:3–16 ฀ 6.฀ Kim฀KH,฀Tucker฀MP,฀Nguyen฀QA฀(2002)฀Effects฀of฀pressing฀lignocellulosic฀biomass฀on฀sugar฀ yield in two-stage dilute-acid hydrolysis process. Biotechnol Prog 18:489–494 7. Galbe M, Zacchi G (2002) A review of the production of ethanol from softwood. Appl Microbiol Biotechnol 59:618–628 8. Kumar S, Singh SP, Mishra IM, Adhikari DK (2009) Recent advances in production of bioethanol from lignocellulosic biomass. Chem Eng Technol 32(4):517–526 ฀ 9.฀ Saka฀S,฀Phaiboonsilpa฀N,฀Nakamura฀Y,฀Masuda฀S,฀Lu฀X,฀Yamauchi฀K,฀Miyafuji฀H,฀Kawamoto฀ H฀(2009)฀Eco-ethanol฀production฀from฀lignocellulosics฀with฀hot-compressed฀water฀treatment฀ followed by acetic acid fermentation and hydrogenolysis. In: Proceedings of the 17th European biomass conference & exhibition, pp 1952–1957 10. Lu X, Yamauchi K, Phaiboonsilpa N, Saka S (2009) Two-step hydrolysis of Japanese beech as treated by semi-flow hot-compressed water. J Wood Sci 55(5):367–375 ฀11.฀ Gross฀JH฀(2004)฀Mass฀spectrometry:฀a฀textbook.฀Springer,฀Berlin 12. Ehara K, Saka S (2002) A comparative study on chemical conversion of cellulose between the batch-type and flow-type systems in supercritical water. Cellulose 9:301–311

Microwave/Infrared-Laser Processing of Material for Solar Energy Taro Sonobe, Kyohei Yoshida, Kan Hachiya, Toshiteru Kii, and Hideaki Ohgaki

Abstract Several approaches have been studied for microwave material processing for solar energy utilization such as upgrading the photocatalytic activity of TiO2, and improvement of efficiency in polymer solar cell. Recently, we observed the emission of zinc and oxygen plasmas from ZnO ceramics during intense absorption of microwaves as well as the deposition of zinc and zinc oxide films. This finding may lead to development of simple microwave-based methods for preparing thinfilm ZnO, an alternative of ITO thin-film, from ZnO ceramics. The mid-infrared free electron laser-based system is also proposed to investigate the mechanism of interaction between microwave and wide-gap semiconducting materials. Keywords Free฀electron฀laser฀•฀Microwave฀material฀processing฀•฀TiO2฀•฀ZnO

1

Introduction

Microwave฀heating฀has฀been฀progressively฀applied฀to฀research฀and฀development฀in฀ material professing so as to achieve energy conservation and efficiency improvement in conventional industrial processes, since it has several unique advantages such as rapid and selective heating over conventional methods. To date, numerous studies have addressed a novel capability of microwave processing such as the sintering of ceramics [1] and metal powder [2]. Sato et al. have reported that highly pure pig irons are obtained in a 2.45 GHz microwave reactor from powder iron ores with carbon as reducing agent [3]. We have also studied several approaches for microwave material processing toward solar energy utilization

T. Sonobe (*), K. Yoshida, K. Hachiya, T. Kii, and H. Ohgaki Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_12, © Springer 2011

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such as upgrading the photocatalytic activity of TiO2 [4], and improvement of efficiency in polymer solar cell [5]. Recently, we observed the emission of zinc and oxygen plasmas from ZnO ceramics during intense absorption of microwaves as well as the deposition of zinc and zinc oxide films [6]. This finding may lead to development of simple microwave-based methods for preparing thin-film ZnO, an alternative of ITO thin-film, from ZnO ceramics. In this paper, we focus on the mechanism of interaction between microwave and ZnO to emit zinc and oxygen plasmas. A mid-infrared free electron laser based system is also proposed to investigate the mechanism of interaction.

2

Experimental

Commercially available ZnO powder (99.9%) was used as the starting material. The powder (1 g) was pressed into a rectangular pellet (27.0 × 6.7 × 1.5 mm3) and then sintered in air in a furnace at 973 K (700°C) for 2 h before microwave heating respectively. The rectangular pellet of ZnO were placed on the quartz wool base in the quartz tube, the inside of the reactor was evacuated continuously using a rotary pump (~103฀Pa),฀and฀then฀the฀samples฀were฀heated฀at฀the฀maximum฀position฀of฀the฀ microwave electric field with 500 W of microwave power for 10 min under vacuum. During microwave heating, optical emission spectra from the chamber were measured using a CCD spectrometer from 400 to 1,050 nm in the wavelength. The detail configuration of microwave heating system was reported in the previous work [7]. X-ray diffraction (XRD) analyses were performed on a powder diffractometer (Rigaku RINT-2100). The ultraviolet–visible–near-infrared (UV–vis–NIR) diffuse reflectance spectra of pellets were obtained with a spectrophotometer (JASCO V-670฀spectrophotometer)฀in฀the฀wavelength฀range฀from฀200฀to฀2,400฀nm.฀PL฀spectra฀ was obtained by He–Cd laser (325/442 nm, Kimmon) excitation using a monochromator฀(Zoliz฀Omni-l฀300)฀and฀a฀CCD฀detector฀(INTEVAC฀Mosir฀350).

3 3.1

Results and Discussion Zinc Plasma Emission from Zinc Oxide Ceramics

The sintered ZnO pellet showed a marked absorption of the microwave under vacuum at the maximum point of the electric field. During microwave absorption, the sample started to glow intensely and emitted a blue-violet plasma continuously in the quartz tube. In contrast, the intense plasma emissions disappeared immediately when the microwave power was turned off, while red glow of the sample gradually faded. Figure 1 shows the optical emission spectra at 1, 60, 300 s and immediately after MW฀power฀off฀subsequent฀to฀the฀start฀of฀the฀plasma฀emission.฀The฀important฀spectral฀ features observed are the transition at 458, 472, 481, and 636 nm, which are indentified

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as arising from neutral zinc; the transitions at 589 and 773 nm, which are identified as arising from singly ionized zinc [8]; and the transitions at 777 and 845 nm, which correspond to neutral oxygen [8]. In addition, a broad peak at approximately 500–1,000 nm that gradually increased in intensity was observed after 30 s; it can possibly be attributed to some different luminescence induced by the microwave electric field. This broad luminescence can be still observed for several seconds after the microwave฀power฀was฀turned฀off.฀Moreover,฀the฀same฀luminescence฀can฀be฀induced฀ without any plasma emission when microwave is irradiated on the sample at high temperature. Figure 2 show the microwave power dependence of the broad

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Fig. 3 Photograph฀of฀the฀quartz฀tube฀reactor฀after฀MW฀plasma฀emission฀and฀XRD฀patterns฀of฀(a) black product on the quartz wall, and (b) white product on the quartz wall [6]

luminescence from ZnO and its peak intensity at 695 nm over applied microwave electric field. It is found that the peak intensity is monotonically increased with increasing the applied microwave electric field. The peak positions are not shifted while increasing temperature. This suggests the distinct behavior from black body radiation. After the emission of microwave plasma, black metallic films as well as white films were deposited on the inner wall of the quartz tube. Figure 3฀shows฀Photograph฀ of฀the฀quartz฀tube฀reactor฀after฀MW฀plasma฀emission฀and฀XRD฀patterns฀of฀(a)฀black฀ product on the quartz wall, and (b) white product on the quartz wall. It is interesting that zinc phase is identified at 36.0° (002), 38.7° (100), and 42.8° (101) in the black metallic film, while the white film exhibits the wurtzite structure of ZnO [9]. These results clearly indicate that one part of the zinc plasma was reoxidized by the atomic oxygen plasma after emission in the microwave electric field, while the other was deposited to form zinc and zinc oxide films outside the microwave electric field in the tube reactor. Figure 4฀ shows฀ the฀ PL฀ spectra฀ of฀ black฀ product฀ on฀ the฀ quartz฀ wall฀ and฀ white฀ product on the quartz wall. A green emission band of photoluminescence at 2.0–2.8 eV was observed, while the near-band-edge peak at 3.25 eV was observed only in black product. The former green luminescence at 2.0–2.8 eV is characteristic of the localized electronic states of lattice defects such as oxygen vacancies, zinc vacancies, so on in ZnO [10], and the latter at 3.25 eV is of near-band-edge luminescence from excitation, which is barely observed. Therefore, it is suggested that thin film fabrication from ZnO ceramics can be feasible after the optimization of microwave applied condition. Figure 5 shows the UV–vis–NIR absorption coefficients obtained from the diffuse฀reflectance฀spectra฀using฀the฀Kubelka–Munk฀relationship฀for฀the฀material฀ sintered at 700°C and subjected to microwave irradiation. As expected from their

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white color before microwave irradiation, the sintered pellets display little absorption at a wavelength of 410 nm. On the other hand, the sample exposed to the microwave plasma displays marked absorption from 400 to 2,400 nm. This suggests the emergence of numerous electronic states in the bandgap of ZnO during the time that the microwave plasma was glowing.

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This modification of the electronic states in the bandgap can also be observed in Fig. 6, which shows a green emission band of photoluminescence at 2.0–2.8 eV after microwave irradiation, in contrast to the broad and weak emission bands observed at 1.7–2.7 eV before microwave heating. These bands are characteristic of the localized electronic states of point defects, such as oxygen vacancies, zinc vacancies, zinc interstitials, oxygen interstitials, and oxygen anti-sites [10]. In addition, the near-band-edge UV emission at 3.0–3.4 eV was clearly separated into two peaks after plasma emission, compared with the single overlapped peak before microwave irradiation. A computational study partially demonstrated that the electronic states in the bandgap of ZnO were modified distinctly because of the introduction of defects [11], and it suggests that such variety of defect electronic states yield฀broad฀PL฀band฀during฀the฀emission฀of฀zinc฀and฀oxygen฀plasma฀under฀microwave irradiation. The distinct reaction of microwave with TiO2 (Rutile) and ZnO [6, 7], which have an almost similar value of bandgap energy and its offset [12], is possibly caused by the different localized electronic states of point defects in TiO2 and ZnO. We can clearly observe that zinc and oxygen plasma were produced directly from the ceramic by microwave irradiation in vacuum, suggesting the occurrence of plasma emission from the ceramics under microwave electric field [6, 7]. As a result, zinc and zinc oxide films were produced directly from the ceramics without using zinc metal and oxygen gas as source materials. Thus, this finding may lead to the development of simple microwave-based methods for preparing thin film ZnO from ceramics, which can contribute to solve the shortage of ITO production.

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Fig. 7 Schematic฀diagram฀of฀MIR-FEL฀based฀PL฀measurement฀system฀(color฀figure฀online)

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Mid-Infrared Free Electron Laser Based System

It is well known that an infrared region light has a good resonance with phonon in some solid compounds such as metal oxides. In particular, ZnO of wide bandgap semiconducting materials shows unique electrical and optical properties through coupling of phonon with electronic structures, resulting in photochemical phenomena with microwave irradiation [6, 7]. The broad and long life time luminescence from ZnO in Figs. 1 and 2 is, possibly, the trace of interaction between microwave and wide-gap semiconducting materials. However, the direct mechanism of interaction between microwave and ZnO to increase a temperature is not clear, since the frequency of microwave is too low to directly couple with phonon and electron. Therefore,฀direct฀excitation฀of฀phonon฀by฀mid-infrared฀free฀electron฀laser฀based฀PL฀ measurement system has been developing to investigate the mechanism (Fig. 7).

4

Conclusion

We studied the effects of microwave irradiation on ZnO ceramics under vacuum to clarify emission of zinc and oxygen plasmas from ceramics, while focusing on the optical properties of the samples. We observed the production of atomic zinc and

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oxygen plasmas from the ceramic during intense absorption of microwaves under vacuum, which is similar to what was observed with TiO2 [6], and we obtained the films composed of zinc metal and zinc oxide. We also investigated the changes in the optical properties of sample surfaces. The UV–vis–NIR absorption coefficient spectra displayed a marked absorption from 400 to 2,400 nm for the sample after plasma฀ emission.฀ In฀ addition,฀ the฀ PL฀ spectra฀ showed฀ a฀ green฀ emission฀ band฀ at฀ 2.0–2.8 eV as well as two separated peaks near the band-edge. We suggest that zinc and oxygen plasma can be produced from the ceramic by microwave irradiation under vacuum. As a result, we were able to produce films composed of zinc metal and zinc oxide without using zinc metal or oxygen gas as a source material. This finding may lead to development of simple microwavebased methods for fabricating thin films from ceramics. In order to investigate the mechanism of interaction between microwave and ceramics, a mid-infrared free electron฀laser฀based฀PL฀measurement฀system฀was฀proposed. Acknowledgement The฀ authors฀ would฀ like฀ to฀ express฀ their฀ gratitude฀ to฀ Professor฀ Naoki฀ Shinohara฀and฀Dr.฀Tomohiko฀Mitani฀at฀Research฀Institute฀for฀Sustainable฀Humanosphere,฀Kyoto฀ University for their support of microwave equipment. A part of this study was supported by the Kyoto University Global COE program on Energy Science in the Age of Global Warming and a Grant-in-Aid฀ for฀ Young฀ Scientists฀ B฀ (20760468)฀ from฀ the฀ Japan฀ Society฀ for฀ the฀ Promotion฀ of฀ Science.

References ฀ 1.฀ Jida฀S,฀Suemasu฀T฀(1999)฀J฀Appl฀Phys฀86:839 2. Roy R, Agrawal D, Cheng J, Gedevanishvili S (1999) Nature 399:668 ฀ 3.฀ Sato฀M,฀Matsubara฀A,฀Takayama฀S,฀Sudo฀S,฀Motojima฀O,฀Nagata฀K,฀Ishizaki฀K,฀Hayashi฀T,฀ Agrawal฀ D,฀ Roy฀ R฀ (2006)฀ In:฀ Proceedings฀ of฀ the฀ 5th฀ Sohn฀ international฀ symposium฀ on฀ advanced processing of metals and materials, p 157 ฀ 4.฀ Sonobe฀T,฀Jitputti฀J,฀Hachiya฀K,฀Mitani฀T,฀Shinohara฀N,฀Yoshikawa฀S฀(2008)฀Jpn฀J฀Appl฀Phys฀ 47:8460 ฀ 5.฀ Yoshikawa฀O,฀Sonobe฀T,฀Sagawa฀T,฀Yoshikawa฀S฀(2009)฀Appl฀Phys฀Lett฀94:083301 ฀ 6.฀ Sonobe฀T,฀Mitani฀T,฀Hachiya฀K,฀Shinohara฀N,฀Ohgaki฀H฀(2010)฀Jpn฀J฀Appl฀Phys฀49:080219 ฀ 7.฀ Sonobe฀T,฀Mitani฀T,฀Shinohara฀N,฀Hachiya฀K,฀Yoshikawa฀S฀(2009)฀Jpn฀J฀Appl฀Phys฀48:116003 ฀ 8.฀ Sansonetti฀JE,฀Martin฀WC฀(2005)฀J฀Phys฀Chem฀Res฀Data฀34:1559 ฀ 9.฀ Li฀Y,฀Meng฀GW,฀Zhang฀LD,฀Phillipp฀F฀(2000)฀Appl฀Phys฀Lett฀76:2011 ฀10.฀ Lin฀B,฀Fu฀Z,฀Jia฀Y฀(2001)฀Appl฀Phys฀Lett฀79:943 ฀11.฀ Catlow฀CRA,฀French฀SA,฀Sokol฀AA,฀Al-Sounaidi฀AA,฀Woodley฀SM฀(2008)฀J฀Comput฀Chem฀ 29:2234 ฀12.฀ Roy฀ Morrison฀ S฀ (1980)฀ Electrochemistry฀ at฀ semiconductor฀ and฀ oxidized฀ metal฀ electrodes.฀ Plenum,฀New฀York

Pongamia pinnata as Potential Biodiesel Feedstock Fadjar Goembira and Shiro Saka

Abstract A review study was done for recent research on Pongamia pinnata, which has mostly emphasized on its potential as fuel feedstock. Regarding the raw Pongamia oil characteristics, seed oil-content is mostly considered. Some biodiesel production methods have been applied, but not the relatively novel process, such as supercritical treatment. Fuel properties and engine performances were also considered by some researchers, although the research results were so much varied. This could be due to the possible existence of varied species, indicated by various scientific names, which are all considered as Pongamia pinnata. Keywords Biodiesel฀feedstock฀•฀Oil฀characteristics฀•฀Pongamia pinnata

1

Introduction

The use of biodiesel as diesel engine fuel is nowadays increasing rapidly. This is due to the depletion of fossil-fuel reserves that makes petrodiesel price increased significantly, and some considerations towards some environmental issues, e.g., global warming due to CO2 emissions from fossil-fuel combustion. In order to fulfill biodiesel demands, various feedstock is being used, such as soybean in the United States, rapeseed in Europe, and palm oil in some Asian countries. However, they are all edible oils, which could create a new problem, i.e., competition between food and energy utilization of the oils. Therefore, some inedible feedstock has started to be taken into consideration, such as Jatropha curcas, and Pongamia pinnata. In this paper, the potential of Pongamia pinnata has been reviewed as biodiesel feedstock and evaluated from the research achievements to clarify the subjects for further study.

F. Goembira and S. Saka (*) Graduate School of Energy Science, Kyoto University, Kyoto, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_13, © Springer 2011

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Taxonomical Classification of Pongamia pinnata

Pongamia pinnata (L.) Pierre, hereinafter mentioned as Pongamia, is a nitrogen fixing tree that is native to India. This tree grows up to the average height of 8 m in 4 or 5 years with more than 50 cm of trunk diameter [1], and starts to produce seeds that could have initial moisture content around 8.56% [2] at the age of 4–7 years [3]. It survives on most soil types, and can withstand in the highest ambient temperatures of 27–38°C and the lowest of 1–16°C. Moreover, it is highly tolerable to drought and salinity [1, 4]. Pongamia breeding can be done by generative, vegetative [4, 5], and micropropagation methods [6, 7]. Pongamia trees are used as ornamental and shade trees that can also control soil erosion [4]. The wood is used for cooking fuels, and the ash is for dyeing, while the leaves and roots are used as poison sources for fish spears [3]. Extracted seed-oil is traditionally used for soap production, external medications, pesticide, and fuel for lamps or cooking [1]. The seed-cake is used as fertilizer and cattle fodder in spite of containing toxic compounds [8], which could however be pre-treated to minimize the risks [9]. Pongamia was found out in this study to be called Pongamia pinnata (L.) Merr., Pongamia glabra Vent., Milletia pinnata (L.) Panigrahi, Derris indica (Lam.) Bennet, Milletia novo-guineensis Kane & Hat., and Cytisus pinnaus (L.) in literatures [1, 3, 10–12]. Such several scientific namings suggest that Pongamia tree includes some different species or sub-species. As discussed later, fuel characteristics of Pongamia biodiesel are varied very much. This might be due to such different species or sub-species studied as Pongamia pinnata. The potential of Pongamia as biodiesel feedstock is due to its seed-oil content, which has been reported to be varied [2, 10, 13–15], but could be as high as 56% [10]. Furthermore, Pongamia’s productivity is up to 2,250 kg oil/ha/year [13], higher than that of soybean and rapeseed, i.e., 400 and 600 kg/ha/year, respectively. However, Pongamia has to compete with Jatropha curcas that can produce higher yield up to 2,500 kg oil/ha/year [16].

3 3.1

Pongamia pinnata as Diesel Engine Fuel Straight Pongamia Oil as Biodiesel Blends

Although the use of straight Pongamia oil in diesel engine is constrained by its high viscosity, blending it with petrodiesel up to 10 vol% [17] and 50 vol% [18] have been proven to be technically feasible. However, the experiments did not consider some important factors, i.e., long term oxidative stability of the blends, effects of the blends on engine, and the cold flow properties of the recommended fuel blends.

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3.2

113

Fatty Acid Methyl Esters (Biodiesel) from Pongamia Oil

Biodiesel can be produced from Pongamia oil by various methods, as reported by various researchers and summarized in Table 1. As can be seen from Table 1, various biodiesel production methods ended up with different yields. The main issue encountered in biodiesel production from Pongamia oil is high free fatty acid (FFA) content [21, 23–28]. However, at present, no reported research results were found on the use of supercritical treatment, which could handle the high FFA content issue [29, 30]. With regard to the fuel standards, there are two standards that could be referred to, i.e., European (EN-14214), and the United States (ASTM-D6751) standards. Based on the reviewed publications, there are some differences of compliance with the standards, which can be seen in Table 2. Most researchers reported compliance with both standards, although very few researchers measured all parameters. Table 1 Pongamia biodiesel production by various methods Method Reaction temp (°C) Reaction time (min) Yield (%) Ref. One-step catalyzed •฀ •฀ •฀ •฀ •฀ •฀ •฀ •฀ •฀

Alkali฀(CH3ONa) Alkali฀(KOH) Alkali฀(KOH)฀+฀tetrahydrofuran Alkali฀(KOH) Alkali฀(solid-Li/CaO) Alkali฀(CH3ONa) Alkali฀(solid-ZnO) Alkali฀(solid-montmorillonite) Alkali฀(solid-Hb฀Zeolite)

70 60 60 65 65 60 120 120 120

60 90 90 180 480 60 1,440 1,440 1,440

84 92 95 98 94.9 97.6 47 59 83

[19] [13] [13] [20] [21] [22] [13] [13] [13]

30 30 300 360 120 210 No data No data

89.5

[23]

90.4

[24]

91

[25]

97

[26]

Two-step catalyzed •฀ Acid฀(H2SO4)฀+ Alkali (KOH) •฀ Acid฀(H2SO4)฀+ Alkali (NaOH) •฀ Acid฀(ortho-phosphoric)฀+ Alkali (KOH) •฀ Acid฀(H2SO4)฀+ Alkali (NaOH)

45 45 45 45 66 66 65 65

Table 2 Compliance of pongamia biodiesel with some fuel standards Compliance with EN-14214 ASTM-D6751 Both standards Method Viscosity at 40°C – [19, 31] [13, 23, 25–27, 32–34] Acid value – – [19, 26, 31–34] Iodine value [32, 33] Not regulated – Flash point – – [13, 19, 26, 27, 31–36] Cetane number – [19] [22, 26, 27, 31–34]

Incompliance with both standards [22, 35] [13] – [22] –

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Table 3 Engine test results as reported by various researchers Parameter Drawn conclusion Corrosion Not significant and better than Jatropha biodiesel Engine power Lower than petrodiesel at higher engine speed Thermal efficiency Lower than petrodiesel Fuel consumption Higher than petrodiesel Smoke density Lower than petrodiesel CO emission Lower than petrodiesel Hydrocarbon emission Lower than petrodiesel NOx emission Lower than petrodiesel Higher than petrodiesel Engine noise Lower than petrodiesel

Ref. [31] [36] [32, 37, 38] [32, 39] [32, 33, 36, 38, 39] [32, 33, 35, 36, 38, 39] [35, 36, 38] [35, 39] [32, 33, 36] [33]

Viscosity is related to the fuel atomization, and potential clogging problem at fuel injectors, while acid value shows the fatty acid content of biodiesel, which is related to the potential of engine corrosion and deposit formation at injectors. As for iodine value, it corresponds to the level of fatty acid unsaturation of biodiesel, which is further related to the fuel oxidative stability. Flash point is connected to fuel volatility that influences safety during storage and transport, while cetane number is used to ensure that complete combustion takes place inside the engine combustion chamber. Further consideration is on the engine test result of Pongamia biodiesel, as summarized in Table 3. From Table 3, it could be concluded that most engine performance parameters show better performance than petrodiesel. Lower engine power and thermal efficiency, together with higher fuel consumption compared to those of petrodiesel are due to lower calorific value of biodiesel than that of petrodiesel [19, 22, 33, 39, 40]. Further, the different results on NOx emission data should be noted, since the higher oxygen content in biodiesel provides higher combustion temperatures together with the higher cetane number of biodiesel compared to petrodiesel, i.e., longer residence time in reaction chamber, which will result in promoting more NOx formation during the combustion process.

4

Conclusions

Pongamia pinnata has been proven to be one of potential energy crops for biodiesel production based on the results of various research activities. However, there is a lack of consistency of research results related to some fuel properties. This could be due to the possible existence of different sub-species of the plant. Therefore, further research activities on the aspect of plant taxonomy and fuel properties are very important to be done in order to complete the research projects that have been done earlier.

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References 1. Daniel JN (1997) Pongamia pinnata – a nitrogen fixing tree for oilseed. In: NFT highlights. NFTA 97–03 2. Pradhan RC, Naik SN, Bhatnagar N, Swain SK (2008) Moisture-dependent physical properties of Karanja (Pongamia pinnata) Kernel. Ind Crops Prod 28:155–161 3. Duke JA (1983) Pongamia pinnata (L.) Pierre, handbook of energy crops. Purdue University 4. Mukta N, Sreevalli Y (2010) Propagation techniques, evaluation and improvement of the biodiesel plant Pongamia pinnata (L.) Pierre – a review. Ind Crops Prod 31:1–12 5. Kesari V, Krishnamachari A, Rangan L (2009) Effect of auxins on adventitious rooting from stem cuttings of candidate plus tree Pongamia pinnata (L.), a potential biodiesel plant. Trees 23:597–604 6. Sugla T, Purkayastha J, Singh SK (2007) Micropropagation of Pongamia pinnata through enhanced axillary branching. In Vitro Cell Dev Biol Plant 43:409–414 7. Sujatha K, Hazra S (2007) Micropropagation of mature Pongamia pinnata Pierre. In Vitro Cell Dev Biol Plant 43:608–613 8. Singh P, Sastry VSB, Garg AK, Sharma AK, Singh GR, Agrawal DK (2006) Effect of long term feeding of expeller pressed and solvent extracted Karanj (Pongamia pinnata) seed cake on the performance of lambs. Animal Feed Sci Technol 126:157–167 9. Vinay BJ, Sindhu-Kanya TC (2008) Effect of detoxification on the functional and nutritional quality of proteins of Karanja seed meal. Food Chem 106:77–84 10. Ramadan MF, Wahdan KMM, Hefnawy HTM, Kinni SG, Rajanna S, Seshagiri M, Rajanna LN, Seetharam YN, Seshagiri M, El-Sanhoty RMES, Morsel JT (2009) Chromatographic analysis for fatty acids and lipid-soluble bioactives of Derris indica crude seed oil. Chromatographia 70:103–108 11. Scott PT, Pregelj L, Chen N, Hadler JS, Djordjevic MA, Greshoff P (2008) Pongamia pinnata: an untapped resource for the biofuels industry of the future. Bioenergy Resour 1:2–11 12. USDA, ARS, National Genetic Resources Program. Germplasm resources information network – (GRIN) (online database). National Germplasm Resources Laboratory, Beltsville, MD. http://plants.usda.gov/java/profile?symbol=MIPI9. Accessed 24 November 2009 13. Karmee SK, Chadha A (2005) Preparation of biodiesel from crude oil of Pongamia pinnata. Bioresour Technol 96:1425–1429 14. Kaushik N, Kumar S, Kumar K, Beniwal RS, Kaushik N, Roy S (2007) Genetic variability and association studies in pod and seed traits of Pongamia pinnata (L.) Pierre in Haryana, India. Genet Resour Crop Evol 54:1827–1832 15. Mukta N, Murthy IYLN, Sripal P (2009) Variability assessment in Pongamia pinnata (L.) Pierre germplasm for biodiesel traits. Ind Crops Prod 29:536–540 16. Razon LF (2009) Alternative crops for biodiesel feedstock, CAB reviews: perspectives in agriculture, veterinary science, nutrition, and natural resources 2009, 4 No. 056. CAB Int 17. Bajpai S, Sahoo PK, Das LM (2009) Feasibility of blending Karanja vegetable oil in petrodiesel and utilization in a direct injection diesel engine. Fuel 88:705–711 18. Agarwal AK, Rajamanoharan K (2009) Experimental investigations of performance and emissions of Karanja oil and its blends in a single cylinder agricultural diesel engine. Appl Energy 86:106–112 19. Srivastava PK, Verma M (2008) Methyl ester of Karanja oil as an alternative renewable source energy. Fuel 87:1673–1677 20. Meher LC, Kulkarni MG, Dalai AK, Naik SN (2006) Transesterification of Karanja (Pongamia pinnata) oil by solid basic catalysts. Eur J Lipid Sci Technol 108:389–397 21. Meher LC, Dharmagadda VSS, Naik SN (2006) Optimization of alkali-catalyzed transesterification of Pongamia pinnata oil for production of biodiesel. Bioresour Technol 97:1392–1397 22. Sarma AK, Konwer D, Bordoloi PK (2005) A comprehensive analysis of fuel properties of biodiesel from Koroch seed oil. Energy Fuels 19:656–657

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23. Sharma YC, Singh B (2008) Development of biodiesel from Karanja, a tree found in rural India. Fuel 87:1740–1742 24. De BK, Bhattacharyya DK (1999) Biodiesel from minor vegetable oils like Karanja oil and Nahor oil. Fett/Lipid 101:404–406 25. Sahoo PK, Das LM (2009) Process optimization for biodiesel production from Jatropha, Karanja, and Polanga oils. Fuel 88:1588–1594 26. Naik M, Meher LC, Naik SN, Das LM (2008) Production of biodiesel from high free fatty acid Karanja (Pongamia pinnata) oil. Biomass Energy 32:354–357 27. Das LM, Bora DK, Pradhan S, Naik MK, Naik SN (2009) Long-term storage stability of biodiesel produced from Karanja oil. Fuel 88:2315–2318 28. Karmee SK, Chandna D, Ravi R, Chadha A (2006) Kinetics of base-catalyzed transesterification of triglycerides from Pongamia oil. J Am Oil Chem Soc 83:873–877 29. Kusdiana D, Saka S (2004) Effects of water on biodiesel fuel production by supercritical methanol treatment. Bioresour Technol 91:289–295 30. Warabi Y, Kusdiana D, Saka S (2004) Reactivity of triglycerides and fatty acids of rapeseed oil in supercritical alcohols. Bioresour Technol 91:283–287 31. Kaul S, Saxena RC, Kumar A, Negi MS, Bhatnagar AK, Goyal HB, Gupta AK (2007) Corrosion behavior of biodiesel from seed oils of Indian origin on diesel engine parts. Fuel Process Technol 88:303–307 32. Baiju B, Naik MK, Das LM (2009) A comparative evaluation of compression ignition engine characteristics using methyl and ethyl esters of Karanja oil. Renew Energy 34:1616–1621 33. Nabi MN, Hoque SMN, Akhter MS (2009) Karanja (Pongamia pinnata) biodiesel production in Bangladesh, characterization of Karanja biodiesel and its effect on diesel emissions. Fuel Process Technol 90:1080–1086 34. Sarin A, Arora R, Singh NP, Sarin R, Malhotra RK, Kundu K (2009) Effect of blends of palm– Jatropha–Pongamia biodiesels on cloud point and pour point. Energy 34:2016–2021 35. Sureshkumar K, Velraj R, Ganesan R (2008) Performance and exhaust emission characteristics of a CI engine fueled with Pongamia pinnata methyl ester (PME) and its blends with diesel. Renew Energy 33:2294–2302 36. Sahoo PK, Das LM, Babu MKG, Arora P, Singh VP, Kumar NR, Varyani TS (2009) Comparative evaluation of performance and emission characteristics of Jatropha, Karanja, and Polanga based biodiesel as fuel in a tractor engine. Fuel 88:1698–1707 37. Kalbande SR, More GR, Nadre RG (2008) Biodiesel production from non-edible oils of Jatropha and Karanj for utilization in electrical generator. Bioenergy Resour 1:170–178 38. Rao TV, Rao GP, Reddy KHC (2008) Experimental investigation of Pongamia, Jatropha, and Neem methyl esters as biodiesel on C.I. engine. Jordan J Mech Ind Eng 2(2):117–122 39. Raheman H, Phadatare AG (2004) Diesel engine emissions and performance from blends of Karanja methyl ester and diesel. Biomass Energy 27:393–397 40. Sahoo PK, Das LM (2009) Combustion analysis of Jatropha, Karanja, and Polanga based biodiesel as fuel in a diesel engine. Fuel 88:994–999

Construction of a Novel Strictly NADPHDependent Pichia stipitis Xylose Reductase by Site-Directed Mutagenesis for Effective Bioethanol Production Sadat Mohammad Rezq Khattab, Seiya Watanabe, Masayuki Saimura, Magdi Mohamed Afifi, Abdel-Nasser Ahmad Zohri, Usama Mohamed Abdul-Raouf, and Tsutomu Kodaki Abstract Xylose reductase (XR) is one of the key enzymes for bio-ethanol production from lignocellulosic biomass. Intercellular redox imbalance, caused by different coenzyme specificity of XR and Xylitol dehydrogenase (XDH), has been thought to be one of the main factors of xylitol excretion. We previously succeeded by protein engineering to improve the ethanol production by reverse the XDH dependence from NAD+ to NADP+. In this study, we employed protein engineering to construct a novel strictly NADPH dependent XR from Pichia stipitis by site directed mutagenesis, in order to effective recycling of cofactor between XR and XDH, which subsequently reduce xylitol accumulation. Double mutant E223G/ S271A showed strictly NADPH dependent with 90% of wild-type activity. Keywords Coenzyme฀specificity฀•฀Site-directed฀mutagenesis฀•฀Xylose฀reductase

1

Introduction

Recombinant S. cerevisiae can ferment xylose through a fungal pathway involving two heterologous oxidoreductase genes. In this pathway, Pichia stipitis xylose reductase (PsXR), which prefers NADPH, reduces xylose to xylitol followed by Pichia stipitis xylitol dehydrogenase (PsXDH), which exclusively requires NAD+, oxidizes xylitol into xylulose. S. cerevisiae xylulokinase (XK) naturally phosphorylates xylulose to xylulose-5-phosphate, which is then metabolized by the glycolytic

S.M.R. Khattab, S. Watanabe, M. Saimura, and T. Kodaki (*) Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan e-mail: [email protected] S.M.R. Khattab, M.M. Afifi, and U.M. Abdul-Raouf Faculty of Science, Al-Azhar University, Assiut Branch, Assiut 71524, Egypt A.A. Zohri Faculty of Science, Assiut University, Assiut 71515, Egypt T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_14, © Springer 2011

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pathway via the pentose phosphate pathway. Overexpression of XK improves the efficiency of xylose fermentation [1, 2]. Although this fungal pathway is highly expressed in S. cerevisiae, the efficiency of ethanol production is somewhat obstructed by the unfavorable accumulation of xylitol due to the redox imbalance of coenzyme specificities between XR and XDH. Protein engineering has been widely used to address this issue. Since PsXDH accepts only NAD+, many researchers have changed the preference of XR to NADH in order to achieve effective recycling of NAD+/NADH pathway [3–5]. We previously succeeded to improve the fermentation process and ethanol production by convert the cofactor usage of XDH to NADP+ dependent [6]. In this study, site-directed mutagenesis of PsXR was performed to construct a strictly NADPH-dependent XR, in order to effective recycling of NADPH cofactor between XR and XDH.

2 2.1

Materials and Methods Cloning of PsXR Gene and Mutants Construct

The plasmid pQE-81L (Qiagen, Hilden, Germany), a plasmid for conferring N-terminal (His)6 -tag on the expressing proteins, was used for protein expression. The plasmid vector was constructed by introducing BamHI and PstI digestion sites to the gene using the following primers: XR Forward (5¢-CATACGGATCCTTCTATTAAGTTGAAC-3¢) and XR-Reversal (5¢-CTTGGCTGCAGTTAGACGAAGATAGG-3¢) [Bold letter for introducing BamHI and PstI digestion sites]. The amplified DNA fragment was introduced into the BamHI/PstI sites in pQE-81L. All XR mutations were introduced by site-directed mutagenesis, which was performed using PfuTurbo DNA polymerase (Stratagene) and PCR Thermal Cycler PERSONAL (TaKaRa, Otsu, Japan). The codons used for mutations which introduced in this study were as follows: E223G (GAA→GGA), E237A (GAG→GCG), E237D (GAG→GAC), E237G (GAG→GGG), S271T (TCC→ACC), S271A (TCC→GCC) and N272D (AAC→GAC). The PCR products were treated with DpnI enzyme to avoid cloning of the template plasmid. The mutations were confirmed by DNA sequencing and verified XR mutants were transferred in Escherichia coli DH5a for further use.

2.2

Expression and Purification of PsXR Enzymes

E. coli DH5a cells harboring the expression plasmids were grown at 37°C until 0.6 at 600 nm on super broth medium (per liter: 12 g tryptone, 24 g yeast extract, 5 ml glycerol, 3.81 g KH2PO4 and 12.5 g K2HPO4; pH 7.0) containing 50 mg ampicillin l−1. Protein expressions were induced by added 1 mM IPTG after cooling and incubate further 24 h at 18°C. The cells were then harvested and sonicated in 20 ml

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buffer A (50 mM sodium phosphate, pH 6.0, containing 0.3 M NaCl, 10 mM xylose, 5 mM 2-mercaptoethanol and 10 mM imidazole) per liter of culture for a total of 4–5 min, with cooling intervals on ice. Cell debris was removed by centrifugation. Ni2+-chelating affinity method (Ni-NTA-6xHis Spin Columns, QIAGEN) was used for purification of PsXR mutants after equilibration with buffer A, the cell lysate was loaded, washed four times by buffer B (buffer A containing 10%, v/v, glycerol and 50 mM instead of 10 mM imidazole), and the enzymes were then eluted by buffer C (buffer B containing 250 mM instead of 50 mM imidazole). Purified enzymes were confirmed by 10% acrylamide SDS-PAGE.

2.3

Enzyme Assays and Kinetic Parameters

Enzymes assays was described previously [7] and the kinetic parameters were calculated by Line weaver–Burk plots. Protein concentrations were determined using the Bio RAD Quick Start Bradford 1x Dye Reagent (Bio-Rad Laboratories, CA, USA) and measured the absorbance at 280 nm.

3

Results and Discussion

Although the differences between the two bindings sites of NAD(P)H are subtle and unclear [8], residues that can potentially increase NADPH dependency were selected. The first residue was Glu223, which is located at the end of the short rigid helix b7 of Candida tenuis XR crystal structure and has a critical effect on the contact of hydrogen bonds with both 2¢- and 3¢-hydroxyl groups of the adenosine ribose [9]. E223G was constructed and the enzyme activity with NAD(P)H were determined. XR activity with NADH was completely lost (Fig. 1). These results are in agreement with those of a previous study on other AKR enzymes in which analogous interactions were observed and there were no obvious potential contacts that precluded the absence of a 2¢ phosphate allowing for NADH binding [8]. Furthermore, this residue was subjected to a mutation trial and the result revealed that alteration of this site inhibits NADH binding [4]. In 3D structure model of PsXR, it has been reported that Glu223 and Phe236 can form three and two hydrogen bonds with NAD+, respectively [10]. As shown in Fig. 1, the specific activity of E223G mutant with NADPH was 39% compared to WT; catalytic efficiency was 12% compared to WT (Table 1). Although there were a decrease in the activity and catalytic efficiency compared to WT, E223G showed strict NADPH dependency. The second selected residue for single mutation was Glu237. This residue was selected from the 3D structure modeling and has one hydrogen bond that interacts with NAD+ but not with NADP+ [10]. This residue did not show any positive results for NADPH preference. Their NADPH/NADH ratio of WT, E237A, E237D, and E237G were 1.42, 1.6, 1.7, and 1.5 respectively as shown in Fig. 1. Although,

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Activity(U/mg)

16 14 12 10 8 6 4 2 0 WT

E223G E237A E237D E237G S271A S271T N272D

GD

GA

Fig. 1 Enzyme activities of PsXR wild-type and mutated enzymes. Black and grey bars indicated the activities with NADPH and NADH respectively; Values are average ±SD, n = 3

Table 1 Kinetic parameters of PsXR wild-type and mutants Kinetic parameters Enzymes Cofactor Km xylosea (mM) Kmb (mM) kcatb (min−1)

kcat/Km (mM−1/min−1)

XR WT NADPH 97.1 ± 4.8 16.2 ± 1.4 622 ± 22 38.6 ± 2.9 S271A NADPH 70.6 ± 8.7 30.1 ± 3.7 874 ± 50 29.0 ± 0.3 E237A NADPH 74.6 ± 9.1 60.3 ± 0.9 562 ± 27 9.31 ± 0.50 E223G NADPH 92.4 ± 8.5 57.4 ± 8.5 269 ± 36 4.71 ± 0.21 NADPH 270 ± 25 26.6 ± 1.2 528 ± 13 19.9 ± 0.6 GA♣ XR WT NADH 170 ± 23 30.6 ± 1.0 449 ± 22 14.7 ± 1.4 S271A NADH 180 ± 12 53.3 ± 4.4 480 ± 42 9.00 ± 0.40 E237A NADH 135 ± 14 9.97 ± 2.94 309 ± 23 33.1 ± 8.5 E223G NADH ND* ND ND ND GA♣ NADH ND ND ND ND a Xylose concentration was 400 mM *ND: Not detected, ♣Double mutant E223G/S271A b Six different concentrations of NAD(P)H between 50 and 300 mM were used

E237A mutant didn’t reveal any improvement toward NADPH, E237A showed positive results in terms of improved NADH preference as its catalytic efficiency increased by 2.26-fold with NADH and decreased by 4.14-fold with NADPH compared to WT (Table 1). For the second round of mutations, we investigated the binding sites of PsXR with NAD(P)H results. Mutations of Lys270 of PsXR improved the preference of NADH, while that of S271A increased the preference of NADPH [11]. S271A showed increase activity of NADPH with 126% of WT and decrease activity of NADH with 82% of WT. An increase of the activities in N272D with both NAD(P)H were observed [11], where the activity were 130% for both NADPH and NADH.

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Based on these results, a combination of S271A or N272D mutants with Glu223 mutants is expected to increase the activity of XR with NADPH. Double E223G/N272D (GD) showed small improvement in NADPH dependent and much improvement with NADH, where the activity increased 127% compared with mutant E223G with NADPH and the activity restored from zero to two with NADH (See Fig. 1). S271A mutant had greater NADPH preference as shown in Fig. 1. The activities with NADPH and NADH were 126% and 85% compared to WT, respectively. On the other hand, the activity of S271T mutant with NAD(P)H was nearly abolished as shown in Fig. 1, although this choice was selected by sequence alignment of Hypocrea jecorina XR, which has a strong NADPH preference. These data reflected the importance of this residue for NADPH preference and encouraged us to perform further investigations by combining S271A and Glu223 mutants. A combination of site-directed mutations of the residues Glu223 and S271A produced unique results. The double mutant E223G/S271A (GA) showed improvement in activity with NADPH compared to single Glu223 mutant. Figure 1 shows the specific activity of the double mutant GA. Its activity was 90% compared to WT. As shown in Table 1, the kcat of WT, and GA were 622, and 528 min−1, respectively; their Km for xylose were 97.1, and 270 mM, respectively; and their catalytic efficiencies were 38.6, 19.9 mM−1/min−1, respectively. We previously succeeded in improving xylose fermentation and ethanol production by combining PsXR WT with the mutated PsXDH which accepts only NADP+ (i.e., quadruple ARSdR mutant) [7], and overexpression of XK [12, 13]. It may provide further clues for understanding of importance of coenzyme specificities of XR and XDH, using the strictly NADPH-dependent PsXR of this study with the strictly NADP+-dependent PsXDH. It could be expected that more efficient xylose fermentation is achieved by an effective recycling of coenzymes of NADPH between XR and XDH. Acknowledgment This work was supported by the New Energy and Industrial Technology Development Organization (NEDO), Japan. It was also supported by a Grant-in-Aid for Young Scientists (B) (no. 21760636 to S.W.) and the Global Center of Excellence (GCOE) program for the “Energy Science in the Age of Global Warming,” a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture, Japan.

References 1. Eliasson A, Christensson C, Wahlbom CF, Hahn-Hägerdal B (2000) Anaerobic xylose fermentation by recombinant Saccharomyces cerevisiae carrying XYL1, XYL2, and XKS1 in mineral medium chemostat cultures. Appl Environ Microbiol 66:3381–3386 2. Matsushika A, Inoue H, Kodaki T, Sawayama S (2009) Ethanol production from xylose in engineered Saccharomyces cerevisiae strains: current state and perspectives. Appl Microbiol Biotechnol 84:37–53 3. Bengtsson O, Hahn-Hägerdal B, Gorwa-Grauslund MF (2009) Xylose reductase from Pichia stipitis with altered coenzyme preference improves ethanolic xylose fermentation by recombinant Saccharomyces cerevisiae. Biotechnol Biofuels 2:9

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4. Liang L, Zhang J, Lin Z (2007) Altering coenzyme specificity of Pichia stipitis xylose reductase by the semi-rational approach CASTing. Microb Cell Fact 6:36 5. Petschacher B, Nidetzky B (2008) Altering the coenzyme preference of xylose reductase to favor utilization of NADH enhances ethanol yield from xylose in a metabolically engineered strain of Saccharomyces cerevisiae. Microb Cell Fact 7:9 6. Watanabe S, Saleh AA, Pack SP, Annaluru N, Kodaki T, Makino K (2007) Ethanol production from xylose by recombinant Saccharomyces cerevisiae expressing protein engineered NADP+-dependent xylitol dehydrogenase. J Biotechnol 130:316–319 7. Watanabe S, Kodaki T, Makino K (2005) Complete reversal of coenzyme specificity of xylitol dehydrogenase and increase of thermostability by the introduction of structural zinc. J Biol Chem 280:10340–10349 8. Wilson DK, Kavanagh KL, Klimacek M, Nidetzky B (2003) The xylose reductase (AKR2B5) structure: homology and divergence from other aldo-keto reductases and opportunities for protein engineering. Chem Biol Interact 143–144:515–521 9. Kavanagh KL, Klimacek M, Nidetzky B, Wilson DK (2003) Structure of xylose reductase bound to NAD+ and the basis for single and dual co-substrate specificity in family 2 aldo-keto reductases. Biochem J 373:319–326 10. Wang JF, Wei DQ, Lin Y, Wang YH, Du HL, Li YX, Chou KC (2007) Insights from modeling the 3D structure of NAD(P)H-dependent D-xylose reductase of Pichia stipitis and its binding interactions with NAD and NADP. Biochem Biophys Res Commun 359:323–329 11. Watanabe S, Pack SP, Saleh AA, Annaluru N, Kodaki T, Makino K (2007) The positive effect of the decreased NADPH-preferring activity of xylose reductase from Pichia stipitis on ethanol production using xylose-fermenting recombinant Saccharomyces cerevisiae. Biosci Biotechnol Biochem 71:1365–1369 12. Matsushika A, Inoue H, Watanabe S, Kodaki T, Makino K, Sawayama S (2009) Efficient bioethanol production by a recombinant flocculent Saccharomyces cerevisiae strain with a genome-integrated NADP+-dependent xylitol dehydrogenase gene. Appl Environ Microbiol 75:3818–3822 13. Matsushika A, Watanabe S, Kodaki T, Makino K, Sawayama S (2008) Bioethanol production from xylose by recombinant Saccharomyces cerevisiae expressing xylose reductase, NADP+dependent xylitol dehydrogenase, and xylulokinase. J Biosci Bioeng 105:296–299

Evaluation of Different Methods to Determine Monosaccharides in Biomass Harifara Rabemanolontsoa, Sumiko Ayada, and Shiro Saka

Abstract Sulfuric acid, trifluoroacetic acid (TFA) and acid methanolysis methods for hydrolysis were evaluated and compared using standard monosaccharides and standard oligosaccharides. As a result, sulfuric acid hydrolysis was found to be suitable to determine crystalline cellulosic and amorphous xylanic saccharides. TFA method, however, could not achieve complete hydrolysis of cellooligosaccharides and xylooligosaccharides, while acid methanolysis was considered appropriate to determine monosaccharides in amorphous hemicellulose. Based on these lines of evidence, a combination of sulfuric acid hydrolysis and acid methanolysis methods was concluded to be appropriate to get accurate monosaccharides determination in biomass species, and the application of this combined method to Japanese beech, bamboo and rice husk samples presented reasonable results. Keywords Acid฀methanolysis฀•฀Biomass฀•฀Monosaccharide฀•฀Sulfuric฀acid฀•฀TFA

1

Introduction

Biomass resources being abundant and available have high prospectives for different applications such as biofuels, biochemicals and biomaterials. For those matters, one of the most interesting constituents of biomass is carbohydrate. Accurate determination of the monosaccharides is often needed to evaluate the potential of a given biomass for a specific application, to monitor processes or to improve them in an efficient way. Several methods are available to determine monosaccharides, and sulfuric acid hydrolysis method is one of the mostly used ones for its convenience as it can be

H. Rabemanolontsoa, S. Ayada, and S. Saka (*) Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_15, © Springer 2011

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combined with lignin determination [1]. Some authors, however, stated that sulfuric acid hydrolysis decomposes labile sugars but it has never been reported which kinds of monosaccharides are decomposed. Trifluoroacetic acid (TFA) hydrolysis and acid methanolysis are yet other widely used methods to depolymerize biomass polysaccharides. Although there are few comparisons of these methods [2], their potentials were not deeply evaluated. Therefore, the present work aims to evaluate those three most commonly used methods to determine monosaccharides in biomass. For that purpose, standard monosaccharides and oligosaccharides were studied for their hydrolysis behaviors and the obtained information was applied to different biomass species such as Japanese beech (Fagus crenata), rice husk (Oryza sativa) and bamboo (Phyllostachys pubescens). Based on these comparisons, an improved combined methodology was proposed for an accurate determination of monosaccharides in biomass.

2

Materials and Methods

Japanese beech (Fagus crenata), husk and straw of rice (Oryza sativa) as well as bamboo (Phyllostachys pubescens) samples were firstly milled with Wiley mill (1029-C, Yoshida Seikakusho Co., Ltd.) and sieved. The fractions containing particles 150–500 mm in size were extracted with acetone. The extractive-free samples were, then, used for the monosaccharides determinations through sulfuric acid hydrolysis and acid methanolysis methods. As for TFA method, holocellulose was used, prepared with sodium chlorite according to Wise et al. [3]. Sulfuric acid hydrolysis was carried out according to the method described by Saeman et al. [4], with minor modifications. In brief, 5 ml of 72% sulfuric acid was added to 0.3 g of extractive-free samples and left to pre-hydrolyze at 20–25°C for 2 h. The samples were, then, transferred to a 500 ml flask with addition of 186 ml of water to bring sulfuric acid concentration to around 3%. The flasks were, then, autoclaved at 121°C for 30 min. Subsequently, the samples were cooled, brought into 500 ml and filtered with 0.45 mm฀ Millipore฀ membrane฀ filter.฀ The฀ filtrate was neutralized using Dionex OnGuard II A cartridge and analyzed with high-performance anion-exchange chromatography (HPAEC) using CarboPac PA1 as column. For฀TFA฀hydrolysis,฀30฀ml฀of฀2฀M฀TFA฀was฀added฀to฀300฀mg฀of฀holocellulose,฀ and the mixture was autoclaved for 1 h at 121°C [5]. TFA was, then, evaporated and dried. The obtained monosaccharides were, then, diluted with 250 ml of deionizer water and analyzed with HPAEC using CarboPac PA1 as column. Acid methanolysis was performed following the method of Sundberg et al. [6] according฀to฀which฀2฀ml฀of฀2฀M฀HCl฀in฀anhydrous฀methanol฀was฀poured฀to฀10฀mg฀ of extractive-free sample for methanolysis at 100°C for 3 h, followed by neutralization with 100 ml of pyridine, cooling and sylilation using 150 ml฀HMDS฀(hexamethyldisilazane) with 80 ml฀TMCS฀(trimethylchlorosilane)฀overnight.฀The฀samples฀were,฀ then, analyzed with gas chromatography.

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Results and Discussion

3.1

Evaluation of Sulfuric Acid Hydrolysis

As shown in Table 1, sulfuric acid hydrolysis applied to standard monosaccharides engendered sugar decomposition mostly for rhamnose (Rhm, 66.2 wt% degraded), mannose฀(Man,฀9.5฀wt%),฀arabinose฀(Ara,฀8.1฀wt%)฀and฀galactose฀(Gal,฀8.1฀wt%).฀ Those monosaccharides are therefore very sensitive to the treatment, whereas xylose (Xyl) and glucose (Glc) are quite stable. The results for xylose and glucose from sulfuric acid hydrolysis are, thus, reliable. Hence, sulfuric acid hydrolysis is appropriate for neutral monosaccharides determination in cellulose and xylan.

3.2

Evaluation of TFA Hydrolysis

TFA hydrolysis was evaluated using rice straw and bamboo extractive-free samples as well as cellooligosaccharides (Cel5 and Cel4) and xylooligosaccharides (Xyl6). As represented in Table 2, the hydrolysates from rice straw, bamboo and cellotetraose (Cel4) still had some oligosaccharides. The 95 wt% xylose yielded

Table 1 Monosaccharides฀recovery฀after฀sulfuric฀acid฀treatment Recovery (wt% of standard monosaccharides) Glc Man Gal Rhm Xyl Ara Standards 1 100.0 87.2 89.4 36.7 99.4 84.1 Standards 2 100.0 97.2 94.7 35.0 99.0 91.6 Standards 3 100.0 87.2 91.7 29.8 100.0 100.0 Mean 100.0 90.5 91.9 33.8 99.5 91.9 Glc glucose, Man mannose, Gal galactose, Rhm rhamnose, Xyl xylose, Ara arabinose

Table 2 Monosaccharides฀ and฀ oligosaccharides฀ yield฀ from฀ 2฀ M฀ TFA฀ hydrolysis฀ of฀ rice฀ straw,฀ bamboo and standard oligosaccharides Yield (wt% of oven-dried samples and oligosaccharides) Hexoses Pentoses Oligosaccharides Glc Man Gal Rhm Xyl Ara Xyl2 Xyl4 Cel2 Cel4 Cel5 Rice straw 17.9 0.4 2.3 0 29.6 0.2 0.04 0.99 0.43 0.06 0 Bamboo 8.5 0.4 0.4 0 27.1 2.5 0.15 0 0 0 0.02 Xyl6 0 0 0 0 95.0 0 0 0 0 0 0 Cel5 98.0 0 0 0 0 0 0 0 0 0 0 Cel4 97.0 0 0 0 0 0 0 0 0 1.98 0 Glc glucose, Man mannose, Gal galactose, Rhm rhamnose, Xyl xylose, Ara arabinose, Xyl2 xylobiose, Xyl4 xylotetraose, Xyl6 xylohexaose, Cel2 cellobiose, Cel4 cellotetraose, Cel5 Cellopentaose

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from xelohexaose (Xyl6) corresponds actually to 83.6 wt% of dehydrated xylose, which is lower than the purity given by the supplier (>95%). Those results demonstrate฀ that฀ 2฀ M฀ TFA฀ hydrolysis฀ cannot฀ achieve฀ complete฀ hydrolysis฀ of฀ the฀ oligosaccharides.

3.3

Evaluation of Acid Methanolysis

Acid methanolysis was evaluated by Bertaud et al. [7] using different aldo-uronic acid, oligosaccharides, polysaccharides and thermomechanical pulp. For aldo-uronic acid analyses, they discovered that the glucuronosyl linkage between methylglucuronic acid and xylose was cleaved only to the extent of 70–80%. That finding might explain the slightly lower xylose yielded from acid methanolysis of Japanese beech and rice husk as compared with the data by sulphuric acid hydrolysis shown in Table 3. As for the oligosaccharide and polysaccharide model compounds, the amount of monosaccharides resulting from the acid methanolysis corresponded well to the quantity given by the suppliers [7]. Therefore, acid methanolysis is considered appropriate for the determination of hemicellulosic monosaccharides.

Table 3 Carbohydrate composition of three biomass species determined by three hydrolysis methods and the combined method Yield (wt% of original oven-dried biomass basis) Hexoses Pentoses Acid sugars Biomass Glc Man Gal Rhm Xyl Ara Gal-A Glc-A S Hol Japanese beech H2SO4 hydrolysis 41.7 1.4 0.5 0.4 21.3 0.3 0 0 58.6 TFA hydrolysis 1.7 0.7 0.2 0.2 14.0 0.1 0 0 14.9 Acid methanolysis 0.5 1.4 3.6 2.3 19.2 0.9 1.7 0.3 26.5 Combined method 41.7 1.4 3.6 2.3 21.3 0.9 1.7 0.3 65.5 Bamboo H2SO4 hydrolysis TFA hydrolysis Acid methanolysis Combined method

40.2 2.3 1.4 40.2

0.4 0 0.5 0.5

0.5 0.1 3.2 3.2

0 0 0.3 0.3

20.3 10.6 23.4 23.4

0.9 0.6 4.2 4.2

0 0 0.3 0.3

0 0 0.6 0.6

55.6 12.0 30.0 64.9

Rice husk H2SO4 hydrolysis TFA hydrolysis Acid methanolysis Combined method

34.9 3.5 0.5 34.9

0 0 0.2 0.2

0.9 0.2 1.7 1.7

0.1 0.0 0.3 0.3

17.8 4.2 17.6 17.8

1.5 0.4 2.1 2.1

0 0 0.3 0.3

0 0 0.1 0.1

49.3 7.4 20.1 51.3

Glc glucose, Man mannose, Gal galactose, Rhm rhamnose, Xyl xylose, Ara arabinose, Gal-A galacturonic acid, Glc-A glucuronic acid, S Hol saccharides in holocellulose S Hol = 162/180 S Hexoses + 132/150 S Pentoses + 176/194 S Acid sugars

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Comparison of Different Hydrolysis Methods

The monosaccharides compositions of three biomass samples subjected to different methods are represented in Table 3. Note that neither the amounts of acetyl groups nor other functional groups were determined. For that reason, the calculated saccharides in holocellulose lack those functional residues to correspond to the actual holocellulose. The high glucose yields obtained from sulfuric acid method represent mostly the crystalline cellulosic saccharides. If starch, other hemicellulosic glucose or both are present in the sample, they will also be included into the determined glucose. The฀ results฀ clearly฀ show฀ that฀ neither฀ methanolysis฀ nor฀ 2฀ M฀ TFA฀ hydrolysis฀ can฀ manage to cleave crystalline polysaccharides. The glucose contents obtained through those methods represent hemicellulosic glucose or amorphous parts of cellulose. TFA and sulfuric acid methods presented low hemicellulosic saccharides when applied to biomass samples. Therefore, those results from the biomass samples are in accordance with the results from the standard samples. Acid methanolysis gave high values of galactose (Gal), rhamnose (Rhm), mannose฀(Man)฀and฀arabinose฀(Ara),฀confirming฀its฀ability฀to฀cleave฀hemicellulosic฀and฀ pectic glycosidic bonds. Although xylose (Xyl) yields for Japanese beech and rice husk are slightly lower by acid methanolysis, the results are still comparable to those of sulfuric acid hydrolysis. Consequently, both methods are valid for xylose determination in biomass. These lines of evidence can suggest that only one simple method to determine complete carbohydrate composition does not exist. Thus, combination of sulfuric acid hydrolysis method for glucose determination and acid methanolysis method for other types of simple sugars is proposed for an appropriate determination of monosaccharides in biomass species. For the particular case of xylose, the higher value between the ones from sulfuric acid hydrolysis and acid methanolysis is chosen. The obtained results by such a combined method is reasonably good as shown in Table 3.

4

Conclusions

Sulfuric acid and TFA hydrolyses as well as acid methanolysis were evaluated. As a result, TFA method was discovered to be insufficient for a complete oligosaccharides hydrolysis. The inability of acid methanolysis to cleave xylose–glucuronic acid bonds in xylan is suggested but the xylose contents obtained from acid methanolysis were still comparable to those from sulfuric acid hydrolysis. Both methods are, therefore, considered reasonable for xylose determination. Furthermore, for its capacity to depolymerize crystalline cellulose without decomposition of the resulting glucose, sulfuric acid hydrolysis can be appropriate for glucose determination. Although acid methanolysis represented a slight drawback in the xylose determination, it is still superior to the other two methods for hemicellulosic and pectic sugar

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determinations. Therefore, the combination of sulfuric acid hydrolysis and acid methanolysis is proposed for an appropriate determination of monosaccharides in biomass. The glucose content is suggested to be determined by sulfuric acid hydrolysis, whereas the other monosaccharides by acid methanolysis. In the case of xylose, the higher value obtained between the two methods is taken as the xylose content. Acknowledgement This work was accomplished under financial support from Kyoto University Global Center of Excellence (GCOE) Energy Science Program.

References 1. Sluiter A, Hames B, Ruiz R, Scarlata C, Sluiter J, Templeton D, Crocker D (2008) Determination of structural carbohydrates and lignin in biomass. In: Laboratory analytical procedure (LAP). National Renewable Energy Laboratory (NREL), Golden, CO 2. Willför S, Pranovich A, Tamminen T, Puls J, Laine C, Suurnäkki A, Saake B, Uotila K, Simolin H, Hemming J, Holmbom B (2009) Carbohydrate analysis of plant materials with uronic acidcontaining polysaccharides-A comparison between different hydrolysis and subsequent chromatographic analytical techniques. Ind Crops Prod 29(2–3):571–580 3.฀Wise฀LE,฀Murphy฀M,฀Daddieco฀AA฀(1946)฀Chlorite฀holocellulose,฀its฀fractionation฀and฀bearing฀ on summative wood analysis and on studies on the hemicelluloses. Pap Trade 122(2):210–218 4.฀Saeman฀JF,฀Moore฀WE,฀Mitchell฀RL,฀Millet฀MA฀(1954)฀Techniques฀for฀the฀determination฀of฀ pulp constituents by quantitative paper chromatography. Tappi 37(8):336–343 5. Albersheim P, Nevins DJ, English PD, Karr A (1967) A method for the analysis of sugars in plant cell-wall polysaccharides by gas-liquid chromatography. Carbohydr Res 5(3):340–345 6. Sundberg A, Sundberg K, Lillandt C, Holmbom B (1996) Determination of hemicelluloses and pectins in wood and pulp fibres by acid methanolysis and gas chromatography. Nord Pulp Pap Res J 11(4):216–220 7. Bertaud F, Sundberg A, Holmbom B (2002) Evaluation of acid methanolysis for analysis of wood hemicelluloses and pectins. Carbohydr Polym 48(3):319–324

Pyrolysis and Secondary Reaction Mechanisms of Softwood and Hardwood Lignins at the Molecular Level Mohd Asmadi, Haruo Kawamoto, and Shiro Saka

Abstract Primary pyrolysis and secondary reactions of Japanese cedar (Cryptomeria japonica, a softwood) and Japanese beech (Fagus crenata, a hardwood) wood lignins were studied with open-top and closed-ampoule reactors in N2 at 400–600°C. Milled wood lignins (MWL) isolated from these wood samples were used along with several model aromatic compounds (guaiacol and syringol and their pyrolysis intermediates). Although the low molecular weight products from beech MWL included more syringyl-type of aromatic rings in primary pyrolysis, in the secondary reaction step, the yields of syringyl-characteristic products were quite lower than those of guaiacyl-characteristic products. Contrary to this, the beech MWL and syringol produced more coke. These results suggest that the syringyl-characteristic products are converted preferentially into coke, instead of other low MW products. The molecular mechanisms of these tar conversions are also discussed with the model compound data. Additional OCH3 group in syringylunit enhances the coke formation through double opportunity of the OCH3 rearrangement pathway, which includes o-quinonemethide as a key intermediate step for coke formation. Keywords Coke฀formation฀•฀Guaiacol฀•฀Lignin฀•฀Pyrolysis฀•฀Syringol

1

Introduction

Softwood and hardwood lignins have different aromatic nuclei compositions, i.e. guaiacyl– (4-hydroxy-3-methoxyphenyl)–type in softwood and guaiacyl– + syringyl– (3,5-dimethoxy-4-hydroxyphenyl)–types in hardwood. Such structural differences would make the pyrolysis behaviors of softwood and hardwood lignins

M. Asmadi, H. Kawamoto (*), and S. Saka Graduate School of Energy Science, Kyoto University, Kyoto, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_16, © Springer 2011

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different. In our previous study, some different features were identified in the pyrolysis behaviors of Japanese cedar (Cryptomeria japonica, a softwood) and Japanese beech (Fagus crenata, a hardwood) wood samples with an ampoule reactor (N2/600°C/40–600 s) [1]. Coke formation from the volatile products was more extensive in beech than cedar. Although lignin-derived tar components were different just after devolatilization, these became similar at longer pyrolysis time. In this paper, primary pyrolysis and secondary reactions behaviors of Japanese cedar and Japanese beech milled wood lignins (MWLs) were compared and discussed at the molecular level.

2

Experimental

Milled wood lignins were isolated from Japanese cedar and Japanese beech wood samples, and guaiacol, syringol and other aromatic compounds were purchased from Nacalai Tesque co. As an indicator of syringyl/guaiacyl (S/G) ratio, the syringaldehyde/vanillin (S/V) ratio obtained by alkaline nitrobenzene oxidation was 2.3 to the beech MWL. Two types of reactors were used in this study, namely open-top and closed ampoule reactors. Open-top reactor was used to study primary pyrolysis, since the volatile (tar) products are cooled down on the upper-side of the glass-wall before suffering from the secondary reactions. On the other hand, secondary reactions of the volatile products are expected in the closed ampoule reactor, became the volatiles are heated further at the set temperature. Sample (10 mg) was put in the bottom of a Pyrex glass ampoule (internal diameter: 8.0 mm; length, 120 mm; glass thickness, 1.0 mm). After exchanging the air inside the reactor with N2, the ampoule was closed (case of closed ampoule reactor) and heated in a muffle furnace at 600°C for 40–600 s. After pyrolysis, the ampoule was cooled by flowing air for 60 s, and the non-condensable gases produced were analyzed by Micro GC with thermal conductivity detector (TCD). Then, inside of the ampoule was extracted with methanol (2.0 ml), and the soluble fraction was analyzed by GC/MS to determine the lignin-derived low molecular weight (MW) products. The insoluble residues were obtained at the bottom of the reactor and on the glass wall at the upper side of the reactor are defined as “primary char” and “secondary char (coke)”, respectively. The amounts of gaseous, tar and char factions were determined by weight difference after gas collection or extraction. Pyrolysis and products analysis were similarly conducted with the open-top reactor, which consists of a glass tube reactor (10 mm in diameter and 300 mm long) attached with a nitrogen bag. Sample was placed at the bottom of the tube reactor and about two third of the reactor from the bottom was heated in muffle furnace at 400°C for 180 s. Thermogravimetric (TG) analysis was also conducted with 1 mg sample at the heating rate: 10°C/min and N2 flow rate: 10 ml/min.

Pyrolysis and Secondary Reaction Mechanisms

3 3.1

131

Results and Discussion Primary Pyrolysis of Milled Wood Lignins

Primary pyrolysis behavior is discussed with the results obtained with the open-top reactor and TG analysis. As a result, the total char (primary + secondary char) yields were lower in beech MWL, and this indicates that the devolatilization efficiency is much higher in beech than cedar. This would arise from the lower content of the condensed-types of the interphenylpropane-unit-linkages in hardwood lignins. It is reported that the ether-types of the linkages are cleaved much more easily in pyrolysis, although the condensed-types are resistant for pyrolytic depolymerization [2]. Gas yields and compositions were not so different for these MWLs. In TG analysis, the DTG peak temperature (326°C) of the beech MWL was lower than that of cedar MWL (353°C). Thus, the pyrolytic devolatilization of beech MWL occurs at lower temperature than that of cedar MWL. These results suggest that the ether linkages with syringyl-moiety in hardwood lignin were cleaved at lower temperature, although further study is necessary to confirm this hypothesis. With the open-top reactor, in which the volatile products were stabilized for secondary reactions, the beech MWL gave 4-substituted syringols with various >C=C< and >C=O types of side-chains as well as the corresponding 4-substituted guaiacols. The cedar MWL gave only the guaiacol-type products. Thus, the primary pyrolysis pathways and reactivities were found not so different for the syringyl- and guaiacyl-types of lignins.

3.2

Secondary Reactions of Volatile (tar) Components

Guaiacol and syringol were used as model aromatic nuclei of lignin in order to know the decomposition pathways of these aromatic nuclei and their reactivities, focusing on the role of additional OCH3 group in syringyl-unit, before discussing the secondary reactions mechanism of MWLs. The coke yields were significantly larger in syringol than guaiacol at 600°C in the closed ampoule reactor. Contrary to this, the yields of low MW products were generally lower in syringol. These results are consistent with the earlier observation, i.e., more extensive coke formation in beech MWL which have syringyl-units as well as the guaiacyl-units. Thus, the syringyl-units are suggested to form more coke instead of the low MW products. Low MW tar components which were identified by GC/MS are shown in Fig. 1. Pyrocatechol (1), 4-methylcatechol (2), 2,4-xylenol (3), o-cresol (4) and phenol (5) were identified from guaiacol, while syringol gave 3-methoxycatechol (6), pyrogallol (7), 5-methylpyrogallol (8), 3-methylcatechol (9), 2-methoxy-6methylphenol (10), 2,6-xylenol (11) and 2,4,6-trimethylphenol (12). Accordingly,

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Syringyl-characteristic products CH3

CH3

O–CH3− Homolysis products

OH

OH

H3CO

OH

OH

Pyrocatechol (1)

OH

HO

OH

OH

HO

OH OH

OH

4-Methylcatechol 3-Methoxycatechol Pyrogallol 5-Methylpyrogallol (2) (6) (7) (8) HO

CH3 OH

OCH3− Rearrangement products

3-Methylcatechol (9)

CH3 CH3

H3CO

CH3

OH

OH

OH

2,4-Xylenol (3)

o-Cresol (4)

Phenol (5)

CH3 H3C

2-Methoxy-6methylphenol (10)

CH3 H3C OH

OH

CH3

CH3 OH

2,6-Xylenol 2,4,6-Trimethylphenol (11) (12)

Fig. 1 GC/MS-detectable tar components from guaiacol and syringol

compounds 1–5 and 6–12 were suggested as guaiacyl- and syringyl-characteristic products, respectively. Formation of these products was explained with the two-types of reactions, i.e. O–CH3 homolysis (H) and OCH3 rearrangement (R) types-reactions as shown in Fig. 2 (case of syringol). The O–CH3 bond homolysis forms phenoxy radicals and methyl radical which are further converted into catechols and methane, respectively, by abstracting hydrogen. Pyrogallols were the products in this pathway from syringol. In addition, syringol produced more methane than guaiacol. This would be explained with additional OCH3 group in syringol. There is more opportunity for O–CH3 homolysis in syringol. The 4-methylated products 2, 3, 8 and 12 may be formed through coupling of conjugated radicals formed from phenoxy radicals with methyl radical. In contrast, the OCH3 rearrangement pathway gives aromatic-CH3 structures such as cresols and xylenols. Hosoya et al. also suggested that o-quinonemethides are key intermediates for coke formation [3]. Additional OCH3 group in syringol makes the chance of this rearrangement reaction twice. This double opportunity for coke formation may increase the coke yield, while decrease the low MW tar components in pyrolysis of syringol. This was also supported by the pyrolysis results of 3-methoxycatechol (6) and 2-methoxy-6-methylphenol (10) as pyrolysis intermediates from syringol. Both compounds with OCH3 group produced large amount of coke even in the early stage of pyrolysis such as 80 s, while other intermediates 1–5, 7–9, 11 and 12, which do not have OCH3 group, did not form any coke at 80 s. Although the reactivity was not so high, demethoxylation reaction was also observed for syringol. This causes the structural change from syringol to guaiacol. Thus, guaiacyl-characteristic products 1–5 were also observed from syringol, although their yields were only very low. Demethoxylation mechanism in the course of OCH3 rearrangement pathway was proposed (not shown in this paper).

Pyrolysis and Secondary Reaction Mechanisms

133 Coke

R

H3CO

H

O

H3CO

OH

H3C

OH

O

OH

o -Quinonemethide

9

OH

OH

OH

+

6

CH3

H2C

H O

Methane

OH

HO

7

+ CH3 H3CO

OH OH

OH

Methane

OCH3 OH O

R

H

CH3

CH3

HO OH

OH

9

+ CH3

CH2 H3CO

H3CO O

OH

o -Quinonemethide

10

Methane

CH3

R H2C

CH3 O

o -Quinonemethide

Coke

H3C

CH3 OH

11

Coke

Fig. 2 A proposed mechanism of pyrolytic conversion of syringol based on two-types of reactions, i.e., O–CH3 bond homolysis (H) and OCH3 rearrangement (R)

As observed with the open-top reactor, the 4-substituted syringols and guaiacols with various >C=C< and >C=O types of side-chains were also observed after a short heating time as 80 s at 600°C in the closed ampoule reactor. However, these primary products disappeared quickly in the closed ampoule reactor where all volatile products are heated further. This changed the GC/MS-detectable tar composition dramatically. As for the secondary products, compounds 1–12, which were identified from guaiacol and syringol, were found to be the major GC/MS-detectable tar components from the beech MWL; the cedar MWL gave the guaiacyl-characteristic compounds 1–5. Figure 3 shows the time-course changes of the GC/MS-detectable tar components from the MWLs as compared with those from guaiacol and syringol. The yields from MWLs were much lower (less than one tenth) than those from guaiacol and syringol. This can be explained with the loss in the primary pyrolysis (as char) and the side-chains attached to the 4-positions of guaiacol and syringol in the chemical structures of primary pyrolysis products. Nakamura et al. [4] and Hosoya et al. [5] reported that guaiacol derivatives with >C=C< types of side-chains underwent the condensation reaction before OCH3 homolysis and rearrangement reactions took place.

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Yield (wt%)

0.8

Beech MWL

0.8

0.6

0.6

0.4

0.4

0.2

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Fig. 3 Formation and decomposition behaviors of GC/MS-detectable low MW tar products in pyrolysis of beech and cedar MWLs (N2/600°C) as compared with those of guaiacol and syringol. Solid-circle: guaiacyl-characteristic products, open-circle: syringyl-characteristic products; O–CH3 homolysis products: 1 and 2 (guaiacyl-characteristic), 6–9 (syringyl-characteristic); OCH3 rearrangement products: 3–5 (guaiacyl-characteristic), 10–12 (syringyl-characteristic)

Syringol produced smaller amount of the GC/MS-detectable tar products than guaiacol. Besides the reasons described above, the pyrolysis experiments with the intermediates showed that the syringyl-characteristic products 6–12 were more reactive than the guaiacyl-characteristic products 1–5 for further decomposition reactions. Additional OCH3, OH and CH3 groups increase the pyrolytic reactivities of the intermediates. Such inherent nature of syringyl-moiety may be a reason for much smaller yields of the syringyl-characteristic products in pyrolysis of MWLs. Interestingly, the yields of syringyl-characteristic O–CH3 homolysis products were especially lower in beech MWL. Pyrolysis results of a mixture of guaiacol and syringol suggested that the interactions between these two aromatic moieties may be a reason. The yields of the O–CH3 homolysis products, especially 3-methoxycatechol (6), were significantly lowered at short heating time as 40 or 80 s by mixing.

4

Conclusions

Devolatilization in primary pyrolysis step was more effective in Japanese beech MWL than Japanese cedar MWL. This may arise from the lower content of condensed type interphenylpropane-unit-linkage in beech MWL. In primary pyrolysis step, the GC/MS-detectable tar components were 4-substituted syringols and guaiacols with >C=C< and >C=O side-chains for beech MWL, while those from cedar MWL were only corresponding guaiacols. In the secondary reaction step, the syringyl-characteristic products disappeared quickly, and hence, the compositions were changed into only guaiacyl-characteristic products even in beech MWL. Based on the results of model aromatic nuclei, i.e., guaiacol and syringol, such observation was explained with the different reactivities of these aromatic moieties. Syringol produced more coke instead of the GC/MS-detectable low MW products.

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This was explained with additional OCH3 group in syringol. Double opportunity of the OCH3 rearrangement reaction was proposed for such higher coke yield, since o-quinonemethide formed in this reaction sequence is a key intermediate in coke formation. Although the reactivity was not so high, demethoxylation of syringol into guaiacol was also observed. As for the reactivities of the intermediates, the syringyl-characteristic products were found to be more reactive for further decomposition into gas and coke than the guaiacyl-characteristic ones. For these reasons, syringyl-moiety inherently produces much less amount of GC/MS-detectable low MW products. Interactions between guaiacyl and syringyl moieties were also suggested to reduce the low MW products, especially syringyl-characteristic O–CH3 homolysis products, from beech MWL. Acknowledgement This work was supported by the Kyoto University Global COE program of “Energy Science in the Age of Global Warming”, and a Grant-in-aid for scientific research (B)(2) (No. 20380103, 2008.4-2011.3).

References 1. Asmadi M, Kawamoto H, Saka S (2010) Pyrolysis reactions of Japanese cedar and Japanese beech woods in a closed ampoule reactor. J Wood Sci 56(4):319–330 2. Kawamoto H, Horigoshi S, Saka S (2007) Pyrolysis reactions of various lignin model dimers. J Wood Sci 53(2):168–174 3. Hosoya T, Kawamoto H, Saka S (2009) Role of methoxyl group in char formation from ligninrelated compounds. J Anal Appl Pyrol 84:78–87 4. Nakamura T, Kawamoto H, Saka S (2007) Condensation reactions of some lignin related compounds at relatively low pyrolysis temperature. J Wood Chem Technol 27:121–133 5. Hosoya T, Kawamoto H, Saka S (2008) Secondary reactions of lignin-derived primary tar components. J Anal Appl Pyrol 83:78–87

Fractionation of Japanese Cedar and Its Characterization as Treated by Supercritical Water Mahendra Varman and Shiro Saka

Abstract Supercritical water treatment (380°C/100 MPa/8 s) was applied to extractive-free sapwood portion of Japanese cedar (Cryptomeria japonica) and the fractionated products were comparatively characterized, for water-soluble portion and water-insoluble portion composed of methanol-soluble portion and methanolinsoluble residue. As a result, the water-soluble portion was determined to be composed of carbohydrate-derived products such as organic acids, sugar-decomposed products, lignin-derived products, etc. The methanol-soluble portion was, on the other hand, mainly composed of lignin-derived products, whereby it consisted of solely guaiacyl-type lignin, representing the nature of softwood. The methanol-insoluble residue was also mainly composed of lignin to be 92.0% in its content. Moreover, the phenolic hydroxyl content determined by aminolysis method was 36.3 PhOH/100 C9. Furthermore, an alkaline nitrobenzene oxidation analysis indicated that, the methanolinsoluble residue was less in oxidation products compared to untreated sample. These lines of evidence suggest that methanol-insoluble residue is composed of lignin with more condensed-type of linkages with high phenolic hydroxyl groups. In addition, the water-soluble portion could be utilized for organic acid production, whereas the methanol-soluble portion and its insoluble residue for phenolic chemical production. Keywords Carbohydrate-derived฀ products฀ •฀ Japanese฀ cedar฀ •฀ Lignin-derived฀ products฀•฀Phenolic฀hydroxyl฀content฀•฀Supercritical฀water฀treatment

1

Introduction

Wood is one of the most abundant biomass resources with waste continuously being generated from forest thinning, lumbering, etc. These wastes are lignocellulosics which could be efficiently converted and utilized for meeting the future fuel and

M. Varman and S. Saka (*) Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_17, © Springer 2011

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chemical needs. In order to convert these biomass resources, an environmentally clean and rapid process is preferred. In this work, therefore, supercritical water treatment was chosen and Japanese cedar (Cryptomeria japonica), as an abundantly available lignocellulosics in Japan, was investigated.

2

Experimental

Extractive-free sapwood portion of Japanese cedar (Cryptomeria japonica) was utilized in this study. The supercritical water biomass conversion system used in this study was associated with a batch-type reaction vessel made of Inconel-625 with a volume of 5 ml [1]. The supercritical water treated (380°C/100 MPa/8 s) product was fractionated by filtration into water-soluble portion and water-insoluble residue after 12 h refrigeration. The water-insoluble residue was washed with methanol to fractionate it further by filtration into methanol-soluble portion and methanol-insoluble residue. These fractionated portions were characterized separately. Characterization of the water-soluble portion was conducted with high performance liquid฀ chromatography฀ (HPLC),฀ ion฀ chromatography฀ (IC),฀ capillary฀ electrophoresis฀ (CE) and ultraviolet–visible (UV–Vis) spectrophotometry. Meanwhile, characterization of the methanol-soluble portion was conducted with gas chromatography–mass spectrometry (GC–MS) for qualitative analysis of low molecular weight products. The conditions of these instruments are elaborated in our previous paper [2]. For characterization of the methanol-insoluble residue, the determinations of lignin content, phenolic hydroxyl content and alkaline nitrobenzene oxidation products were conducted and compared with those of the untreated sample. The methods employed here are described in [2–5].

3 3.1

Results and Discussion Fractionation of the Products

Table 1 shows the obtained yields for fractionated water-soluble portion and waterinsoluble residue after supercritical water treatment (380°C/100 MPa/8 s). The yield of water-soluble portion was the highest. It is known that the water-soluble Table 1 Yields of fractionated water-soluble portion and water-insoluble residue for Japanese cedar as treated by supercritical water at 380°C/100 MPa/8 s Yield (wt%) Water-insoluble Water-soluble Methanol-soluble Methanol-insoluble 74.8 20.4 4.8

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portion contains more carbohydrate-derived products [1]. Compared with subcritical water treatment [1], supercritical water treatment is more efficient for decomposing the carbohydrate portion. The water-insoluble residue, on the other hand, contains more lignin-derived products.

3.2

Characterization of Water-Soluble Portion

The yields of products in the fractionated water-soluble portion are shown in Table 2. Decomposed products of saccharides such as dihydroxyacetone (DA), levoglucosan฀(LG),฀furfural฀(FR),฀organic฀acids฀and฀so฀on฀were฀detected฀apart฀from฀ lignin-derived฀ products฀ (LP).฀ The฀ yields฀ of฀ organic฀ acids฀ are฀ more฀ than฀ 10%฀ in฀ Japanese cedar. Due to the long temperature rising time of approximately 22 s for the reaction vessel to reach 380°C, the carbohydrate portion in Japanese cedar has been decomposed into organic acids during the subsequent 8 s supercritical water treatment. Organic acids are valuable chemicals and could be converted into methane by anaerobic fermentation [6]. Even though the yield of unknowns are higher compared with organic acids, there is a potential for the yield of organic acids to be increased further by prolonging treatment time [6].

Table 2 Yields of products in the fractionated water-soluble portion of Japanese cedar Water-soluble (wt%) DA LG MG FR AA GA LA LP UNK 7.6 1.6 0.3 0.6 5.0 4.9 1.9 8.4 44.5 DA dihydroxyacetone, LG levoglucosan, MG methylglyoxal, FR furfural, AA acetic acid, GA glycolic acid, LA lactic acid, LP lignin-derived products, UNK unknowns

3.3

Characterization of Methanol-Soluble Portion

For the methanol-soluble portion, GC–MS analysis was performed. The total-ion chromatogram of the methanol-soluble portion obtained by GC–MS analysis is shown in Fig. 1. Based on the GC–MS analysis, the molecular weight (MW), the mass fragmentation pattern obtained by electron ionization and the peaks identified from Fig. 1 are shown in Table 3. Identification of the peaks was conducted with the retention times and mass fragmentation patterns compared with those of the authentic compounds. However, peaks 9 and 10 were determined from the mass fragmentation pattern reported by [7]. It could then be elucidated that these identified phenolic compounds must be mainly derived from lignin and the obtained guaiacyl-type lignin-derived products represent the nature of softwood. As a result, the methanol-soluble portion shows the potential for many phenolic chemicals to be recovered, as treated by supercritical water.

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Fig. 1 Total-ion chromatogram for the methanol-soluble portion in GC–MS analysis Table 3 Identified products in the methanol-soluble portion by its mass fragments in GC–MS analyses Peak no. MW Major mass fragments Compound 1 124 109, 124, 81 Guaiacol 2 138 123, 138, 95 4-Methylguaiacol 3 152 137, 152, 122 4-Ethylguaiacol 4 166 137, 166, 122, 94 4-Propylguaiacol 5 146, 118, 117, 123, 161 Unknown 6 164 149, 164, 132, 103, 77 Eugenol 7 164 164, 149, 131 cis-Isoeugenol 8 164 164, 149, 103, 77 trans-Isoeugenol 9 162 147, 162, 119, 91, 77 4-Propynylguaiacol 10 162 162, 147, 119, 91, 77 1-(4-Hydroxy-3-methoxyphenyl)allene 11 166 151, 166, 123 Acetoguaiacone 12 180 137, 179, 122 Guaiacylacetone 13 174, 132, 160, 146, 116 Unknown 14 178 178, 135, 108, 77 trans-Coniferylaldehyde 15 176, 204, 177, 161, 148 Unknown 16 189, 146, 174, 116 Unknown 17 194 194, 167, 139, 111, 177 Ferulic acid 18 188, 202, 160, 145, 132 Unknown Peak numbers are corresponding to those depicted in Fig. 1

3.4

Characterization of the Methanol-Insoluble Residue

Table 4 shows the lignin content for the methanol-insoluble residue. It shows that the lignin content was 92.0% after ash correction of Klason lignin. This suggests that the methanol-insoluble residue is mostly composed of lignin and thus cellulose

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M. Varman and S. Saka Table 4 Lignin฀ contents฀ and฀ the฀ number฀ of฀ phenolic฀ hydroxyl฀ groups฀ over฀ 100฀ phenylpropane (C9) units of lignin (PhOH/100 C9) determined by aminolysis method for the methanol-insoluble residue and untreated sample Methanol-insoluble residue (wt%) Untreated sample (wt%) Yield of lignin upon Lignin untreated sample PhOH/100 C9 Lignin PhOH/100 C9 92.0

4.4

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and hemicellulose are thought to be degraded to various compounds with low molecular weights as collected to be water-soluble portion shown in Table 2.฀Lignin฀ is, thus, recovered mainly as the methanol-insoluble residue as well as methanolsoluble portion. Table 4 also shows the number of the phenolic hydroxyl groups (PhOH) upon 100 phenylpropane (C9) units of lignin for the methanol-insoluble residue. It is apparent that the methanol-insoluble residue has more phenolic hydroxyl groups (36.3 PhOH/100 C9) than the untreated sample (20.1 PhOH/100 C9). Previously, it was demonstrated with lignin model compounds that the condensed-type linkages, such as 5-5 linkage, were stable during supercritical water treatment, whereas the noncondensed-type ether linkages such as b-O-4 linkage, were easily cleaved by supercritical water hydrolysis [1]. After the cleavage of the noncondensed-type linkages, phenolic hydroxyl groups increased. This explains the reason for the higher phenolic hydroxyl content observed in methanol-insoluble residues and it suggests that many noncondensed-type linkages are cleaved and that the residues are rich in condensed-type linkages. From alkaline nitrobenzene oxidation analysis, the yield of oxidation products in untreated sample is around 23% upon lignin as a result of rather high condensedtype lignin in softwood, compared with hardwood [8]. However, the methanol-insoluble residue shows even smaller amount of nitrobenzene oxidation products, as shown in Fig. 2. These results were expected because nitrobenzene oxidation products are mainly derived from the degradation of the noncondensed-type lignin and the fact that most of these linkages are already cleaved under supercritical water treatment as mentioned above. It also suggests that methanol-insoluble residues are rich in condensed-type lignin.

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Conclusions

The characteristics of Japanese cedar after fractionation with supercritical water treatment has been presented. The supercritical water treatment showed the potential as the rapid and nontoxic conversion process of Japanese cedar into organic acids and the possibility for many phenolic chemicals to be recovered. In addition, this line of study will be very useful to optimize further the recovery of useful chemicals from wood wastes of Japanese cedar. Acknowledgement The authors are grateful for the financial support provided under the GCOE program, Kyoto University.

References 1. Ehara K, Saka S, Kawamoto H (2002) Characterization of the lignin-derived products from wood as treated in supercritical water. J Wood Sci 48:320–325 2. Varman M, Miyafuji H, Saka S (2010) Fractionation and characterization of oil palm (Elaeis guineensis) as treated by supercritical water. J Wood Sci 56:488–494 3. Whiting P, Favis BD, St-Germain FGT, Goring DAI (1981) Fractional separation of middle lamella and secondary wall tissue from spruce wood. J Wood Chem Technol 1:29–42 4.฀Lai฀ YZ฀ (1992)฀ Determination฀ of฀ phenolic฀ hydroxyl฀ groups.฀ In:฀ Lin฀ SY,฀ Dence฀ CW฀ (eds)฀ Methods in lignin chemistry. Springer, Berlin, pp 423–433 5.฀Katahira฀R,฀Nakatsubo฀F฀(2001)฀Determination฀of฀nitrobenzene฀oxidation฀products฀by฀GC฀and฀ H-1-NMR฀ spectroscopy฀ using฀ 5-iodovanillin฀ as฀ a฀ new฀ internal฀ standard.฀ J฀ Wood฀ Sci฀ 47:378–382 6. Yoshida K, Miyafuji H, Saka S (2009) Effect of pressure on organic acids production from Japanese beech treated in supercritical water. J Wood Sci 55:203–208 7.฀Ralph฀J,฀Hatfield฀RD฀(1991)฀Pyrolysis–GC–MS฀characterization฀of฀forage฀materials.฀J฀Agric฀ Food Chem 39:1426–1437 8.฀Chen฀ CL฀ (1992)฀ Nitrobenzene฀ and฀ cupric฀ oxide฀ oxidations.฀ In:฀ Lin฀ SY,฀ Dence฀ CW฀ (eds)฀ Methods in lignin chemistry. Springer, Berlin, pp 301–320

Two-Step Hydrolysis of Japanese Cedar as Treated by Semi-Flow Hot-Compressed Water with Acetic Acid Natthanon Phaiboonsilpa and Shiro Saka

Abstract Japanese cedar (Cryptomeria japonica) as one of the softwoods was treated by two-step semi-flow hot-compressed water with 3.0 wt% acetic acid at 210 and 260°C/10 MPa/15 min, for the first and second stages, respectively. Totally, 85.0% of Japanese cedar could be solubilized into the hot-compressed water, while the rest of 15.0% remained as residue composed mainly of 11.7% lignin with 3.3% cellulose being incompletely hydrolyzed. In comparison with the two-step treatment of Japanese cedar without acetic acid addition reported previously, it was revealed that this current two-step treatment with acetic acid could be performed at lower temperatures with comparable yields of hydrolyzed products from hemicellulose and cellulose as well as lignin-derived products. The addition of acetic acid has shown a possibility to improve the hydrolysis and decomposition of wood cell wall components. However, due to decomposition reaction caused by acetic acid applied, the most appropriate optimum treatment conditions should be studied further. Keywords Acetic฀acid฀•฀Hot-compressed฀water฀•฀Hydrolysis฀•฀Japanese฀cedar฀ •฀Softwood

1

Introduction

In our previous work, the two-step semi-flow hot-compressed water treatment of Japanese beech (Fagus crenata) as one of the hardwoods and Japanese cedar (Cryptomeria japonica) as one of the softwoods has been conducted [1–5]. It was reported that, at the first stage (230°C/10 MPa/15 min), amorphous hemicellulose and para-crystalline cellulose, whose crystalline structure is somewhat disordered,

N. Phaiboonsilpa and S. Saka (*) Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_18, © Springer 2011

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were found to be selectively hydrolyzed into hot-compressed water as well as lignin being decomposed in part, while crystalline cellulose was hydrolyzed at the second stage (270–280°C/10 MPa/15–30 min). In addition to various hydrolyzed products recovered in water-soluble portion, their decomposed compounds were obtained. In such studies, a substantial production of decomposed compounds was, however, realized in the second stage due to its relatively high treatment temperature. These decomposed compounds could end up with loss of saccharides and inhibitory effect on the subsequent fermentation step, resulting in a lower yield of ethanol. As a consequence, the hot-compressed water treatment with acetic acid has become of interest as an alternative mean to improve the conversion yield of saccharides with minimizing the decomposed compounds by reducing the treatment temperatures. In addition, the presence of acetic acid in the treatment has no drawback effect to the subsequent process steps in our newly-developed ethanol production process via acetic acid fermentation and hydrogenolysis [5]. Softwoods are generally recognized as being much more resistant to hydrolysis than hardwoods or agricultural residues. This is due to the fact that softwoods have more rigid structure caused by their relatively high content of lignin and abundant condensed-type linkages in its structure. Also, the number of acetyl groups is lower in their hemicellulose than hardwoods, resulting in lesser extent of autohydrolysis to occur [6]. In this work, therefore, two-step hydrolysis of Japanese cedar as treated by semi-flow hot-compressed water with acetic acid has been investigated in order to study the effect of acetic acid for improving its hydrolysis.

2

Experimental

Extractive-free wood flour of Japanese cedar (Cryptomeria japonica) was used [4]. The two-step semi-flow hot-compressed water treatment of Japanese cedar with 3.0 wt% acetic acid aqueous solution was performed at 210 and 260°C/10 MPa/15 min for the first and second stages of the treatment, respectively, to study the effect of acetic acid for hydrolysis. All the detailed experiments and analyses were conducted according to the procedures described in our papers [1, 2].

3 3.1

Results and Discussion Decomposition of Major Cell Wall Components

As treated by two-step semi-flow hot-compressed water with 3.0 wt% acetic acid at 210 and 260°C/10 MPa/15 min, various products from Japanese cedar were obtained. In the first stage, the hydrolyzed products were glucomanno-saccharides such as mannose, glucose and oligomeric glucomannan, galactose and acetic acid from

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the major softwood hemicellulose, O-acetyl-galactoglucomannan; xylo-saccharides such as xylose and xylo-oligosaccharides, arabinose, glucuronic acid and methanol from the minor softwood hemicellulose, arabino-4-O-methylglucuronoxylan; and coniferyl alcohol from guaiacyl unit of softwood lignin. In the second stage, on the other hand, those products from cellulose were cellosaccharides such as glucose, cello-oligosaccharides and fructose, as an isomerized product of glucose. In addition, dehydrated compounds (furfural, 5-hydroxymethylfurfural (5-HMF) and levoglucosan), fragmented compounds (glycolaldehyde, methylglyoxal and erythrose) and organic acids (lactic acid, glycolic acid and formic acid) were recovered in the water-soluble portion. Totally, 85.0% of Japanese cedar could be solubilized into the hot-compressed water, while the rest of 15.0% remained as residue composed mainly of 11.7% lignin with 3.3% cellulose being incompletely hydrolyzed.

3.2

Effect of Additional Acetic Acid on Hydrolysis

Figure 1 shows a comparison of various product yields from Japanese cedar as treated by two-step semi-flow hot-compressed water with and without acetic acid. In comparison with the treatment without acetic acid addition performed at 230 and 270°C/10 MPa/15 min, it was revealed that, by adding 3 wt% acetic acid, the twostep treatment could be performed at lower temperatures (210 and 260°C/10 MPa/ 15 min) with comparable yields of hydrolyzed products from hemicellulose and cellulose, as well as, lignin-derived products. Slightly greater solubility of Japanese cedar into hot-compressed water was also perceived as seen from the lesser yield of residue. Although the treatment was performed at lower temperatures, more extensive decomposition reaction was realized in the treatment with the addition of acetic 100

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Fig. 1 Comparison of various product yields from Japanese cedar as treated by two-step semiflow hot-compressed water without acetic acid at 230 and 270°C/10 MPa/15 min and two-step semi-flow hot-compressed water with 3.0 wt% acetic acid at 210 and 260°C/10 MPa/15 min

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acid, as indicated by a drastic increase in yields of dehydrated and fragmented compounds as well as organic acids, which were collectively reported in terms of decomposed compounds. The concentration of acetic acid solution applied at 3.0 wt% in this present work might be too high, so that the excessive amount of acid played a significant role in the decomposition reaction rather than improvement of the hydrolysis. Moreover, because there still remained some content of incompletely hydrolyzed cellulose left in the residue and its amount was comparable to that from the treatment without acetic acid (See Fig. 1), it does not seem that acetic acid at higher concentrations would help to decompose cellulose more effectively. In other words, it may cause more extensive decomposition to the hydrolyzed products. The most appropriate optimum treatment conditions should be, therefore, studied further. Table 1 shows that, as a result of acetic acid addition, the hydrolyzed saccharides from Japanese cedar were found to be recovered more in monomeric forms, whereas those from the treatment without acetic acid were mainly in oligosaccharides. Monomeric and oligomeric glucose are hydrolyzed products derived mainly from the cellulose hydrolysis in the second stage, while the other saccharides are from hemicellulose in the first stage. For a particular case of fructose, it was generated from isomerization of monomeric glucose, so only its monomeric form was obtained. As the same observations were realized in all saccharides from both hemicellulose and cellulose, it is reasonable to infer that the additional acetic acid can help catalyze the hydrolysis of soluble oligosaccharides obtained in both stages.

Table 1 Comparison of various saccharides from Japanese cedar recovered in monomeric and oligomeric forms as treated by two-step semi-flow hot-compressed water with and without acetic acid addition Yield (wt%) Two-step treatment without Two-step treatment with 3.0 wt% Hydrolyzed acetic acid (230 and acetic acid (210 and saccharides 260°C/10 MPa/15 min) from hemicellulose 270°C/10 MPa/15 min) Monomeric Oligomeric Monomeric Oligomeric and cellulose Glucose 5.5 27.9 18.0 14.9 (16.5) (83.5) (54.7) (45.3) Mannose 0.5 7.7 1.4 5.9 (6.1) (93.9) (19.2) (80.8) Galactose 0.4 1.0 0.7 0.9 (28.6) (71.4) (43.8) (56.2) Xylose 1.2 4.5 3.7 3.2 (21.1) (78.9) (53.6) (46.4) Arabinose 0.4 0.4 0.6 0.1 (50.0) (50.0) (85.7) (14.3) Fructose 0.5 – 2.1 – The numbers in parentheses indicate the proportion of monomeric and oligomeric saccharides compared to their total recovery (%)

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Conclusions

The addition of acetic acid has shown a possibility to improve the hydrolysis and decomposition of cell wall components in Japanese cedar (softwood) as treated by two-step semi-flow hot-compressed water. It was elucidated that the two-step treatment with 3.0 wt% acetic acid could be performed at 10–20°C lower temperatures (210 and 260°C/10 MPa/15 min) with comparable yields of hydrolyzed products from hemicellulose and cellulose, as well as, lignin-derived products, compared to the treatment without acetic acid addition performed at 230 and 270°C/10 MPa/15 min. In addition, the hydrolyzed products were found to be highly recovered as in monosaccharide forms, whereas those from the treatment without acetic acid were mainly in oligosaccharides. However, due to more decomposition reaction caused by acetic acid applied in this present work, the most appropriate optimum treatment conditions should be explored. This line of information could reveal a decomposition behavior of wood cell wall under hot-compressed water and would be very useful to develop the technology to utilize efficiently woods for biochemicals and biofuels. Acknowledgements This work has been done under the NEDO project and under a partially financial support by the GCOE Program, Kyoto University.

References 1. Lu X, Yamauchi K, Phaiboonsilpa N, Saka S (2009) Two-step hydrolysis of Japanese beech as treated by semi-flow hot-compressed water. J Wood Sci 55:367–375 2. Phaiboonsilpa N, Yamauchi K, Lu X, Saka S (2010) Two-step hydrolysis of Japanese cedar as treated by semi-flow hot-compressed water. J Wood Sci 56:331–338 3. Phaiboonsilpa N, Lu X, Yamauchi K, Saka S (2010) Chemical conversion of lignocellulosics as treated by two-step hot-compressed water. In: Yao T (ed) Zero-Carbon Energy Kyoto 2009, Springer, Tokyo, pp 166–170 4. Phaiboonsilpa N, Lu X, Yamauchi K, Saka S (2009) Chemical conversion of lignocellulosics as treated by two-step semi-flow hot-compressed water. In: Proceedings of the world renewable energy congress 2009–Asia, pp 235–240 5. Saka S, Phaiboonsilpa N, Nakamura Y, Masuda S, Lu X, Yamauchi K, Miyafuji H, Kawamoto H (2009) Eco-ethanol production from lignocellulosics with hot-compressed water treatment followed by acetic acid fermentation and hydrogenolysis. In: Proceedings of the 17th European biomass conference and exhibition, pp 1952–1957 6. Galbe M, Zacchi G (2002) A review of the production of ethanol from softwoods. Appl Microbiol Biotechnol 59:618–628

Liquefaction Behaviors of Japanese Beech as Treated in Subcritical Phenol Gaurav Mishra and Shiro Saka

Abstract The liquefaction of Japanese beech (Fagus crenata) was investigated as treated by subcritical phenol using a batch-type reaction vessel. As treated by 270–350°C/1.8–4.2 MPa/3–30 min, Japanese beech was fractionated into phenolsoluble portion and phenol-insoluble residue. It was found that, under the reaction condition of 270°C/1.8 MPa, lignin was mainly liquefied into phenol-soluble portion with some extent of hemicellulose and less cellulose being decomposed, whereas, at 350°C/4.2 MPa, a complete liquefaction of three main cell wall components was realized. The changes observed in liquefaction behaviors of the lignin, hemicellulose and cellulose as treated by subcritical phenol could reveal a prospect in various applications of the obtained liquefied products for biofuels and biochemicals. Keywords Cellulose฀•฀Japanese฀beech฀•฀Lignin฀•฀Phenol฀•฀Subcritical฀fluid

1

Introduction

The global climate change and the decline in the world oil production have put emphasis on the search for other potential alternatives to fossil fuels [1]. Biomass, which is carbon-neutral and environment-friendly, can be used as an alternative to the continuously-depleting fossil fuels. Sub/supercritical fluid science is one of such technologies which are used for the chemical conversion of the biomass into liquefied substances and other valuable products. Japanese beech has been tried and treated with various sub/ supercritical alcohols previously in our laboratory and has showed prospects to obtain

G. Mishra and S. Saka (*) Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_19, © Springer 2011

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the liquid fuel [2]. It was reported in previous works that more than 90% of wood could be decomposed and liquefied when treated with methanol at 350°C/43 MPa. However, it took prolonged treatment time of about 30 min for almost all kinds of alcohols applied. Hence, it is expected that phenol due to its low dielectric constant can dissolve relatively high molecular weight products from cellulose, hemicellulose and lignin. The possibility of wood liquefaction with phenol is also investigated at subcritical conditions to achieve high conversion rate within shorter treatment times [3]. In this study, therefore, phenol was used as a solvent at its subcritical conditions in order to decompose and liquefy Japanese beech, and liquefaction behaviors under various subcritical phenol conditions were investigated.

2

Experimental

Extractive-free wood flour of Japanese beech (Fagus crenata) with particles passed through the mesh size of 280 mm was used in the experiments. As described in Fig. 1, approximately 150 mg of the oven-dried wood flour and 4.9 ml of phenol were fed into a 5-ml reaction vessel made of Inconel-625. It was then subjected to phenol (Tc = 421.2°C, Pc = 6.13 MPa) treatment at subcritical condition (270– 350°C/1.8–4.2 MPa/3–30 min) by immersing it in molten salt bath preheated at a designated temperature. After the treatment, the reaction vessel was dipped in water bath to stop the reaction. The resulted reaction mixture was then filtered with 0.2-mm membrane, and phenol-soluble portion was separated from phenolinsoluble residue. The phenol-insoluble residue was then studied for its chemical composition. In addition, oven-dried phenol-insoluble residue was studied by X-ray diffractometry (RINT 2200V, Rigaku Denki). The apparent crystallinity was then estimated according to the method [4].

Beech wood 150 mg

Phenol 4.9 ml

Subcritical Phenol Treatment

Phenol-Soluble

Phenol-Insoluble

Sulfuric Acid Hydrolysis

Hydrolyzate

Residue

Fig. 1 Fractionation scheme of Japanese beech as treated in subcritical phenol

Liquefaction฀Behaviors฀of฀Japanese฀Beech฀as฀Treated฀in฀Subcritical฀Phenol

3 3.1

149

Results and Discussion Liquefaction Behaviors of Japanese Beech in Subcritical Phenol

Figure 2 shows the changes in the phenol-insoluble residues of Japanese beech as treated by subcritical phenol at various conditions. Under the condition of 270°C/1.8 MPa, Japanese beech was liquefied to some extent with around 40% of phenol-insoluble residue left after the treatment for 30 min. At higher treatment temperatures of 310°C/3.1 MPa and 330°C/3.6 MPa, Japanese beech has been decomposed and liquefied more, around 20% and 3% of phenol-insoluble residues were left after the treatments for 30 min, respectively. On the other hand, at 350°C/4.2 MPa, more than 90% of wood was quickly decomposed and liquefied into the subcritical phenol within only 4 min of treatment time. After 30 min of treatment, only 1.1% of wood was left as phenol-insoluble residue.

3.2

Decomposition of Wood Cell Wall Components

Figure 3 shows the chemical composition of the phenol-insoluble residues observed in Fig. 2, on cellulose, hemicellulose and lignin as treated at 270–350°C/1.8– 4.2 MPa/3–30 min. From the figure, the phenol-soluble portion can be seen as the area above the lignin. At 270°C/1.8 MPa, within a few minutes of treatment time,

Phenol-Insoluble Residue (wt%)

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Treatment Time (min) Fig. 2 Changes in phenol-insoluble residues of Japanese beech as treated by subcritical phenol at various conditions

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Fig. 3 Chemical composition of the phenol-insoluble residue of Japanese beech as treated by subcritical phenol at (a) 270°C/1.8 MPa, (b) 310°C/3.1 MPa, (c) 330°C/3.6 MPa and (d) 350°C/4.2 MPa

lignin was almost completely decomposed and liquefied into the phenol-soluble portion, whereas hemicellulose was solubilized to some extent. Cellulose was found to remain in the phenol-insoluble portion, which was not decomposed completely even with longer treatment time as shown in Fig. 3a. At 310°C/3.1 MPa (Fig. 3b), it can be seen that the hemicellulose portion has started to be decomposed and liquefied leaving only cellulose in the phenol-insoluble portion, at all treatment time. Upon the increase in treatment conditions to 330°C/3.6 MPa, the cellulose portion could be liquefied, as seen in Fig. 3c. Its complete liquefaction was realized after 20 min of treatment time. On the other hand, at 350°C/4.2 MPa (Fig. 3d), lignin, hemicellulose and cellulose were almost completely liquefied into subcritical phenol within 10 min. These different liquefaction behaviors of cellulose, hemicellulose and lignin in subcritical phenol showed a prospect for various applications of the obtained liquefied products. The 270°C/1.8 MPa treatment condition has suggested the almost complete solubilization of lignin just after 3 min treatment in phenol-soluble portion, without decomposing cellulose and hemicellulose. On the other hand, at 350°C/4.2 MPa, all the three cell wall components were decomposed effectively in all treatment times.

Liquefaction฀Behaviors฀of฀Japanese฀Beech฀as฀Treated฀in฀Subcritical฀Phenol

3.3

151

X-Ray Diffractometry of Phenol-Insoluble Residues

The amorphous portion in wood in general corresponds to the presence of hemicellulose and lignin, whereas the crystalline portion is represented by cellulose. The relative degree of crystallinity commonly termed as crystallinity-index or apparent crystallinity is used to show a relative intensity of crystalline portion compared to the amorphous one in wood. It was calculated by the following (1): I −I  ApparentCrystallinity =  002 am  × 100  I002 

(1)

where, I002 = Maximum intensity of 002 lattice diffraction at 2q = 22.5° Iam = Intensity of the diffraction in the same unit at 2q = 18° As seen from Fig. 4, the apparent crystallinity of the original wood was 37%. It was found to be increased to around 55–60% due to the partial removal of the amorphous portion, mainly lignin and some extent of hemicellulose, as treated at 270°C/1.8 MPa for 3 min and longer. At higher treatment temperatures, 310– 350°C/3.1–4.2 MPa, however, a significant change in the apparent crystallinity was realized to become around 70–80% in its crystallinity due to the complete removal of amorphous portion. Because of the complete liquefaction of three cell wall components in the treatment at 330–350°C/3.6–4.2 MPa, the apparent crystallinity of the phenol-insoluble residues were no longer seen after 10 min of treatment time. These observations from Fig. 4 are in good agreement with the results shown in Fig. 3. Hence, the relative increase in the crystalline portion from cellulose can be achieved on removal of hemicellulose and lignin. It is obviously seen that the treatment at 270–310°C/1.8–3.1 MPa suggests the appropriate treatment parameters for lignin removal and its solubilization, whereas the treatment at 330–350°C/3.6–4.2 MPa can be used as the treatment conditions for the complete solubilization of the wood cell wall.

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Fig. 4 Change in apparent crystallinity of phenol-insoluble residue of Japanese beech as treated by subcritical phenol at various conditions

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Conclusions

The liquefaction of Japanese beech was studied in subcritical phenol at various conditions. As a result, under 270°C/1.8 MPa, lignin was decomposed and liquefied within a few minutes, with almost no hemicellulose and cellulose decomposition, suggesting that its treatment condition is appropriate for lignin solubilization, whereas the treatment at 330–350°C/3.6–4.2 MPa, all cell wall components were decomposed and solubilized, suggesting it to be good for the whole wood solubilization. These lines of evidence stipulates that separate treatment conditions can be used for selective liquefaction of lignin as well as whole wood liquefaction for various applications pertaining to lignin and whole wood respectively. Acknowledgement The authors are grateful for the financial support provided under the GCOE program, Kyoto University.

References 1. Dongsheng W, Jiang H, Zhang K (2009) Supercritical fluids technology for clean biofuel production. Prog Nat Sci 19(3):273–284 2.฀Minami฀ E,฀ Yamazaki฀ J,฀ Saka฀ S฀ (2006)฀ Liquefaction฀ of฀ beech฀ wood฀ in฀ various฀ supercritical฀ alcohols. J Wood Sci 52:527–532 3.฀Lee฀SH,฀Ohkita฀T฀(2003)฀Rapid฀wood฀liquefaction฀in฀supercritical฀phenol.฀Wood฀Sci฀Technol฀ 37(1):29–38 4.฀Segal฀ L,฀ Creely฀ JJ,฀ Martin฀ AE฀ Jr,฀ Conrad฀ C฀ (1959)฀ An฀ empirical฀ method฀ for฀ estimating฀ the฀ degree of crystallinity of native cellulose using the X-ray diffractometer. Text Res J 29:786–793

Glycerol to Value-Added Glycerol Carbonate in the Two-Step Non-Catalytic Supercritical Dimethyl Carbonate Method Zul Ilham and Shiro Saka

Abstract A new non-catalytic two-step supercritical dimethyl carbonate method for fatty acid methyl esters (FAME) production has been previously established. The whole method consists of the hydrolysis of triglycerides by subcritical water (270°C/27 MPa/25 min) and subsequent esterification of hydrolyzed fatty acids by supercritical dimethyl carbonate (300°C/9 MPa/15 min) to FAME. High yield of FAME (96 wt%) and high quality of FAME in compliance with the international biodiesel standard could be resulted from this method. However, glycerol is still being produced as a by-product. Therefore, the potential to convert this glycerol to a value-added product, glycerol carbonate, has been studied. This reaction is, then, evaluated for its potential to be coupled with the two-step supercritical dimethyl carbonate by comparison with conversion of glycerol from other methods. Keywords Biodiesel฀ •฀ Dimethyl฀ carbonate฀ •฀ Fatty฀ acid฀ methyl฀ esters฀ •฀ Glycerol฀ carbonate฀•฀Supercritical฀method

1

Introduction

Current environmental issues, fluctuating fuel price and energy security have led to an increase in worldwide biodiesel production. However, the current commercial biodiesel production method produces large surplus of unpurified glycerol as by-product, creating a glut in glycerol market. Without new applications, glycerol Z. Ilham University of Malaya, Kuala Lumbur 50603, Malaysia S. Saka (*) Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan e-mail: [email protected] Present address: Z. Ilham Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_20, © Springer 2011

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price plunged and industrial plants are closing down. Therefore, it is superior if biodiesel production produces higher value-added by-products rather than glycerol. In line with this concept, one-step supercritical dimethyl carbonate method has been established as a new method for biodiesel production without producing glycerol [1]. In order to reduce the severe reaction condition in the one-step method, the two-step supercritical dimethyl carbonate method was introduced [2]. In this study, the glycerol from the two-step method was treated in supercritical dimethyl carbonate to obtain glycerol carbonate and evaluated for its effective production process.

2

Experimental

Chemicals and various authentic compounds for standards were obtained from Nacalai Tesque Inc., all of which are of highest purity available. For glycerol from the two-step supercritical dimethyl carbonate method (hereinafter described as glycerol from the two-step method), glycerol from supercritical methanol method and unpurified glycerol from alkali-catalyzed method were studied just for comparison. Those were, then, treated in the batch-type supercritical biomass conversion system [3] to have a reaction at supercritical conditions with dimethyl carbonate (Tc:274.9°C/Pc:4.63 MPa) in a molar ratio of 1:10. All the experiments and analysis were conducted in compliance with the procedures described in our previous papers [1–3].

3 3.1

Results and Discussion Glycerol Carbonate Formation in Supercritical Dimethyl Carbonate

The two-step supercritical dimethyl carbonate method still yields glycerol as a by-product from triglycerides hydrolyzed with subcritical water to fatty acids [2]. In order to check the potential towards a 100% non-glycerol method, glycerol from this two-step method was treated in supercritical dimethyl carbonate at 300°C/12 MPa/15 min without any catalyst applied. When analyzed and compared to several authentic compounds, the resulted compound was found to be glycerol carbonate (4-hydroxymethyl-1,3-dioxolan-2-one), a value-added derivative of glycerol, as depicted in the chromatogram of Fig. 1. As depicted in Fig. 2, the glycerol from the two-step method was also treated in supercritical dimethyl carbonate at various reaction conditions. It could be seen that the best condition for high yield of glycerol carbonate is at the range of 280–300°C/9–12 MPa/15 min. Treatment in temperatures higher than 300°C as presented by the treatment at 350°C/12 MPa resulted in loss of yield due to the decomposition of glycerol carbonate, even in high-pressurized condition.

Glycerol to Value-Added Glycerol Carbonate in the Two-Step Non-Catalytic CH 2 O

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Fig. 1 Chromatogram of the obtained product after glycerol from the two-step method was treated in supercritical dimethyl carbonate at 300°C/12 MPa/10 min without any catalyst applied. Standards of glycerol and glycerol carbonate are shown as authentic compounds 100

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Fig. 2 Yield of glycerol carbonate as glycerol from two-step method was treated in supercritical dimethyl carbonate at various reaction conditions

The reaction scheme for the conversion could be expected to proceed in a manner described in Fig. 3. Dimethyl carbonate reacted with the primary OH group of glycerol, with higher reactivity than the secondary OH group, contributing to the formation of thermodynamically stable five-member cyclic carbonate. Methanol, also being formed from this reaction was removed by evaporation. This route is in agreement with several previous studies describing a similar method in a catalytic manner [4, 5].

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CH2OH CHOH

CH2 -O

+ CH3OCOOCH3

O CH2OH Dimethyl Carbonate

CH2 - O

C =O

CH - O

CH-OH

CH2OH Glycerol

C= O

+ 2 CH3OH

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Methanol

Glycerol Carbonate

Fig. 3 Reaction scheme for glycerol carbonate formation in supercritical dimethyl carbonate

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40 Glycerol from Alkali-catalyzed Method

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Fig. 4 Yield of glycerol carbonate from various glycerol resources treated in supercritical dimethyl carbonate at 300°C/12 MPa

3.2

Utilization of Glycerol Produced from Other Methods

Glycerol from other methods (glycerol from supercritical methanol and unpurified glycerol from alkali-catalyzed methods [3]) were also treated in supercritical dimethyl carbonate at 300°C/12 MPa to check for the possible conversion of glycerol to glycerol carbonate. Comparison is presented in Fig. 4. As presented, glycerol from alkali-catalyzed method showed lower yield of glycerol carbonate than the ones produced by supercritical methods. This might be due to the amount of impurities in glycerol from alkali-catalyzed method and its complicated separation procedures. It is known that the glycerol from alkali-catalyzed method is not pure, contaminated with alkaline catalyst impurities such as sodium salts and soaps [6]. Therefore, utilization of pure glycerol from supercritical methods is better for higher conversion to glycerol carbonate.

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DMC Upper Fatty acids o

Tc=374 C Pc=22MPa

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Water removal

FAME (Biodiesel) Water and Glyoxal

Methanol Glycerol

Lower

Supercritical dimethyl carbonate o (280-300 C/9-12MPa)

Glycerol Carbonate

Fig. 5 Schematic diagram of the two-step supercritical dimethyl carbonate method coupled with the production of value-added glycerol carbonate

3.3

Two-Step Supercritical Dimethyl Carbonate to Produce Glycerol Carbonate

Based on results presented beforehand, the two-step supercritical dimethyl carbonate is coupled with the treatment of the obtained glycerol in supercritical dimethyl carbonate (280–300°C/9–12 MPa/15 min) to achieve glycerol carbonate, as a valueadded by-product. Glycerol carbonate is a stable, colorless liquid currently used industrially as a solvent, additive and chemical intermediate [7]. The whole schematic diagram of the two-step method is presented in Fig. 5.

4

Conclusions

The results presented in this study showed that glycerol could be converted to value-added glycerol carbonate in supercritical dimethyl carbonate (280– 300°C/9–12 MPa/15 min) without any catalyst applied. In addition, utilization of glycerol produced from supercritical methods showed higher conversion to glycerol carbonate due to its high purity. The two-step supercritical dimethyl carbonate method coupled with this conversion method is, therefore, a mild method, offering better prospect for scale-up application and produces value-added glycerol carbonate as a by-product. Acknowledgement This study is partly funded by Japan Science and Technology Agency (JST) and Global-COE Program “Energy Science in the Age of Global Warming”, Kyoto University, supported by Ministry of Education, Culture, Sports, Science and Technology-Japan, for all of which the authors highly acknowledge.

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References 1. Ilham Z, Saka S (2009) Dimethyl carbonate as potential reactant in non-catalytic biodiesel production by supercritical method. Bioresour Technol 100:1793–1796 2. Ilham Z, Saka S (2010) Two-step supercritical dimethyl carbonate method for biodiesel production from Jatropha curcas oil. Bioresour Technol 101:2735–2740 3. Kusdiana D, Saka S (2004) Effects of water on biodiesel fuel production by supercritical methanol treatment. Bioresour Technol 91:289–295 4. Ochoa-Gomez JR, Gomez-Jimenez-Aberasturi O, Maestro-Madurga B, Pesquera-Rodriguez A, Ramirez-Lopez C, Lorenzo-Ibaretta L, Torrecilla-Soria J, Villaran-Velasco MC (2009) Synthesis of glycerol carbonate from glycerol and dimethyl carbonate transesterification: catalyst screening and reaction optimization. Appl Catal A Gen 366:315–324 5. Climent MJ, Corma A, Frutos PD, Iborra S, Noy M, Velty A, Concepcion P (2010) Chemicals from biomass: synthesis of glycerol carbonate by transesterification and carbonylation with urea with hydroxite catalyst. The role of acid-base pairs. J Catal 269:140–149 6. Hara M (2009) Environmentally benign production of biodiesel using heteregenous catalysts. Chem Sus Chem 2:129–135 7. Pagliaro M, Rossi M (2010) The future of glycerol. Royal Society of Chemistry, Cambridge

Prospect of Nipa Sap for Bioethanol Production Pramila Tamunaidu, Takahito Kakihira, Hitoshi Miyasaka, and Shiro Saka

Abstract The current study was initiated to study the chemical composition of nipa sap and its prospect for bioethanol production. Chemical characterization of its sap yielded in sugars content of 14.5 wt%. In addition, the elemental analysis of nipa sap gave 0.5 wt% in ash content with Na, K and Cl being its main inorganic constituents. Batch fermentative assays were made using Saccharomyces cerevisiae to evaluate the fermentability of nipa sap in comparison to sugarcane sap. Almost 85% of total sugars in nipa sap were converted to ethanol within 20–28 h with nutrient supplementation. The fermentation trend of nipa sap was similar to sugarcane sap with a yield of 0.42 and 0.46 g ethanol/g sugars, respectively. Furthermore, nipa sap could be easily fermented without nutrient supplement which makes it an interesting feedstock for bioethanol production. Keywords Bioethanol฀ •฀ Chemical฀ characterization฀ •฀ Inorganic฀ constituents฀ •฀ Nipa฀sap฀•฀Sugarcane฀sap

1

Introduction

The increasing demand for food and fuel often positions energy crops in a conflict of interest. Yet, the global bioethanol supply is still produced mainly from sugar and starch feedstock. The production and use of ethanol from sugarcane in Brazil is the global model for bioethanol production, distribution and use [1]. Sugarcane in the form of juice and molasses which contain high levels of glucose, fructose and sucrose, are the easiest to be converted to ethanol [2]. Unlike sugarcane,

P. Tamunaidu and S. Saka (*) Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan e-mail: [email protected] T. Kakihira and H. Miyasaka Environmental Research Center, The Kansai Electric Power Co., Inc, Kyoto 619-0237, Japan T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_21, © Springer 2011

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the major carbohydrate in corn grain is starch. Common starchy materials used around the world for bioethanol production include potato and cassava. These crops are capable of producing valuable substrates for the production of renewable fuels and bio-products. However, production of fuel from these feedstock are limited as they are used as food for human or animal consumption. Besides common sugar and starch feedstock, palms have been a sugar-prospective from the ancient days. Main sugar yielding palms like palmyra palm (Borassus flabellifer), sugar palm (Arenga pinnata) and nipa palm (Nypa fructicans) are believed to produce more nutritious sugars than cane sugars [3]. As well as being used as edible sugars, interests on the production of alcohol fuel also emerged from these resources. Among these palms, Food and Agricultural Organization of the United Nations (FAO) described nipa palm as a non-threatened and underutilized palm in South Asia with certain exceptions in Bangladesh [4]. Nipa palm is a type of sugar yielding palm and the only thriving palm found in mangrove forests. Nipa produces an easily fermentable sap which is tapped from its inflorescence continuously for up to 100 years. Hamilton and Murphy reported that nipa palm is believed to produce 6,480–15,600 l of ethanol per hectare. This is twice compared to sugarcane which is 3,350–6,700 l [5]. The current study was initiated to explore the prospect of nipa sap for bioethanol production. Fermentative assays were made to evaluate nipa sap in comparison to sugarcane sap on the basis that each crop produces a functionally equivalent product. Further studies on the influence of inorganic constituents in their sap towards the ethanol productivity were made.

2 2.1

Experimental Collection and Characterization

The nipa sap used in this study was collected from Terengganu, Malaysia. On the other hand, the sugarcane sap was obtained from Miyakojima Island, Japan. Individual sugars and ethanol were quantified by high performance liquid chromatography (HPLC) LC-10A (Shimadzu, Japan) and Shodex SUGAR KS-801 column (Showa Denko, Japan) with water as the eluent. The ashes of the nipa sap samples by incineration at 600°C for 2 h were also determined. Elements were then detected through SEM–EDX analysis by scanning electron microscope JSM-5800 (JEOL Ltd., Japan) equipped with energy-dispersive X-ray instrument (EDAX Corp., USA), at an accelerating voltage of 20 kV.

2.2

Organism, Media and Culture Conditions

The yeast Saccharomyces cerevisiae NBRC 0203 (NITE, Japan) was inoculated in Erlenmeyer flasks containing autoclaved medium of glucose 10 g/l, peptone 5 g/l,

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yeast extract 3 g/l and malt extract 3 g/l (Nacalai Tesque, Japan) and incubated in shaker at 120 rpm for 24 h at 28°C. Nutrient broth peptone 200 g/l, yeast extract 120 g/l and malt extract 120 g/l was also prepared to assist fermentation and was autoclaved at 121°C for 20 min prior to its use.

2.3

Batch Fermentations

Fermentation experiments were conducted by batch in 50 ml shaking flasks using Saccharomyces cerevisiae. Fermentations were conducted on the same conditions among nipa sap, sugarcane sap and sucrose as a control with initial sugar content of 14.4 wt%. Duplicate experiments for the same samples were run parallel without nutrient supplementation. Fermentations were done in incubator at 28°C for a period of 28 h with samples taken aseptically at selective time periods.

3 3.1

Results and Discussion Chemical Composition

Table 1 shows the chemical composition of nipa and sugarcane saps on an average of three random samples. Nipa sap was rich in sugars and predominantly high in sucrose followed by glucose and fructose contents as observed in sugarcane saps. The ash content was slightly higher in nipa saps with 0.5 wt%.

3.2

Elemental Characterization

The ash content described in Table 1 is lower in the sugarcane sap than nipa sap. Figure 1 shows a direct comparison of spectra obtained by energy-dispersive X-rays (EDX) analyses of the ash obtained from nipa and sugarcane sap, respectively. The main constituents were found to be Na, K and Cl in nipa saps, as it grows in

Table 1 Chemical composition of nipa and sugarcane saps Yield (wt%) Chemical composition Nipa sap Sugarcane sap Total chemical composition 15.0 15.0 Sugars 14.5 14.6 Sucrose 10.2 14.4 Glucose 2.3 0.1 Fructose 1.5 0.1 Others 0.5 0.0 Ash 0.5 0.4

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Cl

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Ca

Arbitrary฀Intensity

Na Mg Si P S

Nipa Sugarcane

0

1

2

3

4

5

Energy฀(KeV) Fig. 1 Direct comparison of EDX spectra of inorganic constituents obtained as ash from nipa and sugarcane saps

swampy saline soils along seashores whereby elements like NaCl or KCl naturally exists in this habitat. Other minor constituents detected were Ca, Mg, Si, P and S. Conversely, major constituents detected in sugarcane saps were K, Mg, Ca, P and S.

3.3

Ethanolic Fermentation

Figure 2 shows the obtained ethanolic fermentation of nipa sap, sugarcane sap and sucrose as a control. With nutrient supplementation, over 94% of sucrose available in all substrates was efficiently hydrolyzed to glucose and fructose to be further converted to ethanol. Similar trends in ethanol production were observed for all substrates, even though ethanol yield of pure sucrose was only 0.29 wt% compared to 0.42 and 0.46 wt% in nipa and sugarcane saps respectively. Detail fermentation results are shown in Table 2. Without nutrient supplementation, fermentation did occur for both nipa and sugarcane saps but the ethanol yields were as low as 0.35 and 0.15 wt% respectively. Conversely, significant difference was observed in the fermentation of pure sucrose, with only 0.01 wt% of ethanol yield was obtained after 28 h. Therefore in nipa and sugarcane saps, the microorganisms did not require any external nutrient for self growth or fermentation and probably utilized naturally available nutrients in the form of inorganic constituents from saps. The presence of these constituents may have supplemented the growth and metabolism of the microorganism and further assisted in the ethanolic fermentation process. Some nutrients such as Na, K, Mg and Ca are required in millimolar concentrations to satisfy cellular growth requirements to improve the ethanol fermentation and enhance ethanol productivity [6]. Therefore, this characteristic makes nipa sap a good alternative feedstock for bioethanol production.

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Ethanol / Total sugars (wt/wt)

Theoretical 0.5 Sugarcane sap 0.4

Nipa sap

0.3

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0.1

0 0

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Fermentation time (h) Fig. 2 Ethanol yields from fermentation of nipa sap, sugarcane sap and sucrose under the same incubation conditions at 28°C with (filled symbols) and without (open symbols) nutrient supplement

Table 2 Ethanol productions from nipa sap, sugarcane sap and sucrose with and without supplementation of nutrients using Saccharomyces cerevisiae incubated at 28°C for 28 h Sucrose hydrolysis Ethanol yield Conversion efficiency (%) (wt/wt) efficiency (%) With nutrient Nipa sap 98.6 0.42 85.1 Sugarcane sap 98.7 0.46 89.2 Sucrose 94.7 0.29 56.8 Without nutrient Nipa sap Sugarcane sap Sucrose

4

92.0 56.0 20.5

0.35 0.15 0.01

67.6 28.4 1.4

Conclusions

Nipa sap is mainly composed of sugars rich in sucrose, glucose and fructose with a total chemical composition of 15 wt%. The ash content was as low as 0.5 wt% with Na, K and Cl as its main inorganic constituents. Its habitual environment along the river estuaries and sea directly corresponds to the inorganic constituents available in the sap. Furthermore, it showed good ability to be fermented with or without nutrient supplementation with high yields of ethanol. These results indicated that inorganic constituents naturally available in nipa sap may have assisted the fermentation process. On the whole, nipa sap showed a good prospect for bioethanol production.

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Acknowledgements We would like to thank Dr Naohiro Matsui and Dr Yasuyuki Okimori from The General Environmental Technos Co. Ltd, Osaka, for their generous contribution towards this research.

References 1. Nass L, Arraes P, Ellis D (2007) Biofuels in Brazil: an overview. Crop Sci 47:2228–2237 2. Badger P (2002) Ethanol from cellulose: a general review. In: Janick J, Whipkey A (eds) Reprinted from: Trends in new crops and new uses. ASHS Press, Alexandria, VA, pp 17–20 3. Dalibard C (1999) The potential of tapping palm trees for animal production. Livestock Feed Resources within Integrated Farming Systems 11:61–82 4. FAO – Food and Agriculture Organization of the United Nations (1998) Tropical palms. Non-wood forest products 10, 166 pp. Available online at http://www.fao.org/docrep/X0451E/ x0451e00.HTM. Accessed Jan 2009 5. Hamilton L, Murphy D (1988) Use and management of Nipa Palm (Nypa fruticans, Arecaceae): a review. Econ Bot 42:206–213 6. Robinett R, George H, Herber W (1995) Determination of inorganic cations in fermentation and cell culture media using cation-exchange liquid chromatography and conductivity detection. J Chromatogr A 718:319–327

Dissolution of Cerium Oxide in Sulfuric Acid Namil Um, Masao Miyake, and Tetsuji Hirato

Abstract The dissolution behavior of CeO2 in sulfuric acid was examined using a batch reactor with various acid concentrations (8–14 M) at different temperatures (75–130°C). The dissolution of CeO2 was slow and it took more than 3 days to dissolve 4 mmol of a CeO2 powder completely in 100 mL of 12 M sulfuric acid at 90°C. The dissolution rate increased with increases in the temperature and the sulfuric acid concentration. The dissolution rate could be expressed by a shrinking sphere kinetics model. The variation of the dissolution rate constant with temperature obeyed the Arrhenius equation with the activation energy of 120 kJ mol−1. The reaction rate constant was a function of the acid concentration as C6.5. Keywords Cerium฀ oxide฀ •฀ Cerium฀ polishing฀ powder฀ waste฀ •฀ Extraction฀ •฀Hydrometallurgy฀•฀Sulfuric฀acid

1

Introduction

Cerium oxide (CeO2) has been commonly used as an abrasive for glass polishing. It is also used in the chemical mechanical polishing process for intermetal dielectric planarization in the semiconductor industry [1–4]. Thus, a large quantity of polishing powder wastes (PPWs) containing CeO2, SiO2, Al2O3 and so on is generated from the industries.฀However,฀the฀PPWs฀do฀not฀undergo฀any฀recovery฀process,฀but฀they฀are฀just฀ landfilled. Today, with the increasing demand of rare earth metals in the world, the recovery of rare earth metals from waste materials is required [5]. Therefore, it is important to develop a recovery process for the cerium oxide from PPWs. There are a few papers reporting the separation of CeO2 from PPWs using solvent extraction [6, 7], ion

N.฀Um,฀M.฀Miyake,฀and฀T.฀Hirato฀(*) Department of Energy Science and Technology, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 611-0011, Japan e-mail:฀[email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_22, © Springer 2011

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exchange [8] and electrochemical separation [9–11]. Despite these studies, the dissolution rate of CeO2 in acids has not been sufficiently studied. In this study, the dissolution kinetics of CeO2 in sulfuric acid was investigated. The effects of reaction temperature and acid concentration on the dissolution rate were examined.

2

Materials and Methods

The CeO2 powder (Sigma Aldrich, Ltd.) with the particle size of below 5 mm was used. Dissolution experiments were carried out by putting 4 mmol of the CeO2 powder into 100 mL sulfuric acid solution in a batch glass reactor heated at a desired temperature. The solution was stirred by a magnetic stirrer at 650 rpm. After a given reaction time (4–168 h), the solution containing undissolved CeO2 was filtered. The amount of the remaining CeO2 was determined by measuring the weight of the residue after drying at 45°C for over 24 h. The parameters examined in this study were reaction temperature and acid concentration.

3

Results and Discussion

The CeO2 powder was dissolved in 12 M sulfuric acid at 75, 90, 110 and 130°C to examine the effect of the reaction temperature on the dissolution rate (Fig. 1). The dissolution of CeO2 was quite slow even in such a high concentration acid. 1.0

Dissolution

0.8 130oC 110oC o 90 C 75oC

0.6

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Reaction time/h Fig. 1 Effect of temperature on dissolution of CeO2 in sulfuric acid of 12 M

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At 75°C, only 20% of CeO2 dissolved after the reaction for a week. The dissolution rate increased as the temperature rose, and all the CeO2 could be dissolved in 8 h at 130°C. The effect of acid concentration on the dissolution rate was examined by using different sulfuric acid concentration of 8, 10, 12 and 14 M at 90°C. Figure 2 shows the results of these experiments. As expected, the dissolution rate increases with an increase in the sulfuric acid concentration. From the view point of thermodynamics, the overall dissolution process of CeO2 in an acid solution can be ascribed to the partial reduction of cerium(IV) to cerium(III) [12]: 4CeO 2(s) + 12H + (aq) = 4Ce3 + (aq) + 6H 2 O(l) + O2(g)

(1)

All of the dissolution data obtained in this study could be expressed by a nonporous shrinking sphere kinetic model [13–15] described by (2). 1 − (Wt / W0 )1/3 = kt

(2)

where W0 and Wt represent the initial and residual amounts of CeO2 at time t, respectively, and k represents the apparent rate constant. This model assumes the surface reaction of CeO2฀with฀the฀reactant,฀H+, in the solution, and a decrease in the surface area due to the decrease in the initial particle radius with time t. As shown in Figs. 3 and 4, 1 − (Wt /W0 )1/3 plotted against reaction time t are almost on a straight line for each experimental condition, indicating that the dissolution data reasonably followed the shrinking sphere model. The rate constants k (h−1), which were determined by the slopes of the strait lines in Figs. 3 and 4, are plotted against reciprocal of temperature (1/T) and logarithm of sulfuric acid concentration

1.0

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0.8

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o

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Fig. 4 Plots of 1 − (Wt/W0)

versus reaction time for different acid concentrations

(ln C) in Figs. 5 and 6, respectively. As shown in Fig. 5, the increase in the dissolution rate constant with increasing temperature obeyed the Arrhenius equation with the activation energy of 120 kJ mol−1. The relationship between the rate constant and the acid concentration can be expressed as k = k¢ C6.5 (Fig. 6). The large coefficient of 6.5 indicates a strong effect of acid concentration on the dissolution rate of CeO2.

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−1 −2

ln(k /h−1)

−3

Ea = 120 kJ mol−1

−4 −5 −6 −7 −8 2.5

2.6

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(1/T

)10−3/

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Fig. 5 Effect of reaction temperature on the dissolution rate constant −3

ln(k /h−1)

−4

−5

n=6.5 −6

−7

−8 2.0

2.2

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ln (C /M) Fig. 6 Effect of acid concentration on the dissolution rate constant

4

Conclusions

The dissolution rate of CeO2 in sulfuric acid increased with increasing reaction temperature and acid concentration. The dissolution behavior could be described by the shrinking-sphere model with surface chemical reaction control. The activation

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energy of the dissolution was 120 kJ mol−1. The reaction rate constant could also be expressed as a function of acid concentration as k a C6.5.

References 1. Cook LM (1990) Non-Cryst Solids 120:152 ฀ 2.฀ Hoshino฀T,฀Kurata฀Y,฀Terasaki฀Y,฀Susa฀K฀(2001)฀Non-Cryst฀Solids฀283:129–136 ฀ 3.฀ Sabia฀R,฀Stevens฀HJ,฀Varner฀JR฀(1999)฀Non-Cryst฀Solids฀249:123–130 4. Ong NS, Venkatesh VC (1998) Mater Process Technol 83:261–266 5. Kosynkin VD, Arzgatkina EN, Ivanov EN, Chtoutsa MG, Grabko AI, Kardapolov AV, Sysina NA (2000) J Alloys Compd 303–304:421–425 ฀ 6.฀ Zhang฀Z,฀Li฀H,฀Guo฀F,฀Meng฀S,฀Li฀D฀(2008)฀Sep฀Purif฀Technol฀63:348–352 ฀ 7.฀ Xinghua฀L,฀Xiaowei฀H,฀Zhaowu฀Z,฀Zhiqi฀L,฀Ying฀L฀(2009)฀J฀Rare฀Earths฀27:119 ฀ 8.฀ Li฀X,฀Sun฀Y฀(2007)฀Hydrometallurgy฀87:63–71 ฀ 9.฀ Vasudevan฀S,฀Sozhan฀G,฀Mohan฀S,฀Pushpavanam฀S฀(2005)฀Hydrometallurgy฀76:115–121 ฀10.฀ Balaji฀S,฀Chung฀SJ,฀Thiruvenkatachari฀R,฀Moon฀IS฀(2007)฀Chem฀Eng฀J฀126:51–57 11. Song X, Xu D, Zhang X, Shi X, Jiang N, Qiu G (2008) Trans Nonferrous Met Soc China 18:178–182 ฀12.฀ Preston฀JS,฀Cole฀PM,฀Preez฀AC,฀Fox฀MH,฀Fleming฀AM฀(1996)฀Hydrometallurgy฀41:21–44 ฀13.฀ Abdel-Aal฀EA,฀Rashad฀MM฀(2004)฀Hydrometallurgy฀74:189–194 ฀14.฀ Lee฀IH,฀Wang฀YJ,฀Chern฀JM฀(2005)฀J฀Hazard฀Mater฀B123:112–119 ฀15.฀ Ozdemir฀M,฀Cetisli฀H฀(2005)฀Hydrometallurgy฀76:217–224

Utilization of Magnetic Field for Photocatalytic Decomposition of Organic Dye with ZnO Powders Supawan Joonwichien, Eiji Yamasue, Hideyuki Okumura, and Keiichi N. Ishihara

Abstract The discovery of magnetic field effects (MFEs) on homogeneous chemical reactions have led to leads many reports on these effect, however a few have been applied on heterogeneous systems. The aim of this work, therefore, is to investigate the MFEs on photocatalytic decomposition of methylene blue (MB) using ZnO particles. The UV–VIS–NIR spectrometer was used to monitor the MB concentrations. The dependence of the reaction rate under UV irradiation on light intensity, the kept time between preparation of MB solution and before dispersing catalyst powders, so called settling duration, are studied. It is clear that the magnetic field enhances the decomposition rate of MB using ZnO. In case of zero magnetic field, the results show that the photocatalytic decomposition rate followed a first-order model. On the other hand, the decomposition rate of MB using ZnO did not follow first-order reaction under magnetic field. Furthermore, base on the results it is suggested that the condition of the MB solution is an important factor for MFEs on the photodegradation rate. Keywords Magnetic฀field฀effect฀•฀Methylene฀blue฀•฀Photocatalytic฀decomposition฀ •฀ZnO

1

Introduction

Since 1976, the studies of MFEs on chemical reaction has been started. Most of the works published before 2000 were generally concerned the MFEs on photochemical reactions in homogeneous solutions [1]. There are, however, only several works that have focused the effect of magnetic field on a heterogeneous photocatalytic reaction.

S. Joonwichien (*), E. Yamasue, H. Okumura, and K.N. Ishihara Department of Socio-Environmental Energy Science, Graduate School of Energy Science, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_23, © Springer 2011

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Especially, TiO2 has gained much attention because of the strong photocatalytic abilities to purify pollutants in air and water under UV irradiation [2]. When the photocatalyst TiO2 absorbs the light at the wavelength less than 360 nm, it creates electron–hole pairs, promoting electrons to the conduction band and leaving positive holes in the valence band. The generated electron–hole pairs initiate a complex series of chemical reactions [3, 4]. Therefore, it is expected that the photocatalytic reaction might be accelerated or decelerated by external magnetic field. Furthermore, by considering electron transfer processes, it has been documented that magnetic field can affect the recombination process of cation and anion radicals [5]. In 1983, Kiwi reported the MFEs on the photosensitized electron transfer reaction in the presence of TiO2 and CdS loaded particles [6]. Also, there was a report on magnetic field influenced on the heterogeneous photocatalytic degradation of benzene by Pt/TiO2 [7]. Most of investigations of MFEs on heterogeneous photocatalytic reaction, so far studied only on TiO2 catalyst. Therefore, the aim of this work is to study the influence of applied magnetic field on the photodecomposition rate of organic dye compound using ZnO powders. ZnO has recently attracted a lot of attention because of its direct wide band gap of 3.37 eV at room temperature and the large exciton binding energy (~60 meV) [8], and its ability to decompose many chemical compounds [9] in both acidic and basic medium [10]. The decomposition of MB is used in order to assess the photocatalytic degradation reaction, the related mechanism will be clarified.

2

Experimental

A photocatalyst, zinc oxide (purity 99.9%, surface area of 3.8 g/m2, less than 5 mm) was฀ purchased฀ from฀ Wako฀ Pure฀ Chemical฀ Ind.฀ Ltd.,฀ and฀ methylene฀ blue฀ (MB)฀ powder was received from Nacalai Tesque, Inc, Kyoto, Japan. For the photocatalytic measurement, the decomposition of methylene blue was used in order to evaluate the photocatalytic reaction of ZnO powders. The specimens were irradiated฀ by฀ ultraviolet฀ (UV-LED)฀ lamp฀ (OMRON,฀ ZUV-L8V,฀ Kyoto,฀ Japan)฀ with฀ wavelength of 365 nm. The light is irradiated from the bottom and the distance from the UV light source to the specimen is approximately 10 mm. The experimental setup is schematically shown in Fig. 1. Moreover, the specimen container is sealed with cap in order to prevent evaporation. The experimental setup of a small reaction cell with the photocatalyst powders submerged in a 4 ml MB solution, were prepared as follows: The solid MB powder was dissolved into distilled water, and shaking for 5 min. Then, 0.005 g of catalyst powders was put into MB solution. After settling in the dark for another 5 min, UV light was irradiated to the specimen from the bottom. The UV–VIS–NIR฀spectrometer฀(Perkin–Elmer฀lambda฀900)฀was฀used฀to฀monitor฀the฀MB฀ concentrations. All the experiments were performed two or three times to confirm the reproducibility. Thus, all the values of photocatalytic degradation shown in this study are averaged. The results shown here are the normalized values after irradiation.

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Fig. 1 Schematic representation of experimental setup: (1) permanent magnet, (2) specimen, (3)฀UV-LED฀light฀source

3 3.1

Results Influences of Light Intensity

In this work, the experimental were carried out at the three light intensities corresponding to the three power levels for the lamp. The UV light intensity of 500, 600, 700 mW/cm2,฀under฀constant฀MB฀concentration฀of฀0.08฀mmol/L,฀the฀amount฀ of ZnO powder is about 0.005 g. The influence of light intensity on the rate of photocatalytic decomposition has been examined. Figure 2 represents the photodegradation rate of MB using ZnO powders under different light intensities. In case of zero magnetic field, the light intensity effect showed a little in the photodecomposition rate. While, with magnetic field strength of 0.7 T, the reaction rate revealed the significant change and the reaction rate under the light intensity of 700 mW/cm2 was faster than 600, and 500 mW/cm2, respectively.

Fig. 2 The effect of light intensity on photocatalytic decomposition of MB using ZnO powder, (a) without magnetic field, (b) applying magnetic field

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Influences of Settling Duration

In the experimental, two samples with different duration of time were prepared. Both฀have฀MB฀solution฀with฀same฀concentrations฀of฀0.08฀mmol/L.฀The฀first฀one฀is฀ settled for only 5 min, while the second one is settled for 3 h. After that, catalyst powders were added to the MB solution. Hereafter, the kept time of MB solution after preparation and before dispersing catalyst power will be called the settling duration. Then, a light intensity of 600 mW/cm2 was applied to both samples and the pattern of UV irradiation in time is explained in Fig. 3. For settling duration of 5 min, the MFEs on photodecomposition take place. On the other hand, the experiment was performed under the same condition but MB solution was kept for 3 h before adding catalyst. The small MFEs on photodecomposition were observed at the settling duration of 3 h.

Fig. 3 The settling duration effect of MB solution using ZnO, (a) 5 min, (b) 3 h

4

Discussion

The light intensity effect on photocatalytic decomposition of MB is discussed in terms of kinetics of reaction and MFEs. In order to find the degradation kinetics, the first-order reaction model is applied. The kinetic model is expressed by the equation: ln (C0 / C) = kt,

(1)

where C0, C, t, and k are initial dye concentration, dye concentration at t (min), UV irradiation time, and rate constant (1/min), respectively. It revealed that the light intensity affected on photodecomposition rate. In case of a zero magnetic field (Fig. 2a), it is shown that the rate seems to be less affected and the decomposition rate was independent of light intensity. Moreover, the kinetics reaction rate follows the first-order

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reaction. In case of applied magnetic field of 0.7 T, the photodecomposition rate is extremely dependent on light intensities (Fig. 2b) and did not follow the first-order kinetic reaction. The dependencies of the reaction rates on the light intensity are reported to be attributed to the increased rate of the recombination of photogenerated electron–hole pairs [11]. One possibility is, an increase in the light intensity leads to more excitation and more electron–hole pair generation, along with increasing in OH species creation [12]. Therefore, magnetic field might be affects on hydroxyl radical and/or super oxide species. The settling time effect is also investigated in both cases of presence/absence magnetic field of 0.7 T. The result shows that MFEs become negligible when the same photodecomposition experiment is carried out after settlement of MB solution for 3 h. However, the detail of the mechanism is still not clear. Further investigation is needed to clarify.

5

Summary

The photocatalytic decomposition of MB by ZnO particles under UV irradiation presence and absence magnetic field was investigated. When no magnetic field is applied, the decomposition rate become independent of light intensity, and light intensity seems to influence on the reaction rate of the first-order reaction. On the other hand, in the case of 0.7 T magnetic field, MFEs on the decomposition rate of MB were observed, and the reaction kinetics under magnetic field cannot be explained by the first order mechanism. Furthermore, the condition of MB solution is suggested as one important factor for MFEs on photodecomposition. The further study is needed to explain the full mechanism. Acknowledgement This฀work฀was฀supported฀by฀Global฀Center฀of฀Excellence฀(GCOE)฀Program฀ and Grant-in-Aid for Scientific Research (B) by MEXT, Japan.

References 1. Ulrich ES, Thomas U (1989) Magnetic field effects in chemical kinetics and related phenomena. Chem Rev 89:51–147 2. Karen JB, Richard DN, Carl AK, William AJ (1999) Investigation of the effects of controlled periodic illumination on the oxidation of gaseous trichloroethylene using a thin film of TiO2. Ind Eng Chem Res 38(3):892–896 3. Dindar B, Icli S (2001) Unusual photoreactivity of zinc oxide irradiated by concentrated sunlight.฀J฀Photochem฀Photobiol฀A฀Chem฀140:263–268 ฀ 4.฀ Marto฀J,฀Sao฀MP,฀Trindade฀T,฀Labrincha฀JA฀(2009)฀Photocatalytic฀decoloration฀of฀orange฀II฀ by ZnO active layers screen-printed on cereamic tiles. J Hazard Mater 163:36–42 5. Wakasa M, Suda S, Hayashi H, Ishii N, Okanp M (2004) Magnetic field effect on the photocatalytic reaction with ultrafine TiO2฀particles.฀J฀Phys฀Chem฀B฀108:11882–11885

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6. Kiwi J (1983) Magnetic field effects on photosensitized electron transfer reactions in the presence of฀titanium฀dioxide-฀and฀cadmium฀sulfide-loaded฀particles.฀J฀Phys฀Chem฀87:2274–2276 7. Zhang W, Wang X, Fu X (2003) Magnetic field effect on photocatalytic degradation of benzene฀over฀Pt/TiO2. Chem Commun 17:2196–2197 ฀ 8.฀ Bretagon฀T,฀Lefebvre฀P,฀Valvin฀P,฀Gil฀B,฀Morhain฀C,฀Tang฀X฀(2006)฀Time฀resolved฀photoluminescence study of ZnO/(Zn, Mg)O quantum wells. J Cryst Growth 287:12–15 ฀ 9.฀ Yeber฀ MC,฀ Rodriguez฀ J,฀ Freer฀ J฀ (2000)฀ Photocatalytic฀ degradation฀ of฀ cellulose฀ bleaching฀ effluent by supported TiO2 and ZnO. J Chemosphere 41:1193–1197 ฀10.฀ Curri฀ML,฀Comparelli฀R,฀Cozzoli฀PD,฀Mascolo฀G,฀Agostiano฀A฀(2003)฀Colloidal฀oxide฀nanoparticles for the photocatalytic degradation of organic dye. Mater Sci Eng C 23:285–289 11. Upadhya S, Ollis DF (1997) Simple photocatalysis model for photoefficiency enhancement via฀controlled,฀periodic฀illumination.฀J฀Phys฀Chem฀B฀101:2625–2631 12. Nagakura S, Hayashi H, Azumi T (1998) Dynamic spin chemistry. Kodansha and Wiley, Tokyo and NY

Hybrid Offshore Wind and Tidal Turbine Power System to Compensate for Fluctuation (HOTCF) Mohammad Lutfur Rahman, Shunsuke Oka, and Yasuyuki Shirai

Abstract The hybrid system proposed in this study involves an offshore-wind turbine and a complementary tidal turbine that supplies grid power. The hybrid wind–tidal system consistently combines wind power and tidal power to guarantee the continuous availability of grid power. The power output from the offshore-wind is complemented by tidal power to maintain the grid power. The wind power is subject to short-term fluctuations, and the tidal power is used to compensate for these variations. This indicates that the tidal turbine must be able to increase production very quickly in order to supply grid power. Therefore, a performance analysis is necessary to determine the effective contributions from the tidal and wind turbine generators, and their contributions to the load system. Keywords Flywheel฀•฀Hybrid฀system฀•฀Offshore-wind฀turbine฀•฀Tidal฀turbine

1

Introduction

Offshore wind turbine models have played critical roles in understanding system performance and conducting grid integration studies. Likewise, the development of a tidal system converter model is a nontrivial problem, particularly for studying large scale ocean (tidal) power systems. The development and utilization of the various renewable energy sources represented by offshore-wind has become a strategic choice of energy problem solving. The offshore-wind turbine load is complicated

M.L. Rahman (*), S. Oka, and Y. Shirai Department of Energy Science and Technology, Graduate School of Energy Science, Kyoto University, Kyoto, Japan e-mail: [email protected]; [email protected]; [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_24, © Springer 2011

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because the load of the offshore-wind turbine fluctuates during the day. These fluctuations create imbalances in the power distribution that can affect the frequency and voltage of the power system. Laboratory scale experiments were carried out to show the feasibility of the system and to propose new control strategies using the bi-directional converter and MPPT (Maximum Power Point Tracking) grid connection converter [1, 2]. In the proposed system, in order to compensate for wind fluctuation, a tidal system is operated as a flywheel motor/generator system. In other words, when the power fluctuation exceeds a certain level, the tidal system works as a motor to store the excessive power as rotational energy. Conversely, when the wind power dips to a certain level, the tidal system works as a generator to complement it. The tidal turbine will help to balance the distribution of power in the power system. Figure 1a, b show a photo and conceptual image of the small laboratory-based hybrid power system model that designed and fabricated. The system has two types of generation, the tidal motor/generator and the offshore wind turbine generator. The tidal turbine (induction machine) can act as either a motor or generator, depending on the need. The tidal generator provides smooth output power, whereas the output power of a wind turbine depends on the wind velocity.

Fig. 1 (a) Photo of laboratory scale prototype model of hybrid offshore-wind and tidal turbine system with flywheel. (b)฀HOTT฀conceptual฀image

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Offshore Wind Turbine Generator

Figure 2 shows an experimental model of the offshore-wind turbine generator system [2]. It consists of a coreless synchronous generator and a servo-motor. The offshore-wind turbine is simulated by the servo-motor. In this model system with the small servo-motor, the rated rotating speed is 2,500 rpm and the gear ratio is 10.5:1. In the real system, the wind turbine would have a slower rotating speed without the step-down gear. The rotating speed or the torque of the servo-motor is controlled by a computer. The electrical energy depends on the rpm (rotations per minute)฀of฀the฀servo-motor฀that฀rotates฀the฀coreless฀generator.฀Wind฀turbine฀generated AC power is converted to DC power with the 6-pulse diode rectifier. The parameters of the servo-motor and the coreless synchronous generator are listed in Tables 1 and 2, respectively.

Fig. 2 Offshore-wind turbine generator Table 1 Rating of main components (offshore-wind servo motor) Parameter Value Rated power 3.0฀kW Rated voltage 200 V Rated frequency 60฀Hz Rated speed 2,500 rpm Gear ratio 10.5:1 Table 2 Rating of main components (coreless synchronous generator) Parameter Value Rated power 1.5฀kW Rated voltage 200 V Rated frequency 60฀Hz Rated speed 200 rpm

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Tidal Turbine

Figure 3 shows the experimental model of a tidal turbine induction generator/motor and a servo-motor [2]. The main concept in this project is to apply and control a bi-directional (two way) energy flow scheme, so that energy is injected into the offshore wind turbine or stored as kinetic energy from/to the tidal system (induction machine). Tidal turbine flywheel energy systems, in comparison with conventional batteries, present some interesting characteristics when used as an energy source to compensate for voltage sags and momentary power interruptions. The induction machine is used for bi-directional energy conversion from/to the tidal turbine. The servo-motor is used as an input model of tidal energy to the induction generator, which converts the mechanical energy into electrical energy. The induction machine can work as a motor by using the bi-directional IGBT converter and a one-way clutch.฀ When฀ the฀ induction฀ machine’s฀ rotational฀ speed฀ is฀ larger฀ than฀ that฀ of฀ the฀ servo-motor, the servo-motor clutch turns to the off-state. The design parameters of the servo-motor and the induction machine are listed in Tables 3 and 4, respectively. A speed of 1,110 rpm is selected for the induction machine to store the rotational kinetic energy. In a real system, the tidal turbine rotational speed should be much lower than that of the servo-motor, and a step-up gear will be necessary.

Fig. 3 Tidal turbine generator/motor Table 3 Rating of main components (tidal servo motor) Parameter Value Rated power 1.5฀kW Rated voltage 200 V Rated frequency 60฀Hz Rated speed 2,500 rpm

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Table 4 Rating of main components (induction machine) Parameter Value Rated power 750฀W Rated voltage 200 V Rated frequency 60฀Hz Rated speed 1,110 rpm

Fig. 4 HOTCF฀circuit฀configuration

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HOTCF System

This paper presents an experimental study of how wind power can be complemented by tidal power. A conceptual framework is provided for a tidal power that produces almost stable power output without the intermittent fluctuations inherent when using wind power. The goal of this paper is intended to identify the best technological match between tidal as flywheel and offshore-wind turbines in order to build a new offshore-wind hybrid system [2]. This hybrid design makes system stable, flexible, reliable, durable and easy to scale. Figure 4 shows a schematic configuration of proposed wind & tidal hybrid generation฀system฀(HOTCF)฀model฀experimental฀output฀is฀simply฀rectified฀by฀a฀6-pulse฀ diode bridge to charge a DC capacitor. The tidal turbine induction generator/motor output is connected to the DC capacitor through a 6-pulse IGBT dual way converter.

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The DC link capacitor is connected to the commercial grid through a grid-connected inverter of single-phase and 3-wire. The grid-connected inverter is of a transformerless half-bridge type with a boost-up chopper circuit. The voltage-source inverter output฀current฀is฀controlled฀by฀PWM฀controller฀under฀the฀MPPT฀(Maximum฀Power฀ Point Tracking) control. The MPPT control searches and keeps the DC link capacitor voltage which gives the maximum output power by controlling the output AC current. It gives the DC voltage perturbations of 4 V up and down (2 V/s) every 4 s and checks how to change the output power due to them, and then decides the DC-voltage reference at next stage to give more power. Several small controllers are implemented at both ends to provide the required performance to the system.

5

Experimental Results and Discussion

In this section, one example of the hybrid operation is shown to demonstrate the availability of the proposed system. For the initial operating conditions, the offshore-wind฀only฀generates฀0.2฀kW.฀The฀tidal฀induction฀machine฀works฀in฀the฀motor฀

Fig. 5 Rotating speed of servo-motors and generators

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mode with a rotating speed of 1,190 rpm, while that of the tidal turbine servo-motor is 1,120 rpm (clutch is OFF). Figure 5 shows, the rotating speeds of the offshore-wind generator, tidal induction machine, and tidal servo-motor. The wind fluctuation was simulated by a step down change in the servo-motor rotating speed, as shown in the figure. The tidal system turned to the generator mode at 5 s to boost the tidal servo-motor speed higher than the rotating magnetic field speed (1,200 rpm) to compensate for the change in the wind generator output. The clutch turned to the ON-state and the servo-motor (tidal turbine) started to drive the induction machine. The instantaneous waves of the terminal voltage, current, and powers of the coreless generator (wind) are shown in Fig. 6. As the servo-motor (wind) speed fluctuated, the offshore wind generation power (P2, Fig. 6) decreased at 2.0 s and was shutdown at 8.3 s. To overcome this drawback, a hybrid energy system is needed to produce tidal power (P1, Fig. 7). As shown in Fig. 7, the tidal generation system was first used

Fig. 6 Voltage, current and output of offshore-wind generator system

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Fig. 7 Voltage, current and output of tidal generator system

as฀a฀flywheel฀for฀storing฀the฀rotational฀energy฀with฀small฀loss฀(P1฀=฀−22฀W).฀At฀5฀s,฀ the induction machine changed from the motor to the generator mode and started to฀produce฀an฀active฀power฀of฀100฀W,฀and฀then฀250฀W฀at฀7฀s. Figure 8 shows DC link voltage Vdc, currents Idc1 and Idc2 from the bi-directional converter and diode-bridge, and Idc3 at the grid inverter. The powers, Pdc1 and Pdc2 from the tidal and wind generation systems, and Pdc3 at the power grid, are also shown. The power flows in the hybrid operation are clearly seen in the figure.฀While฀the฀wind฀generator฀output฀was฀decreasing,฀the฀tidal฀generator฀output฀ was built up to compensate for it, and to recover the grid power to the initial value. Note that the MPPT control maintained the DC link capacitor voltage, which gave the maximum output power by controlling the output AC current during the operation. Figure 9 shows the voltage, current, and power at the AC side terminal of the grid connected inverter. In general, the grid power was kept stable according to the DC

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Fig. 8 Voltage, current and powers of DC side (color figure online)

side฀ power,฀ Pdc3.฀ However,฀ transient฀ phenomena฀ in฀ the฀ current฀ and฀ power฀ were฀ observed at the beginning of the tidal generation. The total coordination of the control system, including the MPPT control, should be investigated in the next study.

6

Conclusion

The฀ proposed฀ HOTCF฀ prototype฀ is฀ a฀ HOTT฀ system฀ with฀ an฀ energy฀ storage฀ (flywheel) function. The control flexibility and the system stability can be much improved. A wind-tidal power generation system has a very high power-generating potential because of the abilities of wind and tidal resources to complement each other. This system is going to be economical in the future. Besides the cost, the

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Fig. 9 Experimental result of load side

environmental benefits are likely to facilitate the widespread use and acceptance of these systems. The performance of modular hybrid energy systems can be improved through the implementation of advanced control methods in bi-directional and MPPT system controllers. Optimum resource allocation, based on load demand and renewable resource forecasting, promises to significantly reduce the total operating cost of the system. The hybrid system method is considered to be one of the best techniques for converting tidal energy and wind energy into electricity.

References 1. Rahman ML, Oka S, Shirai Y (2010) DC connected hybrid offshore-wind and tidal turbine (HOTT)฀generation฀system.฀Springer,฀Academic฀Journals,฀pp฀141–150 2.฀Rahman฀ ML,฀ Oka฀ S,฀ Shirai฀ Y฀ (2010)฀ Hybrid฀ power฀ generation฀ system฀ using฀ offshore-wind฀ turbine฀and฀tidal฀turbine฀for฀power฀fluctuation฀compensation฀(HOT-PC).฀IEEE฀Trans฀Sustain฀ Energy 1(2):92–98

Beam Stabilization by Using BPM in KU-FEL Yong-Woon Choi, Heishun Zen, Keiichi Ishida, Naoki Kimura, Satoshi Ueda, Kyohei Yoshida, Masato Takasaki, Ryota Kinjo, Mahmoud Bakr, Taro Sonobe, Kai Masuda, Toshiteru Kii, and Hideaki Ohgaki

Abstract A Mid-Infrared Free Electron Laser (MIR-FEL) facility has been constructed for developing energy materials in Institute of Advanced Energy (IAE), Kyoto University. Since high brightness electron beams are crucial for the FELs, stabilization of the electron beam (beam energy, beam current, bunch spacing and beam trajectory) is very important for a stable FEL operation. For these reasons, the electron beam position which includes the electron beam energy information should be monitored precisely to realize the highly stable electron beam. We have been developing a feedforward and a feedback system using 4-pickup electrode type Beam Position Monitor (BPM) in Kyoto University FEL (KU-FEL) to generate a stable FEL light. A basic design of the BPM readout system has been completed and we have installed BPMs with accuracy of 10 mm for non-destructive measurement in the KU-FEL linear accelerator. BPM signals were observed successfully and a phase stabilized electron beam has been generated by a feedforward system. A feedback system using BPM to stabilize the beam position is under development. Keywords Beam stabilization • BPM • Feedback control • Feedforward control • MIR-FEL

Y.-W. Choi (*), K. Ishida, N. Kimura, S. Ueda, K. Yoshida, M. Takasaki, R. Kinjo, M. Bakr, T. Sonobe, K. Masuda, T. Kii, and H. Ohgaki Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan e-mail: [email protected] H. Zen UVSOR, Institute for Molecular Science, Okazaki, Aichi, Japan T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_25, © Springer 2011

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Introduction

Stabilization of an electron beam’s energy plays crucial role in a stable FEL operation. Energy variations can significantly affect transmission through beam line elements that transport the beam to the experimental area. Instability can result from various reasons in circumstances related to experimental room. Furthermore, FEL power becomes unstable because of these environmental problems. For this reason, we need to develop an energy feedback system using BPMs. In our facility, the instability of the electron beam energy is occurred owing to the fluctuation of the body temperature of the thermionic RF gun, the surface temperature of the cathode because of a back-bombardment effect [1], the surface temperature of accelerator tube, the high-electric noise by the klystron and so on. As mentioned before, this instability brings about the instability of FEL power as shown in Fig. 1. The power stability during 30 min. is about 14% (RMS). So, we have to improve the power stability for FEL applications.

2

Experiment

A new BPM system was introduced to the KU-FEL [2] linac in Kyoto University in 2009. The six BPMs were installed at each position. The structure of the BPM is 4-pickup electrodes type as shown in the left side of Fig. 2. The diameter of the electrode of the BPM is 15 mm. When an electron beam passes through a beam duct, a signal whose amplitude is determined by the beam charge and the beam position of the electron beam is induced by each electrode of the BPM as shown in the left side of Fig. 2. Then a beam position is calculated in aspect of the left, the right, the top and the bottom by processing these

Output Power [a.u.]

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30 min.

0.0 0.520

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Pickup Electrode

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Voltage @2856 MHz

SMA Connector Electron Beam Vacuum Chamber

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#1 #2

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#3

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Fig. 3 Schematic drawing BPMs in KU-FEL

signals. This pickup electrode type BPM is superior in high frequency property. In addition, a technique to measure a bunch length of the electron beam by measuring the strength ratio of the high-frequency component of the evoked signal is also suggested [3]. The basic frequency of the signal evoked by the electron bunch is the same as the electron beam repetition frequency (2,856 MHz) shown in the right side of Fig. 2. The locations of the each BPM installed in KU-FEL are shown in Fig. 3. The BPM #1 and #3 are used to measure the RF phase of the electron beam to keep the bunch spacing in constant by controlling phase of the input RF signal fed into the RF-gun as well as the accelerator tube. The BPM #1 and #2 in the low energy section and BPM #3 and #4 in the high energy section are used to measure electron beam position owing to the electron beam energy in each section. To stabilize the beam energy in each section, we will install feedback loops by controlling input RF powers fed into the RF gun and the accelerator tube, respectively. The BPM #5 and #6 are used to put electron beam at the center in the undulator by controlling bending magnets and steering magnets. The functions of each BPM are summarized in the Table 1. The speed of the feedback control system would be a few seconds to stabilize a long time fluctuation in KU-FEL. To ensure this feedback system, we will use a software feedback system developed by the LabView package.

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Table 1 Functions of each BPM in KU-FEL BPM # Control object Measured object 1 and 2 Energy (low energy Position section) 3 and 4 Energy (high energy section) Position 5 and 6 1 and 3 5

Position RF phase (low energy section, high energy section) Bunch length

Position RF phase Bunch length

Control knob RF power fed into RF gun RF power fed into accelerator tube Steering magnets Phase of RF power fed into RF gun and accelerator tube Quadrupole strengths

Klystron No.2 TV2019B6 PFN1

Signal Generator 2856MHz

RF Gun ~200W Klystron No.2 PV-3030A1

BPM 1

PFN2 Accelerator Tube ~500W Out Phase Test Detector

Function Generator

PC

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Ref Oscillo -scope

Phase Test Out Detector Ref

Fig. 4 Schematic diagram of RF system

3

Results

We succeeded in measuring a change of electron bunch phase by using a high frequency signal output from BPM #1. We also succeeded in keeping a fixed electron bunch phase using a voltage control type high speed phase shifter as shown in Fig. 4. Each phase shifter in this figure is used to compensate the bunch phase shift measured by BPM #1 and #3, respectively. We need an electron beam with constant RF phase for FEL lasing. As shown in the Fig. 5a, the bunch phase was not constant during the macro-pulse because a time varying RF power was fed into the RF gun to compensate the time varying beam loading which was induced by backbombardment effect in thermionic RF gun. After installation of feedforward phase control system indicated as red part in the Fig. 4, we can improve the phase shift

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from 16° to less than 2° during the macro pulse as shown in the Fig. 5b. A preliminary result of the beam position readout measurement by using BPM #3 is shown in Fig. 6a on the horizontal axis for showing in the aspect of the left and right side in the beam duct and Fig. 6b on the vertical axis for showing in the aspect of the top and bottom side in the beam duct. These plots show the response owing to the steering magnet currents. The signals from the pickup electrode were calculated by different-over-sum processing. We observed non-linear response in this measurement because of the strong quadrupole field located near-by BPM #3. The basic design of the beam position feedback system by using BPM is shown in Fig. 7. Our overall system is as like the below. The signals from BPMs will be clipped by NIM clipping modules and be AD converted with CAMAC ADC system connected with PC (LabView). And then, we can achieve the beam stabilization as adjusting power supply of bending magnet or steering magnet through feedback loop by using LabView feedback library.

a

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Steering Magnet Current [A]

Fig. 6 BPM #3 signal owing to steering magnet current

Steering Magnet Current [A]

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Signal processing NIM

CAMAC

Clipping Module (8 ch)

Charge ADC (16 ch)

BPM

Power supply

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4

Conclusions

We have installed six BPMs designed by KEK-ATF group with an accuracy of 10 mm for non-destructive measurement in KU-FEL linear accelerator. And then, we could measure a change of electron bunch phase and compensate electron bunch by using BPM #1 for additional acceleration in accelerator tube. The signal observation by using BPM #3 was complimented successfully. As a result the RF phase drift during the macro pulse was successfully improved from 16° to less than 2°. A new feedback system using BPMs to stabilize the beam position of each part, the beam energy in the low energy and the high energy section has been designed to improve stability of KU-FEL. The linac energy can be determined by measuring the beam position displacement at a location with a large dispersion. Information of electron beam energy derived from the electron beam positions may include noise, a part of which is caused by an electric noise induced by high-power klystrons. This problem can be reduced by integrating the BPM signals, beam currents and cathode surface temperature of RF-gun.

References 1. McKee CB et al (1990) NIM A296:716–719 2. Ohgaki H et al (2008) Lasing at 12 mm mid-infrared free-electron laser in Kyoto University. Jpn J Appl Phys 47:8091–8094 3. Kuroda R et al (2004) Jpn J Appl Phys 43(No. 11A):7747–7752

Analysis of Transient Response of RF Gun Cavity Due to Back-Bombardment Effect in KU-FEL Mahmoud Bakr, Heishun Zen, Kyohei Yoshida, Satoshi Ueda, Masato Takasaki, Keiichi Ishida, Naoki Kimura, Ryota Kinjo, Yong-Woon Choi, Taro Sonobe, Toshiteru Kii, Kai Masuda, and Hideaki Ohgaki

Abstract Thermionic RF guns have advantageous features, such as compactness and high brightness of output beam, against electrostatic guns because of their high acceleration fields. For these reasons, thermionic RF gun has been chosen as electrons injector for Kyoto University free electron laser facility. The most critical issue of the thermionic RF gun is the transient cathode heating due to the electron back-bombardment when the gun is used as a driver linac of an MIR–FEL oscillator, which requires macropulse duration of more than 5 ms and bunch charge of more than 20 pC. Under the condition, the transient cathode heating results in rapid increase of beam current and rapid decrease of beam energy during a macropulse. Several important parameters, such as cathode temperature, current density of the cathode surface, are difficult to be measured during the experiment. A numerical simulation is the best way to expect the behaviour of such parameters. Numerical calculations were carried out to evaluate the cathode temperature and current density during the macropulse, by a simulation code which was developed at Kyoto University. The code simultaneously solves two differential equations; the differential equation of the equivalent circuit of the RF gun and one dimensional thermal equation of the thermionic cathode which includes the heat input from back-bombardment electrons. The results of transient response of the RF cavity due to the back-bombardment effect are presented with conclusions. Keywords Back-bombardment • FEL • Numerical simulation • RF cavity •฀Thermionic cathode

M. Bakr (*), K. Yoshida, S. Ueda, M. Takasaki, K. Ishida, N. Kimura, R. Kinjo Y.-W. Choi, T. Sonobe, T. Kii, K. Masuda, and H. Ohgaki Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011, Japan e-mail: [email protected] H. Zen UVSOR, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_26, © Springer 2011

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Introduction

Thermionic RF guns are quite attractive because of its simple configuration with no high voltage stage, in addition, the beam emittance is possibly low and the bunch length can be compressed to have sufficient peak current to drive free electron laser (FEL) [1]. Due to the economical, compact configuration and high brightness of output beam, thermionic RF gun has been chosen to drive Kyoto University free electron laser (KU-FEL) facility. However, currently there are not so many linac devices with thermionic RF guns are used in FEL applications; because of the great challenges against the back-bombardment (BB) affect, while, strongly restrains further development as the electron source. Some methods to mitigate BB effect [2–4] have been invented without so much success. The mechanism of the BB effect in thermionic RF gun can be simply explained as follows: because the cavity fields oscillate in time, electrons that are emitted late in the RF period does not have the chance to cross the cavity before the accelerating field reverses its direction. A number of these electrons are accelerated back towards the cathode. If these electrons hit the cathode, its kinetic energy transfers to the cathode material and heat it up. Under normal operating conditions, some BB electrons are necessary for the proper operation of the gun. However, since the heating is presented only during the macropulse, the temperature of the cathode is increased during the macropulse. The increasing of cathode temperature causes a ramp in the macropulse current; as one can see from Fig. 1a. Due to the increases of the beam current the beam loading increases, as a result the cavity voltage decreases, and consequently, the beam energy decreases. To reduce the heat transferred by the BB electrons, an external transverse magnetic field has been commonly applied on the cathode surface. However, even with the applying of the transverse magnetic filed the beam current increases and beam energy decreases during the macropulse when the macropulse length is longer than 2 ms and the output beam current is higher than 200 mA [5], which are not sufficient for various

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Fig. 1 (a) Temporal evolution of input, reflected RF power, and beam current, (b) Schematic side view of KU-FEL thermionic RF gun

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FEL applications. In KU-FEL facility two methods to compensate the energy beam decrease due to the BB electrons were conducted; by controlling input RF power and frequency cavity detuning, more details can be found in [6]. KU-FEL thermionic RF is S-band RF gun having 4.5-cell, side-coupled cavities with a thermionic cathode at the first half cell, which is driven by 10 MW RF power, to provide electron beam up to 10 MeV. Figure 1b shows schematic for KU-FEL thermionic RF gun with LaB6 cathode. In this paper, we proposed a developed numerical simulation code to study the transient cathode heating problem due to the BB effect in thermionic RF gun. And determine the change in the cathode temperature and current density during the macropulse.

2

Analysis Method

The BB effect depends on the cavity voltage in the RF gun and current density at the cathode surface. We performed a transient analysis in the thermionic RF gun taking into account the time evolution of the beam loading depends on the cavity voltage and the cathode current density by using an equivalent circuit for RF cavity model and a thermal conduction model. The beam loading is calculated from the cavity voltage by solving the equivalent RF gun circuit and the current density was calculated from the thermal conduction in the cathode by solving one dimensional thermal diffusion equation. The energy distribution and the total power from the BB electrons were determined by simulation codes taking into account the stopping range and deposited heat from the BB electrons inside the cathode.

2.1

Analysis of the RF Cavity Response

The interaction between an RF resonant cavity and an electron beam can be represented by equivalent circuit [7]. In this circuit, the RF power source is expressed by a source Ig, the RF gun is expressed by LCG resonant circuit, and the beam loading is expressed as beam admittance part Yb, which can be divided in the circuit into real part beam conductance Gb and imaginary part beam susceptance Bb. The Gb and Bb depend on the current density on the thermionic cathode surface Jc and the acceleration voltage of the cavity Vc. The circuit constants (external conductance Gex, cavity inductance Lc, cavity capacitance Cc, and cavity conductance Gc) are given as: Cc =

2 π f0 1 1 , Lc = , Gc = , Gex = b Gc 2 π f0 ( R / Q ) ( R / Q) Q0 ( R / Q )

(1)

where f0 denotes the resonant frequency of the RF resonant cavity, Q0 the unloaded quality factor, (R/Q) the (R/Q)-factor of the cavity, and the coupling coefficient b of the input waveguide to the cavity. The source current Ig is described as

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Ig = (8GexPin)1/2. The beam admittance Yb is defined as Yb = Ib/Vc, where Ib denotes the beam loading (induced) current.

2.2

Analysis of the Cathode Current Density

In this analysis, following three assumptions are considered; I- Radiative heat emission occurs only on the surface of the cathode. II- Heat input to the cathode is only from the cathode heater and BB electrons. III- Heat flows only on the beam axis in a macropulse. Under these consedrations, the heat transfer in the cathode is given by one dimensional thermal diffusion equation as: CrV

∂ T ( z, t ) ∂ 2 T ( z, t ) =l + Qb ( z, t ,) ∂t ∂z 2

(2)

where C (J/kg/K) denotes the specific heat capacity, r (kg/m3) the mass density, V (m3) the cathode volume, l (W/m/K) the thermal conductivity, t the time, z the depth of cathode from the surface, T(z, t) the cathode temperature and Qb(z, t) the heat input due to the BB electrons. It is impossible analytically solve (2), since the heat input is time dependent and not uniform. Thus the cathode is divided into 20,000 thin disks, and difference method is used to calculate the heat transfer. The time evolution of the temperature is calculated in each disks of the cathode. The range, R of electrons inside a material is useful for evaluation of effects associated with penetration of electrons in the material, such as BB electrons. The range R of electrons in the energy region 0.3 keV–30 MeV for the absorbers of atomic number 6–92 has been found to be expressed by a single semiempirical equation TIO of the form [8]. R=

a3 ( γ − 1)  a1  ln(1 + a2 ( γ − 1) −   ρ a2 1 + a4 ( γ − 1)a5 

(3)

where, R (m) is the stopping range of the electrons, γ is the incident kinetic energy in the units of the rest energy of the electron, a1,2,….5 are parameters depend on the atomic number and atomic weight of the absorber material; parameters, definitions and more details can be found in ref [9]. It well known that the stopping power of the particles inside material can be defined as the decreases of the particles energy relative to the change the stopping range as dE/dR, hence the stopping power can be determined.

3

Results and Discussion

The simulation was carried out in the same conditions of normal operation at KU-FEL of initial cathode temperature, input RF power, frequency, cavity voltage and electron beam energy. The cathode material is a single crystal of LaB6 with

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radius and thickness 1 and 2 mm respectively, density r = 4,720 kg/m3, specific heat C = 122 J/kg/K, l = 147 W/m/K. RF gun parameters which are used in the calculations are listed in Table 1.

3.1

RF Cavity Response

The beam conductance and beam susceptance in the equivalent circuit depend on the cavity voltage and the current density on the cathode surface, due to that the beam conductance and susceptance depend on energy consumed by the electron beam and riding RF phase of the beam. The beam conductance and beam susceptance of the electron beam were calculated at different cavity voltage and cathode current density by using particle simulation code KUBLAI [10]; the results are depicted at Fig. 2. As shown in Fig. 2, the beam admittance increases when the current density on the cathode surface increases. And the partial differential coefficients of the beam conductance and of the beam susceptance with respect to the current density are positive and negative, respectively. Table 1 Parameters of the RF gun which have been used in the numerical simulation code Resonant frequency (MHz) 2,856 Coupling coefficient (b) 2.79 Q value 12,500 R/Q (W) 980 Accelerating mode p Cathode material LaB6 Initial cathode temperature (°C) 1,562

Fig. 2 (a) Beam conductance and (b) susceptance as a function of the current density Jc with different cavity voltage, which are derived by numerical simulations (KUBLAI code)

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Analysis of the Cathode Current Density

In order to evaluate the effect of BB electrons on the time evolution of the cathode temperature, at first the energy distribution and deposited heat of BB electrons were calculated at different current density and cavity voltage by using the particle simulation code PARMELA [11]. Figure 3a, shows the deposited heat at different BB electron beam energies. However, Fig. 3b shows the energy distribution of the BB electrons inside the cathode material at different cavity voltages and at fixed current density 50 A/cm2 as an example. As shown in Fig. 3, BB electrons hitting the cathode surface have energy distribution. The energy distribution and the total power of BB strongly depends on the cavity voltage and current density on the cathode surface. One can see from Fig. 3a that with increase the electrons energy the depth of the deposited energy

Fig. 3 (a) Energy deposition of BB electrons in cathode material at different electron beam energies, (b) energy distribution of BB electrons at 50 A/cm2, current density at different cavity voltage derived by PARMELA

Fig. 4 (a) The range and stopping power of BB electrons in cathode material calculated by using TIO equation, (b) the change of the cathode temperature and current density during the macropulse (color figure online)

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increase, and the maximum deposition occurred just before electrons stop. Moreover, the total power of BB electrons gets higher when a thermionic RF gun is operated with the condition of higher current density or higher cavity voltage as shown in Fig. 3b. Then, the range and stopping power of BB electrons inside the cathode material were determined by the results from the PARMELA code and (3). Figure 4a shows the range and stopping power as a function of BB electrons energy. Finally, to analyze the BB effect and determine the change in the cathode temperature and current density during the macropulse, a numerical simulation code has been developed at Institute of Advanced Energy, Kyoto University. The code calculates the transition state of a thermionic RF gun from fed RF pulse shape and initial cathode temperature. In this simulation, a differential equation of equivalent circuit of a thermionic RF gun and a differential equation of heat transfer in a thermionic cathode are simultaneously and numerically solved. Figure 4b shows the results of the simulation code which describe the change in the cathode temperature and current density. The change in the cathode temperature and current density were obtained from the time evolution. Demonstration for the simulation code is required to compare the simulation and experimental results.

4

Conclusions

We have developed a numerical simulation code for deep understanding of the back-bombardment effect. The code starts with calculate the energy distribution and the total power of the back-bombardment electrons by using PARMELA, and beam admittance and beam loading by KUBLAI code. Then the range and the stopping power of the BB electrons were calculated to determine the deposited heat by using semiempirical equation TIO. Finally, the change in the cathode temperature and current density were determined by the solving of the differential equation of thermionic RF gun equivalent circuit and a one dimensional thermal diffusion equation of heat transfer in a thermionic cathode. As next step demonstration is required to realize the simulation code. Acknowledgment The author wish to thank the GCOE program, Graduate School of Energy Science in the age of Global Warming Kyoto University, for financial support.

References 1. 2. 3. 4. 5.

Yokoyama M et al (2001) Nucl Instr Meth A475:38 MacKee CB, Maday JMJ (1990) Nucl Instr Meth A296:716 Kii T et al (2007) AIP Conf Proc 879:248–251 Zen H et al (2009) IEEE Trans Nucl Sci 56(3):1487 Oda F et al (2001) Nucl Instr Meth Phys Res A A475:583–587

200 6. 7. 8. 9. 10. 11.

M. Bakr et al. Zen H (2009) Doctor Thesis, Institute of Advanced Energy, Kyoto University Cheo BR et al (1991) IEEE Trans Elec Dev 38(10):2264–2274 Tabata T et al (1972) Nucl Instr Meth 103:85–91 Bakr M et al (2010) Green energy and technology, part III, 202–210 Masuda K (1998) Doctor Thesis, Institute of Advanced Energy, Kyoto University Young LM, James H (2002) Billen: LA-UR-96-1835

Part III

Advanced Nuclear Energy Research

(i)

Contributed Papers

Nuclear Characteristics Transition Depend on the Position of External Source on the Accelerator-Driven System Using KUCA and FFAG Accelerator Jae-Yong Lim, Cheolho Pyeon, Tsuyoshi Misawa, and Ken Nakajima

Abstract By combining the Fixed Field Alternating Gradient (FFAG) accelerator with the A-core of the Kyoto University Critical Assembly (KUCA), accelerator-driven system (ADS) experiments are accomplished successfully using (p, n) reaction on the tungsten target which is located at core outside. In order to increase spallation neutron injection into this core, numerical analyses are performed by adapting the neutron or proton beam duct and the change of tungsten target position. When the tungsten target is moved into core closely, the neutron multiplication calculated by the ratio of neutrons by fission and supplied neutrons from external source increases gradually in inverse proportion to the distance between core and target. When this distance is changed from 70 to 20 cm, 430% reaction rate gain is observed relatively by comparing with 115In(n, n¢)115mIn reaction. Keywords Accelerator-driven system • Fixed field alternating gradient accelerator • Kyoto University Critical Assembly • MCNPX Monte-Carlo code • Neutron multiplication

1

Introduction

As a new option of nuclear power plant, a concept of accelerator-driven system (ADS) suggested and has studied for transmutation of high level radioactive material, energy production and neutron source applications [1, 2]. Since an additional neutron supplied from several types of external source could be maintained neutron multiplication in a subcritical core, this concept possesses the highest reliability in

J.-Y. Lim (*), C. Pyeon, T. Misawa, and K. Nakajima Nuclear Engineering Science Division, Research Reactor Institute, Kyoto University, Kumatori, Sennan, Osaka 590-0494, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_27, © Springer 2011

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safety aspect by cutting the supply of neutrons off. Hence the characteristics of external source become the main issues for developing ADS concept. In order to verify the characteristics of typical ADS, the experimental investigations were performed in several facilities globally such as MASURCA reactor in France, YALINA facilities in Belarus, and Kyoto University Critical Assembly (KUCA) in Japan [3–5]. At a new ADS with the FFAG accelerator, on 4th March 2009, the high-energy neutrons generated by spallation reactions with 100 MeV proton beams, which was contrasted with other external sources such as deuterium–deuterium (D–D), deuterium–tritium (D–T) and Californium in previous mentioned experiments, were successfully injected into a solid-moderated and -reflected core (A-core) in thermal neutron field of KUCA. Unfortunately, the quality of injected proton beams was not satisfied the target goal of FFAG accelerator and the tungsten target for producing spallation neutrons was located at core outside. Especially, a few pA proton beam intensity was not effective for irradiation experiments and was not a sufficient external neutron source for maintaining neutron flux inside critical assembly. In this study, we investigated to increase the amount of injected neutrons into core by numerical simulations and two approaches were proposed. Firstly, the flight path of spallation neutrons was modified like a beam tube in order to collimate it at active core region. Second changes was that a tungsten target was moved close to core for focusing dispersed neutrons by scattering after spallation at target.

2 2.1

ADS Experiments and Calculation Methods Configuration of ADS Experiments

The FFAG accelerator complex consists of four main facilities: (1) Ion source, (2) Ion-beta, (3) Booster and (4) Main. Ion source produces protons with 100 keV energy and produced protons accelerates up to 2.5 MeV through second facility named with Ion-beta. Using Booster located inside of Main ring, protons with 2.5 MeV and 1.17 m injected radius varies that of 20 MeV energy and 1.65 m extracted radius. Finally, Main ring can make 20 MeV proton supplied by Booster accelerate up to maximum 150 MeV proton energy, 1 mA average beam current and 120 Hz pulse repetition rate [6]. In order to transport accelerated protons from Main ring of FFAG accelerator to KUCA, various magnets for bending and focusing were used, because the distance by ~30 m exists between Innovation Research Laboratory (IRL) and KUCA which are set up FFAG accelerator and KUCA A-core respectively. KUCA building is divided four sections and each sections contains comprises solid-moderated and -reflected type-A and -B cores, a water-moderated and -reflected type-C core and Cockcroft–Walton-type pulsed neutron generator. For the proton

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injection experiment, the solid-moderated and -reflected type-A core was combined with a FFAG accelerator at opposite surface of Cockcroft–Walton-type accelerator. The A-core (A3/8″P36EU(3)) was composed of a combination of 23 fuel rods that were loaded on the grid plate. The materials used in the critical assemblies were always in the form of a rectangular parallelepiped, normally 2″ square with thickness ranging between 1/16″ and 2″. The upper and lower parts of the fuel region were polyethylene reflector layers of more than 50 cm length. The fuel rod, a 93% enriched uranium–aluminum (U–Al) alloy, consisted of 36 cells of polyethylene plates 1/8″ and 1/4″ thick, and a U–Al plate 1/16″ thick and 2″ square. The functional height of the core was approximately 40 cm [5].

2.2

Calculation Methods

For the simulations considered with charged particle transport and neutron transport in same time, a Monte-Carlo transport code – MCNPX 2.5.0 was employed [7]. In order to consider the interaction between high energy proton/neutron above 20 MeV and materials, two libraries were compared; the newest ENDF library series – ENDF/B-VI.6 with LAHET physics model and JENDLE High Energy File (JENDL/HE) which was released in 2007 to respond the requirements of reaction data in high energy range up to several GeV [8]. Using these calculation tools, reactivity and Indium irradiation measurement about reference core were accomplished. The difference of reactivity showed only 23 ± 18 pcm using 20 million histories. Thermal neutron flux distribution was estimated through the horizontal measurement of 115In(n, g)116m1In reaction rates by the activation analysis of an indium wire with 1.0 mm diameter. The In wire was set in an aluminum guide tube, from the tungsten target to the center of fuel region, at the center position of fuel assembly axially. In these static experiments conducted at 5th march, 2009, the subcritical system was made by the full insertion of C1, C2 and C3 rods as the same as the kinetic experiments, and the subcriticality was experimentally deduced to be 0.76%Dk/k. The neutron source information for a MCNPX calculation was not taken a isotopic source option and also calculated directly by describing tungsten target with 80 mm j and 10 mm thickness and mono-direction proton beam with 100 MeV energy. Since the effect of the reactivity is not negligible, the In wire was included from tallies taken in the indium wire setting region. The radial reaction distribution by Indium reaction rate in fixed source calculation also showed a good agreement as shown in Fig. 1. Even though ENDF/B-VI.6 library which contains cross-section data about only less 20 MeV of neutron energy was adapted, it was confirmed that the difference between two libraries was negligible because KUCA A-core made well thermalized neutron spectrum by a lot of polyethylene moderators. However, JENDL/HE was selected for a detailed description about high-energy in this study.

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3 3.1

Numerical Analyses for the Core Configuration Changes Effect of the Beam Steaming Duct

The core and neutron source configuration of FFAG/KUCA ADS is slightly different from that of general ADS concept. For the one of main objective of ADS – the transmutation of high-level waste such as minor actinides as well as the effective utilization of generated neutron, a neutron spallation target located at the center of subcriticality system. However, for the safety aspects, KUCA A-core could not be allowed to insert a additional heavy metal inside core. Therefore, the introduction of a neutron guide is requisite for effectively directing the high-energy neutrons generated from the tungsten target to the core center. The neutron guide, which is very similar to the neutron shield and the beam duct, (1) is composed of several shielding materials, including lead (Pb), iron (Fe), boron (B), polyethylene, the beam duct, and a special fuel assembly with a void. For other core configurations are presented here: a core without the neutron guide (Fig. 2a Case 1); a core including only Streaming Void (SV) in the fuel region (Fig. 2b Case 2); a core with the neutron guide with large window including SV (Fig. 2c Case 3), and a core with the neutron guide substituted from Iron to Lead including SV (Fig. 2d Case 4). In case of last two core configurations, based on reference core, the effect of large window on core surface and the reflecting effect by material changes were investigated respectively. By the modification of core configuration, the criticality mass should be changed and different fuel assemblies with the numerals 12, 14 and 20 correspond to fuel plates in the partial assembly in order to compensate changed reactivity.

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The calculated 115In(n, n¢)115mIn reaction rate distribution in arbitrary units for Cases 1 through 4 showed a 27% increase in neutron yield between Cases 1 and 2 in the fuel region as shown in Fig. 3. Only the presence of steaming void inside of core is different between these two core geometries. Since a streaming effect of favoring the external neutron to reach the center of fuel region, the increase in the neutron yield between reaction rate distributions in Cases 1 and 2 demonstrated consequently. Depending on the existence of neutron guide or not, the neutron yield at core region showed extremely differences between reference core and Case 2.

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This comparison proves that the introduction of neutron guide is effective as a meaning of improving the neutron yield in the core region. A few % of the neutron yield changes was observed between reference core and Case 3 and 4 which were modified slightly with reference core for wide windows and neutron reflector with high atomic number respectively.

3.2

Effect of the Tungsten Target Position

As another way to increase neutron supply in the fuel region, the tungsten target which could produce spallation neutrons by interacted with protons moved three closer positions with fuel regions and core characteristics caused by these changes were compared with each other. The tungsten target in the reference case is located at 71.3 cm apart from core center and at the proton beam line which is under the vacuum condition. For assuming a real experiments condition, the tungsten target inside proton beam line was eliminated and it moved three different neutron guide assemblies which were installed at KUCA-A core for the construction of neutron/ proton guide. These neutron guide assemblies consisted of iron cubes, polyethylene and polyethylene with boron for the neutron reflection and shielding and three aluminum cube cans were located at the center of assembly for securing the vacant space as a neutron/proton flight path. The tungsten target eliminated from the proton beam line was inserted in the aluminum can which is located at the straight position with the direction of proton beam. Three selected positions of tungsten

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target were fourth, sixth and eighth guide assemblies and they distanced 19.9, 31.1 and 42.2 cm from core center respectively. By different tungsten target positions, the transitions of neutron multiplication were measured using the two kinds of In wire reaction rate. For the thermal neutron distribution, 115In(n, g)116m1In reaction was used and the fast neutron distribution was tallied by 115In(n, n¢)115mIn reaction with 0.32 MeV threshold energy. When the tungsten target was moved from original position (71.3 cm from core center) to 42.2, 31.1 and 19.9 cm, the amount of protons injected at the tungsten target decreased 50.4%, 29.4%, 12.9% respectively by scattering with the flange of proton beam line and the structure materials such as aluminum, polyethylene and so on. Moreover, we confirmed that the amount of spallation neutron with fast neutron energy also decreased by comparing the peak as shown in the left area of Fig. 4. However, the indium reaction rate by fast neutrons at fuel region increased extremely because of higher neutron efficiency caused by closer distance between the target and fuel region even though the produced spallation neutrons were reduced up to 12.9%. Figure 5 shows the 115In(n, g)116m1In reaction rate distribution depend on the change of tungsten target position. Because this reaction rate caused by the interaction with thermal neutrons, the reaction rate peak was not observed like Fig. 4 but the similar phenomenon that the closest target was more effective was ascertained in the fuel region and the thermal peak region.

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Conclusions

The numerical analyses were carried out about ADS experiments using KUCA with FFAG accelerator to evaluate the increase of spallation neutron amount into subcritical core. Two modifications were suggested for this purpose and the calculation results by MCNPX 2.5.0 Monte-Carlo code with JENDL/HE revealed the following. Firstly, it was confirmed that the collimation effect by adapting a neutron/proton guide tube was very effective by reducing spallation neutron scattering out. Second approach – the change of tungsten target showed that closer target was more profitable for the neutron multiplication even though the protons after leaving from beam tube could not reached to spallation target effectively. The present experiments and numerical analyses could be expected to contribute to determining experiment plans and further researches related with subcriticality measurement and the nuclear design in ADS at KUCA. Acknowledgement This work was partly supported by a “Energy Science in the Age of Global Warming” of Global Center of Excellence (G-COE) program (J-051) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan. A part of this study was supported by the Grant-in-Aid for Scientific Research form MEXT from Japan.

References 1. Salvatores M (1999) Accelerator driven systems (ADS), physics principles and specificities. J Phys IV 9(7):17–33 2. Rubbia C et al (1995) Conceptual design of a fast neutron operated high power energy amplifier, CERN/AT/95-44 (ET), CERN

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3. Millebaud A et al (2007) Prompt multiplication factor measurements in subcritical systems: from MUSE experiment to a demonstration ADS. Prog Nucl Energy 49(2):142–160 4. Kiyavitskaya H (2007) Yalina subcritical facility to investigate neutronics of ADS: Yalinathermal benchmark, Yalina-booster benchmark. In: IAEA technical meeting, Rome, Italy, 12–16 Nov 5. Pyeon CH et al (2008) Static and kinetic experiments on accelerator-driven system with 14 MeV neutrons in Kyoto University Critical Assembly. J Nucl Sci Technol 45(11): 1171–1182 6. Yonemura Y et al (2007) Development of RF acceleration system for 150 MeV FFAG accelerator. Nucl Instr Methods Phys Res Sect A 576:294–300 7. Pelowitz DB (2005) MCNPX user’s manual, version 2.5.0. Los Alamos National Laboratory 8. Sasa T et al (2008) Continuous energy cross section library for MCNP/MCNPX based on JENDL high energy file 2007 -FXJH7-. Japan Atomic Energy Agency

High Performance Computing of MHD Turbulent Flows with High-Pr Heat Transfer Yoshinobu Yamamoto and Tomoaki Kunugi

Abstract The large-scale direct numerical simulations (DNS) of a MagnetoHydro-Dynamics (MHD) turbulent heat transfer have been executed on the massively parallel processing supercomputer systems. The maximum computational speed was measured up 4.35 Tflops and the sufficiently parallelization efficiency was achieved. It has been confirmed that present DNSs have the sufficient spatial resolution. Definitely, we can succeed to establish the DNS data of MHD heat transfer under the high-Reynolds (Re = 14,000) and high-Prandlt number conditions (Pr = 25). Keywords DNS • High-Pr • High-Re • MHD • Parallel computing

1

Introduction

FLiBe which is the molten salt mixture of LiF and BeF is one of the coolant candidates in the first wall and blanket of the fusion reactors, and has several advantages which are little Magneto-Hydro-Dynamics (MHD) pressure loss, good chemical stability, less solubility of tritium and so on. In the contrast, the low thermal diffusivity and high viscosity are the key issues of the FLiBe utilization as a coolant [1]. Moreover, the development of MHD turbulence model with high accuracy is highly demanded to predict the MHD pressure loss and the heat transfer for the fusion reactor designs. A direct numerical simulation (DNS) of turbulent flows is one of the most powerful methods to understand turbulent structures and heat transfer. Molten salt fluids such as FLiBe are the higher Pr fluids (Pr = n/a:Prandtl number = 20–40, n is

Y. Yamamoto (*) and T. Kunugi Department of Nuclear Engineering, Kyoto University, Sakyo Yoshida, Kyoto 611-0011, Japan e-mail: [email protected] T. Yao (ed.), Zero-Carbon Energy Kyoto 2010, Green Energy and Technology, DOI 10.1007/978-4-431-53910-0_28, © Springer 2011

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the kinetic viscosity, a is the thermal diffusivity), however the previous DNS studies have conducted at the only lower Pr condition. Therefore, MHD turbulent heat transfer on higher Pr fluids hasn’t been understood well. Furthermore, a problem of DNS studies limited to lower-Re (:= Ub2h/n is the bulk Reynolds number, Ub is the bulk mean velocity, h is the channel height) and -Pr conditions would be depended on the computational resources limitation.

2 2.1

Numerical Methods Basic Equations and Boundary Condition

The target flow is the incompressible MHD turbulent flows at the low magnetic Reynolds number (Rem = Ub2h/h,h is the magnetic diffusivity) with passive scalar transport. The objective flow geometry and coordinate system are shown in Fig. 1. Basic equations of the present DNS were the continuity equation (1), the momentum equations (2) with the electric field described using the electrical potential approach [2], Poisson equation (3) of the electrical potential, and the energy equation (4), respectively. ∂ui* = 0, ∂xi

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Non-slip and periodic conditions were imposed for boundary conditions of velocity and the constant temperature at top and bottom boundaries (qtop > qbed, qtop: top wall temperature, qbed: Bottom wall temperature), and the periodic conditions were imposed for a passive scalar field. Total electric current in the flow domain was kept zero and the boundary condition of the electric potential was non-conducting condition at all walls and the periodic condition imposed on the horizontal directions.

2.2

Numerical Procedures

The spectral method is used to compute the spatial discretization in the stream (x) and spanwise (z) directions. Nonlinear terms were computed with 1.5 times finger grids in horizontal (x and z) directions to remove the aliasing errors (Padding method). The derivative in the wall normal (y) direction is computed by a secondorder finite difference scheme at the staggered grid arrangement. Time integration method is 3rd-order Runge–Kutta scheme for the convection terms, Crank–Nicolson scheme for the viscous terms and Euler Implicit scheme for the Pressure terms, respectively. The Helmholtz equation for the viscous (diffusion) terms and the Poisson equations of the pressure and the electrical potential are solved by a TriDagonal Matrix Algorithm, TDMA in Fourier space.

2.3

Parallelization

In this DNS study, the Message Passing Interface (MPI) was adapted for a distributed memory parallel programing tool. Domain decomposition in the y direction was used in order to calculate 2D-FFTs for the horizontal directions (x,y). Before performing the TDAM along the y direction, we need to transpose the data form the

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domain decomposition along the y axis to the one along the z axis. In this process, we implemented the following two methods to treat the discontinuous data transfer. (a) Data transposition by MPI_ISEND/IRECIVE with the derivative data type discontinuous data. (b) Data transposition by remote memory access (RMA), called one-sided communication with the packed 1D continuous data. Since the global memory function [3] for the data transfer by the MPI library was implemented in the SX-9 [4], faster data transfer by used MPI_PUT based on RMA, called one-sided communication, can be expected. To avoid the excessively concentration of the data communication between the specified rank and others, scheduling [5] the multi-stages internode data communications via the single-stage crossbar network, were implemented as shown in Fig. 2. To reduce the data communication traffics, a hybrid parallelization by MPI and Microtasking was implemented. Furthermore, to obtain the sufficient parallelization efficiency, the phase shift method, in which a convolutional sum is obtained for a shifted grid system as well as for the original grid system, was adapted instead by the padding method. Using the phase shift method, we can reduce the load of memory copy in the padding method.

2.4

Numerical Condition

Numerical conditions of DNS for 2-D fully-developed turbulent channel flows imposed wall-normal magnetic field, were tabulated in Table 1, where super-script + denotes the nondimensional quantities normalized by the friction velocity and the kinematic viscosity. In the computations, thermal properties of the FLiBe

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3

Results and Discussions

3.1

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Using the program information of MPI/SX [3], computational speed has been measured for the calculation of 10 time steps. This computational speed taken in initialization was included from the measurement. The corresponding numbers of nodes (CPUs) taken up in the SX-9 were 4(64), 8(128) and 16(256) and 4 microtasking process per node were adapted in all cases. Parallelization method (b) with the scheduling inter-node communication was applied in case of the SX-9, because the performance loss in the parallelization method (a) was sensible when using 4 nodes (64CPUs). Figure 3a shows the elapsed time normalized by one when using 4 node (64CPUs) and Fig. 3b shows the computational speed [Tflops] as a function of numbers of CPUs in case of the Padding algorithm. Using parallelization method (b) with the scheduling inter-node communication and the padding algorithm,

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computational speed was 4.11 Tflops, parallel efficiency was 74.3%, parallelization rate was 0.99865, and vector operation ratio was 99.71%, when using 16 nodes (256CPUS) of the SX-9. Elapsed time per one time step was about 3.1 [s] when using 4nodes (64CPUs). On the other hands, computational speed in case of the phase shift algorithm was measured up 4.35 Tflops when using 16nodes (256CPUs). The phase-shift algorithm was about 6% faster than the Padding algorithm in this study. This effective computational speed was corresponded to 17% of the theoretical peak performance.

3.2

Validation of Grid Resolution

Figure 4a, b shows the one-dimensional streamwise pre-multiplied energy spectra of streamwise velocity and temperature near channel center in Ha = 0, where kx is the streamwise wave number and energy spectra were normalized by Kolmogorov scale (:lK) and energy dissipation rate (:e ) and Batchelor scale (:lB) and temperature energy dissipation rate (:eqq ). In the high-accuracy DNS, it was pointed out [6] that more than 1 kx lK and kx lB of grid resolution were required for velocity and temperature field, respectively. In this DNS, it can be confirmed that more than 1 kx lK and kx lB of grid resolution were resolved for velocity and temperature field, respectively. Figure 5a, b shows the instantaneous streamwise turbulent velocity and turbulent temperature in Ha = 0. In the high-Pr temperature field, fine small turbulent fluctuations were observed compared with the velocity field. Eventually, we had established the high-accuracy DNS database of MHD heat transfer in the high-Re and -Pr.

a

b (k x lB )2E qq /( eq t K ฀lB )

3

2

(k x lK )2E uu/( lK /t K )

0.06

0.03

0.2

0.1

0

0 0

0.5

k x lK

1

0

0.5

1

k x lB

Fig. 4 1D-streamwise pre-multiplied energy spectra near channel center in Ha=0, (a) streamwise velocity and (b) temperature

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Y. Yamamoto and T. Kunugi

Fig. 5 Visualization in, Ha = 0, near channel center, top view, (a) streamwise turbulent velocity, −0.1 (black)