Wind Energy

Engineering

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 About the Author
Pramod Jain, Ph.D., is founder and president of Inno­
vative Wind Energy, Inc., a wind energy consulting
company. He is recognized as a global expert in the plann­
ing of wind projects and has worked on projects in the
United States, the Caribbean, Latin America, Mongolia,
Indonesia, Lebanon, Philippines, and Sri Lanka that
range from a single 100-kW turbine to a 100-plus MW
wind farm. He has worked on wind projects for a vari­
ety of clients including Fortune 100 companies, the US
government, Asian Development Bank, Inter-American
Development Bank, UNDP, USAID, universities, util­
ities, municipalities, and land developers. He was a
cofounder and Chief Technologist at Wind Energy
Consulting and Contracting, Inc. He has a Ph.D.
in Mech­a­nical Engineering from the University of
California, Berkeley, an M.S. from University of
Kentucky, Lexington, and a B.Tech. from the Indian
Institute of Technology, Mumbai.

00_Jain_FM_pi-xxiv.indd 2 22/02/16 5:43 pm

 Wind Energy
Engineering
Pramod Jain

Second Edition

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Copyright © 2016 by McGraw-Hill Education. All rights reserved. Except as permitted under the United States
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 Dedicated to
My late father U.M. Jain and my mother Manchi Jain.

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 Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Preface to the Second Edition . . . . . . . . . . . . . . . . . . . . xix
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
1 Overview of Wind Energy Business . . . . . . . . . . . . . 1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Worldwide Business of Wind Energy . . . . . . . . . . . . . 1
Cost of Wind Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Benefits of Wind Energy . . . . . . . . . . . . . . . . . . . . . . . . 7
Wind Energy Is Not a Panacea . . . . . . . . . . . . . . . . . . . 8
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Basics of Wind Energy and Power . . . . . . . . . . . . . . . 11
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Kinetic Energy of Wind . . . . . . . . . . . . . . . . . . . . . . . . . 11
Sensitivity of Power to Rotor Radius
and Wind Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Basic Concepts/Equations . . . . . . . . . . . . . . . . . . . . . . 13
Conservation of Mass . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Conservation of Energy . . . . . . . . . . . . . . . . . . . . . . . . . 15
Conservation of Momentum . . . . . . . . . . . . . . . . . . . . . 16
Derivation of Betz Limit . . . . . . . . . . . . . . . . . . . . . . . . 19
Meaning of Betz Limit . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Wind versus Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3 Properties of Wind . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
How Is Wind Generated? . . . . . . . . . . . . . . . . . . . . . . . 29
Statistical Distribution of Wind Speed . . . . . . . . . . . . 30
Mean and Mode of Weibull Distribution
for Wind Speed . . . . . . . . . . . . . . . . . . . . . . . . 33
Power Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Wind Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Wind Shear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Understanding Wind Shear . . . . . . . . . . . . . . . 41
Density of Air as a Function of Elevation . . . . . . . . . . 42
Density of Air as a Function of Humidity . . . . 43
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

vii

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 viii Contents

4 Aerodynamics of Wind Turbine Blades . . . . . . . . . . 47

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Airfoils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Relative Velocity of Wind . . . . . . . . . . . . . . . . . . . . . . . 49
Rotor Disk Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Lift Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Equal Transit Time Fallacy . . . . . . . . . . . . . . . . 57
Rotation Fluid Flow, Circulation,
and Vortices . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Real Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Flow of Fluid Over an Airfoil . . . . . . . . . . . . . . 62
Effect of Reynolds Number on Lift
and Drag Coefficients . . . . . . . . . . . . . . . . . . 63
Drag-Based Turbines . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5 Advanced Aerodynamics of Wind
Turbine Blades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Blade Element Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Constant-Speed Turbines, Stall- versus
Pitch-Regulated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Variable-Speed Turbines . . . . . . . . . . . . . . . . . . . . . . . . 76
Power Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Vertical Axis Wind Turbine (VAWT) . . . . . . . . . . . . . . 78
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
6 Wind Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Definition of Wind Speed . . . . . . . . . . . . . . . . . . . . . . . 81
Configurations to Measure Wind . . . . . . . . . . . . . . . . . 82
Anemometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Calibration of Anemometers . . . . . . . . . . . . . . . 87
Wind Vane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Placement of Sensors . . . . . . . . . . . . . . . . . . . . . 88
Impact of Inflow Angle . . . . . . . . . . . . . . . . . . . 91
Impact of Temperature . . . . . . . . . . . . . . . . . . . 92
Uncertainty in Wind Speed Measurement
with Anemometers . . . . . . . . . . . . . . . . . . . . 92
Example of Error Estimate . . . . . . . . . . . . . . . . 94
Other Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Data Logger and Communication
Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Designing a Wind Measurement Campaign . . . . . . . 97
Installation of Met-Towers . . . . . . . . . . . . . . . . . . . . . . 99
Example of Met-Tower Installation . . . . . . . . . . . . . . . 100

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 Contents ix

Data Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Data Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Computed Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Turbulence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Wind Shear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Air Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Energy Density . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Remote Sensing to Measure Wind Speed . . . . . . . . . . 111
Pros and Cons of Remote Sensing for
Wind Measurements . . . . . . . . . . . . . . . . . . . 112
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
7 Wind Resource Assessment . . . . . . . . . . . . . . . . . . . . . 117
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Overview of Wind Resource Assessment . . . . . . . . . . 117
Source of Wind Data . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Network of Weather Stations . . . . . . . . . . . . . . 119
Long-Term Reanalysis Data . . . . . . . . . . . . . . . 120
Resource Estimation Models . . . . . . . . . . . . . . . . . . . . . 121
Mesoscale Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
CFD Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
WAsP, A Microscale Model . . . . . . . . . . . . . . . . . . . . . . 122
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Output of WAsP Model . . . . . . . . . . . . . . . . . . . 126
Phases of Resource Assessment . . . . . . . . . . . . . . . . . . 129
Preliminary Wind Resource Assessment . . . . . . . . . . 130
Wind Resource Map Lookup . . . . . . . . . . . . . . 130
Preliminary Analysis of Data from
Neighboring Airports
and Other Met-Towers . . . . . . . . . . . . . . . . . 132
Detailed Analysis of Wind Data
from Reanalysis Datasets . . . . . . . . . . . . . . . 132
Onsite Wind Measurement . . . . . . . . . . . . . . . . . . . . . . 132
Spatial Extrapolation of Wind Resources
from Measured Locations to Planned
Wind Turbine Locations . . . . . . . . . . . . . . . . . . . . . . 133
Hindcasting/MCP of Measured Data . . . . . . . . . . . . . 133
Correlate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Predict . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Annual Energy Computations . . . . . . . . . . . . . . . . . . . 152
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
8 Advanced Wind Resource Assessment . . . . . . . . . . . 155
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Extreme Wind Speed (EWS) . . . . . . . . . . . . . . . . . . . . . 155
WAsP Model in Rugged Terrain . . . . . . . . . . . . . . . . . . 159

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 x Contents

Wake of Turbines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

N.O. Jensen Model for Wake . . . . . . . . . . . . . . . 162
Ainslie’s Eddy Viscosity Model . . . . . . . . . . . . 163
Combining Wind Speed Deficits
from Multiple Turbines . . . . . . . . . . . . . . . . . 163
Turbulence Modeling . . . . . . . . . . . . . . . . . . . . . 163
Optimal Layout of Turbines in Wind Farm . . . . . . . . 164
Wind Turbine Class Selection . . . . . . . . . . . . . . . . . . . . 165
Estimation of Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Uncertainty Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Estimating Uncertainty of Annual
Energy Production: Framework for
Combining Uncertainty . . . . . . . . . . . . . . . . . . . . . . 174
Nonbankable versus Bankable
Resource Estimates . . . . . . . . . . . . . . . . . . . . . . . . . . 175
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

9 Wind Turbine Generator Components . . . . . . . . . . . 179

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Rotor System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Blades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Forces and Moments . . . . . . . . . . . . . . . . . . . . . 187
Rotor Hub . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Alternative Configurations of Turbines . . . . . . . . . . . 188
Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Nacelle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Gearbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Yaw Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
Nacelle Housing and Frame . . . . . . . . . . . . . . . 194
Lifting/Lowering Mechanism . . . . . . . . . . . . . 194
Towers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Spread-Footing Foundation . . . . . . . . . . . . . . . 197
Deep Foundation . . . . . . . . . . . . . . . . . . . . . . . . 198
Design Loads of Wind Turbines . . . . . . . . . . . . 200
Design Wind Conditions . . . . . . . . . . . . . . . . . . 201
Normal Wind Profile Model (NWP) . . . . . . . . 201
Extreme Wind Speed Model (EWM) . . . . . . . . 203
Turbine Certification . . . . . . . . . . . . . . . . . . . . . 203
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

10 Basics of Electricity and Generators . . . . . . . . . . . . . 207

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Basic Principles of Electromagnetism . . . . . . . . . . . . . 207
Faraday’s Law of Induction . . . . . . . . . . . . . . . 208

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 Contents xi

Lenz Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Lorenz Law or Biot-Savart Law . . . . . . . . . . . . 208
Basic Principles of Alternating Current . . . . . . . . . . . . 208
Basic Principles of Electrical Machines . . . . . . . . . . . . 210
Conversion of Mechanical to
Electrical Power . . . . . . . . . . . . . . . . . . . . . . . 211
Synchronous Generator . . . . . . . . . . . . . . . . . . . . . . . . . 212
Analysis of Synchronous Generator . . . . . . . . . . . . . . 215
Variable-Speed Permanent Magnet
Synchronous Generators . . . . . . . . . . . . . . . 218
Direct-Drive Synchronous
Generator (DDSG) . . . . . . . . . . . . . . . . . . . . . 222
Asynchronous Generators . . . . . . . . . . . . . . . . . . . . . . . 222
Variable-Speed . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Generator Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
11 Deploying Wind Turbines in Grid . . . . . . . . . . . . . . . 231
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Single-Line Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
Transmission and Distribution . . . . . . . . . . . . . . . . . . . 234
Standards for Interconnection . . . . . . . . . . . . . . . . . . . 237
Power Factor and Reactive Power . . . . . . . . . . 237
Low-Voltage Ride-Through (LVRT) . . . . . . . . . 238
Short Circuit Current . . . . . . . . . . . . . . . . . . . . . 239
Power Quality: Flicker and Harmonics . . . . . . . . . . . . 240
Weak Grid and Short-Circuit Power . . . . . . . . . . . . . . 240
Wind Farm Topologies . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Protection Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
Grounding for Overvoltage and Lightning
Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Lightning Protection . . . . . . . . . . . . . . . . . . . . . 245
Transformers for Wind Applications . . . . . . . . . . . . . . 247
Wind Plant Interconnection and
Transmission Study . . . . . . . . . . . . . . . . . . . . . . . . . . 248
Transmission Bottlenecks . . . . . . . . . . . . . . . . . . . . . . . 250
SCADA Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . 250
Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Impact of Wind Energy on Grid . . . . . . . . . . . . . . . . . . 252
Wind Energy Penetration . . . . . . . . . . . . . . . . . . . . . . . 253
Impact of Wind Energy on the Grid . . . . . . . . . . . . . . 256
Long-term Generation, Transmission,
and Operations Planning . . . . . . . . . . . . . . . 256

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 xii Contents

Annual and Seasonal Planning . . . . . . . . . . . . 258

Unit Commitment (UC): Daily and
Intraday Scheduling . . . . . . . . . . . . . . . . . . . 258
Economic Dispatch (ED) . . . . . . . . . . . . . . . . . . 263
Automatic Generation Control (AGC)
Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
Governor Response . . . . . . . . . . . . . . . . . . . . . . 267
Inertial Response . . . . . . . . . . . . . . . . . . . . . . . . 268
Impact of Wind Energy on Wholesale
Price of Electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Modeling and Analysis of Impact of
Wind Energy on the Grid . . . . . . . . . . . . . . . . . . . . . 272
Power Flow Study . . . . . . . . . . . . . . . . . . . . . . . 273
Short-Circuit Study . . . . . . . . . . . . . . . . . . . . . . 274
Power System Stability . . . . . . . . . . . . . . . . . . . 275
System Operations . . . . . . . . . . . . . . . . . . . . . . . 279
Wind Energy Forecasting . . . . . . . . . . . . . . . . . 279
Exploiting Flexibility in
Existing Network . . . . . . . . . . . . . . . . . . . . . . 281
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
12 Environmental Impact of Wind Projects . . . . . . . . . . 285
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
Framework for Analyzing Environmental
Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286
Context of Environmental Impact . . . . . . . . . . 286
Temporal and Spatial Scale . . . . . . . . . . . . . . . . 286
Cumulative Effects . . . . . . . . . . . . . . . . . . . . . . 287
Quick Comparison of Wind versus Fossil
Fuel-Based Electricity Production . . . . . . . . . . . . . . 287
Impact of Wind Farms on Wildlife . . . . . . . . . . . . . . . . 288
Noise from Wind Turbines . . . . . . . . . . . . . . . . . . . . . . 292
Mitigation of Noise . . . . . . . . . . . . . . . . . . . . . . 294
Low-Frequency Noise . . . . . . . . . . . . . . . . . . . . 295
Shadow Flicker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
Aesthetic Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
Hazard to Aviation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297
Electromagnetic Interference . . . . . . . . . . . . . . . . . . . . 299
Microwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
TV and Radio Transmissions . . . . . . . . . . . . . . 300
Radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
13 Financial Modeling of Wind Projects . . . . . . . . . . . . 305
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Financial Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

00_Jain_FM_pi-xxiv.indd 12 22/02/16 5:44 pm

 Contents xiii

Revenue Model . . . . . . . . . . . . . . . . . . . . . . . . . . 305

Renewable Energy Credits and
Carbon Credits . . . . . . . . . . . . . . . . . . . . . . . . 309
Revenue Computations . . . . . . . . . . . . . . . . . . . 310
Capital Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
Cost of Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . 313
Cost of Foundation, Erection, Access
Roads, and Other Civil Works . . . . . . . . . . . 314
Substation, Control System, Cables, Installation,
and Others Related to Grid Connection . . . . 314
Other Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Operating Costs . . . . . . . . . . . . . . . . . . . . . . . . . 315
Depreciation and Taxes . . . . . . . . . . . . . . . . . . . . . . . . . 318
Financial Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
Income Statement and Cash Flow
for a Wind Project . . . . . . . . . . . . . . . . . . . . . 319
Balance Sheet for a Wind Project . . . . . . . . . . . 319
Financial Performance . . . . . . . . . . . . . . . . . . . . 319
Net Present Value (NPV) . . . . . . . . . . . . . . . . . . 323
Payback Period . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Internal Rate of Return (IRR) . . . . . . . . . . . . . . 324
Impact of Tax Credits and Accelerated
Depreciation on Financial
Performance . . . . . . . . . . . . . . . . . . . . . . . . . . 324
Financing and Structure of Wind Projects . . . . . . . . . 329
Financial Evaluation of Alternatives . . . . . . . . . . . . . . 334
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
14 Planning and Execution of Wind Projects . . . . . . . . 337
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
High-Level Project Plan and Timeline . . . . . . . . . . . . 337
Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
Prospecting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
Wind Measurement and Detailed
Wind Assessment . . . . . . . . . . . . . . . . . . . . . . 339
Project Siting, Interconnection, and PPA . . . . . 341
Project Engineering and Procurement . . . . . . . 343
Project Financing . . . . . . . . . . . . . . . . . . . . . . . . 348
Construction, Installation, and Commissioning . . . . 349
Construction of Infrastructure . . . . . . . . . . . . . 350
Site Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Foundation Construction and
Turbine Erection . . . . . . . . . . . . . . . . . . . . . . . 351
Collection System and Substation
Construction . . . . . . . . . . . . . . . . . . . . . . . . . . 354
Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . 354

00_Jain_FM_pi-xxiv.indd 13 22/02/16 5:44 pm

 xiv Contents

Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
15 Wind Energy Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
Framework for Wind Energy Policy . . . . . . . . . . . . . . 359
Incentives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362
Supply-Side Incentives . . . . . . . . . . . . . . . . . . . 362
Demand-side Incentives . . . . . . . . . . . . . . . . . . 371
Wind Resource Exploitation . . . . . . . . . . . . . . . . . . . . . 373
Wind Resource Mapping of Country . . . . . . . 373
Long-term Wind Measurements . . . . . . . . . . . 374
Wind Resource Corridors . . . . . . . . . . . . . . . . . 375
Grid Integration Policy . . . . . . . . . . . . . . . . . . . . . . . . . 376
Grid Flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Licensing Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . 380
One-Stop-Shop . . . . . . . . . . . . . . . . . . . . . . . . . . 380
Criteria for Issuing Licenses . . . . . . . . . . . . . . . 382
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385

00_Jain_FM_pi-xxiv.indd 14 22/02/16 5:44 pm

 Preface

I
have been interested in writing short technical articles from
graduate school days. I was never good at it. In those days, I
supposedly wrote dense stuff and the audience I had in mind
were experts in the field. This changed as I wrote for a corporate
audience. When I got into the wind business, I wrote whitepapers
and blogs regularly but never considered writing a book. The idea
of writing this book came to me from a dear friend Satya Komatineni,
author of books on Android. He encouraged me to send a proposal
to McGraw-Hill about the book. This led me down a 9-month-long
adventure. The best metaphor to describe the adventure is that writ­
ing a book is akin to the 9-month process of gestation and birthing
of the first child. Although I have not personally experienced it, I
have lived with someone who experienced it. It is exciting, uncom­
fortable, painful, and, at times, really painful, and in the end the
product makes you forget the pain.
The impetus of writing this book was a lack of books on the mar­
ket that targeted engineers. Specifically, I wanted to write a book that
would give an engineer from any discipline sufficient knowledge
about the multidisciplinary field of wind energy. This book intends to
bring to bear at least five disciplines in order to provide a reasonably
comprehensive understanding of the field of wind energy. The five
disciplines include meteorology, mechanical and aeronautical engi­
neering, civil engineering, electrical engineering, and environmental
engineering. In addition, to these core engineering disciplines, the
book has chapters on finance and project management, two business-
related disciplines that are key to wind energy.
I wrote the book with the following audience in mind. First are
engineers and scientists who are in the wind industry but practice in
a narrow segment of the industry that covers their specific discipline.
Second are engineers and scientists who want to enter the wind
industry. Third are undergraduate engineering students and techni­
cal college students who want to learn about the various disciplines
in wind energy engineering. Finally, another intended audience is

xv

00_Jain_FM_pi-xxiv.indd 15 22/02/16 5:44 pm

 xvi Preface

composed of business people and project managers who work in the

wind energy industry.
Engineers will find sufficient detail about each of the topics. I
have kept the level of math to a level that would be comfortable for a
practicing engineer. In areas that require sophisticated math, I have
attempted to provide insights into the relationships.
As with any endeavor, I had to make decisions about what to
include in the book and what to leave out. This book is not an engi­
neering design manual for turbines. The exposition on turbines is
limited to describing the major components and their functions; it
does not cover the complexity of computing forces and displace­
ments, and design and engineering of the components. I chose to
leave out of the book discussions and debates about climate change
and energy policy. Although these are critical to understanding the
big picture, I am not particularly qualified to write about these issues.
Wherever appropriate, I have briefly discussed these two topics.
The book starts with a brief description of the wind energy busi­
ness with an emphasis on the explosive growth witnessed by the
wind energy industry. Although such explosive growth rate is diffi­
cult to sustain for long periods, I believe that the wind industry will
experience sustained 15 to 20% growth over the next decade. Based
on this conservative estimate, there will be a healthy demand for
engineers, technicians, scientists, project managers, and financiers for
years to come.
The second chapter of the book introduces readers to the concepts
of energy and power, what kind and how much energy is contained
in wind, and how much of it can be captured by a wind turbine.
The third chapter describes properties of wind from a meteoro­
logical perspective. It starts with a description of how wind is gener­
ated. Next, the statistical nature of wind speed is described, followed
by impact of height on wind speed. The chapter then concludes with
dependence of wind energy on air density and dependence of air
density on temperature, pressure, and humidity.
The fourth chapter describes the mechanics of how wind energy
is converted into mechanical energy using aerodynamics of blades.
This is important in order to understand the functioning of a wind
turbine. The fifth chapter presents a more detailed exposition on the
aerodynamics of blades and how power performance curves of tur­
bines are created.
The sixth chapter switches from the science of energy and airflow
to the science of measurement. Measurement of wind speed is a cru­
cial step in a wind project because all utility scale projects require it,
and, in most cases, it is the longest duration task. Measurement is a
key step in reducing uncertainty related to the financial performance
of a wind project.
The seventh chapter deals with wind resource assessment. It is
another pivotal step in the development phase of a wind project. In this

00_Jain_FM_pi-xxiv.indd 16 22/02/16 5:44 pm

 Preface xvii
chapter, different methods of assessment are covered, from methods
based on publicly available wind data and no onsite measurements,
to methods that extrapolate measured data along three spatial axes
and the temporal axis. In the eighth chapter, advanced wind resource
assessment topics such as computation of extreme wind speed and
modeling of rough terrain and wake are described. Losses and uncer­
tainty associated with the various components of wind resource assess­
ment are also covered in this chapter.
The ninth chapter describes the components of a wind turbine
generator. The rotor system, nacelle, and tower and foundation sys­
tems are described. The components of these three systems are
described for different types of utility scale turbines.
The tenth chapter deals with the electrical side of wind energy.
Basic concepts of electricity and magnetism are covered followed by
description of various types of generators used in wind turbines.
In the eleventh chapter, the integration with an electricity grid is
described. It covers how the variability of wind energy is incorpo­
rated in the grid, the grid interconnection standards, and the protec­
tion systems required in a wind farm. In addition, several topologies
of wind farm from an electrical standpoint are explained.
The twelfth chapter covers the environmental impact of wind
projects. It begins by setting the context for impact relative to fossil-
fuel based generation. In the chapter, environmental impacts like
wildlife, noise, aesthetics, shadow flicker, and others are described.
In addition, impact on aviation, radar, and telecommunications are
described.
The thirteenth chapter describes financial models used to evalu­
ate wind energy projects. In this chapter, the various components of
revenue, capital costs, and recurring costs are described. The impact
of incentives, in particular tax incentives in the United States, on the
financial performance is detailed. Finally, the financial performance
measures used to evaluate wind projects are described.
The fourteenth and final chapter describes planning and execu­
tion of wind projects. This chapter serves as a guide to project manag­
ers of wind energy projects during development, construction and
commissioning, and operations.
I learned a lot as I wrote this book. There were quite a few things
that I was certain were true, which turned out to be not so true. There
were more things that I had explained with confidence to colleagues
and clients, which turned out to be full of holes and superficial, at
best. I hope the book serves a similar purpose in helping you to better
understand wind energy.

Pramod Jain
July 2010

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This page intentionally left blank
 Preface to the
Second Edition

A
fter I wrote the first edition, the wind industry in the United
States took a nosedive due to uncertainty around production
tax credits. The amount of wind installations in the United
States declined by about 50% in 2010 compared to 2009. This and a
desire to work in countries with an emerging wind industry prompted
me to look at consulting opportunities outside the United States. US
Agency for International Development (USAID) and later Asian
Development Bank (ADB) projects provided opportunities to work in
countries with emerging wind markets. While consulting with gov­
ernments and developmental agencies, I noticed that these markets
needed a lot more policy support in terms of incentives, tariffs,
renewable energy funds, power purchase agreement, licensing guide­
lines, open access to transmission, grid code for interconnection,
renewable energy zones, and others. In the first edition of the book,
wind energy policy was not covered; therefore, there was a gaping
hole in the book.
Another area that emerging wind markets lack is an understand­
ing of the impact of wind energy on the grid. In most cases, before the
wind farms were interconnected, the grid operators were nonchalant
about integration issues. Time and again, I have observed that grid
operators have a rude awakening as they struggle to integrate the
first wind farm or the few initial wind farms into the grid. Often, this
leads to detrimental consequences for the wind industry—large
amount of curtailment of energy for the interconnected wind farms
and/or denial of interconnection permits for new wind farms. I have
realized that it is, therefore, an imperative that the grid integration
issues be studied, understood, and resolved during the licensing
phase of a wind project. The first edition of the book did not cover
this area, specifically it did not deliberate on the types of studies that
should be performed and the changes that should be made to both

xix

00_Jain_FM_pi-xxiv.indd 19 22/02/16 5:44 pm

 xx Preface to the Second Edition

the physical grid and system operations of the grid before wind
plants are integrated to a grid.
The second edition of the book fills these two gaps: wind energy
policy and grid integration studies. Wind energy policy is described
in Chap. 15, a new chapter. Grid integration is presented in a signifi­
cantly expanded Chap. 11. The other change was to Chap. 1, which
now contains updated statistics of the wind industry.
When I wrote the first edition of the book in 2009–10, no one I
knew used the adjective “mature” to describe the wind industry and
very few were talking about “grid parity” in terms of cost of wind
energy. What a difference a 5-year period makes? Both maturity and
grid parity are commonly used to describe wind energy. Here are my
reasons for claiming that the wind industry has matured:

Nothing says wind industry is maturing as … falling price of the

wind energy in countries with market-based pricing such as the
United States, Brazil, and South Africa.
Nothing says wind industry is maturing as … falling incentives
in US and EU countries.
Nothing says wind industry is maturing as … progressive coun­
tries and cities have policy goals to produce electricity from 100%
renewable sources (with large fraction of it coming from wind).
Nothing says wind industry is maturing as … renewables (wind,
solar PV, and hydro) were 59% of net additions to global power
capacity in 2014 and wind was the largest contributor.

So has wind energy arrived? Well, it has arrived at a pit stop in a

long race. The wind industry is about 35 years old whereas the cen­
tralized power plant industry for generating electricity is about 135
years old. Indeed, the wind industry has a long way to go, and here
is why:

Nothing says wind industry has a long way to go as … wind con­

tributes only 5% to electricity generation worldwide.
Nothing says wind industry has a long way to go as … energy
regulators and grid operators are just beginning to talk about grid
modernization and grid flexibility in order to accommodate larger
penetration of wind energy.

With my views on the current state of affairs of wind energy out

of the way, let me talk about what to watch for in the next 5 years:

As the price of energy produced from solar PV approaches price

of energy from wind, we will see a second wave of innovation to
bring down the cost of wind projects. As the areas with rich wind
resources and good access are used up, development will move to
areas with higher cost of production. This combined with falling

00_Jain_FM_pi-xxiv.indd 20 22/02/16 5:44 pm

 Preface to the Second Edition xxi
price of electricity from solar PV should cause a discontinuity
toward higher level of innovation in the wind industry.
Repowering of existing wind power plant sites should pick up
significantly. Most sites that were developed in the 1980s and 1990s
have very good wind resource, but the wind plants are past their
end of life. Repowering these sites with newer turbines and better
layout will yield high production.
If the cost of energy storage is cut by 50 to 75%, we should see
higher level of energy storage deployments, leading to higher
level of flexibility in the grid, which should lead to much higher
penetration of renewables. Many of the grid integration issues,
especially in smaller grids, can then be resolved with energy stor­
age at a lower cost.

Along with this edition, I have created a website. Please go to

http://WindEnergyEngineeringBook.com, where I will post updates,
blogs, and host a Q&A. I look forward to meeting you there.

Pramod Jain
February 2016

00_Jain_FM_pi-xxiv.indd 21 22/02/16 5:44 pm

This page intentionally left blank
 Acknowledgments

T
he first acknowledgement goes to my family. This book would
not have been possible without the support of my wife
Shobhana, and two wonderful daughters Suhani and Sweta.
The book took a significant toll on the family; I am grateful for
their wholehearted support and backing. I also want to thank my
mother, and sisters Savita and Rekha for their support.
The second acknowledgement goes to all my colleagues in the wind
industry. I have immensely benefited from interactions with them. The
two new chapters in this edition of the book are a result of my consulting
work in the areas of grid integration and wind energy policy on behalf of
two clients—The Asian Development Bank and the US Agency for Inter­
national Development. I also want to thank Ritika Oswal for being my
sounding board on content related to grid integration.
The third acknowledgement goes to companies that shared pictures
and data for the book including Alan Henderson of P&H, Vergnet,
Vensys, Bosch-Rexroth, SKF, Vestas, and GE; WindPower Monthly,
World Wind Energy Association, American Wind Energy Association,
Lawrence Berkeley National Lab, National Renewable Energy Lab,
and others.
Next, I would like to thank the International Electrotechnical
Commission (IEC) for permission to reproduce Information from its
International Standard IEC 61400-1 ed.3.0 (2005 and 2010). All such
extracts are copyright of IEC, Geneva, Switzerland. All rights
reserved. Further information on the IEC is available from www.iec.ch.
IEC has no responsibility for the placement and context in which the
extracts and contents are reproduced by the author, nor is IEC in any
way responsible for the other content or accuracy therein.
Finally, I want to thank McGraw-Hill for accepting my proposal
for the second edition of the book, and helping me with the editing
and publishing process.

xxiii

00_Jain_FM_pi-xxiv.indd 23 22/02/16 5:44 pm

This page intentionally left blank
 New Technical 6x9 /Technical / Title / Author /000-0 / Sample

CHAPTER 1
Overview of Wind
Energy Business
First, there is the power of the Wind, constantly exerted over the
globe… Here is an almost incalculable power at our disposal, yet
how trifling the use we make of it.
—Henry David Thoreau,
American naturalist and author (1834)

Introduction
The energy of wind has been exploited for thousands of years. The
oldest applications of wind energy include extracting water from
wells, making flour out of grain, and other agricultural applications.
In recent times, the use of wind energy has evolved to, primarily,
generation of electricity.
The field of wind energy blossomed in 1970s after the oil crisis,
with a large infusion of research money in the United States, Denmark,
and Germany to find alternative sources of energy. By the early 1980s,
incentives for alternative sources of energy had vanished in the
United States and, therefore, the wind energy field shrank signifi-
cantly. Investments continued in Europe and, until recently, Europe
led in terms of technology and wind capacity installations. In early
2000s, wind installations in the United States, China, and India picked
up steam.

Worldwide Business of Wind Energy

According to the REN21 report,1 “Wind energy is the least-cost option
for new power generating capacity in an increasing number of loca-
tions.” In 2014 wind energy was an 99.5 billion USD2 business in
terms of global new investments and it employed about 1,027,0001
people around the world. Global Wind Energy Council (GWEC)2

01_Jain_ch01_p001-010.indd 1 22/02/16 6:38 pm

 New Technical 6x9 /Technical / Title / Author /000-0 / Sample

2 Chapter One

400

370
350

319
Total installed capacity worldwide, GW

283
300

238
250

198
200

159
150

121
94
100
74
59
48
39

50
31
24

0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Figure 1-1 Total installed capacity of wind power worldwide.2

reports that in 2014, 370 GW of wind capacity was online. Figures 1-1
and 1-2 show the worldwide total installed wind capacity and new
installed capacity, by year. The pace of growth of new installed capacity
has increased. Between 2001 and 2014, the installed wind capacity
has grown by an average of about 16% per year.

60
51.477
45.161
New installations of wind power worldwide, GW

50
40.637
38.989
38.478

35.708

40
26.952

30
20.286
14.701

20
11.531
8.207
8.133
7.27

10
6.5

0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Figure 1-2 New installed capacity of wind power worldwide.2

01_Jain_ch01_p001-010.indd 2 22/02/16 6:38 pm

 New Technical 6x9 Technical

Overview of Wind Energy Business 3

Denmark 3.5
4.8
Portugal 3.5
4.9
Brazil 0.6
5.9
Italy 4.9
8.7
France 4.5
9.3
Canada 3.3
9.7
United Kingdom 4.1
12.4 2009
India 10.9 2014
22.5
Spain 19.1
23.0
Germany 25.8
39.2
USA 35.2
65.9
China 26.0
114.8

0 20 40 60 80 100 120 140

Figure 1-3 Total installed capacity of wind power (GW) by country for top 12
countries.2

Figure 1-3 illustrates the total wind capacity by country. China

leads in wind capacity installations with a total of 114.8 GW and aver-
age annual growth rate in the past 5 years of 34.6%. The United States
has the next highest wind capacity installations with 65.9 GW, fol-
lowed by Germany at 39.2 GW. The United Kingdom leads in offshore
installations, with a total capacity of 3.68 GW followed by Denmark
at 1.27 GW, see Fig. 1-4.
In terms of penetration of wind energy in the total electricity supply,
Denmark leads with 39% in 2014, followed by Portugal, Spain, and

United Kingdom 3680.9

688.0

Denmark 1270.6
663.0

Netherlands 246.8
247.0

Sweden 211.7 Total 2014

164.0
Total 2009

Germany 1049.2
72.0

0 500 1000 1500 2000 2500 3000 3500 4000

Figure 1-4 Total installed capacity of offshore wind power (MW) in the top five
countries.2

01_Jain_ch01_p001-010.indd 3 22/02/16 6:38 pm

 New Technical 6x9 /Technical / Title / Author /000-0 / Sample

4 Chapter One

Germany at 15, 14, and 9%, respectively. In 2014, across Europe the
total wind generation was 284 TWh (10.2% of total EU electricity
consumption)a while in the United States, the total wind generation
was 182 TWh (4.45% of total US electricity consumption).b
The prominence of wind in the last half of the first decade of the
twenty-first century is evident in the fact that it is the leading source
of newly installed electricity generation capacity in the United States.
In the United States, out of a total of 20 GW of new electricity genera-
tion in 2008, 42% was from wind energy.2 The percentage has risen
steadily since 2005, when wind was 12% among generation types in
annual capacity addition. From an energy standpoint, the promi-
nence of wind is even more impressive. The Lawrence Berkeley
National Laboratory (LBL) report2 predicts, “almost 60% of the
nation’s projected increase in electricity generation from 2009 through
2030 would be met with wind electricity. Although future growth
trends are hard to predict, it is clear that a significant portion of the
country’s new generation needs is already being met by wind.” The
LBL report used forecast data from Energy Information Administration
of the US Department of Energy (DOE).

Cost of Wind Energy

The cost of wind energy has fallen in recent years. According to
Windpower Monthly, “a realistic best generation cost” of energy pro-
duced by onshore wind power plants is $71/MWh in 2014 compared
to $81/MWh in 20133; these are worldwide average levelized cost of
wind energy. Table 1-1 compares the range of costs and components
of costs of various source of electricity generation in the United States,
as projected by the US Energy Information Agency (EIA) for the year
2019.4 The calculations are based on 30-year cost recovery period with
real after tax weighted average cost of capital of 6.5%. Three percent
points were added to cost of capital for greenhouse gas (GHG) inten-
sive technologies without carbon capture and storage (CCS), which is
equivalent to emissions fee of $15 per ton of CO2. According to EIA,
the cost of onshore wind energy is cheaper than all sources of genera-
tion except natural gas fired combined cycle and advanced combined
cycle, and geothermal. Other comparisons of levelized costs in the
United States and Europe may be found in the annual compilations
by Windpower Monthly.

aThe European Wind Energy Association, 2014 European Statistics, http://

www.ewea.org/fileadmin/files/library/publications/statistics/EWEA-Annual-
Statistics-2014.pdf.
b
From Electricity Data Browser of US Energy Information Administration , http://
www.eia.gov/electricity/data/browser, June 2015.

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01_Jain_ch01_p001-010.indd 5

Range of Cost (USD/MWh) Components of Average LCOE

Capacity Levelized Fixed Variable O&M Transmission
Plant Type Min. Ave. Max. Factor (%) Capital cost O&M with Fuel Inv.
Dispatchable Technologies
Conventional coal 87 95.6 114.4 85 60 4.2 30.3 1.2
Integrated coal gasification 106.4 115.9 131.5 85 76.1 6.9 31.7 1.2
combined cycle (IGCC)
IGCC with carbon capture and 137.3 147.4 163.3 85 97.8 9.8 38.6 1.2
storage (CCS)
Natural gas-fired
Conventional combined cycle 61.1 66.3 75.8 87 14.3 1.7 49.1 1.2
Advanced combined cycle 59.6 64.4 73.6 87 15.7 2 45.5 1.2
Advanced CC with CCS 85.5 91.3 105 87 30.3 4.2 55.6 1.2
Conventional combustion 106 128.4 149.4 30 40.2 2.8 82 3.4
turbine
Advanced combustion turbine 96.9 103.8 119.8 30 27.3 2.7 70.3 3.4
Advanced nuclear 92.6 96.1 102 90 71.4 11.8 11.8 1.1
Geothermal 46.2 47.9 50.3 92 34.2 12.2 0 1.4

New Technical 6x9 Technical

Biomass 92.3 102.6 122.9 83 47.4 14.5 39.5 1.2

Table 1-1 Projections for Levelized Cost of Energy (LCOE) from Different Sources for New Power Plants Built in 2019.4 Values Are Average, Minimum, and
Maximum over 22 US Regions, and the Components of the Average LCOE. All the Values Are in 2012 US Dollars.
5
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01_Jain_ch01_p001-010.indd 6

Range of Cost (USD/MWh) Components of Average LCOE

Capacity Levelized Fixed Variable O&M Transmission
Plant Type Min. Ave. Max. Factor (%) Capital cost O&M with Fuel Inv.
Non-Dispatchable Technologies
Wind 71.3 80.3 90.3 35 64.1 13 0 3.2
Wind-offshore 168.7 204.1 271 37 175.4 22.8 0 5.8

New Technical 6x9 /Technical / Title / Author /000-0 / Sample

Solar PV 101.4 130 200.9 25 114.5 11.4 0 4.1
Solar thermal 176.8 243.1 388 20 195 42.1 0 6
Hydro 61.6 84.5 137.7 53 72 4.1 6.4 2

Table 1-1 Projections for Levelized Cost of Energy (LCOE) from Different Sources for New Power Plants Built in 2019.4 Values Are Average, Minimum, and
Maximum over 22 US Regions, and the Components of the Average LCOE. All the Values Are in 2012 US Dollars. (Continued)
22/02/16 6:38 pm
 New Technical 6x9 Technical

Overview of Wind Energy Business 7

$80
Average levelized PPA price in US (2013 $68.19
$70 $64.26
$61.08
$60
$50.54$51.64
$50 $45.54
$42.20
$/MWh)

$37.53 $38.40
$40 $35.92
$33.51
$30 $25.59

$20

$10

$0
9

06

07

08

09

10

11

12

13
-9

-0

-0

-0
20

20

20

20

20

20

20

20
96

00

02

04
19

20

20

20

PPA Year

Figure 1-5 Generation-weighted nationwide average levelized wind PPA price

in the United States in 2013 dollars.5

Data compiled by Lawrence Berkeley National Lab,5 see Fig. 1-5,

indicates that in the United States, the national average levelized
power purchase price (PPA) of electricity from wind has been in
decline from 2009 when it was $68.19/MWh to 2013 when it was
$25.59/MWh, a historic low. The 2013 number is an average over the
four regions of the United States and is from a sample of 18 projects
with capacity of 2761 MW; vast majority of the projects are from Inte-
rior region of United States (mid-west United States) where the average
levelized PPA was $22/MWh. The PPA is the cost of wind energy to
the buyer. In the United States, in addition to the PPA, the producer
of wind energy in 2013 would receive $23/MWh of production tax
credit (PTC) for the first 10 years of production. A US DOE 2015 Wind
Vision report6 states that cost of wind energy (in 2013) was $45/MWh
(levelized cost which includes PPA and PTC for 10 years).
Note, the cost of wind energy in 2013 is much lower than EIA’s
2019 projection of average cost of wind energy in Table 1-1. In author’s
opinion, the average levelized PPA price of wind energy in the United
States is likely to settle in the range of $30/MWh to $45/MWh for the
foreseeable future.

Benefits of Wind Energy

The primary benefits of wind energy are environmental and cost.
Wind energy production results in zero emissions. Compared to fos-
sil fuel−based energy generation, no pollutants are produced. In the
United States, every megawatt-hour of wind energy production that
is not produced by a conventional source reduces GHG emission by

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 New Technical 6x9 /Technical / Title / Author /000-0 / Sample

8 Chapter One

an equivalent of 0.558 tons of CO2. According to the DOE’s 20% Wind

Energy by 2030 Technical Report,7,8 overall 25% of CO2 emissions
from the electricity production sector can be reduced in the United
States if 20% of electricity is produced by wind energy. In the United
States, wind energy production in 2007 reduced CO2 emissions by
more than 28 million tons.
Wind energy is among the cheapest sources of renewable energy.
The cost of electricity production using wind in regions with good
wind resources is comparable to fossil fuel−based electricity produc-
tion. In most cases, the cost is lower or about the same when cost of
GHG emissions are taken into account.
In addition to the aforementioned benefits, wind energy provides
income to farmers, ranchers, and landowners that have sufficient
wind resources on their property. The income is in terms of land lease
payments, while majority of the land is still available for other uses.
Wind energy generators are available in wide range of capacities,
from small to utility scale. On small scale, wind energy can be used to
power remote locations that do not have access to electricity. Often,
the levelized cost of extending the grid to remote locations and
transporting electricity is higher than the levelized of wind energy.
Other financially viable use of wind energy is in grids that use diesel
or heavy oil as fuel. Such applications are called wind-diesel hybrids.
Every kilowatt-hour of wind energy generation replaces 1 kWh of
electricity generation from oil; even accounting for lower efficiencies
of diesel generators in hybrid applications, the levelized cost of wind
energy in good wind resource locations is usually lower.

Wind Energy Is Not a Panacea

Despite the significant benefits, wind energy is not a cure-all. The pri-
mary disadvantages of wind energy are variability and uncertainty of
the resource. Other disadvantages, to a lesser extent, are requirement
for large upfront investment and impact on the environment.
Wind energy production depends on wind conditions. Even in
areas with abundant wind resources, there is a high degree of diurnal
and seasonal variability, and unpredictability. When the wind is not
blowing, there is no energy production and other sources of electric-
ity must be deployed. As the penetration of wind increases, the mix
of generation assets, and the method of committing and dispatching
the incumbent generation assets changes. Utilities perceive this as a
difficult change. The Deploying Wind Turbines in Grid chapter
addresses this issue in detail, and points out that several countries
and regions within the US have successfully integrated large penetra-
tion of wind power.
People do not like to live in areas that have high wind. Therefore,
high-wind areas are usually far away from population centers.

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 New Technical 6x9 Technical

Overview of Wind Energy Business 9

This implies electricity generated from wind energy must be

transported to population centers, which requires expensive
transmission lines. In conventional methods of electricity generation,
fuel is transported to a power plant, which is close to a population
center. In contrast, wind resource cannot be transported and long-
distance transmission is required.
From an environmental perspective, wind farms can cause harm
to birds, bats, and other wildlife, although most studies suggest that
the harm is minimal. Aesthetic impact is another area of concern if a
wind plant is located in an area of scenic value. Wind farms require
significantly more land per kilowatt compared to fossil fuel−based
electricity plants; however, continued use of the majority of the land
mitigates this concern.
Other disadvantage of wind energy is significantly higher cost of
small wind projects. Small winds projects (< 100 kW), especially wind
projects of size 15 kW or less, are expensive. The capital cost per
kilowatt may be three to five times the cost per kilowatt of a large
wind farm. In addition, the capacity factors of small wind projects are
much lower compared to large wind farm. These two factors lead to
higher levelized cost of energy from small wind projects. However,
the higher levelized cost must be compared against the cost of other
options for providing electricity like extending grid or oil-based
generation of electricity, both of which are expensive options.
In conclusion, any potential negative impacts of wind energy
should be rigorously analyzed and strategies put in place to mitigate
the impact. On balance, there is compelling evidence that wind energy
delivers significant benefits to the environment and the economy.

References
1. Renewable Energy Policy Network for the 21st Century (REN21). Renewable 2014
Global Status Report, REN21, Paris, France.
2. Global Wind Energy Council. Global Wind Statistics 2014, February 2015.
3. Milborrow, D. “Onshore wind is more competitive than ever,” WindPower
Monthly, January, 2015.
4. U.S. Energy Information Administration. Annual Energy Outlook 2014. DOE/
EIA-0383, April 2014.
5. Wiser, R., and Bolinger M. 2013 Wind Technologies Market Report, Lawrence
Berkeley National Laboratory, Berkeley, CA, August 2014.
6. US Department of Energy. Wind Vision: A New Era for Wind Power in the United
States. DOE/GO-102015-4557. US Department of Energy, Washington, DC, April
2015.
7. Energy Efficiency and Renewable Energy, US Department of Energy. 20% Wind
Energy by 2030. US Department of Energy, Washington, DC, 2008. www.nrel.
gov/docs/fy08osti/41869.pdf. DOE/GO-102008-2567.
8. American Wind Energy Association. 20% Wind Energy by 2030: Wind, Backup
Power, and Emissions, American Wind Energy Association, Washington, DC, 2009.
http://www.awea.org/pubs/factsheets/Backup_Power.pdf.

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