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CHAPTER 25
WIND TURBINES
Todd S. Nemec
GE Energy
Schenectady, New York
1 MARKET AND ECONOMICS
837
2 CONFIGURATIONS
837
3 POWER PRODUCTION AND
ENERGY YIELD
839
4 ROTOR AND DRIVETRAIN
DESIGN
841
REFERENCES
842
1 MARKET AND ECONOMICS
Wind power has long been used for grain-milling and water-pumping applications. Signifi-
cant technical progress since the 1980s, however, driven by advances in aerodynamics, ma-
terials, design, controls, and computing power, has led to economically competitive electrical
energy production from wind turbines. Technology development, favorable economic incen-
tives (due to its early development status and environmental benefits), and increasing costs
of power from traditional fossil sources have led to significant worldwide sales growth since
the early 1980s. Production has progressed at an even faster pace, beginning in the late
1990s. Figure 1 shows the new U.S. installations since 1980.
The spike in U.S. wind turbine installations from 1982 to 1985 was due to generous
tax incentives (up to 50% in California1), access to excellent wind resources, and high fossil
fuel prices. Today Germany, the United States, Spain, and Denmark lead in installed MW,
although significant growth is occurring worldwide.2 From an energy-share standpoint, the
northern German state, Shleswig-Holstein, produces approximately 30% of its electric energy
from wind power, while Denmark produces about 20%.3
Like other power-producing technologies, wind turbines are measured on their ability
to provide a low cost of electricity (COE) to customers, and high project net present value
(NPV) to the plant owners. Unlike fossil plants, however, fuel (wind energy) is free. This
causes COE to be dominated by the ratio of costs per unit energy, rather than a combination
of capital costs, fuel cost, and thermal efficiency. For customers purchasing based on highest
NPV, high power sale prices and energy production credits can drive turbine optimization
to a larger size (and/or energy capture per rated MW), and higher COE,