Energy Efficiency in Industry 366263922X, 9783662639221

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Markus Blesl Alois Kessler

Energy Efficiency in Industry

Energy Efficiency in Industry

Markus Blesl • Alois Kessler

Energy Efficiency in Industry

Markus Blesl Institute of Energy Economics and Rational Energy Use University of Stuttgart Stuttgart, Germany

Alois Kessler Research and Development EnBW Energie Baden-Württemberg AG Karlsruhe, Germany

ISBN 978-3-662-63922-1 ISBN 978-3-662-63923-8 https://doi.org/10.1007/978-3-662-63923-8

(eBook)

# Springer-Verlag GmbH Germany, part of Springer Nature 2021 This book is a translation of the original German edition „Energieeffizienz in der Industrie“ by Blesl, Markus, published by Springer-Verlag GmbH, DE in 2017. The translation was done with the help of artificial intelligence (machine translation by the service DeepL.com). A subsequent human revision was done primarily in terms of content, so that the book will read stylistically differently from a conventional translation. Springer Nature works continuously to further the development of tools for the production of books and on the related technologies to support the authors. This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer-Verlag GmbH, DE part of Springer Nature. The registered company address is: Heidelberger Platz 3, 14197 Berlin, Germany

Foreword

The issue of energy efficiency is one of the key challenges for both European and German energy policy. Against the backdrop of our climate protection targets, but also in view of limited resources and potentially further increases in energy prices, the economical use of energy must be one of our priorities. Energy efficiency offers the opportunity to create win-win-win situations: the competitiveness of regions and companies is increased, consumers are relieved of energy costs, and the environment is protected. The introduction of renewable energies is also significantly promoted by increased energy efficiency. Against this background, the European target of saving 20% energy by 2020 is one of the core issues of European energy policy. With the new European Energy Efficiency Directive, the EU is now providing the framework for the development of energy efficiency services and the systematic exploitation of energy efficiency potential in the industrial sector. It also provides a further incentive for the development of innovative and energysaving technologies. In Germany, industry and the “trade, commerce, and services” sector use around 43% of the final energy provided. It is therefore important that energy savings are targeted here. Energy efficiency is often not a matter of course in industry, despite the associated cost savings. I am pleased that this is a practical and comprehensive examination of numerous “crosssectional technologies” as well as particularly energy-intensive sectors. EU Commissioner for Energy Stuttgart, Germany February 2010 to September 2014

Günther H. Oettinger

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Preface by the Authors to the 1st edition

In the discussion about the economical use of energy, a lack of information is often highlighted by those involved as a major obstacle. This lack motivated us to find a remedy. In many years of professional practice and especially during the work on this book, it then became apparent that there are already numerous studies, instructions, or concepts in many areas and that new study results have just recently appeared. The difficulty in the fastmoving operational practice is to maintain an overview of the diverse information available, to select the “right” information, and to combine it into an individual and sustainable energy efficiency concept. This book is therefore aimed primarily at practitioners and is intended to provide a compact introduction to the multifaceted subject area of industrial energy efficiency and to concept development. However, students of relevant disciplines will certainly also benefit from this book. Despite intensive work, this book is neither perfect nor complete—both were neither intended nor affordable. The future will show where there is a need for updates and expansions, which we are in any case continuously dedicated to professionally. The book has arisen from and alongside our professional work. Without the support, help, and assistance of numerous colleagues, such a work would not be possible. We would therefore like to thank all those who have contributed to the success of this book. We would especially like to thank Prof. Dr. Alfred Voß and Prof. Dr. Wolfram Münch for granting us some professional freedom and for their idealistic support and encouragement. We would like to thank our colleagues Martin Brodbeck, Jean-Christian Brunke, Florian Conradi, Marcus Dörr, Thomas Frank, Markus Hornberger, Marlies Hummel, Ralf Kuder, Thomas Wagner, and Sylvia Wahren for their valuable help. We would also like to thank Ms. Iryna Salamatina and Ms. Ana Guitu for their technical support in the preparation of the manuscript. Last but not least, our special thanks also go to our families for their understanding. Stuttgart, Germany Karlsruhe, Germany January 2013

Markus Blesl Alois Kessler

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Preface by the Authors to the 2nd edition

The basic intention of the book has not changed. Nevertheless, time has not stood still. New findings have led to a methodological expansion as well as to a complete revision of the book's content. Between the basic technologies (e.g. lighting) on the one hand and the industry processes (e.g. chlor-alkali electrolysis) on the other hand, a new class of so-called crosssectional processes has been identified, which build on basic technologies and are nevertheless widespread in many industries, such as electroplating, drying processes, or the provision of refrigeration. The most detailed possible indication of specific savings costs for the individual energy efficiency measures as well as the addition of numerous examples and checklists will hopefully improve the practical usefulness of the book. The chapter on individual energy-intensive industries has been expanded to include a consideration of the plastics processing industry. Our special thanks go to Mr. Raphael Vering and Jean-Christian Brunke for their discussion of the content and expert comments. We would also like to thank Mrs. Agnieszka Drynda for her technical support in the preparation of the manuscript. Last but not least, our special thanks also go to our families for their lasting understanding. Stuttgart, Germany Karlsruhe, Germany November 2017

Markus Blesl Alois Kessler

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Preface by the Authors to the English Version of the 2nd edition

The idea of a machine translation of this book arose at the beginning of 2019. After two and a half years, it is finally ready. The translation is probably not perfect, but certainly helpful and stimulating. The book is not a 1:1 translation of the German second edition. We have adapted, expanded, and updated the book in many places, added new sources, or removed outdated ones. In this way, we also hope to meet the broader demands of an international specialist audience. We would like to thank the publisher for the excellent preparatory work and the participating editors Ms Nikita Dhiwar, Mr Bansal Nurpur, and Dr Daniel Fröhlich for their support. And last but not least, we thank our families for their understanding. Stuttgart, Germany Karlsruhe, Germany June 2021

Markus Blesl Alois Kessler

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Contents

1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

2

Fundamentals of Energy Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Legal Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Considerations on the Systematics of Energy Efficiency . . . . . . . . . . 2.2.1 General Measures to Improve Energy Efficiency . . . . . . . . . . 2.3 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.1 Technical Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.2 Economic Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3.3 Stationary and Mobile Measurement Technology . . . . . . . . . Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3 4 10 13 18 19 21 38 46

3

Electricity-Based Enabling Technologies . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Electrical Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1 Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1.2 Power Factor Correction . . . . . . . . . . . . . . . . . . . . 3.1.1.3 Uninterruptible Power Supply . . . . . . . . . . . . . . . . 3.1.1.4 Cable Dimensioning . . . . . . . . . . . . . . . . . . . . . . . 3.1.2 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Electric Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2.1 Energy-Efficient Light Sources and Lighting Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2.2 Lighting Management . . . . . . . . . . . . . . . . . . . . . . 3.2.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Electric Drives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.2 The Economic Efficiency of Drive Systems . . . . . . . . . . . . .

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51 51 51 51 55 58 58 59 60 60 67

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68 70 71 72 73 78

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3.3.3

4

Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.3.1 Optimising the Efficiency of the e-Machine . . . . . . 3.3.3.2 Optimising the Efficiency of the Drive System . . . . 3.3.4 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.2.1 Correct Dimensioning . . . . . . . . . . . . . . . . . . . . . . 3.4.2.2 Use of Efficient Fans . . . . . . . . . . . . . . . . . . . . . . . 3.4.2.3 Speed Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.2.4 Maintaining Performance Through Maintenance . . . 3.4.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.2.1 Dimensioning the Pump . . . . . . . . . . . . . . . . . . . . 3.5.2.2 Optimisation of the Pump System and the Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.2.3 Optimisation of Existing Pump Systems . . . . . . . . . 3.5.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 Electricity-Based Basic Technologies for Heat Generation . . . . . . . . Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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80 80 82 85 86 87 88 88 88 89 90 90 91 92 95 96

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96 103 105 106 110

Fuel-Based Enabling Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Heat Generation by Means of Burners . . . . . . . . . . . . . . . . . . . . . . . 4.1.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.2.1 Substitution of a Cold Air Burner by a Hot Air, Recuperator or Regenerator Burner . . . . . . . . . . . . 4.1.2.2 Substitution of a Regenerator, Recuperator, Hot Air or Cold Air Burner by an Oxygen Burner . . . . . . . . 4.1.2.3 Substitution of a Recuperator or Hot Air Burner by a FLOX Burner . . . . . . . . . . . . . . . . . . . . . . . . 4.1.2.4 Substitution of a Recuperator Burner by a Regenerator Burner . . . . . . . . . . . . . . . . . . . . 4.1.2.5 Further Measures . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Heat Exchangers for Heat Recovery and Waste Heat Utilisation . . . . 4.2.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2.1 Maintenance and Cleaning . . . . . . . . . . . . . . . . . . .

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113 113 113 117

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118

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120 121 121 123 126 127 128

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4.2.2.2 Feeding into Heat Networks . . . . . . . . . . . . . . . . . 4.2.2.3 Mobile Thermal Storage Units . . . . . . . . . . . . . . . . 4.2.2.4 Use of Waste Water Heat . . . . . . . . . . . . . . . . . . . 4.2.2.5 Electricity Generation from Waste Heat . . . . . . . . . 4.2.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Heat and Cold Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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128 129 130 131 135 135 136 138 139 139

Electricity-Based Cross-Section Processes . . . . . . . . . . . . . . . . . . . . . . . 5.1 Compressed Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.2.1 Dimensioning of Compressed Air Systems . . . . . . . 5.1.2.2 Use of Speed-Controlled Compressor Drives . . . . . 5.1.2.3 Leakage in Compressed Air Systems . . . . . . . . . . . 5.1.2.4 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.2.5 Waste Heat Recovery from Compressed Air Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.2.6 Substitution of Compressed Air Applications . . . . . 5.1.2.7 Organisational Measures . . . . . . . . . . . . . . . . . . . . 5.1.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Data Centers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.2.1 Efficient Use of Efficient IT Hardware . . . . . . . . . . 5.2.2.2 Efficient Storage and Data Management . . . . . . . . . 5.2.2.3 Cooling Optimisation . . . . . . . . . . . . . . . . . . . . . . 5.2.2.4 Optimisation of the Power Supply . . . . . . . . . . . . . 5.2.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 Electroplating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2.1 Reduction of Voltage Losses . . . . . . . . . . . . . . . . . 5.3.2.2 Optimisation of the Airflow . . . . . . . . . . . . . . . . . . 5.3.2.3 Process Heating . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2.4 Process Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2.5 Optimisation of the Rectifier . . . . . . . . . . . . . . . . . 5.3.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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143 143 144 147 148 149 150 151

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152 152 152 153 154 154 157 157 157 159 163 165 166 167 168 168 169 172 173 174 175 176

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Contents

Fuel-Based Cross-Sectional Processes . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Boilers for Steam Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.2.1 Installation of a Caustic Expansion and Cooling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.2.2 Installation of an Economiser . . . . . . . . . . . . . . . . . 6.1.2.3 Benefits of Condensing Boiler Technology . . . . . . . 6.1.2.4 Installation of a Closed Condensate Return System . 6.1.2.5 Heat Recovery from Steam . . . . . . . . . . . . . . . . . . 6.1.2.6 Stepless Burner Control . . . . . . . . . . . . . . . . . . . . . 6.1.2.7 Measures from Other Basic and Cross-Cutting Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Industrial Furnaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.2.1 Improvement of the Wall Structure by Means of Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.2.2 Heating and Optimisation of Burner Technology . . . 6.2.2.3 Waste Heat Recovery . . . . . . . . . . . . . . . . . . . . . . 6.2.2.4 Intelligent Control and Regulation Technology . . . . 6.2.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 Drying Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.2.1 Mechanical Pre-Drying . . . . . . . . . . . . . . . . . . . . . 6.3.2.2 Optimisation of Heating and Insulation . . . . . . . . . . 6.3.2.3 Hot Steam drying Instead of Fresh Air Drying . . . . 6.3.2.4 Dry Air Drying by Means of Refrigeration Dryers . . 6.3.2.5 Improving Process Control . . . . . . . . . . . . . . . . . . 6.3.2.6 Alternative Drying Processes . . . . . . . . . . . . . . . . . 6.3.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 Painting Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4.2.1 Planning and Organisational Measures . . . . . . . . . . 6.4.2.2 Optimisation of Pre-treatment . . . . . . . . . . . . . . . . 6.4.2.3 Optimisation in the Area of Paint Application . . . . . 6.4.2.4 Optimisation of the Paint Drying/Curing Process . . . 6.4.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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179 179 180 182

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183 183 184 185 186 186

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186 187 188 188 191

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192 194 195 196 196 197 200 202 202 203 203 204 204 205 208 209 210 214 214 216 220 224 228 229

Contents

7

8

Coupled and Other Cross-Sectional Processes . . . . . . . . . . . . . . . . . . . . 7.1 Combined Production and Use of Electricity and Heat . . . . . . . . . . . 7.1.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.1.1 Combined Heat and Power Plants . . . . . . . . . . . . . 7.1.1.2 Steam Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.1.3 Heat Pumps and Chillers . . . . . . . . . . . . . . . . . . . . 7.1.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Heating, Ventilation and Air-conditioning Systems for Industrial Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.2.1 Heat Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.2.2 Maintenance and Servicing . . . . . . . . . . . . . . . . . . 7.2.2.3 Ceiling Spotlights . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.2.4 Optimisation of Building Operation . . . . . . . . . . . . 7.2.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 Refrigeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.2 Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.2.1 Drawing up an Inventory of Refrigeration Systems and Operating Methods . . . . . . . . . . . . . . . . . . . . . 7.3.2.2 Minimisation of the Cooling Demand . . . . . . . . . . . 7.3.2.3 Reduction of Electricity Consumption for Refrigeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.2.4 Control Optimisation of Refrigeration Systems . . . . 7.3.2.5 Optimisation of Power, Pressure and Temperature Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4 Other Cross-Cutting Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.1 Conveyor Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.2 Handling Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.3 Industrial Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.4 Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.5 Waste Water Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4.6 Vacuum Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Industries with Their Highly Specialized or Energy-Intensive Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Manufacture of Basic Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.1 The Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.2 Fundamentals of the Technology . . . . . . . . . . . . . . . . . . . . .

xvii

. . . . . . . .

233 233 234 235 238 240 243 244

. . . . . . . . . . .

246 247 247 248 250 250 251 252 253 256 260

. .

261 262

. .

263 264

. . . . . . . . . .

266 267 268 268 269 271 274 275 276 278

. . . .

283 286 287 287

xviii

Contents

8.1.3

8.2

8.3

Individual Processes and Measures . . . . . . . . . . . . . . . . . . . 8.1.3.1 Ethylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3.2 Propene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3.3 Methanol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3.4 Benzene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3.5 Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3.6 Ammonia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3.7 Soda Ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3.8 Phosphoric Acid . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.4 Recommendations for Energy Optimisation in the Chemical Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.5 Savings Potential Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . Manufacture of Iron and Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 The Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1.1 Fundamentals of the Technology . . . . . . . . . . . . . . 8.2.2 Individual Processes and Measures . . . . . . . . . . . . . . . . . . . 8.2.2.1 Dry Coke Cooling . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.2.2 Gas Recirculation on Sintering Equipment . . . . . . . 8.2.2.3 Energy Efficiency Measures at the Blast Furnace and Steelworks . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.2.4 Energy Efficiency Measures for Electric Arc Furnaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.2.5 Alternative Reduction Processes . . . . . . . . . . . . . . . 8.2.2.6 Secondary Metallurgy, Primary Forming, Rolling, Bending, Surface Treatment . . . . . . . . . . . . . . . . . . 8.2.2.7 Cross-Process Energy Efficiency Measures . . . . . . . 8.2.2.8 Recommendations for Energy Optimisation in Iron/Steel Production . . . . . . . . . . . . . . . . . . . . . 8.2.3 Savings Potential Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . Production of Aluminium and Non-ferrous Metals . . . . . . . . . . . . . . 8.3.1 The Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3.2 Fundamentals of the Technology . . . . . . . . . . . . . . . . . . . . . 8.3.3 Individual Processes and Measures . . . . . . . . . . . . . . . . . . . 8.3.3.1 Energy Efficiency Measures in Primary Aluminium Electrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3.3.2 Efficiency Potentials in Anode Production . . . . . . . 8.3.3.3 Optimisation of Copper Production . . . . . . . . . . . . 8.3.4 Recommendations for the Energetic Optimisation of Metal Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3.5 Savings Potential Curve . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . .

293 293 294 295 297 299 301 302 303

. . . . . . . .

304 304 307 308 308 309 309 310

.

310

. .

312 314

. .

315 316

. . . . . .

317 318 322 323 324 326

. . .

326 328 329

. .

333 333

Contents

8.4

8.5

8.6

8.7

xix

Manufacture of Glass and Ceramics . . . . . . . . . . . . . . . . . . . . . . . . 8.4.1 The Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4.2 Fundamentals of the Technology . . . . . . . . . . . . . . . . . . . . . 8.4.2.1 Optimum Composition of the Charge . . . . . . . . . . . 8.4.3 Individual Processes and Measures . . . . . . . . . . . . . . . . . . . 8.4.3.1 Optimisation of the Furnace and Firing System . . . . 8.4.3.2 Recommendations for the Energetic Optimisation of Glass Production . . . . . . . . . . . . . . . . . . . . . . . . 8.4.4 Savings Potential Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . Production of Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.1 The Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.2 Fundamentals of the Technology . . . . . . . . . . . . . . . . . . . . . 8.5.3 Individual Processes and Measures . . . . . . . . . . . . . . . . . . . 8.5.3.1 Burning Clinker in the Kiln Process . . . . . . . . . . . . 8.5.3.2 Grinding of Clinker and Additives to Cement . . . . . 8.5.3.3 Overall Process Optimisation . . . . . . . . . . . . . . . . . 8.5.3.4 Recommendations for Energy-Efficient Cement Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5.4 Savings Potential Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . Manufacture of Mechanical Pulp, Paper and Paperboard . . . . . . . . . 8.6.1 The Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.2 Fundamentals of the Technology . . . . . . . . . . . . . . . . . . . . . 8.6.3 Individual Processes and Measures . . . . . . . . . . . . . . . . . . . 8.6.3.1 Optimised Paper Drying Through Adjusted Temperature and Pressure Parameters . . . . . . . . . . . 8.6.3.2 Optimisation of the Paper Machine Operation . . . . . 8.6.3.3 Thermal Recovery of Black Liquor . . . . . . . . . . . . 8.6.3.4 Recommendations for Energy-Efficient Paper Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6.4 Savings Potential Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . Processing of Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.1 Casting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.1.1 Optimisation of Melting and Furnace Technology . . 8.7.1.2 Optimisation of the Ladle Economy . . . . . . . . . . . . 8.7.1.3 Avoidance of Heat Loss . . . . . . . . . . . . . . . . . . . . 8.7.1.4 Optimisation of Mould and Core Production . . . . . . 8.7.1.5 Increasing Yield and Quality . . . . . . . . . . . . . . . . . 8.7.1.6 Heat Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.1.7 Recommendations for the Energetic Optimisation of the Casting Process . . . . . . . . . . . . . . . . . . . . . . 8.7.2 Solid Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.2.1 Increase of the Material Utilisation Rate . . . . . . . . .

. . . . . .

335 335 335 337 338 338

. . . . . . . . .

341 342 344 344 344 347 347 348 349

. . . . . .

351 351 354 354 354 360

. . .

360 361 362

. . . . . . . . . .

362 362 364 365 366 375 376 376 378 379

. . .

380 381 382

xx

Contents

8.7.2.2 8.7.2.3 8.7.2.4

9

Reduction of the Heating Energy Used . . . . . . . . . . HR and Waste Heat Utilisation . . . . . . . . . . . . . . . Use of Efficient Equipment and Equipment Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.2.5 Recommendations for the Energetic Optimisation of the Solid Forming Process . . . . . . . . . . . . . . . . . 8.7.3 Sheet Metal Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.3.1 Use of Efficient Equipment and Equipment Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.3.2 Increase of the Material Utilisation Rate . . . . . . . . . 8.7.3.3 Use of Lubricants . . . . . . . . . . . . . . . . . . . . . . . . . 8.7.3.4 Consideration of the Entire Process Chains and Application of New Processes . . . . . . . . . . . . . . . . 8.7.3.5 Recommendations for the Energetic Optimisation of the Sheet Metal Forming Process . . . . . . . . . . . . 8.8 Processing of Foodstuffs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.1 The Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.2 Fundamentals of the Technology . . . . . . . . . . . . . . . . . . . . . 8.8.3 Dairies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.4 Breweries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.5 Meat Processing Industry . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.6 Industrial Bakeries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8.7 Savings Potential Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9 Processing of Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9.1 The Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9.2 Fundamentals of Technology . . . . . . . . . . . . . . . . . . . . . . . . 8.9.2.1 Production Process Steps in Plastics Processing . . . 8.9.2.2 Methods of Shaping . . . . . . . . . . . . . . . . . . . . . . . 8.9.3 Individual Processes and Measures . . . . . . . . . . . . . . . . . . . 8.9.3.1 Pre-Treatment Measures . . . . . . . . . . . . . . . . . . . . 8.9.3.2 Measures in the Field of Extrusion . . . . . . . . . . . . . 8.9.3.3 Measures in the Field of Injection Moulding . . . . . . 8.9.3.4 Measures in the Blow Moulding Sector . . . . . . . . . 8.9.3.5 Measures in the Field of Thermoforming . . . . . . . . 8.9.4 Savings Potential Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. .

383 384

.

384

. .

385 386

. . .

387 387 388

.

389

. . . . . . . . . . . . . . . . . . . . . .

390 391 391 393 394 398 402 405 409 416 416 418 418 419 422 423 425 425 427 428 429 431

Energy Efficiency from an Energy Economic Perspective . . . . . . . . . . . 9.1 Prospects for Energy Efficiency in Germany and Europe . . . . . . . . . 9.2 Potentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2.1 Energy Savings Potential for Germany . . . . . . . . . . . . . . . . . 9.2.2 Potential Energy Savings for the EU28 . . . . . . . . . . . . . . . .

. . . . .

443 443 446 446 448

Contents

9.3

Barriers to the Implementation of Energy Efficiency Measures . . . . . 9.3.1 Causes of Market Failure . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3.2 Overcoming the Barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3.2.1 Approaches to Overcoming Barriers Using the Example of the Swedish Iron and Steel Industry . . . 9.3.2.2 Energy Efficiency Networks . . . . . . . . . . . . . . . . . 9.4 Energy and Economic Effects of a Stronger Energy efficiency Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.1 Rebound Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.2 Carbon Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.3 Employment Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xxi

. . .

451 452 454

. .

455 457

. . . . .

460 462 463 464 465

Summary and Perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.1 Generalised Motives Guiding Action . . . . . . . . . . . . . . . . . . . . . . . . 10.2 Need for Further Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

469 469 471

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

473

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

477

10

Abbreviations

AAM AbCh AdCh ABS AC AGEB approx. ASHRAE ASME AStV ASU BAFA BAM BAT BGB BImschG BITKOM

BMU BMWi BOF CA CCE

Anion exchange membranes (Anionenaustauschermembran) Absorption chiller Adsorption chiller Acrylnitril-Butadien-Styrol Copolymer Alternating current Working Group on Energy Balances (Arbeitsgemeinschaft Energiebilanzen) Approximately American Society of Heating, Refrigerating, and Air Conditioning Engineers American Society of Mechanical Engineers Workplace Ordinance (Arbeitsstättenverordnung) Air separation unit Federal Office of Economics and Export Control (Bundesamt für Wirtschaft und Ausfuhrkontrolle) Federal Institute for Materials Research and Testing (Bundesanstalt für Materialforschung und -prüfung) Best available technology Civil Code (Bürgerliches Gesetzbuch) Federal Immission Control Act (Bundesimissonsschutzgesetz) German Federal Association for Information Technology, Telecommunication and New Media (Bundesverband Informationswirtschaft, Telekommunikation und neue Medien e. V.) Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit) Federal Ministry of Economics and Energy (Bundesministerium für Wirtschaft und Energie) Basic oxygen furnace Compressed air Cost of conserved energy xxiii

xxiv

CCGT CCG CCh CDP CED CHP CIP COP CP CRM CSP CSU DC DCIE DENA DH DIN DOD DoE DRI e.g. EAF EB ECG EDL EDL Act EDL-RL EEG EEI EEM EER EERE EIB el. EMC EMS Eq. etc. ETS EU e.V. Fa.

Abbreviations

Combined cycle gas turbine (Gas- und Dampfkraftwerk, GuD) Conventional control gear (Konventionelles Vorschaltgerät KVG) Compression chiller Cathodic dip painting Cumulative energy demand Combined heat and power Continuous improvement process Coefficient of performance Heat capacity flow rate Compression refrigeration machine Compact strip production Commissioning and startup (Inbetriebnahme IBN) Direct current Data Center Infrastructure Efficiency German Energy Agency (Deutsche Energieagentur) District heating German Institute for Standardization (Deutsches Institut für Normung) Defrost on demand US Department of Energy Direct reduced iron for example Electric arc furnace Electronic ballast (Elektronisches Vorschaltgerät, EVG) Electronic control gear (Elektronisches Vorschaltgerät, EVG) Energy service Law on energy end-use efficiency and energy services Directive on energy end-use efficiency and energy services Renewable Energy Sources Act (Erneuerbare Energien Gesetz) Energy efficiency index Energy efficiency measure Energy efficiency ratio American Energy Efficiency and Renewable Energy Office European Installation Bus Electrical Electromagnetic compatibility Energy management system Equation and so on Emission Trading Scheme European Union Registered association (eingetragener Verein) Company (Firma)

Abbreviations

FC FCC FEC FEM FLOX Ltd. GHG HAT HBI HE HC HR HSLA HT HTST HVAC HVCs ICSG IEA IEC IEKP IER ICT IPCC IR IRR ISO IT JRC KTL KWKG LCA LCC LON bus LT LTST LPC LV LVC MB M-Bus

xxv

Frequency converter Fluid catalytic cracking Final energy consumption Finite element method Flameless oxidation Limited liability company Greenhouse gas Humid air turbine Hot briquetted iron Heat exchanger Hydrocarbon Heat recovery High strength low alloy High temperature High temperature short time Heating, ventilation, and air conditioning High-value chemicals International Copper Study Group International Energy Agency International Electrotechnical Commission Integrated energy and climate package Institute of Energy Economics and Rational Energy Use Information and communications technology Intergovernmental Panel on Climate Change Infrared Internal rate of return International Organization for Standardization Information technology Joint Research Centre Cathodic dip coating (kathodische Tauchbeschichtung) Combined heat and power act (Kraft-Wärme-Kopplungs-Gesetz) Life cycle analysis Life cycle cost Local operating network Low temperature Low temperature short time Low pressure cooking Low voltage Ladle vapour condenser (LaVaCon) Magnetic ballast (Konventionelles Vorschaltgerät KVG) Metering bus

xxvi

MEPS MQL MBS MCR MT MTBE N.N. NE NPSH NRW OECD ORC p.a. PC PCM PDCA PF PROFIBUS PSA PU PUE PVC RCO RFID RVS RNV ROI RTO SEER SGP SME Spec. SPS STIG SWPB SZW TBE TCO TCS th. THD

Abbreviations

Minimum energy performance standards Minimum quantity lubrication Mains backup system (Netzersatzanlage, NEA) Measuring, control, and regulating Medium temperature Methyl tert-butyl ether Standard Zero (Normal Null) Non-ferrous Net positive suction head North Rhine-Westphalia Organisation for Economic Co-operation and Development Organic Rankine cycle per annum Personal computer Phase change material Plan-do-check-act Product family Process field bus Pressure swing adsorption Polyurethane Power usage effectiveness Polyvinyl chloride Regenerative catalytic oxidizer Radio frequency identification Room ventilation system Regenerative afterburning (Regenerative Nachverbrennung) Return on invest Regenerative thermal oxidizer Seasonal energy efficiency ratio Shell gasification process Small and medium-sized enterprises Specific Smart power strips Steam injected gas turbine Side worked manual side feed Filler metal Technical building equipment Total cost of ownership Trade Commerce Service (Gewerbe, Handel, Dienstleistung GHD) Thermal Total harmonic distortion

Abbreviations

TMP TT UBA UF UHT UN USA USD UPS UV VAwS VDI VDMA VDZ VOC VoLL VVG W&I WHU WIP ZVEI

xxvii

Thermomechanical pulping Customer takt time Federal Environmental Agency (Umweltbundesamt) Ultrafiltration Ultra-high temperature United Nations United States of America US dollars Uninterruptible power supply Ultraviolet Ordinance on Substances Hazardous to Waste Water (Verordnung über abwassergefährdende Stoffe) Society of German Engineers (Verein Deutscher Ingenieure e.V.) German Engineering Federation (Verband Deutscher Maschinen- und Anlagenbau e.V.) Cement industry association (Verein Deutscher Zementwerke e.V.) Volatile organic compound Value of lost load Low-loss ballast Maintenance and servicing Waste heat utilization Waste incineration plant (Müllverbrennungsanlage MVA) German Electrical and Electronic Manufacturers’ Association (Zentralverband Elektrotechnik- und Elektronikindustrie e.V.)

List of Formula Symbols Used

A At cp D d E Em Et fa ftpv I i ie in ir H hv k κ K0 KE L Lm l m mL mtr n ns P

Area Payment in period t Specific heat capacity Duration Inner diameter Illuminance Maintenance value of the illuminance Deposit in period t Annuity factor Total present value factor Investment, light intensity Interest rate Effective interest rate Nominal interest rate Real interest rate Head Evaporation enthalpy Heat transfer coefficient Isentropic exponent Net present value at start date Final capital value Luminance Maintenance value of the luminance Length Mass Drying gas mass Dry mass Count variable Specific speed Power xxix

xxx

PA PB PE PN PS p p Q q qn qr R r ΔTmin η ηf ηLB ηN ρ Δp Φ Φe t T Tin Tout U v V VB W xp x1 xin Xout z z

List of Formula Symbols Used

Fuel power Heating power Flue gas losses Nominal power Chimney losses Inflation factor (1 + r) Pressure Flow rate, thermal energy Interest factor Nominal interest factor (1 + in) Real interest factor (1 + ir) Bending radius, general gas constant Inflation rate (decimal) Minimum temperature difference Luminous efficacy, efficiency Firing efficiency Luminaire operating efficiency Nominal efficiency Density, reflectance Pressure difference Luminous flux Electromagnetic radiation Time Temperature Inlet temperature of the drying gas Outlet temperature of the drying gas Mains voltage Flow velocity Volume Container volume Work Humidity Equilibrium humidity Initial or inlet moisture Final or outlet moisture Geodetic altitude Count variable

List of Figures

Fig. 2.1 Fig. 2.2 Fig. 2.3 Fig. 2.4 Fig. 2.5 Fig. 2.6 Fig. 2.7 Fig. 2.8 Fig. 2.9 Fig. 2.10 Fig. 2.11 Fig. 2.12 Fig. 2.13 Fig. 2.14 Fig. 2.15 Fig. 2.16 Fig. 3.1 Fig. 3.2 Fig. 3.3 Fig. 3.4 Fig. 3.5 Fig. 3.6 Fig. 3.7 Fig. 3.8

Fig. 3.9

Electricity consumption in German industry in 2015 by sector . . . . . . . . . . Fuel consumption in German industry in 2015 by sector . . . . . . . . . . . . . . . . Material utilization and specific energy consumption of different manufacturing processes . .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . Branche-specific material savings potentials . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . . Construction of the composite curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Determining the pinch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Morphological box for the viewpoints model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Energy costs in the individual stages of cost accounting . . . . . . . . . . . . . . . . . Differentiated overhead calculation (schematic) . .. . .. . . .. . .. . . .. . .. . . .. . . . Internal rate of return of an investment for a given plant lifetime and for a required payback period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Energy savings potential curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interest rate potential curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Types of costs in a life cycle cost analysis . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . . Exemplary representation of an energy value stream . . . . . . . . . . . . . . . . . . . . . Continuous improvement process in the PDCA cycle according to DIN ISO 50001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Procedure for the analysis of operational energy systems . . . . . . . . . . . . . . . . Components of the power supply of an industrial plant (schematic) . . . . Most common vector groups of a transformer .. . .. . .. . . .. . .. . .. . .. . .. . .. . . Power loss and efficiency of a C0Ck transformer . . . . . . . . . . . . . . . . . . . . . . . . . Distribution of industrial distribution transformers by type and size . . . . Age structure of industrial distribution network transformers . . . . . . . . . . . . Distribution of the phase angle cos(φ) of industrial plants by total power and number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Main topologies for large UPS systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Payback period for the replacement of 200 fluorescent tubes (58 W by 35 W) as a function of operating hours and electricity price . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Savings effect from lighting requirements, daylight use and presence control .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . . .. . .. . .. . . .. . ..

4 5 11 17 20 20 22 23 25 29 30 31 32 34 36 36 52 53 55 55 56 57 59

68 71 xxxi

xxxii

Fig. 3.10 Fig. 3.11 Fig. 3.12 Fig. 3.13 Fig. 3.14 Fig. 3.15 Fig. 3.16 Fig. 3.17 Fig. 3.18 Fig. 3.19 Fig. 3.20

Fig. 4.1 Fig. 4.2 Fig. 4.3 Fig. 4.4 Fig. 4.5

Fig. 4.6 Fig. 4.7 Fig. 4.8 Fig. 4.9 Fig. 4.10 Fig. 4.11 Fig. 4.12 Fig. 5.1 Fig. 5.2 Fig. 5.3 Fig. 5.4 Fig. 5.5 Fig. 5.6 Fig. 5.7

List of Figures

Schematic structure of an asynchronous three-phase motor . . . . . . . . . . . . . . Efficiency as a function of the load level for three-phase asynchronous machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . Distribution of costs for an IE3 motor over its lifetime . . . . . .. . . . . . .. . . . . . Replacing an IE1 motor with an IE3 motor with lower rated power . . . . Efficiencies of standard and high-efficiency centrifugal fans in comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pump characteristic curves for positive displacement pumps (left) and centrifugal pumps (right) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Efficiencies of centrifugal pumps with different impeller types . . . .. . .. . . System characteristics in the Q/H diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pump diagram with efficiencies, motor power and NPSH value . . . . . . . . Energy consumption of different control types . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of the electricity savings achieved in the project “Lighthouses of energy-efficient pump systems in industry and commerce” .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. Energy consumption by economic sector and burner type (PJ) . . . . . . . . . . Number of burners by type and economic sector . . . . . . . . . . . . . . . . . . . . . . . . . Combustion efficiency for natural gas L with air preheating . . . . . . . . . . . . . Fuel savings as a function of exhaust gas temperature and oxygen enrichment (natural gas, λ ¼ 1.1 and air temperature ¼ 15  C) . . . . . . . . . Additional energy consumption depending on the gas–air ratio (lambda) and the exhaust gas temperature of the combustion (Mäder et al. 2009) . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . . Comparison of waste heat sources and sinks at different temperature ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heat demand and waste heat potential in Germany 2015 . . . . . . . . . . . . . . . . Average heat transfer coefficient as a function of the layer thickness s* of the dirt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Optimum heater temperatures and efficiencies for waste heat recovery using a Stirling engine . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . Specific investment for ORC plants in the range up to 100 MWel . . . . . . Schematic layout of the ORC plant at the Lengfurt cement plant (Bavaria) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Economic insulation thickness according to VDI 4610 . .. . . .. . .. . .. . . .. . . Fields of application of different types of air compressors . . . . . . . . . . . . . . . Energy flow diagram of a typical compressed air system . . . . . . . . . . . . . . . . Power consumption as a function of the volume flow for different control systems . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . Typical breakdown of the energy consumption of a server . . . . . . . . . . . . . . Illustration of the hot aisle-cold aisle arrangement . . . . . . . . . . . . . . . . . . . . . . . . Example of air conditions in a data center with hot aisle-cold aisle arrangement with adverse bypasses and recirculation of air . .. . . .. . . .. . . . Process sequence in electroplating . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .

74 76 79 81 89 93 95 98 99 102

104 116 116 117 120

122 124 126 129 133 134 135 138 146 146 150 158 163 164 168

List of Figures

Fig. 5.8 Fig. 5.9 Fig. 6.1 Fig. 6.2 Fig. 6.3 Fig. 6.4 Fig. 6.5 Fig. 6.6 Fig. 6.7 Fig. 6.8 Fig. 6.9 Fig. 6.10 Fig. 6.11 Fig. 6.12 Fig. 6.13 Fig. 6.14 Fig. 6.15 Fig. 6.16 Fig. 6.17 Fig. 6.18 Fig. 6.19 Fig. 6.20 Fig. 7.1 Fig. 7.2 Fig. 7.3 Fig. 7.4 Fig. 7.5 Fig. 7.6 Fig. 7.7 Fig. 7.8

Thermography on a damaged contact terminal (courtesy of Werner Meiser, Norbert Zewe GmbH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Influence of shielding and auxiliary cathodes on the layer thickness distribution during electroplating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Efficiency increase and temperature reduction by installing an economiser .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . . Energy flow diagram of an industrial furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Relative energy savings in flue gas heat recovery by recuperative combustion air preheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific energy demand of dryers by industry (estimated) . . . . . . . . . . . . . . . Drying curve .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . . Plant example for drying with superheated steam . . . . . . . . . .. . . . . . . . . . . . . . . Sequence of the water-based painting and paint drying process . . . . . . . . . Comparison of the drying time of different processes . . . . . . . . . . . . . . . . . . . . Test setup and determined heating curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Consumption of paints and varnishes by application area . . . . . . . . . . . . . . . . Air sinking velocity and degree of material utilisation of various application methods . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. Energy consumption shares of a powder coating plant . . . . . . . . . . . . . . . . . . . Energy flows of aqueous cleaning systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distribution of energy flows and energy losses in a cleaning system . . . Comparison of energy consumption of spray and dip pretreatment . . . . . Comparison of heat losses of different lock alternatives . . . . . . . . . . . . . . . . . Energy consumption of different ventilation variants during paint application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Energy comparison of a water-based and a powder coating system . . . . . Distribution of the annual energy consumption of a cathodic dip coating among the subsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comparison of exemplary heat losses of wet and powder coating dryers . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . Circuit diagram of the Steam Injected Gas turbine (STIG) . . . . . . . . . . . . . . . Circuit diagram of the Humid Air Turbine process (HAT) . . . . . . . . . . . . . . . Examples of a CHP unit with single-stage (above) and two-stage (bottom) heat extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Schematic diagram of the simple steam turbine circuit for waste heat recovery plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Own electricity generation, residual electricity purchases and sale of electricity to the public grid by sector for 2015 . . . . . . . . . . . . . . . . . . . . . . . . Potential for heat supply by heat pumps in Germany for selected sectors . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . . Impact of construction severity on the energy saving effect of night setback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cooling demand of the manufacturing industry in Germany 2013 . . . . . .

xxxiii

170 170 184 191 191 199 201 205 206 206 207 210 213 214 217 217 218 220 221 223 224 225 235 236 237 239 240 242 251 254

xxxiv

Fig. 7.9 Fig. 7.10 Fig. 7.11 Fig. 7.12 Fig. 7.13 Fig. 8.1 Fig. 8.2 Fig. 8.3 Fig. 8.4 Fig. 8.5 Fig. 8.6 Fig. 8.7 Fig. 8.8 Fig. 8.9 Fig. 8.10 Fig. 8.11

Fig. 8.12 Fig. 8.13 Fig. 8.14 Fig. 8.15

Fig. 8.16 Fig. 8.17 Fig. 8.18 Fig. 8.19 Fig. 8.20 Fig. 8.21 Fig. 8.22

List of Figures

Functioning of a refrigeration system or heat pump in the process diagram (left) and as a cycle in the pressure-enthalpy diagram (right) . . Distribution of energy consumption for continuous conveyors . . . . . . . . . . Exemplary limit curve for the selection of electric vs. pneumatic actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Direct and indirect waste water discharge by sector in Germany 2010 . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . Distribution of energy consumption for vacuum generation in Germany by generator type . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . . Shares of individual processes in the fuel demand of German industry 2010 . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . Allocation of pressure-operated membrane processes . . . . . . . . . . . . . . . . . . . . Conventional process for methanol production from natural gas . . . . . . . . Proportions of processes for chlorine production (own representation according to (Euro Chlor 2011)) .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. Energy savings marginal cost curves of the chemical industry . . . . . . . . . . Energy savings marginal cost curves of the German iron and steel industry at plant and process level in the period 2013–2035 . . . . . . . . . . . . . Energy consumption for non-ferrous grades in Germany 2007 . . . . . . . . . . Schematic diagram of an electrolytic cell for aluminium production . . . . Production processes for global copper production in 2000 . . . . . . . . . . . . . Energy savings cost curve for the production of primary and secondary aluminium in Germany in 2013 .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . . Left-hand pie chart shows the structure of production volumes and the right-hand pie chart the structure of total turnover in the glass industry (BV Glas 2014) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Structure of a glass melting tank .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. Comparison of a conventional and a FLOX burner . . . . . . . . . . . . . . . . . . . . . . . Specific energy requirement as a function of throughput with a cullet content of 80% . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Energy savings and energy savings costs of individual energy-saving measures for the production of container and flat glass in Germany in 2013 (own representation based on Brunke 2017) . . . . . . . . . . . . . . . . . . . . . Section of cement production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Energy saving measures for the German cement industry . . . . . . . . . . . . . . . . Paper manufacturing process .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . . Energy savings cost curve for the production of pulp, paper and board in Germany 2013 (Brunke 2017) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of manufacturing processes according to DIN 8580 . . . . . . . . . . Specific energy consumption when melting aluminium in various crucible furnaces as a function of furnace utilisation . . . . . . . . . . . . . . . . . . . . . Electrical efficiency as a function of geometrical and magnetic properties for different materials . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . ..

258 270 271 276 278 284 290 296 301 306 320 323 326 331 333

335 336 339 340

342 345 352 355 363 364 367 371

List of Figures

Fig. 8.23 Fig. 8.24 Fig. 8.25 Fig. 8.26 Fig. 8.27 Fig. 8.28 Fig. 8.29 Fig. 8.30 Fig. 8.31 Fig. 8.32 Fig. 8.33 Fig. 8.34 Fig. 8.35 Fig. 8.36 Fig. 9.1 Fig. 9.2 Fig. 9.3 Fig. 9.4 Fig. 9.5 Fig. 9.6 Fig. 9.7

Energy flow diagram for melting cast iron in the MF induction furnace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific final energy consumption of different furnace types . . . . . . . . . . . . Specific primary energy consumption of different furnace types . . . . . . . . Energetic comparison of liquid metal delivery of aluminium for different transport distances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Production shares of individual solid forming processes for steel in 2018 . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . Production volume of shaped sheet steel parts in 2016 by sales sectors . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . . Changing the sequence of manufacturing and coating steps . . . . . . . . . . . . . Process (light grey) and products (dark grey) of a milk processing plant according to Gospodarić (2015) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Process for brewing . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . Final energy savings potential cost curve for the food industry in Germany (as of 2014) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Final energy savings potential cost curve of sector-specific measures in the food industry in Germany (as of 2014) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Quantity of processed plastic products broken down into product groups in Germany in 2013 (GKV 2014) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Energy flows during injection moulding (SKZ 2012) . . . . . . . . . . . . . . . . . . . . Final energy savings potential cost curve for the plastics processing industry in Germany (as of 2014) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Relative economic savings potential in Germany for electricity by 2035 in the respective sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Final energy consumption by sector/subsector and energy carrier in Germany 2015 .. . . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . . Absolute energy savings potential by sector up to the year 2035 in TJ . . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. Annual savings potentials (electricity and fuel) in EU industry28 in relation to a reference development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Final energy consumption of the industrial sector in the respective EU27 countries in PJ in 2015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Economic final energy savings potential in the EU28 until 2030 in PJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . Economic effects of energy efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xxxv

371 373 373 374 381 386 390 394 399 410 411 417 422 431 447 447 449 450 450 451 461

List of Tables

Table 2.1 Table 2.2 Table 2.3 Table 2.4 Table 2.5 Table 2.6 Table 2.7 Table 2.8 Table 2.9 Table 2.10 Table 3.1 Table 3.2 Table 3.3 Table 3.4 Table 3.5 Table 3.6 Table 3.7 Table 3.8 Table 3.9 Table 3.10

Energy tax savings due to different legal privileges 2016 in Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methodological delimitation of different levels of consideration in the analysis of energy efficiency measures . . . . . . . . . . . . . . . . . . . . . . . . . . . System for thematic classification based on energy and process complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Characterization of process waters in textile finishing . . . . . . . . . . . . . . . . . . Exemplary heat supply and demand flows in the pinch analysis . . . . . . Classification of energy costs according to cost areas or production factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Physical effects used in measurement technology with example applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Classification of energy carrier flows . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . Typical characteristics of flow meters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Decision criteria for the preparation of a measurement concept . . . . . . . Overview of the economic efficiency of energy efficiency measures for transformers and UPS systems . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. Electricity consumption for lighting by sector compared to final energy consumption in 1996 and 2015 in Germany . . . . . . . . . . . . . . . . . . . . Properties and parameters of illuminants . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . . Economic efficiency of energy efficiency measures in the field of lighting . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Distribution of the quantity and electricity consumption of drives by power classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Efficiency classes for electric drives according to different standards in comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Factors for calculating the nominal efficiency of different efficiency classes according to IEC/EN 60034-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–2–3 classification for electric motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Efficiencies and maximum reduction ratios of different gear types . . . . Potential for brake energy utilisation of drives in selected applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9 10 14 18 20 23 39 40 44 46 60 61 65 71 74 75 77 80 82 84 xxxvii

xxxviii

Table 3.11 Table 3.12 Table 3.13 Table 3.14 Table 3.15 Table 3.16 Table 3.17 Table 4.1 Table 4.2

Table 4.3 Table 4.4 Table 4.5 Table 4.6 Table 4.7 Table 4.8 Table 4.9 Table 4.10 Table 4.11 Table 5.1 Table 5.2 Table 5.3 Table 5.4 Table 5.5 Table 5.6 Table 5.7 Table 5.8 Table 5.9

List of Tables

Overview of the economic efficiency of energy efficiency measures for electric drives . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . .. Number and energy consumption of fans for selected sectors in German industry by rated power class (2008) . . . . . . . . . . . . . . . . . . . . . . . . Indicative values for the economic efficiency of energy efficiency measures for fans . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . . Number and energy consumption of pumps in selected sectors of German industry by rated power class (2008) . . . . . . . . . . . . . . . . . . . . . . . . Interactions between pump control and energy efficiency . . . . . . . . . . . . . . Indicative values for the cost-effectiveness of energy efficiency measures for pumps . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . . Classification of electrothermal processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Classification of burners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Additional investment of different burner systems compared to a cold air burner as well as technical characteristics of the respective systems .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. Investment for cold air, warm air, recuperator and regenerator burners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Additional costs for flameless burners compared to basic designs of the same type . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . .. Overview of the economic efficiency of energy efficiency measures for burners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Systematics of the processes for heat recovery and waste heat utilisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Technical properties and areas of application of common heat exchanger types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comparison of mobile heat storage systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Classification of insulation materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thermal conductivity of different insulation materials . . . . . . . . . . . . . . . . . Overview of the cost-effectiveness of energy efficiency measures for heat and cold insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Number of compressors, compressor capacity and electricity consumption for compressed air generation in Germany by sector . . . . Equivalent length of pipeline components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Indicative values for the cost-effectiveness of energy efficiency measures for compressed air systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ICT applications in industry . . . .. . . .. . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . . Levels of IT provisioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distribution of electricity consumption in data centers by size class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distribution of electricity consumption in data centers by size class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comparison of UPS systems with different efficiencies . . . . . . . . . . . . . . . . Indicative values for the cost-effectiveness of energy efficiency measures in data centers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

85 86 90 92 100 105 107 114

118 119 121 122 123 127 131 137 137 138 144 149 153 155 156 156 158 165 165

List of Tables

Table 5.10 Table 5.11 Table 6.1 Table 6.2 Table 6.3 Table 6.4 Table 6.5 Table 6.6 Table 6.7 Table 6.8 Table 6.9 Table 6.10 Table 6.11 Table 6.12 Table 6.13 Table 6.14

Table 6.15 Table 6.16 Table 6.17 Table 6.18 Table 7.1 Table 7.2 Table 7.3 Table 7.4 Table 7.5 Table 7.6

xxxix

Influence of a retrofitted bath tank cover on the required exhaust air performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of the economic efficiency of energy efficiency measures in electroplating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Steam and hot water demand up to 350  C in the German industry 2015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Classification of steam and hot water generator types . . . . . . . . . . . . . . . . . . Overview of the economic efficiency of energy efficiency measures for steam boilers . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. Industrial furnaces in selected sectors of German industry by furnace design and energy consumption (2012) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Basic design of industrial furnaces with characteristics and examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fields of application for industrial furnaces in cross-section processes . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . Energy saving measures for industrial furnaces . . . . . . . . . . . . . . . . . . . . . . . . . Properties of refractory materials and high-temperature insulation materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Examples of electrical heating methods with application examples . . . Overview of the cost-effectiveness of energy efficiency measures for industrial furnaces . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. Quantity structure of the dryers in the cross-section processes . . . . . . . . Overview of the economic efficiency of energy efficiency measures for industrial furnaces . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. Properties of common painting processes . . . .. . . . . . . . . .. . . . . . . . .. . . . . . . . . Prognosis of the energy consumption of different exhaust air cleaning processes of wet paint spray booths using the VDMA projection model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Energy cost comparison of radiation versus circulating air drying processes . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . Energy cost comparison of UV and thermal curing coating system . . . Comparison of the energy costs of circulating air and MW lacquer drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of the economic efficiency of energy efficiency measures for paint shops . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . . Final energy and electricity consumption as well as production and office space by sector in 2013 . . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . . Systematics of air handling units based on DIN 1946 . . . . . . . . . . . . . . . . . . Overview of the economic efficiency of energy efficiency measures in industrial buildings . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. Examples of fields of application for refrigeration and air conditioning by sectors, industries and companies . . . . . . . . . . . . . . . . . . . . . . Properties of the most common refrigerants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of data and key figures for the evaluation of refrigeration systems .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . ..

172 176 180 181 187 189 190 190 192 193 195 197 198 208 212

215 226 227 227 228 248 249 252 255 256 262

xl

Table 7.7 Table 7.8 Table 7.9 Table 7.10 Table 7.11 Table 7.12 Table 7.13 Table 7.14 Table 8.1 Table 8.2 Table 8.3 Table 8.4 Table 8.5 Table 8.6 Table 8.7 Table 8.8 Table 8.9 Table 8.10 Table 8.11 Table 8.12 Table 8.13 Table 8.14 Table 8.15 Table 8.16 Table 8.17 Table 8.18 Table 8.19 Table 8.20 Table 8.21

List of Tables

Overview of the economic efficiency of energy efficiency measures for refrigeration systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Systematics of conveyor technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Workpiece characteristics relevant to decision-making in the selection of handling equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Quantity structure for air separation plants in Germany 2013 . . . . . . . . . Systematics of welding processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Waste water ingredients and treatment processes . . . . . . . . . . . . . . . . . . . . . . . Pressure ranges in vacuum technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The most common vacuum pump types and their capacities . . . . . . . . . . . Energy efficiency potentials of the energy-intensive industry in Germany until 2030 . . . . .. . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . .. . . . .. Basic operations in chemical engineering . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . Distribution of separation processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Characterisation of the processes for benzene production . . . . . . . . . . . . . . Characterization of the processes for chlorine production . . . . . . . . . . . . . . Characterization of the processes for soda production . . . . . . . . . . . . . . . . . . Characterization of the processes for phosphoric acid production . . . . . Energy saving measures considered in the chemical industry . . . . . . . . . . List of energy-saving measures considered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Production of the most important non-ferrous metals in Germany 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Production volume and heat demand data of secondary aluminium smelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific energy consumption and specific CO2 emissions of primary aluminium production in the EU27 in 2010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Current and future technologies in primary aluminium production and their potential analysis with all process steps . . . . . . . . . . . . . . . . . . . . . . . Comparison of the latest pyrometallurgical processes . . . . . . . . . . . . . . . . . . List of energy-saving measures considered in aluminium production in Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . List of energy-saving measures considered in glass production in Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . List of energy-saving measures considered in cement production in Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Compilation of specific and absolute energy consumption in paper, board and cardboard production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific thermal and electrical energy demand of paper and board machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Possibilities for energy and CO2 savings through the use of low-temperature waste heat in the paper industry . . . . . . . . . . . . . . . . . . . . Energy-saving measures considered in the paper industry in Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

268 269 270 273 274 275 277 277 285 288 289 299 300 302 303 305 319 323 325 329 330 332 334 343 353 358 359 361 363

List of Tables

Table 8.22 Table 8.23 Table 8.24 Table 8.25 Table 8.26 Table 8.27 Table 8.28 Table 8.29 Table 8.30 Table 8.31 Table 8.32 Table 8.33 Table 8.34 Table 8.35 Table 8.36 Table 8.37 Table 8.38 Table 8.39 Table 8.40

Table 8.41 Table 8.42 Table 8.43 Table 8.44 Table 8.45 Table 9.1 Table 9.2

xli

Quantity structure of furnace types used in German foundries in 2012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distribution of specific energy consumption in the casting of steel, iron and non-ferrous metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of melting processes and preferred energy sources in each case . . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .. Overview of the most common moulding and core making processes Comparison of energy consumption of hot-air and microwave drying ovens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Percentage of regeneration for different sand types and processes . . . . Approaches for reducing the thermal energy used . . . . . . . . . . . . . . . . . . . . . . Breakdown of energy consumption in the food industry in Germany by area of application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measures and their relevance in the dairy sector (good EEM "; medium EEM !; weak EEM #) . . . . . . . . . . . . . . . . . . . . . . . . Specific energy consumption in dairies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heat treatment processes in milk processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific energy consumption of breweries as a function of production volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measures and their relevance in the area of breweries (good EEM "; medium EEM !; weak EEM #) . . . . . . . . . . . . . . . . . . . . . . . . Specific energy consumption of meat processing plants (in relation to raw material input) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measures and their relevance in the meat processing industry (good EEM "; medium EEM !; low EEM #) . . . . . . . . . . . . . . . . . . . . . . . . . . Specific energy consumption of bakeries depending on bakery products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . Final energy consumption structure and final energy savings potential in the food industry in Germany (as of 2014) . . . . . . . . . . . . . . . . . . . . . . . . . . . Sector-specific energy-saving measures considered in the food industry in Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Number of companies and employees as well as turnover in the plastics processing industry in Germany in 2013, broken down into product groups (Statistisches Bundesamt 2013) . . . . . . . . . . . . . . . . . . . . . . . . . Determining the number of machines in Germany . . . . . . . . . . . . . . . . . . . . . . Key figures for insulation in plastics processing in Germany . . . . . . . . . . Key figures for heat recovery in plastics processing . . . . . . . . . . . . . . . . . . . . Key figures for heat recovery in plastics processing in Germany . . . . . . Energy-saving measures considered in the plastics processing industry in Germany . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Obstructive and facilitating aspects in the implementation of energy efficiency measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Barriers to Energy Efficiency in the Swedish Iron and Steel Industry by Ranking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

366 366 367 377 378 378 383 392 395 396 396 399 400 402 403 407 413 414

417 423 424 424 426 430 452 456

xlii

Table 9.3 Table 9.4

List of Tables

Classification of the rebound effect and impact on potential energy savings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463 Sectors at risk of carbon leakage in Germany with simultaneously high additional ETS costs and high international trade intensity . . . . . . 465

1

Introduction

Modern life is inconceivable without the use of energy. However, the barely restrained consumption of resources by more than 7.5 billion people is reaching its limits. Not only are the fossil fuels that are mainly used today finite, but many other resources, such as water or arable land, are not available in unlimited quantities. Moreover, the absorption capacity of our environment and atmosphere for the residual and waste products is limited. Numerous cultures before us have ultimately perished from an overuse of their environmental resources. Our biblical ancestors were already aware of the danger of overexploitation of their barren land; even today, numerous dietary rules and other commandments bear witness to this. Sustainability is therefore the order of the day. The global sustainability strategy can be roughly divided into three fields of action. In addition to the avoidance of residual and waste products by closing material cycles and the use of renewable energy sources, the most economical, rational or even efficient use of energy makes a strong contribution to the moderate use of our resources. Our energyintensive lifestyle itself, on the other hand, is rarely questioned. Efficiency is to be understood here as the correct use of resources, that is, the ratio of benefit to expenditure, whereby this includes all production factors. In this way, we follow the minimum principle, which is common in economics, of achieving a defined goal or result with the lowest possible use of resources. In contrast to this, on the one hand, there is the maximum principle of achieving the highest possible result with a defined use of resources and, on the other hand, effectiveness in general, that is, pursuing the right goals. Effectiveness therefore describes the ratio of the actual to the planned benefit. Energy efficiency therefore does not mean “saving at any price”, but rather the equally targeted and economical use of energy, labour and capital. For the balancing of energy flows in the economy, the classification into the sectors households, trade, commerce and services (TCS), industry as well as transport has proven itself. The energy supply sector is often reported separately. The use of energy permeates

# Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Blesl, A. Kessler, Energy Efficiency in Industry, https://doi.org/10.1007/978-3-662-63923-8_1

1

2

1

Introduction

all areas of life. While the household and transport sectors are structured in a comparatively simple way, a systematic description of the multi-layered topic of energy efficiency in the industry sector has not yet been achieved. One reason for this may be that the technologies applied are often very complex on the one hand, and that industry itself is divided into numerous sectors with their sometimes highly specific processes. This book aims to close this gap. This book concentrates on the description of the efficient use of final or useful energy. Energy efficiency in the energy supply sector, that is, the provision of final energy from primary or secondary energy sources, is to be excluded, even though energy-intensive companies in particular often have their own power plants. Although industry, of course, cannot do without buildings, we will largely refrain from describing the interrelationships between the topic of “energy-efficient buildings” here, as there are already several successful presentations on this topic.

2

Fundamentals of Energy Efficiency

Along the generation and application of energy, the following conversion stages are generally distinguished in the energy industry: • Primary energy is the energy content of energy carriers that occur in nature and have not yet been technically converted. It is classified between “inexhaustible” or regenerative, fossil (oil, coal and natural gas) and nuclear energy sources. • Secondary energy is the energy content of energy carriers that have been obtained from primary energy through one or more conversion steps (e.g. electricity, fuel and heating oil). • Final energy consumption (FEC) only includes the use of those traded final energy sources that are used for the production of useful energy and are thus finally withdrawn from the market as energy sources. • Useful energy includes all technical forms of energy that the consumer ultimately requires, that is, heat, mechanical energy, light, electrical and magnetic field energy (e.g. for electroplating and electrolysis) and electromagnetic radiation, in order to be able to perform energy services. Useful energies must generally be generated at the time and place of demand from final energy by means of energy converters (e.g. motors, boilers and light sources). Of course, (energy) efficient technologies can also be applied to the provision of primary energy. In the following, however, we focus on the last two conversion stages. The complex aspects in the methodological design of energy efficiency assessments have been discussed in detail by Miller et al. (2016) and Sutherland et al. (2018). The Fraunhofer Institute for Systems and Innovation Research (ISI) has analysed the energy consumption of German industry in more detail in a study for the Working Group on Energy Balances (AGEB) (Rohde 2016). As of 09/2016, industrial electricity

# Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Blesl, A. Kessler, Energy Efficiency in Industry, https://doi.org/10.1007/978-3-662-63923-8_2

3

4

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Fundamentals of Energy Efficiency

Fig. 2.1 Electricity consumption in German industry in 2015 by sector

consumption in 2015 is provisionally stated at 821 PJ. Of this, 572 PJ is accounted for by mechanical drive energy alone and 140 PJ by electrical process heat. Of the mechanical drive energy, approximately 7.36% is accounted for by compressed air generation (see Sect. 5.1) and 11.3% by pump drives (see Sect. 3.5). According to the preliminary calculations, fuel consumption (including district heating) in 2015 amounts to 1755 PJ, of which 1543 PJ is accounted for by process heat. The distribution of fuel and electricity consumption among individual sectors and processes is shown in Figs. 2.1 and 2.2. The exact figures can be found in the appendix of this book.

2.1

Legal Framework

In recent years, a dynamic development of regulation and the legal framework in the field of energy efficiency can be observed at European and national level. Starting from the European perspective, the national implementation in laws as well as the technical implementation in standards are presented. In its “Policies Database”, the IEA lists 5577 measures, laws, regulations, etc. on energy policy worldwide—e.g. over 400 for the USA alone and almost 200 for Germany. About 500 items in the database concern industry. Across the EU, there are 84 individual regulations on industrial energy efficiency (IEA n. y.). The European legal framework and its national implementation.

2.1

Legal Framework

5

Fig. 2.2 Fuel consumption in German industry in 2015 by sector

At the European level, the so-called Ecodesign Directive was already introduced in 2005 and the Energy End-Use Efficiency and Energy Services Directive (“ESD”. . .) in 2006. In the Energy Services Directive, energy efficiency is defined as “the ratio of the yield of output, services, goods or energy to energy input”. Directive 2012/27/EU of October 25th, 2012 replaces the ESD of 2006. An EU Energy Efficiency Action Plan was first adopted in 2006. Among other things, it stipulates that the member states must regularly report their measures and progress to Brussels. The European states must in turn transpose EU directives into national law, which entails new laws or amendments to existing laws and regulations. In October 2014, the European Council adopted a climate and energy package for 2030, setting a binding climate target for the EU’s internal greenhouse gas (GHG) reduction of at least 40%. In addition, a binding target for the share of renewable energies in energy consumption of at least 27% and an indicative energy efficiency target of also at least 27% were adopted. This can be seen as an important signal for European energy policy. Germany has already adopted dozens of individual measures to reduce CO2 emissions and increase energy efficiency with the so-called “Integrated Energy and Climate Package, IEKP” in 2007. Building on this, the German government presented a new national energy concept on 28 September 2010. According to this concept, primary energy consumption is to be reduced—in annual terms—by 20% by 2008 and by 50% by 2050. Primary energy productivity is to increase by 2.1% annually. At the same time, electricity consumption is to be reduced by 10% by 2020 and by 25% by 2050. The second National Energy Efficiency Action Plan (second NEEAP) describes a total of 89 measures on how these targets have been pursued to date and how they can be achieved in the future (BMWi 2011). In the third

6

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Fundamentals of Energy Efficiency

NEEAP from 2014, the assessment of the effectiveness of these measures was updated (BMWi 2014). In June 2005, the EU Framework Directive 2005/32/EC introduced an instrument for the environmentally sound design of energy-using products, the so-called Ecodesign Directive. The Ecodesign Framework Directive 2005/32/EC, the revision of which was already proposed by the EU Commission in mid-2008, was replaced by a more far-reaching EU Framework Directive 2009/125/EC. This currently valid Ecodesign Framework Directive considers all so-called “energy-related” products and came into force on 20 November 2009. In principle, the EU Framework Directive 2009/125/EC makes it possible to introduce binding minimum requirements within the European Union with regard to the environmentally sound design of energy-related products. Concrete requirements for individual product groups can be defined in cooperation between the EU institutions (Commission, Council and Parliament) by means of regulations. Uniform minimum energy efficiency standards throughout Europe are intended to tap energy efficiency potential and at the same time prevent fragmentation of the European market. • The European Commission is currently examining 48 categories (so-called “batches”) of energy-related products with a view to possible implementing measures for the EU Ecodesign Directive, including market relevance, CO2 emissions and avoidance costs. By the second quarter of 2010, the EU had adopted EU regulations for nine product groups. Directive 2005/32/EC was transposed into national law by the Energy-using Products Act (EBPG) of February 27, 2008. The Act on the Environmentally Sound Design of Energy-Related Products (Energy-Related Products Act—EVPG) transposes the recast Ecodesign Directive into national law and replaces the EBPG (EVPG 2011). In principle, the instrument is based on a comprehensive life cycle assessment that includes various product-related environmental effects. Previous regulations concern, for example, stand-by operation and a ban on light bulbs. Energy efficiency standards for industrial motors and circulating pumps as well as various household appliances are regulated in further ordinances. The new regulations are expected to lead to noticeable savings in electricity consumption (Behrend and Erdmann 2010). The EVPG essentially makes the following regulations: Energy consumption-relevant products covered by an implementing measure may only be placed on the market in Germany or—if they are not placed on the market—put into service if they meet the requirements formulated in the respective implementing measure. In addition, the CE marking must be applied and a declaration of conformity issued for the product. This applies regardless of the place of origin of the products. The current status of the work on the directive can be found on the Internet on the website of the Federal Institute for Materials Research and Testing (BAM) (BAM n.y.). • The implementing measures generally provide for conformity with the ecodesign requirements to be verified by the manufacturer itself. In the event that conformity has to be verified by a third body, the federal states shall, upon request, designate the bodies approved for this purpose.

2.1

Legal Framework

7

• Market surveillance is the responsibility of the competent Land authorities, which are given the necessary enforcement powers by law. In addition, violations of the regulations on compliance with the ecodesign requirements are punishable by fines. • Market surveillance measures are notified to BAM—a subordinate authority of the Federal Ministry of Economics and Energy (BMWi)—which forwards the notifications to the Commission and also informs the other EEA Member States if the product concerned is withdrawn from the market. • Industry is supported in fulfilling its obligations by a comprehensive range of information provided by BAM, which is aimed in particular at small and medium-sized enterprises (SMEs) and micro-enterprises. Products that do not meet the requirements of the respective EU regulation may no longer be placed on the European internal market, that is, made available in the distribution chain for the first time. With the EU regulation on low-voltage three-phase motors, there are binding regulations for motors and the use of frequency inverters for the first time. National Legislation Related to Energy Efficiency On November 4th, 2016, the Paris Agreement on Climate Change entered into force with the aim of limiting global warming to well below 2
C. The German Federal Government has set out its results in the Climate Protection Plan 2050. In the Climate Protection Plan 2050, the Federal Government has specified its results and underpinned them with measures. GHG emissions in Germany are to be less than 55% of 1990 levels in 2030 and less than 70% in 2040. Emissions in industry are to be reduced from 181 million tonnes of CO2eq. to 140–143 million tonnes of CO2eq. by 2030. However, emissions from electricity generation are not included here because they are assigned to the conversion sector as a whole, for which a separate reduction target is envisaged. The Renewable Energy Sources Act (Erneuerbare-Energien-Gesetz, EEG 2014) regulates the planned expansion of renewable energies, which are to cover 40–45% of gross electricity consumption by 2025, around 55–60% by 2035 and over 80% by 2050 (EEG 2014). Although the share of electricity costs in the gross production value is on average about 2%, there are industrial sectors with much higher electricity cost shares (steel about 10%, cement about 18%). In particular, the EEG levy has risen significantly in recent years: From 2.05 €ct/kWh in 2010 to 6.756 €ct/kWh in 2020. According to EEG 2017 § 61, the EEG levy has to be paid in a reduced form for newly constructed plants generating RES or CHP electricity above the minimum threshold of 10 kW. Since January 1, 2017, 40% of the EEG-surcharge has to be paid. The necessary grid expansion also leads to increasing grid usage fees. At the same time, the so-called “merit order effect”, that is, the priority of renewable energies, dampens the exchange electricity prices. Under certain circumstances, according to EEG 2017 § 64, a reduced EEU levy may apply to electricity cost-intensive companies under the “Special Compensation Rule”. The exact implementation rules are described by the Federal Office of Economics and Export Control (BAFA) in the 2016 information sheet for electricity cost-intensive companies (BAFA 2016).

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Fundamentals of Energy Efficiency

The Act on Energy Services and Other Energy Efficiency Measures (EDL-G 2016) obliges all non-SMEs to conduct an energy audit in accordance with DIN EN 16247–1 by an independent and expert auditor for the first time by December 5, 2015 and every 4 years thereafter. The electricity tax is an indirect consumption tax and is levied in accordance with the Stromsteuergesetz (Electricity Tax Act) (StromStG 2015). The electricity tax is passed on to the end consumer via the electricity price. For companies in the manufacturing sector, a large part can be waived, refunded or reimbursed if certain conditions are met. The amount of the tax is defined in § 3 StromStG. The standard tax rate is 2.05 €ct/kWh of electricity. An exemption is possible, for example, if only electricity from renewable energies is used. An exemption is also possible if an energy management system (EMS) according to DIN ISO 50000-family. The Act for the Preservation, Modernisation and Expansion of Combined Heat and Power Generation (KWKG 2016) came into force on 1 January 2016. Compared to the KWKG 2012, the expansion target is defined on the basis of absolute values. Accordingly, net electricity generation from CHP plants is to increase moderately to 110 TWh by 2020 and 120 TWh by 2025. The incentive instrument in the form of a remuneration obligation remains in place in accordance with Section 3 KWKG 2016. What is new is the direct marketing obligation for CHP electricity pursuant to Section 4 (1), according to which operators of CHP plants >100 kWel must market the electricity generated directly or consume it themselves. For smaller plants, there is also the option of selling the electricity to the grid operator at the “usual price”. The 25th Subsidy Report of the German Government (BMF 2015) lists or estimates the various tax incentives for the years 2013–2016. The figures for 2016 are summarised in Table 2.1. Emissions Certificate Trading The United Nations Framework Convention on Climate Change (UNFCCC) was adopted in May 1992. By the end of the United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro, the UNFCCC had been signed by 155 Parties and entered into force on March 21, 1994. According to this agreement, GHG emissions are to be reduced to 1990 levels by the year 2000. As part of the conferences of the parties (“climate summits”) that have been held annually since then, an additional protocol to the UNFCCC was adopted at the third conference in 1997 in Kyoto, Japan, known as the Kyoto Protocol. Due to the Kyoto Protocol’s target of reducing the EU’s GHG emissions by 8% from 1990 levels between 2008 and 2012, a European Emissions Trading Scheme (ETS) was co-decided in 2003. In December 2015, at the 21st UN Climate Change Conference in Paris (also the 11th meeting on the Kyoto Protocol), a new climate change agreement was agreed to limit global warming to 2
C. Two trading phases (2005–2007 and 2008–2012) were initially envisaged for the introduction of the system, for each of which each participating state had to draw up a National Allocation Plan (NAP). In these two phases, the allowances were issued by the

2.1

Legal Framework

9

Table 2.1 Energy tax savings due to different legal privileges 2016 in Germany

Designation Electricity tax reduction Energy tax Peak balancing electricity Peak balancing energy Energy-intensive processes Electricity Energy-intensive processes Energy Producer privilege energy Power generation from CHP

Legal basis § 9a Electricity Tax Act § 54 Energy Tax Act § 10 Electricity Tax Act § 55 Energy Tax Act § 9b Electricity Tax Act

Beneficiary undertakings 96,857 20,046 23,419 11,473 1077

Tax savings (€ million) 720 160 1900 180 1000

§§ 37, 51 Energy Tax Act

3176

590

§§ 26, 37, 44, 47 Energy Tax Act §§ 37, 53 Energy Tax Act

500

350

17,717

2050

governments to the national installation operators and can be traded throughout the EU. In the first (trial) phase, at least 95% of the allowances had to be issued free of charge to the plant operators. This affected installations from the • • • • • •

Energy and heat generation. Iron and steel works. Refineries, coke ovens and incinerators. Cement and lime industry. Glass, brick and ceramic industry. Pulp and paper mills.

In the second phase, emission limits were reduced by 6.5% compared to 2005. The scheme currently covers around 50% of the EU’s CO2 emissions, which in turn account for around 40% of the EU’s total GHG emissions. From 2012, civil aviation emissions will also be integrated into the scheme, accounting for around 3% of emissions within the EU-25. An 8-year third trading phase will start in 2013. Instead of the previous NAPs, there will be an EU-wide allowance cap, which will be reduced by 1.74% per year, reaching a cap of 1813.1 million EUAs (European Union Allowance) in 2020. Rising energy and emissions costs can jeopardize profitability and competitiveness in some industries and lead to relocations of production. This effect is known as carbon leakage. Vulnerability exists if ETS costs are at least 5% of gross value added and the industry’s trade intensity exceeds 10%. If only one of these two criteria exceeds 30%, an industry is also considered vulnerable. EUAs are based on best available techniques (BAT) and are allocated free of charge to the operators of installations in the affected sectors each year until the end of the third trading period. The possible effects of carbon leakage are discussed in more detail in Sect. 9.4.2.

10

2.2

2

Fundamentals of Energy Efficiency

Considerations on the Systematics of Energy Efficiency

Energy efficiency measures can be systematised according to various criteria or indicators. In addition to methodological aspects, energy-economic or technical aspects can also be helpful. From a methodological point of view, different depths of observation of the energy interrelationships can be undertaken. The correlations are summarised in Table 2.2 and explained below. • In the simplest case, the efficiency of a device is an initial indicator for evaluating its energy efficiency. By definition, the efficiency is the quotient of the power output to the power input at the time under consideration. In contrast, the degree of utilization is the quotient of the work done in the period under consideration. In addition to the temporal expansion of the balance area, an energetic expansion is also conceivable in which the energy demand of auxiliary consumers is also taken into account. Efficiencies under nominal conditions and, if applicable, also for part-load operation can be found in data sheets. • After the analysis of individual energy converters and consumers, an expansion of the balance area leads to an overall view of the energy flows of a manufacturing process. Energy flow diagrams are used for visualization, often referred to as Sankey diagrams after their first application by the Irish engineer Cpt. Sankey (Sankey 1896). In this way, a complete picture of all essential energy inflows and consumers is created. • Looking beyond one’s own company becomes even more complex. Valuable information can be gained by comparing companies within the branche. In some cases, so-called industry energy concepts can serve this purpose. Exchanging ideas with companies from other sectors can also broaden one’s own horizons without competitive aspects inhibit the exchange of ideas. • Extensive measurements are already necessary to create an energy flow diagram, but only through continuous planning and tracking of energy consumption in the sense of energy efficiency controlling is lasting success in the rational use of energy and in the implementation of individual measures possible. A more energy-economic view is oriented towards the type of energy. As mentioned at the beginning, a distinction can be made between primary and secondary energy sources as Table 2.2 Methodological delimitation of different levels of consideration in the analysis of energy efficiency measures Depth of observation Single unit, transducer Overall process, production site External exchange (within or outside the branche) Longer-term planning and control of energy consumption

Resources Efficiency/utilisation Energy flow diagram Sector-specific key figures Energy efficiency controlling

2.2

Considerations on the Systematics of Energy Efficiency

Material utilization

95

85

Casting

30–38

Sintering

28.5 41

Cold and semi-hot extrusion 75–t80

50

46–49

Hot die forging

40–50

75

Energy consumption

Manufacturing process

90

100

11

25 %

Material utilization

Maschining processes

0

66–82

0

25

50 MJ/kg

100

Energy consumption

Fig. 2.3 Material utilization and specific energy consumption of different manufacturing processes

well as final and useful energy. Types of useful energy that are used across sectors and independently of processes are also referred to as cross-sectional technologies and are subsequently dealt with in Chaps. 3 and 4. DIN 8580 provides a systematic classification of the manufacturing processes by means of a two-digit number. A practical overview and description of the most common processes can be found, for example, in (Fritz and Schulz 2008). There are generic studies on the energy efficiency of different manufacturing processes, which also establish the relationship between optimum material utilisation and the required manufacturing energy input, as illustrated by an example in Fig. 2.3. Similar to the classification of manufacturing processes, in chemical technology we speak of basic operations. An increase in energy efficiency is possible, for example, through combined processes. In addition to energy consumption, other optimization goals such as shorter throughput times, reduced inventories or lower material consumption are conceivable, but this can also lead to conflicting goals. If we consider energy efficiency as the highest possible ratio of benefit to (energy) expenditure, there are in principle two levers for increasing it—maximising the benefit and minimising the expenditure. A value-based approach, such as the energy value stream analysis described in Sect. 2.3.2, can be helpful here. However, the energy expenditure of a particular process or production step can only be one of many evaluation criteria. It is not the energy comparison of individual processes, but of individual products or assemblies that is decisive. A complete change of process (e.g. in joining technology adhesive bonding instead of welding) always has complex repercussions on the entire product and is hardly ever carried out for reasons of energy efficiency alone.

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Fundamentals of Energy Efficiency

An increase in benefit can be achieved, for example, through a higher production volume or through higher capacity utilization. On the other hand, higher speeds, for example on machine tools, lead to higher energy consumption and higher wear. Only in exceptional cases is recuperation of the braking energy (economically) possible. A systematic approach to the identification of energy efficiency potentials can be based on four different approaches: I. Checklists enable process-independent control, for example to reduce demand, runtime, temperature or losses, to increase capacity utilization or throughput. Checklists reflect collected knowledge and proven measures. A good example of this is provided by (WKÖ 2009). II. Guides are function-oriented, but cross-sectoral, valid for individual (cross-sectional) technologies (see Chaps. 3 and 4). Good examples are the comprehensive brochures published by the American Energy Efficiency and Renewable Energy Office (EERE) at the Department of Energy (DoE) as “Sourcebook for Industry” on various crosscutting technologies (see https://www1.eere.energy.gov/library/) or also the “Reference Guides” from the Canadian CESIG (Customer Energy Solutions Interest Group (see https://www.ceati.com/projects/public-reports/). III. Databases also document the available experience across industries, especially for cross-sectional technologies. In almost all renowned universities in the USA, teams of students work under the guidance of lecturers on consulting projects on energy efficiency for industrial companies. In recent years, around 19,500 analyses and over 146,000 individual measures have been documented (IAC 2021). In Europe, about 8000 individual measures have been documented in the “De-risking Energy Efficiency Platform”, more than 2100 relate to measures in German industry. The measures cover the cross-sectional technologies of heating, waste heat, compressed air, drives, refrigeration and pumps. Particularly noteworthy is the statistical data evaluation and the presentation of payback periods and specific savings costs. The database thus provides statistically well-founded figures on the cost-effectiveness of implemented energy efficiency measures in the individual trades (DEEP 2017). IV. Industry energy concepts analyse the energy interrelationships with a focus on the special features of individual industries and processes. A current comprehensive analysis of energy-intensive industries is available in Fleiter et al. (2013). Individual industries are often also analysed under the direction of an industry association, as the example (Franzen 2008) for the foundry industry shows. In addition to the “Reference Document on Best Available Techniques for Energy Efficiency” (EU 2008), numerous sector-specific documents have also been produced on behalf of the EU, which are available on the Internet on the website of the Joint Research Centre (JRC) at the European IPPC Office (JRC n.y.). In addition to the commonly used distinction between cross-cutting and sectoral technologies, which is also expressed in the above-mentioned consulting approaches, a

2.2

Considerations on the Systematics of Energy Efficiency

13

third category is to be introduced in the context of this book. While cross-sectional technologies such as burners or heat exchangers are themselves based on a few physical principles, various cross-sectional technologies can be combined to form more complex process technologies. An example of this is furnaces, which are made up of heat generators, possibly fans, transport equipment, heat insulation and possibly heat recovery. Increasing specialisation then leads to sector-specific technologies such as blast furnaces for pig iron production. Although the transitions appear to be fluid and a strict distinction on the basis of the above-mentioned criteria is hardly possible, the following chapters have been structured according to the energy or process-related complexity. The allocation of individual topics and technologies is summarised in Table 2.3. It is important to note that the savings potential at component level is in any case lower than in a comprehensive consideration of the entire system.

2.2.1

General Measures to Improve Energy Efficiency

In addition to the cross-sectional and process technologies and the branche-specific starting points, there are also some universal measures for improving energy and resource efficiency. Even if this may seem trivial to some readers, practical experience shows the need to raise awareness of these simple points. Minimization of Stand-by Consumption In private households, the topic of stand-by consumption is often discussed in connection with the many electronic devices (TV, HiFi, PC, monitors, displays, etc.). Many office devices also have a not inconsiderable stand-by consumption. Office equipment often hardly differs in terms of practical equipment and performance features. In contrast, the devices differ significantly in terms of their power consumption, so that small additional costs in the procurement of energy-efficient office equipment are quickly amortized by the low energy consumption. To ensure that energy costs are also taken into account in the procurement phase, it is important to firmly anchor this criterion in the purchasing process and in the selection of suppliers. The first step in the procurement of energy-efficient office equipment should be a needs analysis. The following questions can be addressed as part of the needs analysis: • • • • •

Which basic functions are required? What are the techno-economic alternatives to achieve the performance? Does integrating multiple functions into one device offer a viable alternative? Which additional functions are needed in everyday office life? Are there accessories (timer, switchable plugs) for more efficient use of the equipment?

In the case of machines and systems in production, but also in cross-sectional technologies, the issue of standby consumption has hardly been taken into account to date. Here, a distinction must be made between unplanned downtimes (production

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Fundamentals of Energy Efficiency

Table 2.3 System for thematic classification based on energy and process complexity

Basic technologies

Technology Transformers

Lighting

Electric drives Fluid handling (pumps, compressors, fans) Insulation Burner

Crosssectional processes

Heat exchanger for heat recovery and waste heat utilisation Compressed air

Primary components Coils, core, sheet metal, insulation Bulb and socket Rotor and stator, coils Impeller, housing

Plant components Feedthroughs, housings, cooling Ballast, reflector, heat sink, housing Bearings, fans, gears Drive, gearbox, inverter

Insulation material Supply of fuel and oxidant

Brackets, mounting aids Igniter, flame tube, blower

Heat exchanger

Pipes and fluid transport

Compressor and drive

Preparation (filter, dryer), storage, distribution Power supply, cooling, inverter ventilation Pumps, heating and cooling, cleaning

Data centers

Hardware: server, storage

Electroplating

Electrolyte baths, rectifiers

System components Switch

Final energy Power

Dimmer, sensors, MCR Control, inverter Pipeline, fittings, control devices, sensors Jacket

Heat

HR, sensors, lambda controller Control, ORC plants etc.

Regulation DL applications

Power

UPS, MBS

HR, RVS systems, sensors, control devices (continued)

2.2

Considerations on the Systematics of Energy Efficiency

15

Table 2.3 (continued) Technology Steam boiler

Industrial furnaces

Dryer

Painting systems

Primary components Burner, combustion chamber, housing, heat exchanger, insulation Housing, insulation/ refractory, Burner/heat generation Housing, insulation, burner/heat generator Housing/ cabin, paint application

Refrigeration systems

Chiller, compressor and drive

HVAC systems

Fan, pumps, heat exchanger

Plant components Pipes and fluid transport

System components Sensors and control equipment

Fans, HR, flue gas ducting, transport facilities

Sensors and control equipment

Transport equipment, fans, HR, flue gas ducting HVAC, HR, drying, compressed air, transport equipment

Sensors and control equipment

Storage tank, heat exchanger, distribution, pumps, fans Piping, heat distribution systems, filters, air conditioning, HR

Exhaust air aftertreatment, sensor technology, control devices Regulation, cold application, insulation,

Final energy Heat

Electricity and heat coupled

Control devices, sensors

disruptions) and planned downtimes, for example during breaks, overnight, at weekends or during public holidays. Unplanned downtimes and their effects can be reduced by measures to improve the production process. In the following, however, the focus of the considerations will be on reducing the energy consumption of plants and machines during planned idle times. In Schöfberger (2010), the plant of an automobile manufacturer producing the drive train is mentioned as an example, which requires an electrical power of around 54 MW during production and still 9 MW independent of production. In view of process stability or possible quality losses, systems are often not switched off at the weekend, but merely put into a sleep mode. Only targeted long-term recording of

16

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Fundamentals of Energy Efficiency

energy consumption can provide information about the energy consumption of systems in the respective operating modes. On this basis, in conjunction with corresponding process knowledge, concrete measures for reducing power consumption can then be derived. Example 1: Injection Moulding Machine The example of an injection molding machine shows how standby and offline energy consumption can differ. In regular operation, the machine requires about 90 kWh of electrical energy and 47 kWh of thermal energy per hour. In heat-up mode, the hourly electrical consumption increases to 99 kWh, while the thermal energy consumption drops to 38 kWh. In stand-by mode, about 20 kWhel and 5 kWhth are still required. Even offline, about 2 kWhth are still consumed. Such detailed consumption figures can be used to determine the point in time at which the additional consumption of a shutdown/restart cycle of the machine is more efficient than leaving it in standby mode (Neher 2011). Example 2: Implementation of a Stand-by Manager for a Machine Tool New software enables a machine tool to automatically switch individual function modules to an energy-saving state when defined events occur. The time after which the machine switches to standby mode can be freely parameterized. In this specific case, the predicted annual energy savings through standby switching in 3-shift operation is approximately 25 MWh, which corresponds to approximately 23% of the total energy consumption of the machine (Abele et al. 2011). Closing Loops Energy efficiency is a contribution to resource efficiency. Conversely, the economical use of materials makes a direct contribution to saving energy—and not only in energy-intensive industries. According to a survey of manufacturing companies in 2009, the Fraunhofer ISI puts the material savings potential at 48 billion euros (Fraunhofer ISI 2012). The relative and absolute potentials are estimated quite differently depending on the sector, as shown in Fig. 2.4. Example: Waste Water Treatment and Heat Recovery in the Textile Industry

Wet chemical processes are hardly replaceable in textile finishing so far (Ströhle 2008). The careful use of water as a resource is becoming increasingly important. The starting point for process optimization are considerations and decisions regarding resource management: • • • •

Continuous dyeing instead of the obsolete exhaustion dyeing. High performance instead of simple washing aggregates. Optimization of liquor flows with counterflow and partial flow water management. Pollution-dependent fresh water supply.

2.2

Considerations on the Systematics of Energy Efficiency

17

Fig. 2.4 Branche-specific material savings potentials

Mercerizing produces washing water with a high caustic soda concentration of approximately 60 g/l. The caustic soda concentration is then concentrated in the washing water. Ultrafiltration purifies the caustic soda in the wash water and concentrates it in an energy-saving manner before the caustic soda is further thermally evaporated. In this way, the caustic soda can be reused in the mercerizing plant. Thus, a lye recycling of 75–80%, a process water recycling of 80–85% and a heat recovery of 70% are possible. Membrane plants for water recycling of textile waste water pay for themselves after 2–3 years. If sizing and/or caustic soda are also recycled, the payback time is less than 2 years. Ultrafiltration can be applied with novel backwashable, chemical and temperature resistant ceramic membranes. This makes it possible to effectively protect reverse osmosis from fouling. In addition to the purification of the process waste water, material recovery and cascading of the heat are also possible. Table 2.4 summarises the waste water qualities of the individual processes. ◄ Maximizing the output of good parts and thus minimizing the proportion of recycled material also contributes to energy and resource efficiency. This is particularly evident in casting processes. Typical yield rates reach 85–95% for simple parts of heavy grey cast iron. By contrast, the proportion of good parts in machine malleable cast iron or in castings made of spherulitic cast iron is only 40–50% (IfG 2008) and therefore still offers considerable potential for improvement.

18

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Fundamentals of Energy Efficiency

Table 2.4 Characterization of process waters in textile finishing Process Temperature (
C) Oxygen content (g/l) Accompanying substances

2.3

Pre-treatment 80–90 5–25

Dye works 40–60–95 1–3

Print shop 60–95 2–15

• Smoothing • Caustic soda • Washing/ wetting agent • Alkaline earth salts • Organic pollution

• Dissolved dyes • Dye pigments (vat, disperse, pigment dyes)

• Dissolved dyes • Thickener • Salts • Washing/ wetting agent

Methods

In addition to the relevant methods for analyzing and optimizing the use of energy, materials and resources in production, there is a wide variety of engineering methods and management approaches that can be linked to energy-related issues and thus contribute to the identification and implementation of energy-saving measures. The Failure Mode and Effects Analysis (FMEA) or the Six Sigma method are well known from quality assurance. The Finite Element Method (FEM) or the component value analysis have been established in design for a long time. In the following, an attempt is made to systematically classify the various approaches. • To identify energy efficiency measures, a certain basic knowledge is necessary, which can be taken from reference books, guides, databases, checklists or industry energy concepts. During on-site inspections, initial measures can be derived directly from this. • Based on this, a visualization of measurement data and key figures in the form of energy balances, flow diagrams or as a cadastre is necessary. • Cost accounting is necessary for the business allocation of individual expenses and costs. In capital budgeting, the costs of individual production factors such as capital, personnel, energy or materials are subjected to a profitability analysis. The evaluation of individual measures is carried out according to criteria such as the amortization period and/or the interest rate. • Prioritization and selection of measures can be done using benchmarks, an ABC or Pareto analysis, and savings cost potential curves. In pinch, energy value flow or exergy analysis, various of the aforementioned aspects are combined, resulting in more complex methods. Different approaches can also be chosen and combined when implementing measures.

2.3

Methods

19

• Internally, an EMS in conjunction with energy (efficiency) controlling will contribute to the systematic implementation of energy efficiency measures in a continuous improvement process (CIP). • Furthermore, additional expertise can be used by involving external partners. Examples include various forms of contracting or participation in energy efficiency networks. The most important methods are described below.

2.3.1

Technical Analyses

The Pinch Analysis The pinch analysis according to Linnhoff (Linnhoff 1998) is used in particular for the analysis and optimal connection of heat exchangers. The starting point for this is measured or calculated data on the heat supply and the heat demand of the processes to be optimised. A simplified example is shown in Table 2.5. Here, “hot” streams are understood as heat sources and “cold” streams as heat sinks. Each flow has an input temperature TS and a target temperature TT. The heat capacity flow rate (CP) is defined as the product of the mass flow and the specific heat capacity of the flow, measured in enthalpy change per temperature unit (Linnhoff 1998). In the example, the CP for stream 1 is calculated as: 2000 kW/(180–80
C) ¼ 20 kW/
C. These data result in the “composite curves” as a graphical representation of heat supply and demand of the considered processes and form the basis for determining the minimum energy consumption of a thermal plant. To construct a composite curve, the enthalpies of overlapping temperature intervals are added up. In the example, the intervals {80–180
C} and {40–80
C} each contain only one stream. The associated CP values correspond to the CP values of these streams. In the interval {80–130
C}, however, both streams are included, so that the CP value here is obtained by adding CP{80–130} ¼ 20 + 40 ¼ 60. In this way, a “hot” and a “cold” composite curve can be constructed, representing the heat sources and sinks respectively, which is shown in Fig. 2.5 (Linnhoff 1998). To determine the minimum energy consumption, the “hot” and “cold” composite curves are plotted against each other, as shown in Fig. 2.6. For this purpose, the “cold” composite curve is shifted to the left until the minimum vertical distance between the “hot” composite curve and the “cold” composite curve corresponds to the minimum temperature difference ΔTmin (Linnhoff 1998). This results process-specifically from the process-engineering requirements for the necessary degree of freedom of heat exchangers (in the example, a minimum temperature difference of 10
C was selected). The overlap of the two curves on the abscissa indicates the maximum possible process heat recovery. The remaining heat supply (¼ cooling demand) at low temperature or the remaining heating demand at high temperature are referred to as QCmin (here 120 kW) and QHmax (here 960 kW) respectively.

20

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Fundamentals of Energy Efficiency

Table 2.5 Exemplary heat supply and demand flows in the pinch analysis Power 1 2 3 4

Stream type Hot Hot Cold Cold

Input temperature TS (
C) 180 130 60 30

T [°C]

Target temperature TT (
C) 80 40 100 120

Power (kW) 2000 3600 3200 3240

CP (kW/
C) 20 40 80 36

T [°C] 180 20

180 C P

=

CP

130

130 1

CP

80

=

40

CP

80 2

CP

=

=6

=

20

0

40

40

40

0

0 2000 4000 6000 . Enthalpy flow h [kW]

0

0

2000 4000 6000 . Enthalpy flow h [kW]

Fig. 2.5 Construction of the composite curves T [°C]

T [°C] Cold composite curve

200 150 100

Hot composite curve Pinch

ΔTmin = 10°C

200

max

= 960

150 100

50

50

0

0

Q

min

. Enthalpy flow h [kW]

Q Heat recovery

= 120

. Enthalpy flow h [kW]

Fig. 2.6 Determining the pinch

The minimum distance between the “hot” and “cold” composite curve is called the “pinch”. Above the “pinch point”, a net heat input is necessary (heat sink), whereas below it, heat is released (net heat source). When designing an optimized network with minimum energy consumption, three rules must be observed: • Heat must not be transferred via the pinch. • No external cooling may be used above the pinch. • No external heat source may be used below the pinch.

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Methods

21

By extending the pinch analysis with exergetic aspects, chemical and physical aspects can finally be integrated. The application of the method is supported in complex practice by relevant software. The Pinch Center at the Lucerne University of Applied Sciences and Arts in Switzerland offers a variety of support options (https://pinch-analyse.ch/en/ tutorials-en). Life Cycle Analysis The design of energy-efficient production can be carried out from a more technical or economic perspective and for different levels of consideration from the entire factory down to individual processes, products or assemblies. From development to disposal, all stages in the life cycle can be analysed, balanced, evaluated and finally measures implemented. The morphological box shown in Fig. 2.7 summarizes these different viewpoints (Götze and Sygulla 2012). Life cycle analysis (LCA) follows the “law of becoming and passing away” and involves a structured breakdown into the phases of design/planning, manufacture/construction, use/operation, dismantling/disposal, for example. The depth of consideration of the phases can be refined down to individual processes. While the ability to influence the use of raw materials and energy is greatest at the beginning of the life cycle, the greatest expenditure often occurs later during product use. The importance of the planning phase for energy-efficient products or factories can therefore hardly be overestimated and is described in detail by Müller et al. (2009). Life cycle cost (LCC) analysis is dealt with in the following Sect. 2.3.2. LCA as a holistic assessment is historically based on earlier concepts such as the cumulative energy demand (CED) according to VDI Guideline 4600 and life cycle assessment. Methodological weaknesses of the CED, such as an uncertain data situation or the focus solely on energy aspects, limit its applicability, so that the CED should be used in a larger context, if necessary as one of several indicators for the energy-ecological assessment of production processes (Sygulla and Götze 2010). A comprehensive description of the economic methods for energy and material flow management and the associated cost accounting and evaluation system is available in Tschandl and Posch (2012).

2.3.2

Economic Analyses

Cost Accounting Cost accounting is to be understood as a regularly prepared, short-term and profit-related account that takes into account the determination, collection and evaluation of the total consumption of value in the production of operational services. Against the background of the generally increasing importance of energy aspects in corporate management, partial energy cost accounting can also be developed from cost accounting. For this, a mapping and analysis of the energetic value consumption with the associated costs is necessary. This results in information for energy-related planning, management and control of operational

22

2

Perspective Object Life cycle Focus

Economic-ecological balancing & evaluation

Technical balancing & evaluation Factory

Logistics

Fundamentals of Energy Efficiency

Process chain

Process

Production system

Framework concept Product

Component assembly

Material

Development

Production

Utilization

Recycling / Disposal

Description & balancing

Analysis & forecast

Evaluation

Design & implementation

Fig. 2.7 Morphological box for the viewpoints model

production and logistics processes up to the energy cost shares of individual products (Bierer and Götze 2010). Only then is it possible to adequately evaluate and control energy efficiency measures, energy services and energy flows in the company. The following special features of energy as a production and cost factor must be taken into account: • Primary and final energy sources are mostly procured externally, whereby the markets differ. While there are numerous suppliers for electricity, compressed air or cooling, for example, could only be procured by a few service providers, if at all. Ultimately, non-tradable useful energies are required, which are provided directly on site from final energy sources by means of appropriate devices. • Since energy can neither be “produced” nor “consumed”, but only transformed, energyrelated (production) processes are fundamentally linked to input and output and are therefore to be understood as co-production processes. The allocation of cost shares according to the polluter pays principle is often no longer clearly possible. • Flexible production requires the equally flexible provision of energy. Energy consumption can be understood as the consumption of goods, and energy costs can consequently be understood as the consumption of goods in the production of goods and services, valued at factor prices. For self-generated final and useful energy, the factor prices and quantities of the energy sources consumed in their generation and the energy converters used, etc. must be used. In addition to the energy carriers and converters, costs for auxiliary and operating materials, disposal costs and administrative activities, for example, for certificates, must also be included. In view of the diversity and complexity, a differentiated approach is necessary in terms of cost-benefit aspects when recording individual consumptions with regard to the informative value for cost accounting. Energy costs can basically be differentiated into cost types according to the relevant classification and allocated to cost units via individual cost centres, as shown schematically in Fig. 2.8 (own illustration based on Bierer and Götze 2010). Energy cost types can be further differentiated by cost area or by production factor, as summarised in Table 2.6. Cost centre accounting determines where costs are incurred in the company and what proportion of these are attributable to energy costs in each case. Individual billing units are defined for this purpose:

2.3

Methods

23

Fig. 2.8 Energy costs in the individual stages of cost accounting Table 2.6 Classification of energy costs according to cost areas or production factors Cost elements according to cost areas • Energy procurement costs, e.g. for electricity, fuel or combustibles • Storage costs, e.g. for tanks, silos or accumulators • Costs for investments in units, e.g. heating plants, CHP units, heating networks • Costs for energy disposal, e.g. of ash, slag, waste gases • Other energy-related costs, e.g. for administration, insurance, certificates

Types of costs according to production factors • Material costs, e.g. for auxiliary/operating materials for the energy plants • Personnel costs, e.g. for employees in the operational energy industry • Costs for third-party services such as rents, leases, repairs of energy facilities • Costs for legal assets such as certificates • Capital costs, e.g. for investments in generation plants • Risk costs, e.g. for insurance premiums • Charges, e.g. for energy-related taxes • Imputed interest for invested energy plants, energy stocks, buildings

• In the preliminary cost centers, (energy) costs are accounted for that arise at upstream points in the company (e.g. maintenance, heating center). In contrast, the (energy) costs of the actual product creation and processing are posted to the final cost centers. • In addition, the cost centres can be categorised according to the degree of energy procurement into very strongly characterised energy cost centres (e.g. heating centre, compressed air centre), into mixed cost centres that are nevertheless characterised by energy and production (e.g. hardening shop, paint shop) and into non-energy cost centres that are not characterised by energy (administration).

24

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Fundamentals of Energy Efficiency

Taking the direct costs into account, overhead or allocation rates can then be calculated for the total costs of material, main production, administration and sales points. These form the interface to cost unit accounting and are used to determine the overhead shares for each cost unit when applying overhead or base object costing (Bierer and Götze 2010). Investment decisions for or against energy saving measures are practically always made only on the basis of the directly saved variable energy costs. From a longer-term perspective, however, other energy cost components (e.g. internal network costs) must also be taken into account in such decisions. It is true that the implementation of an energy saving measure does not lead to savings in the short term, for example, in the plant network of the electricity, heating, compressed air or refrigeration supply, so that the orientation on variable energy procurement costs that can be avoided in the short term appears to be justified. In the long term, however, the consideration of the full costs of supply can lead to the fact that expansion measures in further supply structures can be avoided or delayed. In multi-level, multi-product companies with make-to-order or series production, overhead costing is often used due to the heterogeneous cost structures. In this method, overhead costs are allocated separately to material, production, administration and sales centers using the overhead rates determined in Cost Center Accounting. Production overhead is often allocated to products as machine hour rates. The differentiated overhead costing is shown schematically in Fig. 2.9. In this way, it is possible to determine both the production costs of energy goods and services, if these are the main purpose of energy systems. In addition, energy cost shares for other cost objects can be determined, for example, by allocating energy costs as direct costs or as special direct costs in energy-intensive processes, if the energy costs cannot be allocated to individual product units but rather to individual production costs or orders. Since material costs clearly outweigh energy costs in many manufacturing companies, it is obvious to methodically include material costs more strongly in cost accounting. With flow cost accounting—analogous to energy cost accounting—the material costs are allocated to the cost objects via cost elements and cost centers. A more detailed description of the procedure can be found, for example, in Schmidt et al. (2012) or Tschandl and Posch (2012). Investment Calculation In practice, an investment decision is still often made today solely on the basis of the static payback period, which is understandable but not very appropriate. The payback period is rather a measure of the investment risk. However, the evaluation of the investment should be based on the internal rate of return (IRR). Against this background, a brief overview of the basic features of investment appraisal is given below. An investment is the transfer of cash into physical or financial assets. Expenditure means payments and liabilities equal to the monetary value of purchases (of goods or services) per period. Revenues are therefore receipts and receivables equal to the monetary value of sales of goods and services per period. The financially valued consumption of the production factors (material, capital and personnel) for the operational achievement

2.3

Methods

25

Fig. 2.9 Differentiated overhead calculation (schematic)

production of a period causes costs. Conversely, services are the results of the production of goods and services, valued in terms of prices. (Note: In technical terminology, there are no “investment costs”.) According to the guideline VDI 2067, four types of costs can be distinguished: • • • •

consumption-related costs (e.g. fuel costs); operational costs (e.g. maintenance and repair, personnel costs); capital-related costs (e.g. interest, depreciation); other costs (e.g. insurance, taxes).

In the case of operational costs, it is also useful to distinguish between fixed and variable (labour-dependent) costs. In principle, a distinction can be made between static and dynamic procedures in investment appraisal. The static procedures include the cost comparison and profit comparison calculation as well as the static amortization calculation. Static methods do not take into account temporal differences in cash inflows and outflows. However, neglecting temporal (interest) effects is only appropriate for short observation periods. Although short payback periods are repeatedly required in industrial energy efficiency, the life of the investment is often many years, so that dynamic methods are preferable for economic efficiency considerations. Dynamic methods include the present value method, the net present value method, the IRR method, the annuity method and the dynamic payback calculation. • The present value method is based on a comparison of the cash inflows/outflows occurring during the useful life of an investment, discounted to the reference date. • The net present value method balances the discounted cash inflows/outflows of an investment. • The IRR determines the effective interest rate of an investment.

26

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Fundamentals of Energy Efficiency

• The annuity method converts an initial investment into a series of payments with constant annual disbursements. • The dynamic amortization calculation determines the period for recovering the capital employed at imputed interest or the useful life after which the net present value becomes positive for the first time. Cash flows are recorded in dynamic investment accounting using payment series. “Payments” are generally amounts of money that are received or spent. The value of a payment is determined not only by its amount but also by the time at which it is due. Therefore, an amount of money invested today will have a higher value at a later date than the amount originally invested due to accumulated interest. Conversely, an amount due at a later date will have less value at the present time than an amount of the same amount due today. This is referred to as the time value of money. If, for example, an amount K0 is invested with an interest rate of i for z years, then its value grows exponentially to the final value KE: K E ¼ K 0  ð 1 þ i Þ z ¼ K 0  qz ,

ð2:1Þ

K0 ¼ Capital at start time i ¼ Interest rate (decimal: 0.05 instead of 5%) z ¼ Duration in years In this case, one speaks of compounding or accumulation. If the payment is related to the initial time, it is called discounting. The above equation reverses to K0 ¼ KE  qz. In the case of the same recurring cash inflow/outflow amounts g, the total present value factor ftpv results from the cash flow in the sense of a series development. K 0 ¼ g  ð1 þ iÞ1 þ g  ð1 þ iÞ2 þ . . . þ g  ð1 þ iÞn Xn , qn  1 ¼g ð1 þ iÞt ¼ g  n ¼ g  f tpv t¼1 q ð q  1Þ

ð2:2Þ

Conversely, an initial investment can be divided into equal annual amounts, called annuities. The annuity factor fa is the reciprocal of the total present value factor fbws: g ¼ K 0  f a ¼ K 0  f 1 tpv ,

ð2:3Þ

K0 ¼ Capital at start time fbws ¼ Total present value factor fa ¼ Annuity factor The annuity method can be used to compare investments of different lifetimes. On the other hand, the assumption that investments of different lifetimes are annuated uniformly over, say, 15 years “for better comparability” often leads to incorrect decisions. Both the

2.3

Methods

27

present value factor and the annuity factor can easily be taken from relevant tables (e.g. VDI 2067). Interest is the price paid for borrowed or invested capital. The interest rate is stated as a percentage per accounting period. In addition to inflation compensation and the net return, investors expect a risk premium to cover possible defaults on individual investments. The benchmark for the risk-free interest rate is often 10- or 30-year government bonds with the highest credit rating. For long-term investments, it is often not possible to forecast the inflation rate. Calculations are then made adjusted for inflation using a real interest rate reduced or discounted by the average annual inflation rate. Financial mathematically correct applies: qr ¼

qn 1 þ in ¼ , p 1þr

ð2:4Þ

qn  1, p

ð2:5Þ

ir ¼

r ¼ Inflation rate as decimal number in ¼ Nominal interest rate ir ¼ Real interest rate qn ¼ Nominal interest factor (1 + in) qr ¼ Real interest factor (1 + ir) p ¼ Inflation factor (1 + r) Likewise, energy price forecasts for long periods are hardly possible because the volatility of energy prices is significantly greater than the fundamental development. For long-term investments, therefore, a constant development in real terms is often assumed in order to subsequently examine in a sensitivity analysis how investment decisions would change if energy prices were to rise or fall in real terms. The nominal interest rate refers to an interest period of 1 year. For m interest or repayment periods of less than 1 year, the actual interest rate increases and is referred to as the effective interest rate. This can be determined using the following formula:   i m ie ¼ 1 þ n  1, m

ð2:6Þ

ie ¼ Effective interest rate in ¼ Nominal interest rate m ¼ Number of interest periods during the year The question of the interest or “return” on an investment often arises. For this purpose, the IRR method can be used as a special form of the net present value method. The interest

28

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Fundamentals of Energy Efficiency

rate is determined at which the initial investment is just balanced by the sum of the payment surpluses discounted with this interest rate. This interest rate is referred to as the “internal rate of return” (IRR). If the IRR is higher than an investor’s minimum return requirement, the investor will evaluate the investment as economic. If disbursements are set as negative numbers and revenues as positive numbers, the general equation for this is: K0 þ

Z X E t þ At ¼ 0, qt 1

ð2:7Þ

K0 ¼ Initial investment (set negative) Et ¼ Deposit of period t (set to positive) At ¼ Disbursement of period t (set negative) z ¼ Number of periods With constant deposit surpluses (Et + At) ¼ constant, Eq. (2.7) can be simplified with (2.2) written as: K 0 þ ðE t þ At Þ  f tpv ¼ 0:

ð2:8Þ

The resolution of this equation according to the interest factor q or the interest rate i is only possible iteratively. In practice, spreadsheet programs or the linear approximation of the zero point help. The numerical values determined in this way are illustrated in curve form in Fig. 2.10. With a known plant service life and the required static amortisation, the IRR on the investment can be read off. It is clear that for long-lived investments the achievable rate of return is approximately the reciprocal of the payback period in years. For example, a required static amortization of 4 years results in a maximum IRR of 25% even in the long run. Even with a scheduled asset life of 9 years, a 4-year amortization achieves an interest rate of 20%. Often, payback periods of a maximum of 2 years are specified even for long-term investments for energy efficiency measures, which corresponds to a return requirement of at least 50%! Excessively high payback requirements can be a major obstacle to the implementation of high-yield measures. When analysing energy saving potentials in companies, numerous measures are often identified. A quick rough assessment is possible using the payback calculation, which determines the number of years required until the capital invested in a measure is recovered through cost savings (payback time). Often the interest rate is disregarded, although a dynamic application is also possible. The static payback time must be at least shorter than the required time and also shorter than the lifetime of the measure. It is important to realise that, despite the same payback period, the profitability of an investment differs simply because of the different useful lives, which is also reflected in Fig. 2.10. For example, an investment that pays for itself after 3 years (static) already has an IRR of 20% for a useful life of 5 years and achieves an annual rate of return of 31% for a useful life of 10 years.

2.3

Methods

29

Fig. 2.10 Internal rate of return of an investment for a given plant lifetime and for a required payback period

Savings Potential Curves From the investment I for a conservation measure and the total present value factor ftpv, the annuity of the conservation investment can be calculated according to Eq. (2.3). If this is related to the associated energy saving, the specific costs of the saved energy (Cost of Conserved Energy, CCE) result, described for the first time in Meier (1982) according to Eq. (2.9): CCE ¼

I 1 f , E tpv

ð2:9Þ

CCE ¼ Cost of Conserved Energy I ¼ Investment of the energy saving measure ftpv ¼ Total present value factor If these costs are calculated for each energy-saving measure and sorted according to their amount, the result is a step-shaped progression as a function of the cumulative energy savings, as shown in Fig. 2.11 (own illustration based on Zweifel et al. 2017). The use of economic cost curves to represent measure-related energy savings in an economic framework is a common method. Examples include the savings supply curves from Lawrence Berkeley National Laboratory (Hasanbeigi et al. 2013) or the GHG reduction cost curve from McKinsey (2007). In comparison with the (marginal) costs of energy procurement, it is thus possible to estimate which measures can be regarded as economic under the selected boundary

30

2

Fundamentals of Energy Efficiency

Fig. 2.11 Energy savings potential curve

conditions. From the point of view of economic theory, this is an elegant concept. In operational application, some not inconsiderable problems arise: • If replacement investments are made during the investment cycle (at the end of a plant’s life), only the additional investments for more efficient plants compared to standard plants should be included in the economic efficiency analysis. In the case of early replacement of inefficient plants, on the other hand, a residual value should be taken into account. If, on the other hand, the full amount of the (replacement) investment is included in the economic efficiency calculation of the energy efficiency measure, only very few measures will be able to meet the economic efficiency criteria. • In addition to the initial investment I as an expense, the annual savings should also be taken into account, which on balance reduce the expense. Engineering costs and other transaction costs, on the other hand, increase the expense and thus reduce the savings effect. • Investment or implementation barriers and rebound effects (see Sect. 9.4) also reduce the theoretically possible potential. • Often individual savings measures are not independent of each other, so that in practice an incremental approach becomes necessary. • If both capital expenditure and saved energy costs are considered dynamically and discounted, the economic order of the measures becomes dependent on the ratio of

2.3

Methods

31

capital costs to energy cost savings. Capital-intensive measures tend to be shifted backwards in the order if the interest rate requirements are high. • As can be seen from Eq. (2.9), the potential curve already implicitly contains a given base rate of return, which is reflected in the total present value factor. However, the exact return on individual measures cannot be read from the curve. To overcome this deficiency, it is proposed to calculate the effective rate of return (IRR) for all savings measures according to Eq. (2.8) and to rank the measures according to the amount of achievable rate of return. This leads clearly to an IRR potential curve of the energy saving measures, as it is schematically shown in Fig. 2.12. Life Cycle Cost Analysis The total costs of the target-related consumption of goods valued at factor costs are aggregated to so-called “life cycle costs” (LCC) (Lindner and Götze 2012). When comparing investment alternatives, all fixed and variable costs from production through use to disposal must be considered. Fixed costs include capital-related costs (interest and depreciation), income taxes (corporate income tax and trade tax) and non-consumption-related costs (personnel costs, fixed maintenance costs). Variable costs are consumptiondependent (fuels, auxiliary and operating materials, variable maintenance costs). In the case of projects with longer planning and construction periods, the construction period

Fig. 2.12 Interest rate potential curve

32

2

Fundamentals of Energy Efficiency

Fig. 2.13 Types of costs in a life cycle cost analysis

interest, for example, must also be considered as financing costs, which is determined by compounding all payments made before a plant is put into operation. Usually, only the nominal figures without interest during construction (“over night costs”) are disclosed in published data on investments, which limits comparability with other data. A complete overview of all costs incurred in the life cycle of capital goods is given in Fig. 2.13 (Seinschedt et al. 2003). LCC analysis can become very complex if not only specific machines and processes, but complete production/process chains are to be compared. Here it becomes clear that energy efficiency is not an end in itself, but a complex economic issue with numerous references that require careful consideration. Energy Value Stream Analysis Value stream mapping is a business method for production optimization. It records the actual state of a production with all processes, the flow of materials and information, presents these graphically in an easily understandable way with defined symbols and key figures and thus enables resource consumption and wastage to be identified at a glance. The energy value stream analysis can therefore be understood as an application of the value stream analysis with a special focus on energy. Using simple design guidelines, the process can then be designed more efficiently (Erlach 2013). The energy value stream analysis presents all energy consumers in production transparently and in their organizational context. The explicit allocation of energy consumption and consumers is not self-evident, since in many companies the energy consumption is recorded centrally for the entire production system. Therefore, direct energy consumption measurements are often a prerequisite for the reasonable use of energy value stream analysis. Through the transparent presentation of energy consumption, the energy drivers of the value stream can be identified relatively easily, resulting in starting points for immediate measures. Finally, the analysis and evaluation of the production processes with regard to their energy efficiency is carried out using key figures. The decisive factors here are energy

2.3

Methods

33

intensity, which indicates the product-specific energy consumption, and the degree of efficiency, which permits an evaluation of the processes in relation to the company’s own objectives or in comparison with best-practice processes or the current state of the art, and is thus a measure of the quality of the production processes. An energy value stream is drawn up for each product family, starting with the products with the highest sales. Based on the customer demand (sales volume in the previous fiscal year), the production rate is calculated as the so-called “customer takt time” (TT): TT ¼

Available working time per year Factory days  Working time ¼ Customer demand per year Number of pieces

ð2:10Þ

The energy consumption is assessed on the basis of this customer takt time. The boundary conditions resulting from the customer requirements are recorded in a box below a “house”, which symbolizes the customer. Likewise, the production processes in the value stream are graphically represented using meaningful characteristics (employees per shift, number of alternative operating resources, etc.) and key figures (processing time, setup time, batch size, cycle time, etc.), as shown in Fig. 2.14 as an example. The difference between the cycle time and the customer takt time is a measure of the (unproductive) standby time of the equipment. As this is an energy value stream, the energy consumption (of electricity, natural gas, compressed air) of the individual production processes is also recorded. These are combined relative to a product in the energy intensity (Erlach and Westkämper 2009). Immediate measures can already be derived during the creation of the energy value stream. For more detailed analyses, key figures such as energy intensity and the degree of efficiency must be used. The energy intensity here indicates the energy requirement of a specific process for the production of a single product. It is calculated from the energy consumption (average power consumption in normal operation based on sample measurements) multiplied by the customer takt time and the number of resources working in parallel: Energy intensity ½kWh ¼ Power consumption  Customer takt time  Number of resources:

ð2:11Þ

Higher energy intensities thus characterize the energy drivers of a value stream. The energy intensities of the processes are entered below the timeline in the value stream, together with the stock ranges and processing times. The efficiency level EL characterises the quality of the individual production processes compared to a reference value, for example, according to the state of the art. Since the efficiency level is a percentage value, the specific energy requirement, for example related to the product mass, must first be determined for its calculation due to uniform reference values. The efficiency level is then calculated as the ratio of the reference value and the specific energy requirement of the process under consideration.

34

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Fundamentals of Energy Efficiency

Process denomination 1

2

PT Processing time Customers Product family (PF) Number of variants representatives Annual quatities FD Factory days WT Working time TT Customer takt time

CT Cycle time CO Changeover time LS Lot size V Availability  Good yield Electrical energy Gas Compressed air EI Energy intensity Number of employees Number of available resources

Fig. 2.14 Exemplary representation of an energy value stream

EL ½% ¼

Reference value for own use : Specific energy requirement of the production process

ð2:12Þ

The energy value stream analysis provides indications for energy saving potentials and shows energy wastage: • Obvious energy wastage is documented as immediate measures in the value stream. • By plotting energy intensity on the timeline, energy drivers can be identified. • The degrees of efficiency show the quality of the processes relative to each other. Thus, the energy value stream analysis can provide valuable information on the economical use of energy in production. Energy Management as a Continuous Improvement Process The standards (DIN ISO 14001, DIN 15900, DIN ISO 50001, EMAS—Eco Management and Audit Scheme) standardize numerous terms and definitions for energy management and EMS, the common core of which can be understood as a systematic approach to the efficient provision and use of final energy. Energy management thus includes all operational levels at which a company is confronted with energy, starting with energy purchasing. The appropriate design of the EMS is a company-specific matter for creating suitable structures and processes at all levels (e.g. management, controlling, production). Numerous brochures and guides provide insight into the requirements for introducing and implementing EMS (Posselt 2016; GUTcert 2018; TÜV Süd 2019; UBA 2020).

2.3

Methods

35

In ISO 50000-family, energy management is standardized as a recursive procedure (DIN EN ISO 50001 2018). In a CIP, a PDCA cycle (“plan-do-check-act”) should be run through repeatedly, as shown in Fig. 2.15. The individual steps are described below. Plan Do

Check Act

Based on an energy policy defined by the management, existing EMS elements are bundled, an EMS concept is created and documented in a manual The introduction of the EMS is supported by work instructions. Aspects of life cycle costing can be included in the purchasing guidelines. Measurements on energy aspects supplement the analyses carried out to date Internal audits can be used to check all defined aspects. Deviations are documented in report form Based on the findings to date, an action plan is decided and implemented. In a management review, the entire process and the results are analyzed so that continuous improvements are possible

For certification according to DIN ISO 50001, the following requirements, among others, must be met: • • • • • • • • • • •

Define the scope of the EMS. Define energy policy and make it known to employees. Appoint energy officers and representatives. Recording and evaluating energy aspects. Form energy key figures. Record and monitor energy consumers. Evaluate current energy consumption. Determine, optimize and document energy-relevant process flows. Conduct energy audits and management reviews. Identify energy saving potentials. Ensure continuous improvement of energy performance.

The design requires transparency with regard to the decision-making processes and the data basis when recording, allocating, evaluating and managing energy-relevant data. This energy controlling is therefore an essential part of energy management and the basis for the development and implementation of economic energy efficiency measures. The analysis can be carried out in stages with an increasing level of detail, whereby responsibility for the individual stages can also be transferred to external energy consultants, for example. The implementation of more complex measures is usually carried out with external support, which is indicated by the highlighting in Fig. 2.16. I. With an approximate analysis at the company level, the overall company energy flows are tabulated and subdivided according to operating areas and production processes. Four tables should be created:

36

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Fundamentals of Energy Efficiency

Fig. 2.15 Continuous improvement process in the PDCA cycle according to DIN ISO 50001

Fig. 2.16 Procedure for the analysis of operational energy systems

(a) Recording of energy consumption according to energy source, period, quantity, costs.

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(b) Allocation to individual consumers according to energy source, period, quantity, costs. (c) Recording of production frame data by period, product, quantity, value/turnover. (d) Recording of energy outputs (e.g. waste heat) according to period, area, quantity, value, etc. Essential data can be taken from the energy bill of the supplier(s). If there are several transfer points, an allocation to the relevant company/production areas or buildings is necessary. Internal submeters should also be assessed for the analysis. II. With a detailed analysis at machine or system level, the analysis is further detailed using lists of performance and operating times, e.g. for individual equipment groups, pumps, drives or lighting systems. It is important to define a balance area. In addition to the recording of direct process and machine parameters for each balance room, attention must be paid to the recording of other framework data (room climate, production portfolio, throughput, cycle times, shift operation, etc.). • The main consumers can be localised and visualised using an energy location plan (cadastre). Here, the production areas of the production with the equipment and energy consumers located there are drawn schematically and sorted according to connected load or energy consumption classes. • Four quadrants can be distinguished on the basis of a plant number-consumption matrix. The most interesting area is formed by plants with a high number and high consumption at the same time, whereas a few plants with low consumption at the same time do not need to be considered further. According to the Pareto principle (“80/20 rule”) or an ABC analysis, key drivers and priorities can be identified. • Load profiles provide information about base and peak loads. Avoiding peak loads (e.g. by staggering machine start-ups) can help to reduce the service charges to be paid. Avoiding stand-by consumption or switching off the compressed air system during non-production times reduces the base load and makes a significant contribution to energy efficiency. • Before (temporary or permanent) special measurements are carried out, it must be specified in a measurement concept (1) with which objective (2) how often (3) which measured value (4) is to be recorded, logged, stored if necessary and further processed at which location. Questions regarding measurement accuracy and sampling rate must also be clarified. Each measurement must be documented (measuring point, measuring device, accuracy, time/period, interval). Depending on the measurement objective, different temporary (current clamp, multimeter, temperature measuring device, thermal imaging camera, ultrasonic measuring device) or stationary measuring devices (current/heat quantity/gas/volume flow meter) are used. Bus systems (M-Bus, LON-Bus, EIB, PROFIBUS) are used for the transmission of

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measured values. These differ in their transmission rate, compatibility, costs and complexity. III. Individual measures can already be identified during inspections on the basis of checklists or derived from the detailed analysis and evaluated and prioritized according to various decision criteria such as investment amount, amortization, energy quantity saved, energy cost savings, economic efficiency or environmental relevance. It is also important to critically examine possible effects/repercussions on the production process (stability, quality, etc.). For example, a reduction in compressed air consumers can lead to a lower volume of waste heat and thus influence heat recovery. IV. The implementation can be carried out with external support. In the case of more complex interventions, it is often necessary to interrupt production, which can be kept as short as possible through detailed planning of the processes. V. A visualization of selected data helps to verify the effectiveness of the implemented measures with regard to energy consumption and to check them on an ongoing basis. In this way, continuous energy controlling is created. Gradual deviations, which may indicate malfunctions, can thus be detected and remedied at an early stage. With an energy register, which contains energy sources and sinks as a work plan, energy flows can be brought together if necessary. For this purpose, the energy source (medium) and quantity, temperature level and source or sink should be identifiable in the plan. With (Schulze et al. 2016) a very comprehensive scientific work on the operational aspects of industrial energy management is available.

2.3.3

Stationary and Mobile Measurement Technology

A comprehensive treatment of measurement technology is not possible here. Rather, the aim of this chapter is to elaborate the measurement technology specifics for the identification and implementation of energy efficiency measures. In some places, reference is made to the relevant standard works (Czichos 2018; Hering and Schönfelder 2012; Lerch 2012) for further details. Basics The basic principles of measuring technology are standardized in DIN 1319-1. Components of a measuring device are basically • • • •

the transducer, probe, actuator or sensor, the measuring or computing system for processing/evaluating measured values, the display system (pointer, scale, display) and the data memory, if applicable. In terms of system technology, the measured variables to be recorded can be divided into three groups (a) shape and material variables, (b) functional or process variables and

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Table 2.7 Physical effects used in measurement technology with example applications Physical effect Piezoelectric effect Resistive effect Magnetoresistive effect Magnetostrictive effect Inductive effect Capacitive effect Gaussian effect Hall effect Eddy current effect Thermoelectric effect Thermal resistance effect Pyroelectric effect Photoelectric effect Electrochemical effect Doppler effect

Typical applications or measured variables Force, pressure, acceleration, vibration Strain gauges Speed, temperature, potential-free current measurement, magnetic field Path and speed in processes Conductivity, flow rate Level, tank pressure, humidity Magnetic field, current, angle, rotational speed Magnetic field, current, speed, acceleration Corrosion, crack testing, conductivity Temperature difference (or temperature at known reference temp.) Temperature Thermal radiation Luminous flux, illuminance, filling level detection Temperature, volume, speed Particle velocity in liquids and gases

(c) environmental interactions, of which the process variables will be of particular importance here. A distinction is made between kinematic, mechanical, fluidic, thermal, optical and electrical measurands. A distinction is made between active and passive sensor functions. Active sensors generate an electrical signal without an external auxiliary voltage (example: piezo crystal). Passive sensors, on the other hand, require an external auxiliary voltage (example: capacitive humidity measurement). The most important physical effects used in connection with energy efficiency issues are summarised with some examples in Table 2.7 (Hering and Schönfelder 2012). From an energetic point of view, in addition to the electric current as a pure form of exergy, primarily material flows of gaseous, liquid or solid media are to be considered from a metrological point of view, whereby these can be subdivided again into classical energy carriers and other enthalpy flows, which are summarized in Table 2.8. A more detailed analysis of the state and process variables to be measured shows that, in connection with energy-related issues, it is primarily a matter of measuring temperatures, pressures and flow rates. From the point of view of energy efficiency, the output (of intermediate products, products and services) must be determined in addition to the input (of energy), which is usually associated with counting and will not be discussed further here. A presentation of the time measurement should also be omitted at this point. Measurement Error and Accuracy Measurements are generally subject to errors, even if they are carried out very conscientiously. In principle, a distinction is made between systematic and random errors. The

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Table 2.8 Classification of energy carrier flows State Gaseous Liquid Solid

Energy source Natural gas, hydrogen, etc. Fuel oil, diesel, etc. Coal, coke, wood, etc.

Enthalpic flow Compressed air, steam, cold air, etc. Hot water, cold water, hydraulic oil, etc. Component heat

former are based on known causes, can be quantified and are therefore correctable, the latter are not. A typical random error occurs when reading a measuring instrument scale. Furthermore, a distinction is made between static and dynamic measurement errors, which arise from the non-ideal transmission behavior of the measuring device during dynamic processes. The following effects must be taken into account: • The insertion of the measuring device itself influences the quantity to be measured. • If the measurement result is a function of several measurands, the laws of error propagation must be observed. • Random measurement errors are subject to a normally distributed scatter and must be quantified by statistical methods. The accuracy class is also decisive for the selection of measuring instruments. This describes an upper error limit guaranteed by the manufacturer. According to VDE 0410, the classes 1; 1.5; 2.5 and 5.0 are offered for operational measuring instruments. Since the accuracy class refers to the full scale value, the relative measuring error increases sharply in the lower part of the measuring range. In principle, measurements should only be made as accurately as necessary. The measuring span is one of the most important characteristics of a transmitter. The measurement inaccuracy usually increases towards the edges of the measuring range. Electrical Work and Power Due to P ¼ U  I, the electrical power is measured indirectly via the measurement of current and voltage. For symmetrically loaded three-phase connections in star or delta connection, Pges ¼ 3Ustrand  Istrand ¼ √3Uconductor  Iconductor. The directly accessible phase-to-phase voltages are generally used for power measurement. The associated currents in the conductors L1, L2, L3 and the neutral conductor are measured by induction terminals (so-called Rogowski coils). The clamps are designed as coils so that the current to be measured induces a secondary current which can be evaluated with a measuring device. A comprehensive description of electrical power measurement can be found in (Lerch 2012, Sect. 11.10). Temperature Measurement The temperature measurement methods are ultimately based on temperature-dependent material properties such as thermal expansion, the change in electrical resistance, the

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strength of the electromagnetic force or thermal radiation. A distinction is made between contact and non-contact measuring methods. The former include resistance thermometers and thermocouples in particular. Among the non-contact methods, thermal imaging cameras have become established. A very comprehensive presentation of the subject can be found, for example, in ABB (2013). • Resistance thermometers exploit the temperature dependence of the electrical resistance in semiconductors or conductors. Platinum is used very frequently due to its good linearity in the temperature range between approximately 200
C and 850
C. With the 2-wire circuit, the temperature-dependent line and terminal resistances of the measuring lines are not taken into account. With a 3-wire circuit, this influence can be eliminated under the assumption of exactly the same ratios in both conductors. Since this cannot be guaranteed in practice over longer periods of time, a 4-wire circuit can be used to compensate separately for the resistance in the supply and return lines. • Thermocouples use the thermoelectric Seebeck effect: If two metallic conductors are connected to each other, a voltage is generated which depends on the material pairing as well as on the temperature difference (thermoelectric voltage). The temperature difference to a reference junction of known temperature is measured. Modern temperature transmitters have an internal reference junction whose temperature is measured by an integrated sensor and used for the internal correction in the transmitter. • Thermal imaging cameras work similarly to radiation thermometers (pyrometers), but provide not only an average temperature of the surface viewed through the lens, but also a concrete image of the object by means of infrared-sensitive photo arrays. The thermal radiation behaviour of objects depends on the material. Metals, for example, can also reflect heat radiation, so that measurement errors can occur. Therefore, the exact knowledge and adjustment of the emissivity ε is important. The IR detectors operate at different wavelengths and must be cooled down to temperatures down to 200
C by nitrogen, Peltier or Stirling cooling for optimal function. Common Sources of Error in Temperature Measurement For contact measurements with touch thermometers, the sensor and the measured object must be at the same temperature. Care must be taken to ensure good thermal coupling. The energy exchange takes a certain time. The smaller the mass or heat capacity of the measured object in relation to the sensor, the greater the influence of the sensor on the measurement. In addition to the sensor, the (metallic) contact line to the sensor can also sensitively disturb the thermal balance and thus the measurement. When using resistance thermometers, the measuring current must not heat the resistor significantly and should therefore not exceed 10 mA (for metallic 100 Ω resistors). The design of the measuring resistor as well as the protection tube, if present, influence the service life and also the long-term stability of the measurement.

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Pressure Measurement When measuring pressure, a distinction must first be made between absolute pressure, atmospheric pressure and gauge pressure. In practice, pressure differences are often measured as well. Pressure measurement is based on the measurement of changes in the properties of a sensor, for example, changes in volume, shape, resistance, capacitance or inductance. A comprehensive description of pressure measurement technology can be found, for example, in ABB (2012). The spectrum of pressures occurring in practice ranges from ultra-high vacuum (10–12 bar) to ultra-high pressure of 105 bar. The measuring methods are correspondingly diverse. Typical designs for pressure gauges are: • Spring pressure gauges have pressure-sensitive devices such as diaphragms, tube springs, capsules or spring bellows, which usually indicate pressure changes analogously via a mechanism. • Electrical pressure gauges measure the change in capacitance on an air-gap capacitor whose electrodes are separated by a diaphragm in two pressure chambers. Since the measurement is position dependent, gauges with automatic zero adjustment should be preferred. For the design of a measuring point, the parameters such as process pressure and temperature, ambient conditions, possible overloads, material compatibility, corrosion resistance, required device protection class, etc. must be known or defined. Other parameters such as flow rate or tank level are often derived from pressure measurements. A decoupling between the sensitive pressure transmitters and the harsh environmental conditions (dirt, corrosion, temperature, changes in aggregate state, mechanical vibrations, hazardous substances, electromagnetic fields, etc.) is possible through isolating diaphragm systems, so-called pressure sensors. This also allows better accessibility, for example, for maintenance work. However, temperature-related changes in the volume of the measured liquid can affect the accuracy of the measurement. The tightness of the measuring system is particularly important for the reliable function of the measurement. If problems could arise when the filling liquid comes into contact with the process medium, special filling liquids such as medical white oils (food industry) or fluorocarbons (chlorine chemistry) must be used. Slow processes such as clogging due to deposits, crystallization, polymerization, etc. lead to changes in the pressure conditions in the pipeline and can be detected by suitable evaluations and pressure measurement monitoring devices. Periodic patterns in the course of the measured value can also be detected, for example, by means of a Fourier analysis. Common Sources of Error in Pressure Measurement • With absolute pressure measuring cells, leaks in the vacuum reference chamber lead to an increasing reference pressure and thus to measuring errors.

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• During pressure measurements on process steam lines, cooling and condensation can occur in the differential pressure line, which can lead to not inconsiderable measurement errors. This can be countered to a certain extent by deliberately accepting condensation and keeping the liquid column in the differential pressure line as constant as possible. Compressed Air Measurement Dynamic pressure measurement during operation is primarily used for compressor control and for assessing compressed air networks. The maintenance time of filters is determined on the basis of differential pressure measurements. Instead of mechanical diaphragm pressure switches, electronic pressure transducers are predominantly used today due to better repeatability. A volume flow measurement is used to verify the delivery capacity of compressors and to determine the total compressed air consumption or the consumption of individual production sites. It should be noted here that the consumption values depend on the ambient conditions and therefore all values must be converted to standard conditions. The characteristics of the main measurement methods are well described in DENA (2003). A simple leakage estimation is possible by measuring the pressure drop during breaks in operation without compressed air consumption. Ultrasonic measuring devices can be used to locate and then repair leaks. For the measurement of compressed air quality, the standard ISO 8573 Parts 1 to 7 applies. Here, special attention must be paid to a representative sampling point. Flow Measurement Numerous methods are available for flow and quantity measurement of liquid and gaseous media in closed pipelines. Direct flow measurement methods include volumetric oval gear meters, annular piston meters and rotary piston meters. Indirect flow measurement methods such as turbine wheel, vane wheel or screw wheel meters as well as vortex or swirl flow meters use flow effects. Other volumetric flow measurement methods such as the differential pressure or variable area method rely on pressure differences (ABB 2011). An overview of the different flow measurement methods and their characteristics is shown in Table 2.9. Common Sources of Error in Flow Measurement are: • The moving parts of oval gear, annular piston and rotary piston meters are susceptible to wear, which can lead to measured value drift. However, wear on static measuring orifices or contamination of nozzles or orifices can also lead to systematic measuring errors. • For measurement methods based on flow effects, sufficient inlet/outlet distances must be ensured. • The measuring accuracy depends on the viscosity and this in turn depends on the temperature, so that the temperature influence must also be taken into account for accurate measurements.

2 Classes 1.6/2.5/6 1

1:12 1:10

Ultrasonic flowmeter

Swirl flow meter 1:5 (1:10)

1:15–1:25

Oval wheel meter Ring piston meter Rotary piston meter Impeller counter Turbine meter Vortex flow meter

Accuracy (%) 1.1–0.3 0.2–2 1 2–3 2–3 0.75 (liquid) 1 (gaseous) 0.5

Differential pressure measuring Variable area flowmeter

Measuring span 1:2–1:10 1:5–1:250 1:20 (1:50) 1:100–1:350 1:5–1:20 1:15–1:20

No

Yes

0.005–0.2 0

No

No

Moving parts Yes Yes Yes Yes Yes No

0.7 (water) 0.07 (air) 0.005–1

Pressure drop (bar) 4 3 0.03 0.25–0.75 0.5–1 0.9 (water) 0.06 (air)

++

+

+

Sterilization  +    +

Yes

No

Yes

Yes

Interface No No No No No Yes

2

Flow meter

Indirect volume counters

Device type Direct volume counters

Table 2.9 Typical characteristics of flow meters

44 Fundamentals of Energy Efficiency

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Measurement Signal Processing Today, current output signals of 4–20 mA are used as standard for measurement signal processing. The range up to 4 mA is used for power supply of the measuring device. The range above 20 mA is used for fault indication. Fieldbus systems are also used for measurement signal transmission. The measurement signal transmission can also be disturbed by electromagnetic influences, although the devices comply with the applicable EMC standards. Interference can be caused, for example, by fluctuations or interruptions in the supply voltage, by atmospheric interference (lightning strike), by switching operations in the low-voltage network or by switching power supplies. Interference can lead to a reduction in function or even to a loss of function of the measuring device. Development of a Measurement Concept Energy-related measurements serve various operational goals. They form the basis for energy procurement, they help to identify optimisation measures, they are necessary for correct allocation to cost centres or they are part of a certified EMS. The concept should be based on the one hand on the physical energy flow and on the other hand on the hierarchical production structures (factory > production areas > production line > individual workstation/machine). Individual production areas are usually defined as independent units (cost centers) in the cost center structure. Performance evaluations of different production locations are thus possible on the basis of key figures. The design of a measurement concept is based on various criteria, as illustrated in Table 2.10. The most important criterion is certainly the necessary measurement continuity. A distinction is made between continuous and temporary measuring points: • Continuous measuring points are required for periodic energy balancing, for example, for the recording and billing of energy consumption. Continuous measuring points are also required for the process-engineering evaluation of the main energy consumers or for the assessment of slowly progressing changes. Often existing measuring points from the process control can be used. While a quarter-hourly resolution has become established for billing-relevant measurements, a second-by-second resolution is often necessary for an in-depth understanding of the process. • Temporary measurements, on the other hand, are required, for example, for the analysis of the load or standby behaviour of individual machines, for the creation of an energy consumption register or for the control of implemented energy saving measures. Here, too, different temporal resolutions may be necessary for different knowledge objectives. Other important criteria for the selection of a measuring method are, in addition to the temporal sampling rate, the associated data volume, the type of output signal (simple display, analog or digital electrical signal), the required installation volume or environmental conditions or the required protection class.

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Table 2.10 Decision criteria for the preparation of a measurement concept Structural level Critirion Costs Local and temporal continuity Sampling frequency Insight target Degree of automation Measurement accuracy

Central (e.g. plant, hall) High investment, production downtime cost Permanently installed measurement for permanent data acquisition Installation only possible with interruption of production Rough time resolution (daily to yearly) for energy billing Energy management or energy controlling Automatic measurement Relevant for billing, calibrated if necessary

Decentralized (e.g. line, place, machine) High variable costs Mobile measurement for temporary measurements Installation possible during operation Fine temporal resolution (milliseconds to minutes) for detailed analyses Load control, individual optimization Manual measurement Indicative

One of the most important goals of a measurement concept is to contribute to adequate energy controlling. The measured energy flows should support cost type, cost centre and cost unit accounting (see Sect. 2.3.2) and thus contribute to transparency and the conscious use of energy resources.

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Seinschedt F, Rainfurth C, Lay G (2003) Life cycle costing als Instrument zur Preisfindung für produktbegleitende Dienstleistungen. In: Kinkel S, Jung-Erceg P, Lay G (eds) Controlling Produktbegleitender Dienstleistungen. Physica-Verlag, Heidelberg, pp 91–100 Ströhle J (2008) Umweltschutz durch Abwasserrecycling und Wärmerückgewinnung in der Textilveredlung. Benninger, AG, Uzwil StromStG (2015) Stromsteuergesetz vom 24. März 1999 (BGBl. I S. 378; 2000 I S. 147), zuletzt geändert durch Artikel 11 des Gesetzes (BGBl. I, S 2178). http://www.gesetze-im-internet.de/ bundesrecht/stromstg/gesamt.pdf. Last checked 03.12.2015 Sutherland JW, Dornfeld DA, Linke BS (2018) Energy efficient manufacturing – theory and applications. Wiley, Hoboken. https://doi.org/10.1002/9781119519904 Sygulla R, Götze U (2010) Kumulierter Energieaufwand (KEA) – Methodik und Implikationen für die Gestaltung einer energieeffizienten Produktion. In: Neugebauer (2013), pp 145–158 Tschandl M, Posch A (eds) (2012) Integriertes Umweltcontrolling – Von der Stoffstromanalyse zum Bewertungs- und Informationssystem, 2nd edn. Wiesbaden, Gabler Verlag/Springer Fachmedien TÜV Süd (2019) IS0 50001 – whitepaper: energy management systems, reduce energy costs and achieve a competitive advantage. TÜV SÜD Management Service GmbH, Munich UBA (2020) Energy management systems in practice from energy auditing to an ISO 50001 management system: guide for companies and organizations. German Environment Agency (UBA), Dessau-Roßlau WKÖ (2009) Energieeffizienz – Tipps für Unternehmen. Wirtschaftskammer Österreich, Wien Zweifel P, Praktiknjo A, Erdmann G (2017) Energy economics, theory and applications. Springer. https://doi.org/10.1007/978-3-662-53022-1

3

Electricity-Based Enabling Technologies

3.1

Electrical Power Supply

A reliable power supply is the indispensable basis of every production operation. The following chapter is devoted in particular to energy efficiency aspects, which are otherwise rarely the focus of attention. For a general presentation of the electrotechnical interrelationships of the (industrial) power supply, reference should also be made to the relevant textbooks. These system components are arranged schematically in Fig. 3.1. Most losses in the power supply occur in transformers and the uninterruptible power supply (UPS), if present. This is followed by the cables and lines and then the compensation and filter systems. The compensation and filter systems are of particular importance here, as their use significantly reduces the losses in the other components and thus saves energy overall. They also ensure a good quality of the mains voltage.

3.1.1

Transformers

Over the past five decades, continuous improvements in transformer design have reduced load losses by around 30–50% and idling losses by as much as a factor of 3–4. In this respect, the early replacement of older transformers can also be very economical. Frequency converters, for example, for speed control of drives, are examined in connection with drive systems in Sect. 3.3.

3.1.1.1 Basics Distribution transformers according to DIN EN 50464-1 have a power range of 50–2500 kVA. Transformers with higher power ratings are referred to as power transformers. The following explanations are basically transferable. Transformers are # Springer-Verlag GmbH Germany, part of Springer Nature 2021 M. Blesl, A. Kessler, Energy Efficiency in Industry, https://doi.org/10.1007/978-3-662-63923-8_3

51

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Fig. 3.1 Components of the power supply of an industrial plant (schematic)

mainly used to reduce high voltages from the upstream high/medium voltage network of the energy supplier to a level at which the connected consumers can be operated. For safety reasons, transformers can also be designed as so-called isolating transformers and, if the voltage level remains unchanged, merely provide galvanic isolation of the networks. A basic distinction is made between oil and dry-type transformers. In oil transformers, a special transformer oil is used for insulation and heat transfer. Power transformers are generally designed as oil transformers. Dry-type transformers are usually designed as cast resin transformers and are used especially for small, low-maintenance distribution transformers. Since they do not contain any flammable oils, they are usually fire-retardant and also protected against any contamination. In cast resin transformers, the individual windings are insulated with epoxy resin, which also serves as a heat conductor. However, since the heat conduction properties of the resin are less good than those of oil, cast resin transformers have larger dimensions and usually also higher prices than comparable oil transformers. Switching Groups and Areas of Application Transformers can be designed with different vector groups. These determine the wiring of the individual coils on the iron core and thus fundamentally determine the operating behaviour (load behaviour, phase shift, neutral point). The most common vector groups are summarised in Fig. 3.2 (Kiank and Fruth 2011): The vector group Yyn0 is mostly used for high and medium voltage transformers. In this vector group, the neutral point can only be loaded with approximately 10% of the rated current. Unbalanced loads, which easily occur in the medium and especially in the low voltage network, can hardly be compensated with this. The vector group Dyn5 is one of the most common vector groups for distribution transformers and can be heavily loaded asymmetrically, since the neutral point can be loaded with the entire rated current. The vector group YNd5 is the vector group commonly used for generator transformers. Due to the zigzag switching on the secondary side, the vector group Yzn5 is particularly recommended for frequent and heavy unbalanced loads (Kiank and Fruth 2011).

3.1

Electrical Power Supply

53

Fig. 3.2 Most common vector groups of a transformer

Overall, a distinction must be made between no-load and load losses. No-load losses are independent of the load and always occur at the same level. Load losses depend on the load, increase quadratically with the current flow and reach their regular maximum when the transformer is loaded with the rated current. The design of transformers is characterized by the iron/copper ratio. While a higher iron content reduces the magnetic no-load losses, a higher copper content minimizes the ohmic load losses. Idling Losses Eddy current and hysteresis losses are counted among the no-load losses. Other losses arise from stray fields leaving the iron core. The eddy current losses arise from parasitic currents induced in electrically conductive materials in the vicinity of the coil. This particularly includes the core of the transformer, but currents can also be induced in the shell. According to Lenz’s rule, these currents are generated in such a way that they set up a magnetic field opposite to the excitation magnetic field. Since by far the largest part of the magnetic flux is in the iron core of the transformer, this must be constructed in such a way that eddy currents are minimised as far as possible. For this purpose, the core is made of

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electrically insulated sheets. Since a transformer is operated with alternating voltage, the magnetic field in the core is always realigned according to the mains frequency. With each pole reversal, the magnetic domains, so-called “White’s areas” must be realigned. Energy must be expended for this pole reversal, which is subsequently lost in the form of heat. Although these losses can be minimized by using transformer laminations with a very low remanence flux density and coercivity, the production of such laminations is not easy. Load Losses The load losses (“copper losses”) are—in contrast to the no-load losses—dependent on the load of the transformer. In order to optimise the load losses, it seems expedient to make the wire cross-section of the conductors as large as possible. This reduces the resistance of the windings, but very quickly increases the weight and material costs. Above a certain diameter of the windings, the skin effect also becomes noticeable, which partially relativizes the advantage of a larger diameter. The load losses are usually determined by short-circuiting the transformer on the secondary side and then increasing the voltage on the primary side until the rated current flows. Efficiency The efficiency of a transformer is not constant, but depends on its load. The classification of transformers into loss classes is regulated in DIN EN 50464-1. The no-load losses are standardized with increasing losses in 5 classes from A0 to E0 and the load losses in 4 classes from Ak to Dk. The resulting efficiency maxima range from 97.01 to 99.55%. The no-load losses form an offset. Under load, the losses increase quadratically with the current (Fig. 3.3). Depending on the design, the maximum efficiency can be 25% (for idle optimisation) or 45–50% (for load optimisation). At a transformer load of 100%, 80–90% of the power loss is accounted for by the power losses. Reducing load losses is therefore particularly important for transformers with a high load. In principle, the waste heat can be used to provide space heating, although so far only projects in the municipal environment have been reported. Quantity Structure Based on the SEEDT study (SEEDT 2005), an estimate for the year 2012 shows about 110,200 distribution network transformers owned by industrial customers, of which about 85,800 are liquid transformers. The distribution of power ratings is shown in Fig. 3.4 and the age structure in Fig. 3.5. The load profile at the transformer is decisive for estimating the load losses. An evaluation of 6220 load curves of customers >100 MWh results in a load factor of 0.1274, that is, the load-dependent losses at distribution transformers are about 12.74% higher than with a linear course of the annual duration curve.

3.1

Electrical Power Supply

55

Fig. 3.3 Power loss and efficiency of a C0Ck transformer

Fig. 3.4 Distribution of industrial distribution transformers by type and size

3.1.1.2 Power Factor Correction Power factor correction is a reduction of the capacitive or inductive currents oscillating in the network between the generator and the consumer. These are generated, for example, by electric motors, frequency converters, switching power supplies and many other devices. Reactive currents cause losses even if they do not perform any active work. Power factor correction therefore allows a reduction of losses in other components, possibly a longer service life or smaller dimensioning and finally a protection of sensitive devices through a higher voltage quality.

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Fig. 3.5 Age structure of industrial distribution network transformers

Usually, only inductive reactive power occurs in industrial plants due to the machines used, since 50% of the power consumption for mechanical drive work alone is consumed by electric motors. To compensate for this, it is sufficient to connect capacitors in parallel with the machines concerned. In terms of their proximity to the consumer, four different types of compensation (individual compensation, group compensation, central compensation and mixed compensation) can be distinguished (Kiank and Fruth 2011). Very large consumers are compensated individually, smaller consumers are grouped together or centrally compensated. In principle, smaller compensators are specifically more expensive, so that central compensation is often the most favorable variant in terms of acquisition costs. An improvement of the phase angle cos(φ) from 0.8 to 0.95, for example, reduces the apparent power by 16% and the losses by 29%. The specific ohmic losses of commercially available power factor correction systems are practically negligible at around 0.5 W/kVAr. Example: Power Factor Correction for Self-Generation Particularly in the case of companies with self-generation, the active power reference can become very small, so that the reactive power reference dominates in relation to the active power and the shift factor cos(φ) assumes very small values (ZVEI 2013). Since electricity supply contracts typically regulate the permissible shift factor and not the absolute reactive power draw, a suitable compensation device must be installed in such a case. Quantity Structure The evaluation of the reactive power behaviour from 2008 shown in Fig. 3.6 shows that about 14% of the industrial customers achieve a phase angle of cos(φ) 90

Comment Gradual ban by EU as of 09/2009 For low-voltage halogen lamps, an additional power supply unit with corresponding conversion losses is necessary

Approx. 80

Use electronic ballast (ECG)!

Up to 39

For outdoor use

Up to 85

Also for indoor use

Only outdoors, e.g. for tunnels

Decrease in luminous flux over the service life

Approx. 130 Approx. 50

Approx. 16,000 Approx. 16,000

Up to 176

Approx. 16,000

Up to approx. 100 White: approx. 30 Colored: >80

Up to 20,000

Color vision not possible Up to 96

Up to 100,000

Approx. 70–90

maintenance factor). The maintenance factor is made up of the room maintenance factor, the luminaire maintenance factor, the lamp luminous flux maintenance factor and the lamp service life factor. Guide values or recommendations have been published by the International Commission on Illumination. The maintenance factor is always less than 1 (Müller et al. 2009). Dimmable systems can automatically compensate for the increase in replacement value, which leads to energy savings of around 10% over the service life. The Ra index was introduced to describe and evaluate the colour rendering properties of a lamp. To determine the Ra value, eight test colours are illuminated with a reference light source of the best possible colour rendering [Ra ¼ 100] and compared with the light source to be evaluated. The greater the difference between the reference light source and the light source to be evaluated, the lower the Ra value. At values of 60, colour rendering is

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already very poor. For normal visual tasks, the index should reach at least 80 and for high requirements, a value of at least 90 must be achieved. The light colour of a lamp is described by the colour temperature in Kelvin (K). Common lamps have values below 3300 K (warm white ¼ cosy). Neutral white with 3300–5300 K creates a rather businesslike mood. Daylight white with over 5300 K is only used for special visual tasks indoors with more than 1000 lux. The light colour is indicated internationally and across manufacturers with a three-digit sequence of numbers, for example, “930”. Three digits identify the colour effect of fluorescent and compact fluorescent lamps. The first digit of this code provides information about the colour rendering properties of the lamp: “9” represents the best colour rendering in the Ra range between 90 and 100. The second and third digits of the code provide information about the colour temperature. The first two digits of the Kelvin number are included in the colour designation, for example, 30 for 3000 K (warm tone). Standardization While EU Regulation 874/2012 regulates the energy labelling of electrical lamps and luminaires, Regulations 244/2009 and 859/2009 (for gas discharge lamps), 245/2009 (for incandescent lamps) and 1142/2012 (for LEDs) prescribe the minimum technical efficiency levels per technology. DIN EN 12464-1:2019 “Lighting of workplaces, Part 1: Indoor workplaces” (similar to ISO 8995) applies to the standard-compliant design of indoor lighting systems. The illuminance is based on the visual task, for which minimum values are defined in each case. A maintenance schedule for cleaning and luminaire replacement needs to be drawn up to ensure that the maintenance value for illuminance is maintained in all cases. The maintenance value depends on the ageing behaviour of the lamp and ballasts, the luminaire, the environment and maintenance. The reference value for a clean room atmosphere, modern lamp and luminaire technology and a maintenance interval of 3 years is 0.67. Measurements on Lighting Systems There are suitable procedures for the inspection of lighting installations, which are mainly intended for professional users such as architects and lighting designers and not for laypersons. Measurements are carried out • to check the lighting project planning, • to examine the actual condition of existing lighting systems in order to possibly arrange for maintenance or repair of the system or to compare different lighting systems. Specifications are made in the standards and regulations to ensure uniform measurement and evaluation practices. Important measurement parameters are: • the illuminance E as horizontal, vertical or cylindrical illuminance; • the luminance L; • the reflectance of, for example, ceiling, walls, floor in indoor workplaces;

3.2

Electric Lighting

67

• the mains voltage U and/or the ambient temperature in the case of lighting installations with lamps whose luminous flux depends on the operating voltage and/or the room or ambient temperature. In practice, illuminance measurements are most frequently performed. For this purpose, measuring instruments are to be used whose relative spectral sensitivity is well adapted to that of the eye. Furthermore, obliquely incident light must be evaluated true to angle. In preparation for a measurement, the following should be established: • • • •

geometric dimensions of the lighting installation, type of facility or space and activity, quantities to be measured and position of the measuring points, general condition of the equipment, such as age, date of last cleaning and lamp replacement, degree of soiling.

Illumination measurements must be carried out in stationary operating condition. Influences by extraneous light (e.g. daylight in the case of interior lighting or advertising lighting in the case of exterior lighting) must be excluded. Likewise, interference caused by obstacles or shadows cast by the measuring persons must be avoided. Photometers are divided into three classes according to their measurement quality in accordance with DIN 5035-6 (A: precision measurements, B: operational measurements, C: orientation measurements) (Fördergemeinschaft Gutes Licht 2016).

3.2.2

Measures

Despite the relatively minor importance of lighting in terms of final energy consumption, energy efficiency measures in this area can certainly be worthwhile: • In areas with high visual requirements, the energy consumption for lighting is relatively high. These include, for example, the areas of assembly or quality control. • Replacing outdated lighting systems with modern, efficient ones, including their optimisation and conversion, can pay for itself in a short time. • In cooled rooms (cold stores, offices), efficient lighting reduces the heat load so that electricity can be saved for both lighting and heat dissipation. Beyond the efficiency of the individual components, efficient lighting is understood to be the interaction of illuminant, ballast and lamp body. In addition, efficiency is determined by operational maintenance and servicing. The optimisation of lighting equipment can be divided into two categories: 1. Use of efficient light sources and lighting technology. 2. Light management to control burning time and brightness.

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3.2.2.1 Energy-Efficient Light Sources and Lighting Technology The different luminous yields of various light sources are already shown in Table 3.2. By means of a suitable luminaire, the light produced is emitted with as little loss as possible in the direction of the surface to be illuminated by means of suitable optical equipment such as reflectors. In principle, when modernising lighting installations, it can be assumed that energy savings are proportional to the switch-on time. Figure 3.8 illustrates an example in which 200 double-flame T8 fluorescent lamps, each with 58 W and conventional control gear (CCG), are replaced by 200 new T5 lamps, each with 35 W and electronic control gear (ECG). A static amortisation of 5 years is achieved between approximately 3000 h and 3700 h burning time, depending on the electricity price. At an electricity price of 15 ct/ kWh, the static amortisation at 3000 h burning time is approximately 5 years, while at half the burning time the amortisation increases to almost 12 years (Prietze 2009). The power consumption is mainly determined by the lamp and the luminaire. Ballasts are always required for gas discharge lamps due to their negative current/voltage characteristics (see above). To clarify the consumption of the ballast/lamp system, an energy classification was specified by the EU in Directive 2000/55/EC on “Energy efficiency requirements for ballasts for fluorescent lighting”. The Energy Efficiency Index (EEI) distinguishes between seven ballast classes: A1: Dimmable electronic ballasts. A2: Electronic ballasts with reduced losses. A3: Electronic ballasts. B1: Very low loss magnetic ballasts. B2: Low loss magnetic ballasts.

Static amortisation [a]

16

12

Electricity price: 0.10 €/k Wh 0.12 €/k Wh 0.15 €/k Wh

8 5 4

0 1500

3000

4500

6000

Operating hours per year [h/a]

Fig. 3.8 Payback period for the replacement of 200 fluorescent tubes (58 W by 35 W) as a function of operating hours and electricity price

3.2

Electric Lighting

69

C: Magnetic ballasts with moderate losses. D: Magnetic ballasts with very high losses. Increasing energy awareness has led to technical developments in ballasts for fluorescent lamps: Groups C and D ballasts are no longer approved in the EU. With the (inductive) low-loss ballast (LLCG) as the successor to the conventional ballast (CCG) and the EB (ECG), significantly more efficient devices have been developed. The EB converts the 230 V/50 Hz mains voltage into a high-frequency alternating voltage of 25–40 kHz, which reduces the power consumption of a 58 W lamp to around 50 W with almost the same luminous flux. In this example, the power requirement for the lamp/ECG system is reduced to 55 W, which represents a saving of 23% compared with the CCG system. The use of efficient ballasts is promoted by EU measures. The majority of today’s lighting systems with fluorescent lamps or compact fluorescent lamps are equipped with EBs. The simple conversion of T8 fluorescent lamps with conventional ballasts to modern T5 lamps with EBs leads to energy savings of around 50%. In addition to the considerable energy savings, which lead to payback periods of a few years for the EBs, the high-frequency operation of fluorescent lamps and increasingly also that of other discharge lamps on ECGs brings further advantages (O.Ö. Energiesparverband 2010): • • • • • • • • • • • •

Low VG losses and higher luminous efficacy. Increase of the lighting comfort and the lighting quality (flicker-/flare-free). Reduce operating costs. Reduced air conditioning capacity. No starter, no compensation capacitor. Use with AC or DC voltage. Constant lamp power over wide voltage range. Suitable for safety lighting. Low magnetic interference induction. Use in medically used rooms. Switching off in case of defective lamps (fire protection). Approximately 50% longer lamp duration.Dimmability

In addition to ballasts, other components may be necessary for operation. Starters for fluorescent lamps close or open the preheating circuit of a fluorescent lamp and thus initiate the ignition process. ECGs do not require starters. Metal halide lamps and high-pressure sodium lamps require starting voltage pulses in the order of 1–5 kV. For the immediate hot re-ignition of extinguished metal halide lamps or high-pressure sodium lamps, ignitors with considerably higher voltages than 5 kV are required (e.g. for floodlighting systems). Transformers with an output voltage of 12 V are required for the operation of low-voltage (LV) halogen incandescent lamps. It is important that the transformer is switched on the primary side, otherwise the idling losses will permanently lead to standby power consumption. Electronic transformers offer additional convenience, for example,

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through no-load cut-off, short-circuit resistance and lamp-protecting switch-on. The advantages of electronic transformers are: • • • •

Compact design and low weight. Low power dissipation due to low internal resistance, therefore high efficiency. No noise emission. Overload and overtemperature protection through adapted power feedback control without Switching off the lamps. • Soft start—no current peaks when switching on. • Electronic short circuit protection. Due to the low voltages, LV installations are rather harmless, although very high currents flow at reduced voltage. These can lead to overloads and fire hazards if cables, contacts, terminals and switches are insufficiently dimensioned. LV plug-in systems with plugs, couplings and cables have proven themselves for professional installation.

3.2.2.2 Lighting Management The term lighting management covers all measures for adapting the lighting to the needs or wishes of the user. Sensors, timers, programs or manual operations are used to control the lighting. The individual functions that can be implemented by controlling the lighting are: • • • • • •

Manual or automatic dimming. Use of daylight. Presence control. Pre-programming of break times. Lighting situation depending on the time of day. Colour change of the illumination (LED).

In addition, the consumptions are recorded and stored. Control is usually via BUS systems, such as DALI (Digital Addressable Lighting Interface). Figure 3.9 illustrates how a lighting management system works and shows the potential savings (Prietze 2009). As shown darkly in the figure above, the electric lighting is only switched on when an employee is present. The light demand is determined by sensors and only the illuminance necessary for optimal lighting of the workplace is generated. In this way, 30–70% of the energy consumption for lighting can be saved. There are also systems, e.g. in warehouses or outdoors, which do not switch off the lighting but dim it (approximately 10–20% of the illuminance). Especially in less frequented rooms such as warehouses, corridors or toilets, lighting control by motion detectors is effective.

3.2

Electric Lighting

71

Electric lighting 100% electricity consumption with T5 & ECG - Savings through uae of day light - Saving through presence control

100%

Saving

50% 0% 3 0 Day light

6

9

12

15

18

21

24 Savings potential approx. 30–70%

Presence

Daytime [h]

Fig. 3.9 Savings effect from lighting requirements, daylight use and presence control

3.2.3

Recommendations

The selection of measures for efficient lighting should start where long burning times and high illuminance levels are necessary or where many luminaires are used for large areas. The cost-effectiveness of the measures described above was investigated in detail in our own studies. The economic efficiency and effectiveness of individual measures can be assessed on the basis of the internal rate of return (IRR) and the relative final energy savings compared with the respective initial state or reference case. Average values for this are shown in Table 3.4.

Table 3.4 Economic efficiency of energy efficiency measures in the field of lighting No. L1 L2 L3 L4

Measure Presence-dependent lighting with motion sensors in low-frequency rooms Lowering of lamps in the production halls Installation of light sensors for daylightdependent brightness control Use of efficient lamps: replacement of T8 with T5 with ECG

Amortization (a) 5–7

Interest (%) 15

Energy saving (%) 10–50

5–7 2

15 50–60

10 10–60

1–2

50–100

50

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3 Electricity-Based Enabling Technologies

In the specific individual case, the energy cost savings achieved in each case and thus the cost-effectiveness of the measures depend on the individual electricity price, the burning time and other technical lighting parameters. In the case of some light sources, the service life and thus the maintenance effort depends on the switching frequency. The most important measures and recommendations for the energy optimisation of lighting systems are listed in the following checklist, based on (O.Ö. Energiesparverband 2010). 1. Efficient lighting • Are the most suitable light sources used for the respective requirements (illuminance, colour rendering,. . .) at the workplace? • Is the use of more efficient light sources possible and has it been tested? • Are electronic ballasts used to operate the fluorescent lamps? • Are specular reflectors used to optimise the light distribution on fluorescent tubes? • Have measures been taken to direct daylight, such as skylights, light pipes or light-directing sunshades? 2. Light management • Has an adjustment of the artificial lighting to the actual demand been implemented? Are daylight sensors in use? • Is presence control available in low-traffic areas?

3.3

Electric Drives

The explanations in this chapter are essentially based on Waide and Brunner (2011). Other sources are cited accordingly. Electric motors consume 43–46% of the world’s electricity, making them the largest converters of electrical energy. In EU industry, drive systems require 69% of the electricity (approx. 900 TWh). This makes the topic of “drives“a strategically important, if not decisive, point when planning and operating a new industrial plant. This topic also offers a significant contribution to energy efficiency for existing plants and systems. A far-reaching study on the energy efficiency of electric drives and systems was carried out by Fraunhofer ISI in the so-called Motor Challenge Program, supported by the EU and published on the Internet. It cannot be ruled out that further energy efficiency requirements for industries will be passed by politicians, for example, in the form of laws or regulations, in order to promote the more efficient use of energy. Minimum Energy Performance Standards (MEPS) for electric motors are already in force in the USA. If these were introduced globally, it is estimated that 322 TWh of electricity could be saved per year by 2030, saving 206 Mt of CO2. This saving could be significantly greater if motors were correctly sized. If drives

3.3

Electric Drives

73

were technically converted as quickly as possible to the variant with the lowest life cycle costs, total (cumulative) global savings of 42,000 TWh of electricity, 29,000 Mt of CO2 and USD 2.8 trillion would be possible by 2030. This would mean annual savings of 3890 TWh of electricity, 2490 Mt of CO2 and USD 264 billion from 2030. In Germany, the use of efficient engines would result in approximately 27 TWh of electricity savings and a resulting 16 Mt of CO2 savings by 2020. For a better understanding, we will refer to motors and drives in the following. According to Table 2.3, the term “drive system” refers to all necessary components which, together with the motor, provide the drive and its control. Depending on the structure of the drive system, this may include a frequency inverter, a coupling, a gearbox with over- or reduction ratio, the bearings as well as gears or belts in addition to the motor. The term “overall system” covers other components, in particular (pipe) lines or ventilation shafts, but also fittings, orifices or storage tanks. For energy optimisation of the overall system, please refer to the following chapters. While the potential for optimisation in the design of the e-machine is comparatively small, much greater potential can be tapped in the drive and overall system.

3.3.1

Basics

There are many different types of motors. Their distribution varies depending on the industry. As Table 3.5 shows, the largest number of motors in the world has an output of less than 0.75 kW. They use 9% of the total electricity converted by motors. Above all, these motors are often a component of other products and are hardly interchangeable. Although large drives with an output of more than 375 kW are negligible in terms of numbers (0.03%), they nevertheless use 23% of the drive current (Waide and Brunner 2011). These drives are predominantly one-offs, for which a minimum efficiency should be agreed at the time of ordering. Many of the measures described below are also applicable to this motor segment. Approximately 10% of the volume share of drives in the medium power segment combines 68% of the electricity consumption. In industry, three-phase asynchronous machines predominate with a share of approximately 87% (Müller et al. 2009), so that we focus here on this type of motor as a cross-sectional technology. Many savings opportunities are universal and have mainly to do with the correct design of the motors. The different types of electric motors with their technical characteristics are described in (DoE EERE 2014). Asynchronous motors use copper windings in the rotor. These are usually short-circuited at the ends. Due to an alternating field in the stator, the rotor rotates according to the mains frequency (e.g. 50 Hz or 3000 rpm, depending on the number of poles). In asynchronous motors, a current and thus a magnetic field is induced in the rotor; this is in the opposite direction to the causative magnetic field in the stator, which thus leads to power transmission and torque. The rotating magnetic field in the stator thus pulls the rotor along, there is a slip between the stator and the rotor, which is why the rotor runs

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Table 3.5 Distribution of the quantity and electricity consumption of drives by power classes Power Number (%) Share of electricity consumption (%)

375 kW 0.03 23

Fig. 3.10 Schematic structure of an asynchronous three-phase motor

behind the magnetic field in the stator. Because of this “running behind”, this form of threephase machine is called asynchronous. The schematic structure of an asynchronous threephase motor is shown in Fig. 3.10. For three-phase or AC motors, there are two basic ways to control the speed: • The pole-changing function can be used to switch between different numbers of poles and thus achieve different speeds of rotation. • With a frequency converter as a ballast, both the frequency and the amplitude of a voltage can be changed. In electric motors, ohmic losses in the stator (1–5%) and rotor (0.5–6%), mechanical friction losses (0.5–1.5%) and magnetisation losses (0.5–3%) occur in particular. Highefficiency electric motors are particularly optimized with respect to electrical and magnetic losses. Optimization measures include thicker winding wire cross-sections, thinner geometrically adapted iron core laminations made of high-quality materials, extended stator

3.3

Electric Drives

75

Table 3.6 Efficiency classes for electric drives according to different standards in comparison Efficiency class (general) Super premium

International IE4

Premium

IE3

High

IE2

USA NEMA Super P. NEMA Premium EPAct

EU (until 1998) –

EU (as of 2009) IE4

China –

–

IE3

–

Eff1

IE2

–

Eff2

IE1

–

Eff3

–

Grade 1 Grade 2 Grade 3

Standard

IE1

Lower than standard

–

and optimized fans. In the widely used type of asynchronous machine with squirrel cage rotor, the stator winding is made of copper wire and aluminium is used for the rotor cage, which is usually cast. Technological developments now make it possible to also use copper in the rotor and thus reduce the total losses by 15–20%. A fundamentally helpful selection criterion for efficient motors is the stated efficiency class, which is now internationally uniform (ZVEI 2015). An overview of different classifications can be found in Table 3.6. Before actually purchasing a new or replacement more efficient drive, attention must be paid to the dimensioning of the motor. Even an efficient motor has a poorer efficiency in the partial load range and is not as efficient as a motor that is precisely designed to meet the requirements. Thus, the first measure is to effectively select a sufficiently powerful but not oversized motor, which is often neglected due to only roughly known maximum (load) requirements. If a high-efficiency motor is operated at less than 50% of its rated load (partial load operation), the efficiency and thus the efficiency is greatly reduced. For older motors, a strong reduction of the efficiency already occurs below 75% of the nominal load. Figure 3.11 shows the characteristic curves for the efficiency of various powerful motors as a function of the load level (Rudolph and Wagner 2008). The use of high-efficiency motors has other advantages besides better efficiency. Highefficiency motors can be operated for several hours with an overload of 10–20% without suffering damage, which can be helpful in some design situations. The motors operate more efficiently, so they give off less heat, which also reduces the need for room cooling. This means that smaller motors can be used, which have a good efficiency at their operating point and a lower purchase price. The rated efficiency ηN can be calculated according to IEC/EN 60034-30 for 2-, 4- and 6-pole 50 Hz three-phase induction motors with rated powers PN between 0.75 and 200 kW

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3 Electricity-Based Enabling Technologies

Fig. 3.11 Efficiency as a function of the load level for three-phase asynchronous machines

according to Eq. (3.1). Between 200 and 375 kW, the efficiency is assumed to be constant. The parameters A to D are summarized in Table 3.7. ηN ¼ A  lgðPN Þ3 þ B  lgðPN Þ2 þ C  lgðPN Þ þ D:

ð3:1Þ

IE3

IE2

IE-Code IE1

Factor A B C D A B C D A B C D

2-pole 0.5234 5.0499 17.4180 74.3171 0.2972 3.3454 13.0651 79.0770 0.3569 3.3076 11.6108 82.2503

4-pole 0.5234 5.0499 17.4180 74.3171 0.0278 1.9247 10.4395 80.9761 0.0773 1.8951 9.2984 83.7025

6-pole 0.0786 3.5838 17.2918 72.2382 0.0148 2.4978 13.2470 77.5603 1.1252 2.6130 11.9963 80.4769

Table 3.7 Factors for calculating the nominal efficiency of different efficiency classes according to IEC/EN 60034-30

3.3 Electric Drives 77

78

3.3.2

3 Electricity-Based Enabling Technologies

The Economic Efficiency of Drive Systems

By 2020, an estimated 15% of the energy consumed by electric drives can be saved economically through the use of speed control alone. The use of speed control in only 35% of all electric motors can provide savings of 1.2 billion euros per year in German industry alone. And the use of highly efficient motors is already worthwhile from approximately 2000 h/a operating time. As energy prices continue to rise, this limit is expected to fall in the future. The economic efficiency of a motor depends in particular on the efficiency and the annual service life. In addition, points such as acquisition and maintenance costs, operating and energy costs as well as possible failure costs also play a role. Often, the costs of a motor are weighted much higher in the acquisition and the operating costs influenced by the efficiency are hardly taken into account. The service life is also often only taken into account in terms of the reliability of the motor. Possible reasons for such a shortened consideration are: • Lack of information about the large part of the (energy) costs during operation. • Separate budgets for acquisition, operating and maintenance costs are assigned to different cost centers and make an overall view difficult. Energy costs are hardly ever recorded and allocated in detail anyway. • The more complex the manufacturing systems, the less energy costs are considered in the purchase. The amount of the investment or the possible cycle time is decisive for the purchase decision. The efficiency of motors as an integrated system component is losing focus. In a life cycle cost analysis over, for example, 20 years, the acquisition costs of a highefficiency IE3 motor amount to about 2.3% of the total costs incurred by the operation of this motor. 1% of the costs must be spent on maintenance and repair. The remaining 96.7% of the costs (assuming an operating time of 4000 h/a) are caused by the electricity consumption. According to another source (StMUG 2010), the acquisition costs amount to 15%, the maintenance costs to 5% and the operating costs to 80% of the total costs. Overall, the energy cost share in relation to the life cycle costs depends in particular on the motor power and, of course, on the annual operating time. Smaller drives are specifically more expensive, that is, the investment has a larger share in the life cycle costs than with large drives. Figure 3.12 shows the life cycle cost shares over an operating period of 3 years for 2000 and 8000 operating hours as an example. Careful consideration of life cycle costs is therefore essential, especially for electric motors. Life cycle costs refer to all costs incurred over the entire lifetime of a motor, from purchase and installation, through operation and maintenance, to electricity costs and disposal (see also Sect. 2.2 and Fig. 2.3). This approach enables a realistic comparison of the economic efficiency of electric motors and makes it possible to illustrate how important efficient motors are after a certain service life. For the 0.75–375 kW motor segment

3.3

Electric Drives

79

2000 Operating hours

8000 Operating hours

100%

80% Energy

60%

Maintanance Assembly

40%

Planning Investment

20%

1 kW

10 kW

100 kW

1 kW

10 kW

100 kW

2100 €

6600 €

35,000 €

3000 €

12,300 €

92,000 €

Fig. 3.12 Distribution of costs for an IE3 motor over its lifetime

considered here, motors have an average lifetime of at least 12 years (75 kW). In addition to the “direct” costs, consequential costs, e.g. for the loss of production (due to engine failure), are also important for consideration if there are different expected values for different engines. Finally, dismantling and disposal costs must also be taken into account in the long term. The 1–2–3 test described by the Austrian Energy Agency (Österreichische Energieagentur 2010) has proven useful for an initial rough estimate of the economic efficiency of replacing an engine. In this test, the age, the nominal power and the annual operating time of the drive are assessed with scores and the sum of the scores is then subjected to a ranking. Table 3.8 shows an example of the evaluation for a 12-year-old 5 kW motor and a operating time of 4500 h/a. In total, 12 points are achieved for this case. With >10 points, replacing the motor with an efficient drive is likely to be very economical. With 6–10 points, the economic efficiency of a replacement should first be examined in more detail. With up to 5 points, no measures are necessary. In addition to saved electricity costs, high-efficiency motors have another component that can be relevant for an economic analysis. If necessary, the power charges can be reduced by avoiding voltage/power peaks.

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Table 3.8 1–2–3 classification for electric motors Assessment points Age (a) Rated power (kW) Operation time (h/a)

3.3.3

1 1500