Energy studies 2nd ed w shepherd (worldsci, 2003)

Published by
Imperial College Press
57 Shelton Street
Covent Garden
London WC2H 9HE
Distributed by
World Scientific Publishing Co. Pte. Ltd.
5 Toh Tuck Link, Singapore 596224
USA office: Suite 202, 1060 Main Street, River Edge, NJ 07661
UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE

British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library.

ENERGY STUDIES, SECOND EDITION
Copyright © 2003 by Imperial College Press
All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means,
electronic or mechanical, including photocopying, recording or any information storage and retrieval
system now known or to be invented, without written permission from the Publisher.

For photocopying of material in this volume, please pay a copying fee through the Copyright
Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to
photocopy is not required from the publisher.

ISBN 1-86094-322-5

Printed in Singapore.


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PREFACE

The industrially developed countries of the world have become rich and prosperous
by the profligate use of fossil fuels: coal, oil and natural gas. Countries of the
developing areas of the world, mainly in the Pacific Rim and Far Fast, are starting
to use fossil fuels, especially oil, at increasing rates. But both oil and natural gas
reserves are fast depleting and are non-renewable. Each source has only a few tens
of years of stock remaining. How is future world energy demand to be met?
To address such a fundamental problem, it is vitally important that all of the
various elements comprising the problem are well understood. In the case of world
energy, the problem elements are the individual energy sources, both old and new.
At least ten distinct types of energy source exist:
coal
oil
natural gas
nuclear
geothermal
biological/chemical
hydroelectric
wind
wave/tidal
solar energy
Each of these sources is examined in Energy Studies, in an attempt to take
stock of the development of each, towards either depletion or viable widespread
utilisation. Environmental implications, economic assessments and industrial risks
are also considered.

By doing this, the authors are able to conclude with an illustrative example of
an energy strategy with which to address the world energy future, so encouraging
readers to weigh for themselves the complex problem which now stares mankind in
the face.

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Preface to the Second Edition

Chapter 1 is written mainly for students of the physical sciences and engineering.
More general readers are advised to begin reading from Chapter 2.

W. Shepherd and D. W. Shepherd
July 1997

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PREFACE TO
THE SECOND EDITION

In the five years that have elapsed since the original publication, the issues of energy
matters and environmental concerns have become prominent. Energy supply and
use is now a matter of frequent reports, not only in trade journals but in the popular
press.
Up-to-date figures are now given for items of fuel supply and also for the use of
renewable sources such as wind energy and photovoltaics. The chapters on geothermal energy and nuclear energy have been extended. Increased coverage is given to
waste and waste disposal, in Chapter 13.
The energy strategy proposed in the first edition is unchanged. It is the view of
the authors that this remains the logical, sensible and workable way to proceed.

W. Shepherd and D. W. Shepherd
June 2002

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ACKNOWLEDGEMENTS

Much of the material in this book has been taught in undergraduate and postgraduate courses at the University of Bradford, England, and Ohio University,
Athens, Ohio, USA. The authors are grateful to both universities for permission
to reproduce teaching and examination materials.
The information was obtained from a vast number of sources, some original.
Wherever possible the authors have attributed their sources. Thanks are due to
the publishers of pre-existing material for their generous permission to reproduce
previously published information. The authors apologise if any pre-existing material is not adequately attributed — this is not an attempt to deceive but due to
inadvertence.
Dr James Brooks of Glasgow, Scotland, a distinguished geochemist, read the
manuscript. His many helpful criticisms and suggestions have enhanced the presentation, especially the chapters on fossil fuels and on geothermal energy.
The authors’ work was greatly helped by the superb facilities of the Alden
Library at Ohio University. Special thanks are due to Lars Lutton, photographer,
Samuel Girton and Scott Wagner, graphic artists, and especially to Peggy Sattler,
graphic design manager in the Instructional Media and Technology Services Unit.
We are grateful to Mr Michael Mitchell of Bradford, England, for his valuable

help with the computer-generated diagrams.
The typing of the manuscript, with its many revisions during the evolution, was
largely done by Suzanne Vazzano of Athens, Ohio. Her professionalism and good
nature were indispensable in its completion.

Athens, Ohio, USA
1997

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ACKNOWLEDGEMENTS FOR
THE SECOND EDITION

The authors would like to thank the publishers of the many new sources that are
included in this second edition, in addition to re-acknowledgement of the original
sources.
Once more the chief sources of information are British Petroleum plc of London,
England, and the US Energy Information Administration of Washington, DC, USA.
Dr James Brooks of Glasgow, Scotland, has once again reviewed the chapters on
the fossil fuels plus the work on geothermal energy. His careful scrutiny and helpful
suggestions are much appreciated. Ms Ann Mandi of Brown University, USA, also
reviewed the manuscript and made many helpful suggestions.
Much of the artwork is due to the staff of the Instructional Media Services
Unit at the Alden Library of Ohio University. Special mention must be made of
Kelly Kirves, graphic artist, and Emily Marcus, media artist. Particular thanks
are due to Lara Neel, graduate assistant, who transferred the manuscript, including
artwork, onto computer discs. All of this work was supervised by Peggy Sattler,
the production manager of the unit. The book cover is only a small part of Peggy’s
significant contributions to the overall presentation.
The typing of the revised manuscript, with its many revisions, was largely done
by Suzanne Vazzano, helped by Erin Dill, Tammy Jordan, Juan Echeverry and
Brad Lafferty. Their professionalism and good nature were indispensable to its
conclusion.

Athens, Ohio, USA
2002

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CONTENTS

Preface

v

Preface to the Second Edition

vii

Acknowledgements

ix

Acknowledgements for the Second Edition

xi

CHAPTER 1 ENERGY AND POWER
1.1.
Energy Conversion . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2.
Mechanical Energy . . . . . . . . . . . . . . . . . . . . . . . . .
1.2.1. Linear motion . . . . . . . . . . . . . . . . . . . . . . .
1.2.2. Rotational motion . . . . . . . . . . . . . . . . . . . . .
1.3.
Electrical Energy . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.
Chemical Energy . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5.
Nuclear Energy . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6.
Thermal Energy . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7.
Thermodynamics and Heat Energy . . . . . . . . . . . . . . . .
1.7.1. Quantity of heat . . . . . . . . . . . . . . . . . . . . . .
1.7.2. Mechanical equivalent of heat . . . . . . . . . . . . . . .

1.7.3. The first law of thermodynamics . . . . . . . . . . . . .
1.7.4. The second law of thermodynamics . . . . . . . . . . .
1.7.4.1. Ideal heat engine . . . . . . . . . . . . . . . .
1.7.4.2. Practical heat engine . . . . . . . . . . . . . .
1.7.4.3. Ideal reverse heat engine . . . . . . . . . . . .
1.7.5. Worked examples on thermodynamics and heat energy
1.8.
Entropy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.8.1. Entropy in heat–work systems . . . . . . . . . . . . . .
1.8.2. Entropy on a cosmic scale . . . . . . . . . . . . . . . . .
1.9.
Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.10. Units and Conversion Factors . . . . . . . . . . . . . . . . . . .
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1.11. Problems on Energy and Power . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

24
28

CHAPTER 2 ENERGY RESOURCES AND ENERGY USE
2.1.
Energy Input to the Earth . . . . . . . . . . . . . . . . . . . . .
2.1.1. Solar radiation rate and annual variation . . . . . . . .
2.1.2. Terrestrial energy from inside the earth . . . . . . . . .
2.1.3. Tidal (gravitational) input energy . . . . . . . . . . . .
2.2.
Energy Flow upon the Earth from Natural Sources . . . . . . .
2.3.
Energy Outflow from the Earth . . . . . . . . . . . . . . . . . .
2.4.
Energy Stored Within the Fossil Fuels . . . . . . . . . . . . . . .
2.5.
Energy Production and Consumption . . . . . . . . . . . . . . .
2.5.1. Energy consumption in the world . . . . . . . . . . . .
2.5.2. Energy production and use in the UK . . . . . . . . . .
2.5.3. Energy production and use in the USA . . . . . . . . .
2.5.4. World fossil fuel production and consumption . . . . . .
2.6.
Risks Associated with Energy Systems . . . . . . . . . . . . . .
2.6.1. Industrial accidents and industrial diseases . . . . . . .
2.6.2. Large-scale accidents and sabotage . . . . . . . . . . . .
2.6.3. Management of energy waste . . . . . . . . . . . . . . .

2.6.4. Ecosystem effects . . . . . . . . . . . . . . . . . . . . .
2.6.5. Water supply problems . . . . . . . . . . . . . . . . . .
2.6.6. Emissions . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6.6.1. Carbon dioxide emissions . . . . . . . . . . . .
2.6.6.2. Gaseous emissions and the “greenhouse” effect
2.7.
Summary — Where Do We Go from Here? . . . . . . . . . . . .
2.7.1. An energy strategy . . . . . . . . . . . . . . . . . . . .
2.8.
Problems and Review Questions . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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CHAPTER 3 ELECTRICITY
3.1.
Introduction . . . . . . . . . . . . . . . . . . .

3.2.
Some Basic Electrical Relationships . . . . . .
3.2.1. Voltage, current and power . . . . . .
3.2.2. Worked examples on electrical circuits
3.3.
The Generation of Electricity . . . . . . . . . .
3.4.
The Siting of Electrical Power Plants . . . . .
3.4.1. Fuel supply . . . . . . . . . . . . . . .
3.4.2. Water supply . . . . . . . . . . . . . .
3.4.3. Land elevation . . . . . . . . . . . . .
3.4.4. Road and rail access . . . . . . . . . .
3.4.5. Height of the structures . . . . . . . .
3.4.6. Disposal of waste products . . . . . .

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3.4.7. Proximity to populated areas . . . . . . . . . . . .
3.4.8. Environmental implications . . . . . . . . . . . . .
3.5.
World Electricity Consumption . . . . . . . . . . . . . . . .
3.6.
UK Electricity . . . . . . . . . . . . . . . . . . . . . . . . .
3.6.1. Consumption and supply . . . . . . . . . . . . . .
3.6.2. Organisation of the UK electricity supply industry
in 2001 . . . . . . . . . . . . . . . . . . . . . . . .
3.7.
US Electricity Consumption and Production . . . . . . . .
3.8.
Combined Heat and Power (CHP) . . . . . . . . . . . . . .
3.8.1. CHP in the UK . . . . . . . . . . . . . . . . . . .
3.8.2. CHP in the USA [15] . . . . . . . . . . . . . . . .
3.9.
Efficient Utilisation of Electrical Energy . . . . . . . . . . .
3.9.1. Avoiding waste . . . . . . . . . . . . . . . . . . . .
3.9.2. Monitoring and control . . . . . . . . . . . . . . .
3.9.3. Redesigning to reduce energy costs . . . . . . . . .
3.9.4. Maintenance of equipment . . . . . . . . . . . . .
3.9.5. Power factor correction . . . . . . . . . . . . . . .
3.9.6. Maintenance of supply current waveform . . . . .
3.9.7. Choice and use of electric motors . . . . . . . . . .
3.9.8. Load factor . . . . . . . . . . . . . . . . . . . . . .
3.9.9. Choice of lighting systems . . . . . . . . . . . . . .
3.10. Problems and Review Questions . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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CHAPTER 4 COAL
4.1.
Introduction . . . . . . . . . . . . . . . . . . .
4.1.1. Composition and ranking of coal . . .
4.1.2. Coal mining . . . . . . . . . . . . . .
4.2.
World Reserves, Production, and Consumption
4.2.1. World coal reserves . . . . . . . . . .
4.2.2. World coal production . . . . . . . . .
4.2.3. World coal consumption . . . . . . . .
4.2.4. UK coal production and consumption
4.2.5. US coal production and consumption

4.3.
Coal Transportation . . . . . . . . . . . . . . .
4.3.1. Surface transportation . . . . . . . . .
4.3.2. Coal slurry pipelines . . . . . . . . . .
4.4.
Emissions and Effluents from Coal . . . . . . .
4.4.1. Open coal fires . . . . . . . . . . . . .
4.4.2. Effluents due to coal burning . . . . .
4.4.2.1. Sulphur oxides . . . . . . . .
4.4.2.2. Nitrogen oxides . . . . . . .

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4.4.2.3. Particulates . . . . . . . . . . . . . .
4.4.2.4. Carbon dioxide . . . . . . . . . . . .
4.4.2.5. Carbon dioxide emissions due to coal
4.5.
Advanced Coal Technologies . . . . . . . . . . . . . . .

4.5.1. Fluidised-bed combustion . . . . . . . . . . . .
4.5.2. Combined-cycle generation . . . . . . . . . . .
4.6.
Liquid Fuels from Coal . . . . . . . . . . . . . . . . . .
4.6.1. Indirect liquefaction . . . . . . . . . . . . . . .
4.6.2. Pyrolysis . . . . . . . . . . . . . . . . . . . . .
4.6.3. Solvent extraction . . . . . . . . . . . . . . . .
4.6.4. Direct hydrogenation (catalytic liquefaction) .
4.7.
Problems and Review Questions . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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CHAPTER 5 PETROLEUM
5.1.
Introduction . . . . . . . . . . . . . . . . . . . . . . .
5.2.
History and Development of the Petroleum Industry .
5.2.1. The Seven Sisters [6] . . . . . . . . . . . . . .
5.2.2. European oilfields . . . . . . . . . . . . . . .
5.2.3. OPEC . . . . . . . . . . . . . . . . . . . . . .
5.3.
World Oil Reserves . . . . . . . . . . . . . . . . . . .
5.4.
World Production and Consumption of Crude Oil . .

5.4.1. World oil production . . . . . . . . . . . . .
5.4.2. World oil consumption . . . . . . . . . . . .
5.4.3. UK oil production and consumption [10–12]
5.4.4. US oil production and consumption . . . . .
5.5.
Synthetic Crude Oil . . . . . . . . . . . . . . . . . . .
5.5.1. Shale oil . . . . . . . . . . . . . . . . . . . .
5.5.2. Tar sands . . . . . . . . . . . . . . . . . . . .
5.6.
Environmental Issues . . . . . . . . . . . . . . . . . .
5.7.
Problems and Review Questions . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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CHAPTER 6 NATURAL GAS
6.1.
Introduction . . . . . . . . . . . . . . . . . . . . . . .
6.2.
History and Development . . . . . . . . . . . . . . . .
6.3.
Natural Gas Reserves . . . . . . . . . . . . . . . . . .
6.4.
Production and Consumption of Natural Gas . . . . .
6.4.1. World natural gas production . . . . . . . . .
6.4.2. World natural gas consumption . . . . . . . .
6.4.3. UK natural gas production and consumption
6.4.4. US natural gas production and consumption
6.5.
Coal-Bed Methane . . . . . . . . . . . . . . . . . . . .

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CHAPTER 7 GEOTHERMAL ENERGY
7.1.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.2.
Geological Structure of the Earth . . . . . . . . . . . . . . . .
7.3.
Origin of Geothermal Heat Flow . . . . . . . . . . . . . . . . .
7.4.
Geothermal Energy Resources . . . . . . . . . . . . . . . . . .
7.5.
Geothermal Reservoirs . . . . . . . . . . . . . . . . . . . . . .
7.6.
Locations and Types of Principal Geothermal Sources . . . . .
7.6.1. Dry steam sources . . . . . . . . . . . . . . . . . . . .
7.6.2. Wet steam sources . . . . . . . . . . . . . . . . . . . .
7.6.3. Hot brine sources . . . . . . . . . . . . . . . . . . . .
7.6.4. Dry rock sources . . . . . . . . . . . . . . . . . . . . .

7.6.5. Molten magma . . . . . . . . . . . . . . . . . . . . . .
7.7.
Worldwide Applications of Uses of Geothermal Energy . . . .
7.8.
Geothermal Prospects in the UK . . . . . . . . . . . . . . . . .
7.8.1. Shallow drilling . . . . . . . . . . . . . . . . . . . . .
7.8.2. Worked example . . . . . . . . . . . . . . . . . . . . .
7.9.
Geothermal Uses in the USA and Elsewhere . . . . . . . . . .
7.9.1. Hot springs and bathing spas (balneology) . . . . . .
7.9.2. Agriculture . . . . . . . . . . . . . . . . . . . . . . . .
7.9.3. Aquaculture . . . . . . . . . . . . . . . . . . . . . . .
7.9.4. Industry . . . . . . . . . . . . . . . . . . . . . . . . .
7.10. Geothermal District Heating . . . . . . . . . . . . . . . . . . .
7.11. Geothermal Heat Pumps . . . . . . . . . . . . . . . . . . . . .
7.12. Electricity Generation from Geothermal Sources . . . . . . . .
7.12.1. Worldwide geothermal electrical power production . .
7.12.2. Technologies of geothermal electrical power generation
7.12.3. Locations of geothermal electricity-generating stations
7.13. Environmental Features of Geothermal Power . . . . . . . . .
7.13.1. Geothermal site exploration and development . . . . .
7.13.2. Protection of the local atmosphere . . . . . . . . . . .
7.13.3. Protection of ground water . . . . . . . . . . . . . . .
7.13.4. Enhancement of reservoir water . . . . . . . . . . . .
7.13.5. Ecological effects of geothermal plants . . . . . . . . .
7.13.6. Effects on local geological structure . . . . . . . . . .

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6.5.1. World reserves of coal-bed methane
6.5.2. US reserves of coal-bed methane . .
6.6.
Natural Gas Hydrates . . . . . . . . . . . . .
6.7.
Environmental Aspects of Natural Gas . . .
6.8.
Synthetic Gas from Coal . . . . . . . . . . .
6.9.
Problems and Review Questions . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . .

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7.14. Problems and Review Questions . . . . . . . . . . . . . . . . . . . . . 209
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
CHAPTER 8 NUCLEAR ENERGY
8.1.
Basic Atomic Theory . . . . . . . . . . . . . . . . .

8.2.
Basic Nuclear Theory . . . . . . . . . . . . . . . . .
8.2.1. Nuclear fission . . . . . . . . . . . . . . . .
8.2.2. Worked examples . . . . . . . . . . . . . .
8.3.
Radioactivity . . . . . . . . . . . . . . . . . . . . . .
8.3.1. Nature of radioactivity . . . . . . . . . . .
8.3.2. Energy and decay rate . . . . . . . . . . . .
8.3.3. Worked examples . . . . . . . . . . . . . .
8.4.
Nuclear Radiation . . . . . . . . . . . . . . . . . . .
8.4.1. Forms of radiation . . . . . . . . . . . . . .
8.4.2. Units of measurement of radiation . . . . .
8.4.3. Effects of nuclear radiation . . . . . . . . .
8.4.4. Sources and amounts of nuclear radiation .
8.4.4.1. Natural radiation sources . . . . .
8.4.4.2. Man-made sources . . . . . . . . .
8.4.5. Uses of nuclear radiation . . . . . . . . . .
8.4.5.1. Geological dating . . . . . . . . .
8.4.5.2. Archaeological dating . . . . . . .
8.4.5.3. Medical tracer elements . . . . . .
8.4.5.4. Small nuclear power packs . . . .
8.4.5.5. Biological effects on human tissue
8.5.
Nuclear Reactors . . . . . . . . . . . . . . . . . . .
8.5.1. Thermal (fission) reactors . . . . . . . . . .
8.5.2. Uranium supplies . . . . . . . . . . . . . .
8.5.3. Plutonium . . . . . . . . . . . . . . . . . .
8.5.4. Fast breeder reactors . . . . . . . . . . . .
8.5.5. Reactor safety . . . . . . . . . . . . . . . .

8.5.6. Nuclear reactor accidents . . . . . . . . . .
8.5.6.1. Three Mile Island . . . . . . . . .
8.5.6.2. Chernobyl . . . . . . . . . . . . .
8.6.
Nuclear Waste . . . . . . . . . . . . . . . . . . . . .
8.6.1. Sources of waste . . . . . . . . . . . . . . .
8.6.2. Waste disposal . . . . . . . . . . . . . . . .
8.6.3. Terrorist action . . . . . . . . . . . . . . .
8.7.
Nuclear-Powered Electricity Generation . . . . . . .
8.7.1. Nuclear generation in the USA . . . . . . .
8.7.2. Nuclear generation in the UK . . . . . . . .
8.8.
Nuclear Fusion . . . . . . . . . . . . . . . . . . . . .

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8.8.1.
8.8.2.

Basic theory . . . . . . . . . . . . .
Nuclear fusion reactors . . . . . . .
8.8.2.1. Nuclear plasma properties
8.8.2.2. Heating of the plasma . . .
8.8.2.3. Plasma confinement . . . .
8.8.2.4. Fusion reactor research . .
8.9.
Problems and Review Questions . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . .

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CHAPTER 9 WATER ENERGY
9.1.
Hydroelectric Power Generation . . . . . . . . . . . . . . . . .
9.1.1. Principles of hydroelectric plant operation . . . . . .
9.1.2. Types of hydraulic turbine . . . . . . . . . . . . . . .
9.1.2.1. Impulse turbines . . . . . . . . . . . . . . . .
9.1.2.2. Reaction turbines . . . . . . . . . . . . . . .
9.1.2.3. Axial flow turbines . . . . . . . . . . . . . .
9.1.3. Pumped storage systems . . . . . . . . . . . . . . . .
9.1.4. Worked examples on hydroelectric power generation .
9.2.
Tidal Power Schemes . . . . . . . . . . . . . . . . . . . . . . .
9.2.1. Tidal power sites . . . . . . . . . . . . . . . . . . . . .
9.2.2. Principles of tidal power operation . . . . . . . . . . .
9.2.3. Costs of tidal barrage schemes . . . . . . . . . . . . .
9.2.4. Combination of a pumped storage facility with a tidal
barrage scheme . . . . . . . . . . . . . . . . . . . . . .
9.2.5. Features of tidal barrage schemes . . . . . . . . . . .
9.2.6. Worked examples on tidal energy schemes . . . . . . .
9.3.
Wave Power . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.3.1. Basic properties of ideal deep-water waves [5] . . . . .
9.3.2. Power extractable from practical deep-water waves . .
9.3.3. Worked examples on wave energy . . . . . . . . . . .

9.3.4. Types of wave power converters . . . . . . . . . . . .
9.3.5. Worked examples on wave energy devices . . . . . . .
9.3.6. Features of wave power systems — summary . . . . .
9.4.
Ocean Currents and Underwater Turbines [15, 16] . . . . . . .
9.5.
Problems and Review Questions . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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CHAPTER 10 WIND ENERGY
10.1. Background and History . . . . . . . . .
10.2. Availability of Wind Supply . . . . . . .
10.2.1. Wind energy supply in Europe .
10.2.2. Wind energy supply in the USA

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10.4.
10.5.

Theoretical Maximum Power Extractable from the Wind
Practical Power Extractable from the Wind . . . . . . .
10.5.1. Power coefficient . . . . . . . . . . . . . . . . . .
10.5.2. Axial thrust (pressure) . . . . . . . . . . . . . .
10.5.3. Tip-speed ratio (TSR) . . . . . . . . . . . . . . .
10.5.4. Solidity factor . . . . . . . . . . . . . . . . . . .
10.5.5. Shaft torque and power . . . . . . . . . . . . . .
10.6. Efficiency of Wind-Powered Electricity Generation . . . .
10.7. Large Wind Machine Systems . . . . . . . . . . . . . . .
10.7.1. Historical background . . . . . . . . . . . . . . .
10.7.2. Facing the wind — the yaw effect . . . . . . . .
10.7.3. Centrifugal forces . . . . . . . . . . . . . . . . .
10.7.4. Gyroscopic forces and vibrations . . . . . . . . .
10.7.5. Modern large wind power installations . . . . . .
10.7.6. Worked examples on wind turbine operation . .
10.8. Vertical Axis Wind Machines . . . . . . . . . . . . . . . .
10.8.1. The Savonius design . . . . . . . . . . . . . . . .
10.8.2. The Darrieus design . . . . . . . . . . . . . . . .
10.8.3. Other forms of vertical axis machine . . . . . . .
10.9. Small and Medium Size Machines . . . . . . . . . . . . .
10.10. Electrical Engineering Aspects of Wind-Generated
Electrical Power . . . . . . . . . . . . . . . . . . . . . . .
10.10.1. Electricity generator systems . . . . . . . . . . .
10.10.2. Small electrical generators . . . . . . . . . . . .
10.11. Wind Machine Site Selection . . . . . . . . . . . . . . . .
10.12. Pros and Cons of Wind-Generated Electrical Power . . .
10.13. Problems and Review Questions . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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309
311
311

312
314
315
316
318
319
319
320
321
321
322
327
332
332
334
334
335

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336
336
337
339
340
341
345

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347
347
352
357
358
358
360
368
370
373
374

CHAPTER 11 SOLAR HEATING OF WATER OR AIR
11.1. Radiation from the Sun . . . . . . . . . . . . . . . . . . . . .
11.2. Seasonal Variation of Solar Radiation . . . . . . . . . . . . .
11.3. Classification of the Collection of Solar Energy . . . . . . . .
11.4. Solar Water Heating (Domestic) . . . . . . . . . . . . . . . .
11.4.1. The “greenhouse” effect . . . . . . . . . . . . . . . .
11.4.2. Solar flat-plate collectors . . . . . . . . . . . . . . .
11.4.3. A typical domestic solar water heating system . . .
11.4.4. Worked examples involving solar flat-plate collectors
11.5. Solar Water Heating (Industrial) . . . . . . . . . . . . . . . .
11.5.1. Solar tracking systems . . . . . . . . . . . . . . . . .

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Contents

11.5.1.1. Parabolic dish collector . . . . . . .
11.5.1.2. Solar power tower . . . . . . . . . .
11.5.1.3. Linear focus collectors . . . . . . .
11.5.2. Solar non-tracking systems . . . . . . . . . .
11.5.2.1. Evacuated tube collectors . . . . . .
11.5.2.2. Compound parabolic concentrator .
11.5.3. Worked examples involving solar thermionic
concentrator systems . . . . . . . . . . . . .

11.6. Passive Solar Space Heating of Buildings . . . . . . .
11.6.1. Direct gain solar systems . . . . . . . . . . .
11.6.2. Indirect gain solar systems . . . . . . . . . .
11.6.2.1. Thermal storage wall . . . . . . . .
11.6.2.2. Solar greenhouse (sunspace) . . . .
11.6.2.3. Roof pond . . . . . . . . . . . . . .
11.6.2.4. Solar salt pond [3] . . . . . . . . . .
11.7. Problems and Review Questions . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xxi

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374
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380
384
385
387
387
390
391
391
391
395

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397
397
398
399
400
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401
401

402
402

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404

404
407
407
409
410
411
412
413
419
420
426
428

CHAPTER 12 SOLAR PHOTOVOLTAIC CONVERSION
12.1. Basic Features of Solar Cells and Solar Systems . . . . . . . .
12.2. Cost of Solar Photovoltaic Electricity . . . . . . . . . . . . . .
12.3. Physical Nature of Semiconductor Materials [6] . . . . . . . .
12.3.1. Group-3 (acceptor) impurities . . . . . . . . . . . . .
12.3.2. Group-5 (donor) impurities . . . . . . . . . . . . . . .
12.4. Photovoltaic Materials . . . . . . . . . . . . . . . . . . . . . .
12.4.1. Crystalline silicon (c–Si) . . . . . . . . . . . . . . . .
12.4.2. Amorphous (uncrystalline) silicon (a–Si) . . . . . . .
12.4.3. Materials other than silicon . . . . . . . . . . . . . . .
12.5. Operation of the Semiconductor Diode and
Solar Photovoltaic Cell . . . . . . . . . . . . . . . . . . . . . .
12.6. Physical Properties of the Solar Photovoltaic Cell . . . . . . .
12.7. Electrical Output Properties of the Solar Photovoltaic Cell . .
12.7.1. Maximum power delivery . . . . . . . . . . . . . . . .
12.7.2. Equivalent circuits . . . . . . . . . . . . . . . . . . . .
12.7.3. Load lines in the current–voltage plane . . . . . . . .

12.7.4. Arrays of solar photovoltaic cells . . . . . . . . . . . .
12.7.5. Effect of temperature on solar cell operation . . . . .
12.8. Applications of Photovoltaic Cells . . . . . . . . . . . . . . . .
12.9. The Future Challenge for Photovoltaics . . . . . . . . . . . . .
12.10. Worked Examples . . . . . . . . . . . . . . . . . . . . . . . . .
12.11. Problems and Review Questions . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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CHAPTER 13

BIOLOGICAL ENERGY AND
CHEMICAL ENERGY
13.1. Biomass and Biofuels . . . . . . . . . . . . . . . . . . . .
13.1.1. Natural vegetation . . . . . . . . . . . . . . . . .
13.1.2. Energy tree plantations . . . . . . . . . . . . . .
13.1.3. Specific energy crops . . . . . . . . . . . . . . . .
13.1.4. Use of wastes . . . . . . . . . . . . . . . . . . . .

13.1.5. Water-based biomass . . . . . . . . . . . . . . .
13.2. Photosynthesis . . . . . . . . . . . . . . . . . . . . . . . .
13.3. Methods of Industrial Biomass Conversion . . . . . . . .
13.3.1. Combustion . . . . . . . . . . . . . . . . . . . .
13.3.2. Pyrolysis . . . . . . . . . . . . . . . . . . . . . .
13.3.3. Gasification of biomass . . . . . . . . . . . . . .
13.3.4. Liquid and gaseous fuels from biomass . . . . . .
13.3.4.1. Chemical reduction . . . . . . . . . . .
13.3.4.2. Aerobic (alcoholic) fermentation . . . .
13.3.4.3. Anaerobic digestion to produce biogas
13.4. Wood as a Fuel . . . . . . . . . . . . . . . . . . . . . . .
13.5. Energy from Wastes . . . . . . . . . . . . . . . . . . . . .
13.5.1. Solid waste disposal in landfill sites . . . . . . .
13.5.2. Solid waste disposal using municipal
incinerators (combustors) . . . . . . . . . . . . .
13.5.3. Worked examples on solid waste incineration . .
13.5.4. Liquid and gaseous wastes . . . . . . . . . . . .
13.6. The Fuel Cell . . . . . . . . . . . . . . . . . . . . . . . .
13.7. Problems and Review Questions . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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429
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429
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430
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431
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446
448
449
449
451
452

CHAPTER 14 THE ENERGY FUTURE
14.1. The Energy Problems . . . . . . . . . . . . . .
14.2. An Energy Strategy . . . . . . . . . . . . . . .
14.3. The Long-Term Energy Future . . . . . . . . .
14.3.1. Nuclear fission using breeder reactors
14.3.2. Solar energy . . . . . . . . . . . . . .
14.3.3. Controlled thermonuclear fusion . . .
14.3.4. Geothermal energy [4] . . . . . . . . .
14.4. What Shall We Do When the Oil Runs Out? .
References . . . . . . . . . . . . . . . . . . . . . . . . .

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455
455
456
457
458
458
459
459
460
460

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ANSWERS

461

Index

483

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CHAPTER 1

ENERGY AND POWER

Energy is the capacity or capability to do work. All materials possess energy,
because they can all be utilised in some form of energy conversion process. For
example, most substances will burn or vaporise, and the consequent heat energy
can be harnessed within mechanical energy systems that create motion against
some form of mechanical resistance.
Energy can take several forms, as classified in Table 1.1. Mass or matter is a
form of highly concentrated energy. Some forms of matter can be utilised in nuclear
energy applications, as discussed in Chapter 8.
Table 1.1.
biofuels (e.g. wood)
chemical
electrical
gravitational
heat (thermal)
magnetic

1.1.

Forms of energy.

mass
mechanical – kinetic
mechanical – potential
nuclear
radiation
sound

Energy Conversion

The many applications of the use of energy usually involve transformations between
different forms of energy — a process known as energy conversion. Any conversion
between different energy forms is imperfect in that some of the energy has to be
used to facilitate the conversion process. The converted energy output is lower than
the energy input and this feature is usually described as the conversion efficiency.
Figure 1.1 illustrates the large range of variation of energy conversion efficiencies,
from very large electricity generators (mechanical to electrical converters) which
can operate continuously at about 99% efficiency to the incandescent electric lamp
(electrical to radiant converter) which is only a few percent efficient [1]. Some
well-known energy conversion processes involve two successive stages. An example
1

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Energy Studies

Fig. 1.1.

Efficiencies of energy converters (based on [1]).

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Energy and Power

3

is the motor car engine in which chemical energy in the form of oil or petrol (gasoline) is converted to heat and then to rotational energy.
1.2.

Mechanical Energy

The widely used Laws of Motion for bodies of constant mass were developed by
the English scientist Isaac Newton in the 17th century. It is now known that in

extreme cases Newton’s Laws are insufficient — for very small masses quantum
mechanics must be employed; with very high speeds, Einstein’s theory of special
relativity becomes relevant; with very large masses, the concepts of space and time
are modified by the theory of general relativity. Nevertheless, for general conduct of
life on earth using realistic sizes and time spans, the work of Newton remains valid.
1.2.1.

Linear motion

When a constant force F is applied to an object and causes it to move through a
distance x in the direction of the force, then the work done W is equal to the energy
expended:
W = Fx

(1.1)

In (1.1), if the force is in newtons (N) and the distance in metres (m), the work or
energy W has the unit of joules (J) or newton-metres (Nm).
If a body of mass m moves in a straight line with a linear velocity v which is
the time rate of change of its position,
dx
for small changes of x
dt
x
v = for large changes of x
t
v=

(1.2)

If a body of mass m moving in a straight line is subjected to changes of velocity,
the rate of change of the velocity with time is known as the acceleration a:
a=

d
dv
=
dt
dt

dx
dt

=

d2 x
dt2

(1.3)

In S.I. units, mostly used in this book, the velocity is measured in metres/sec
(m/s) and the acceleration in metres/sec/sec or metres/sec2 (m/s2 ).
When a force F is applied to a body of constant mass m and causes the linear
velocity v to change, the resulting acceleration can be shown experimentally to be
proportional to the applied force:
F = ma = m

dv
d2 x
dv

= m 2 = mv
dt
dt
dx

(1.4)


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Energy Studies

Equation (1.4) is sometimes referred to as Newton’s Second Law of Motion.
Mass m may be combined with velocity v to define an important physical property known as the momentum:
Linear Momentum = mv = m

dx
dt

(1.5)

Comparison of (1.4) and (1.5) shows that

Force = time rate of change of linear momentum
F =m

(1.6)

dv
d
= (mv)
dt
dt

Equation (1.6) shows that momentum has the dimension of force × time or mass
× velocity.
A mass m possesses energy of two kinds, known as potential energy, associated
with its position, and kinetic energy, associated with its motion. The gravitational
potential energy of a body of mass m, at height h above a datum plane, is given by
WPE = mgh

(1.7)

where g is the gravitational acceleration constant, of value g = 9.81 m/s 2 . If the
mass m is in kilogrammes and height h is in metres, the potential energy WPE is in
joules.
While a mass m is in linear motion at a constant velocity v, the kinetic energy
WKE associated with the motion is
WKE =

1
mv 2
2

(1.8)

It can be seen from (1.8) that the derivative of kinetic energy WKE with respect to
velocity gives the momentum
dWKE
= mv
dv

(1.9)

Both kinetic energy and momentum, like mass, satisfy important conservation
rules. In this book the most relevant rule is the Principle of Conservation of Energy,
which states that “in any physical system the total energy remains constant —
energy may be converted to a different form, it may be wasted, but it cannot be
destroyed”. When a mass m in linear motion is acted upon by a force F , then, in
moving between two locations:

force ×

work done on
change of kinetic
distance
= or against the = energy between
moved
mass
the two locations

(1.10)

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Energy and Power

5

Example 1.1
A mass m initially rests on a ledge at height h metres above ground level, which
is the datum plane. Define the conditions of velocity, kinetic energy and potential
energy (i) initially, (ii) as the mass falls to ground, (ii) finally after the mass comes
to rest.
(i)

(ii)

With the mass at rest, its initial velocity vi is zero and therefore so are its
initial momentum and kinetic energy. Its total energy is then the potential
energy given by (1.7), illustrated in Fig. 1.2.
As the mass falls to the ground it possesses an instantaneous velocity v ,
initially zero and increasing uniformly due to gravitational acceleration. Its
final velocity becomes zero on impact with the ground. At any arbitrary
height h during the fall, the mass possesses both potential energy mgh and
kinetic energy 12 mv 2 , which sum to the initial energy mgh. After striking

the ground the final velocity vf is zero, the momentum of the motion is
transferred to the ground and the kinetic energy is converted to local heat
and sound due to impact. Since the ground level is the datum plane, the
potential energy after impact is also zero here.

m

m
h
vЈ
hЈ

m

ground
(datum plane)

(a)
WPE = mgh
WKE = 0
vi = 0

(b)
WPE = mghЈ
WKE = ½ mvЈ2
v = vЈ
Fig. 1.2.

(c)
WPE = 0

WKE = 0
vf = 0

Mass falling freely under gravity.


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Energy Studies

1.2.2.

Rotational motion

Most energy conversion processes involving mechanical energy incorporate rotational devices. For example, electromechanical energy converters use rotors that
have the form of solid cylinders, Fig. 1.3(a). Petrol engines and diesel engines usually incorporate flywheels, Fig. 1.3(b). The rotor of a water or gas turbine also has
the nature of a non-uniform flywheel.
To illustrate some of the principles of rotational motion, the example used is
that of a concentrated mass m in circular motion at radius r about a fixed centre point, Fig. 1.4. The motion is characterised by the angular velocity ω in
radians/sec (rad/s) and the instantaneous tangential velocity v of the mass in
metres/sec (m/s), where
v = ωr

(1.11)

A centripetal force acting radially inwards is required to keep the mass moving in
a circle and is provided along the tie rod. With rotational motion, the externally
applied force F acting tangentially on the mass (through a rigid tie-rod), Fig. 1.4,
times the radius r is called the torque T , which acts as a rotation producing force:
v
(1.12)
T = Fr = F
ω
Torque is measured in newton-metres (Nm) and is a very important property of
rotating energy converters. The tangential or linear acceleration of the mass m is
given, from (1.11), by
a=

dv
dω
=r
dt
dt

(1.13)

Combining (1.12) and (1.13) leads to
T = Fr
= mar
=m

dv

r
dt

∴ T = mr2

dω
= mr2 α
dt

(1.14)

In (1.14) the term α is the angular acceleration in rad/s2. The quantity mr 2 in
(1.14) is known as the polar moment of inertia J and is an important physical
property in rotational structures, having the dimension kgm2 .
J = mr2 = [mass] [radius of gyration]2

(1.15)

Expression (1.15) is true directly for the flywheel and cylinder of Fig. 1.3. For more
complicated structures with distributed, non-uniform mass, the effective radius of
gyration is more complicated but the relationship (1.15) is still valid in principle.