Renewable energy systems

RENEWABLE

ENERGY SYSTEMS

DAVID BUCHLA

THOMAS KISSELL

THOMAS FLOYD

Renewable Energy

Systems

David Buchla

Thomas Kissell

Thomas Floyd

T h í / V / l f t jg I

PMóiMQ BOU j

PEARSON

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10 987654321

PEARSON ISBN 10: 0-13-262251-3

ISBN 13: 978-0-13-262251-6

BRIEF CONTENTS

CHAPTER 1 Energy S ources and E nvironm ental E ffects

CHAPTER 2 E lectrical Fundam entals 43

CHAPTER 3 S olar P hotovoltaics 87

CHAPTER 4 Solar P ow er S ystem s 117

CHAPTER 5 Solar Tracking 151

CHAPTER 6 Charge C ontrollers and Inverters 183

CHAPTER 7 W ind P ow er S ystem s 215

CHAPTER 8 W ind Turbine C ontrol 251

CHAPTER 9 Biom ass Technologies 277

CHAPTER 10 G eotherm al P ow er G eneration 307

CHAPTER 11 Energy from W ater 335

CHAPTER 12 Fuel C ells 369

CHAPTER 13 G enerators 393

CHAPTER 14 The E lectrical P ow er G rid 429

CONTENTS

Preface viii

CHAPTER 1

CHAPTER 2

CHAPTER 3

CHAPTER 4

CHAPTER 5

Energy S ources and E nvironm ental E ffects 1

1-1 Fossil Fuels: Oil, Coal, and Natural Gas 2

1-2 Nuclear Energy 8

1 -3 The Solar Resource 15

1 -4 The Wind Resource 20

1-5 Geothermal Resources 25

1 -6 Hydroelectric Resources 30

1 -7 Biomass and Biofuel Resources 34

Electrical Fundam entals 43

2-1 Energy, Charge, and Voltage 44

2-2 Electrical Current 47

2-3 Resistance and O hm ’s Law 49

2-4 Power and W att’s Law 54

2-5 Series and Parallel Circuits 56

2-6 Conductors, Insulators, and S em iconductors 59

2-7 M agnetism and Electrom agnetic Devices 63

2-8 Capacitors, Inductors, and Transform ers 69

2-9 Protective Devices 74

2-10 Basic Electrical M easurem ents 77

Solar P h o to volta ics 87

3-1 The PN Junction 88

3-2 Photovoltaic Cell S tructure and O peration 91

3-3 Types of P hotovoltaic Technologies 93

3-4 M ultijunction Thin-Film 97

3-5 Photovoltaic Cell Characteristics and Param eters 98

3-6 Solar M odules and Arrays 102

3-7 Solar Module Data Sheet Param eters 107

3-8 Concentrating Photovoltaics 110

Solar P ow er S ystem s 117

4-1 Stand-Alone P hotovoltaic S olar Pow er S ystem s 118

4-2 Sizing the Stand-Alone System 123

4-3 Grid-Tie P hotovoltaic Solar P ow er S ystem s 129

4-4 Solar Concentrators 133

4-5 Solar Hot W ater System s 140

S olar Tracking 151

5-1 Movement o f the Sun 152

5-2 Costs and Benefits o f Tracking 155

v

Contents

5-3 Single-Axis and Dual-Axis Solar Trackers 158

5-4 DC Motors 163

5-5 Stepper Motors 174

CHAPTER 6 C harge C ontrollers and Inverters 183

6-1 Battery Chargers 184

6-2 Pulse Width Modulation Charge Controller 187

6-3 Maximum Power Point Tracking Charge Controller 190

6-4 Charge Controller Specifications and Data Sheet 194

6-5 Inverters 196

6-6 Inverter Functions 202

6-7 Inverter Specifications and Data Sheet 207

CHAPTER 7 W ind P ower System s 215

7-1 Power in the Wind 216

7-2 Wind Power Curve 221

7-3 Betz’s Law 224

7-4 Blade Aerodynamics 229

7-5 Horizontal-Axis Wind Turbine 232

7-6 Vertical-Axis Wind Turbine 239

7-7 Wind Farms 242

CHAPTER 8 W ind Turbine Control 251

8-1 Pitch and Yaw Control 252

8-2 Turbine Orientation 258

8-3 Drive Train Gearing and Direct-Drive Turbines 260

8-4 Wind Measurement 265

8-5 Braking 268

CHAPTER 9 B iom ass Technologies 277

9-1 The Carbon Cycle 278

9-2 Biomass Sources 280

9-3 Biofuels: Ethanol 284

9-4 Biofuels: Biodiesel and Green Fuels 288

9-5 Biofuels from Algae 291

9-6 Anaerobic Digestion 295

9-7 Biomass Combined Heat and Power 299

CHAPTER 10 Geotherm al Power Generation 307

10-1 Types of Geothermal Resources 308

10-2 Geothermal Electrical Power 310

10-3 Low-Temperature Applications for Geothermal Heat 317

10-4 Geothermal Heat Pumps 321

10-5 Environmental Impacts 328

Contents

CHAPTER 11 Energy from W ater 335

11 -1 Energy in Moving W ater 336

11-2 Hydroelectric Dam O peration 341

11-3 W ater Turbines 345

11 -4 Tidal Power Generation 351

11 -5 Wave Power Generation 357

CHAPTER 12 Fuel C ells 369

12-1 Basic Fuel Cell O peration 370

12-2 Types of Fuel Cells 375

12-3 Vehicle Applications 381

12-4 Stationary Fuel Cell Applications

CHAPTER 13 G enerators 393

13-1 M agnetism and Electrom agnetism 394

13-2 DC G enerators 402

13-3 AC Synchronous Generators 412

13-4 AC Induction G enerators and Permanent M agnet Generators 418

CHAPTER 14 The Electrical P ower G rid 429

14-1

14-2

14-3

14-4

14-5

14-6

APPENDIX 459

GLOSSARY 461

INDEX 473

Three-Phase AC 430

Three-Phase Transformers 434

Grid Overview 442

Smart Grid 446

Power Transmission 450

Connecting to the Grid 452

Renewable Energy Systems is an introductory text with broad coverage o f all the major

renewable energy systems, resources, and related topics. The major types o f systems are

solar, wind, geothermal, biomass, and hydropower (including water in rivers and oceans).

Related topics include electrical fundamentals, charge controllers, inverters, generators,

fuel cells, the electrical power grid and the smart grid.

In the past few years, interest in renewable energy has grown in both the public and

private sectors, with significant government support for research and for constructing large

systems, such as solar installations, wind farms, and other projects. As a result o f this

research, exciting new technology is being developed that attest to a future with a variety of

new opportunities. Innovations in the field include m ore efficient multijunction photovoltaic

(PV) cells and cells with built-in charge storage using supercapacitors, high-flying wind

turbines, systems for capturing tidal and wave energy in the ocean, and enhanced algae￾growing methods, to name a few. Many people are optimistic about the future potential of

renewable energy for supplying a larger portion o f the worldwide energy needs.

Energy is a complex topic involving competing interests, but in general there is broad

agreement by the public that the world needs to move toward more renewables for supplying

energy needs. A single technology cannot solve all o f the energy needs o f the future or is

best in all situations because resources vary significantly by location. In addition, different

applications often compete for finite resources. For example agricultural land can be

used for food production or for growing com for ethanol or for a utility PV system. It is

clear, however, that more people must understand renewable energy and its promise and

limitations including all viable renewable energy technologies, sources, energy conversion

systems and the environmental impacts (both positive and negative).

Renewable energy systems convert basic resources into usable forms o f energy,

including electricity, heat, and mechanical motion. In some cases, the renewable source

is used to create a fuel, as in the case of ethanol or hydrogen fuel for use in fuel cells.

Fuel cells in themselves are not a renewable source: Fuel cells may convert solar or other

renewable source to the fuel used by the fuel cell but most fuel cells convert natural gas (a

fossil fuel) to electricity. Fuel cells are becoming more important in providing electrical

energy, particularly in remote areas or for backup power.

Many changes have occurred in recent years to renewable energy systems. For

example, the capture of solar energy is shifting from smaller, customer-owned systems

that are designed to supplement utility power, to large arrays that produce significant

power (more than 1 megawatt [MW]) and are owned by utilities, the military, or industrial

complexes. About half o f solar power generation in the United States is in large utility

power installations. Wind turbines have become massive with power outputs as high

as 5 MW to 10 MW. Innovations in major system s like variable-speed generation and

new power electronic and supervisory control systems are improving the efficiency of

wind farms. New, enhanced geothermal production can capture more of the available

energy with techniques such as fracking in hot dry rocks and injecting fluids in a closed￾loop arrangement, which helps conserve water in desert environments. The organic

Rankine cycle (ORC) is more prevalent in large systems because it can be used to obtain

energy from lower-temperature sites. Future geothermal power plants may also be able

to sequester carbon dioxide, actually helping the environment. Tidal energy has been

captured in several parts of the world; a new crossflow turbine operates in the mouth of

the Bay o f Fundy, almost directly northeast o f the coast o f M aine, and a new wave energy

system is being installed off the coast of Oregon. We have attempted to highlight these

new systems and innovations throughout this text. In particular, the sidebars in many o f the

chapters feature innovative ideas; not all will eventually pan out, but they show the nature

o f this growing and dynamic field.

Chapter 1 presents an overview of the principal energy resources: fossil fuels, nuclear

energy (including the future potential o f fusion energy), and renewable energy, and where

Preface ix

these resources are located. M ost renew able energy is converted to electricity; for this

reason C hapter 2 provides an introduction to electricity and magnetism, and discusses

basic circuit laws, com ponents, circuits, electrical measurem ents, and safety. Chapter 3

introduces the photovoltaic (PV) cell and its application to solar power systems. Solar

m odules and m anufacturer’s specification sheets are also covered. Chapters 4 and 5

continue the topic o f solar energy with coverage o f various types o f solar energy systems

and their operation, including concentrating system s and tracking methods for panels and

heliostats. C hapter 6 discusses com ponents that are important in many renewable energy

system s, such as certain solar, wind, and fuel cell system s, with particular attention being

paid to battery chargers, charge controllers, and inverters. Chapter 7 is an introduction to

wind energy, including power in the wind, B etz’s law, and an overview o f wind turbines.

C hapter 8 delves further into the operation o f w ind turbines with details o f turbine control,

m easurem ents, and braking system s. C hapter 9 covers the m ajor types o f biomass and

the system s used for converting biom ass into oil or electrical power, and heat energy.

Biomass has been used by hum ans for heat since our early ancestors first used wood fires

for cooking and heat; today, biom ass is used for power generation, heat, and biofuels

(prim arily ethanol). Chapter 10 gives an overview o f geothermal energy and energy

conversion system s for both electrical system s and heat pumps. Geotherm al heat pumps

are proving their worth in m any areas, and geotherm al energy is a significant resource

that has barely been tapped. C hapter 11 covers various system s for extracting energy from

moving water, including water from hydroelectric dams, streams, tides, and waves, and the

m ethods for converting this energy to electricity. Chapter 12 discusses fuel cells and their

applications, which have great potential to bring reliable power to rem ote locations o f the

world. C hapter 13 expands the discussion o f m agnetic theory, which was introduced in

C hapter 2, and applies this to various types o f electrical generators and how they are used

in renew able energy system s. Finally, C hapter 14 gives an overview o f the electrical grid,

including the sm art grid, and m ethods o f pow er transm ission, and it introduces the topic

o f three-phase ac and transform ers.

Features

• T he book is in full-color.

• C hapter openers have a chapter outline, objectives, key terms list, and introduction.

• Section openers in each chapter give a b rief overview o f w hat each section within a

chapter covers.

• Section checkups contain questions related to each section within a chapter. Answers

to section checkups are provided at the end o f the chapter.

• Key term s are shown in bold and color in the running text. Definitions for key terms

are provided at the end o f the chapter and in the end-of-book glossary. Bold term s in

black are defined in the end-of-book glossary only.

• M argin features are given throughout the book at appropriate places to highlight

interesting innovations o r historical inform ation related to the topic being covered.

• W orked-out examples are provided throughout the text.

• Each chapter com es with abundant illustrations. M any are original and previously

unpublished.

• Im portant formulas are num bered throughout each chapter, and they are listed at the

end o f each chapter for quick reference.

• A sum m ary o f the chapter discussion is provided at the end o f each chapter.

• A true/false quiz, a m ultiple-choice quiz, and a set o f chapter questions and problem s

appear at the end o f each chapter.

• Answ ers to the chapter true/false m ultiple-choice quizzes are given at the end o f the

chapter.

• A suggested class discussion item appears at the end o f each chapter under the

heading For Discussion.

• A list o f variables and their meanings is provided at the end of the book.

Instructor Supplem ents

To access supplem entary materials online, instructors need to request an instructor

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P o w e rP o int S lides

PowerPoint slides that support the text with illustrated chapter summaries and discussions,

new examples, selected key terms, and a true/false quiz are available for instructors.

O nline In stru cto r’s M anual

Answers and solutions to all questions and problems are in the Instructor’s Manual.

Illustration of Features

• Chapter opener Each chapter begins with a full-page opener.

FIGURE P-1 Typical

Chapter Opener

Preface

• Section opener Each section within a chapter begins with a brief introduction and

overview.

• S ection C h ecku p Each section w ithin a chapter ends with a series o f questions

related to the section.

Preface

• Examples Worked-out examples illustrate and clarify basic concepts and procedures.

FIGURE P-4 Typical

Examples

M argin features Interesting sidebars are presented throughout the book. Their topics

range from items with historical interest to new technology.

FIGURE P-5 Typical

Margin Feature, Key

Term, and Glossary Term

Preface xiii

• Key term s a n d o th er glossary term s Key term s are highlighted in bold and blue;

these term s are defined at the end o f each chapter and in the end-of-book glossary.

O ther important term s are shown in bold and black throughout the book; these term s

are defined in the end-of-book glossary only. See the examples in Figure P-5.

A cknow ledgm ents

The authors wish to thank Vem Anthony, Lindsey Gill, Rex Davidson, and M aren Beckm an

at Pearson Education; Penny Walker at Aptara; and M arianne L’Abbate at Double Daggers

Editing Services for their help in bringing this book to reality. We relied heavily on the

expertise o f num erous reviewers who contributed to the content and coverage o f the topics.

These reviewers include Jam es A. Buck, Wayne Technical & Career Center; Lazaro Hong,

Pim a C om m unity College; and Dana Veron, University o f Delaware.

Finally, we gratefully acknowledge the support o f our wives, Lorraine, Kathleen, and

Sheila. We dedicate this book to them.

David Buchla

Tom Kissell

Tom Floyd