452 CHAPTER 18 Renewable Energy Resources
Wind Energy
Wind results from the sun warming the atmosphere.
Wind energy is an indirect form of solar energy: The ra-
diant energy of the sun is trans-
formed into mechanical energy
through the movement of air
molecules. Wind is sporadic over
much of Earth’s surface, vary-
ing in direction and magnitude.
Like direct solar energy, wind en-
ergy is a highly dispersed form of energy. Harnessing
wind energy to generate electricity has great potential.
New wind turbines are huge—100 m (328 ft) tall—
and have long blades designed to harness wind energy
efficiently (Figure 18.9a, b). As turbines have become
larger and more efficient, costs for wind power have de-
clined rapidly—from $.40 per kilowatt-hour in 1980 to a
current cost of $.04 to $.07 per kilowatt-hour. Wind power
is cost-competitive with many forms of conventional en-
ergy. Advances such as turbines that use variable-speed op-
eration may make wind energy an important global source
of electricity during the first half of the 21st century.
During the 1990s and early 2000s, wind became the
world’s fastest-growing source of energy (Figure 18.9c).
According to the Global Wind Energy Commission, in
2012, China, Germany, and the United States led the world
as the top producers of wind energy. China is rapidly ex-
panding its wind energy capacity, with plans to produce at
least 100 GW by 2015. This is more than the total global
wind energy production in 2005. Denmark currently gen-
erates 21 percent of its electricity using wind energy, much
of it offshore where ocean winds are strong. Other leading
wind energy countries include Spain and India.
Harnessing wind energy is most profitable in ar-
eas with consistent winds, such as islands, coastal areas,
mountain passes, and grasslands. The world’s largest
concentration of wind turbines is currently located in the
Tehachapi Pass at the southern end of the Sierra Nevada
mountain range in California.
In the continental United States, some of the best lo-
cations for large-scale electricity generation from wind en-
ergy are on the Great Plains. The 10 states with the greatest
wind energy potential, according to the American Wind
Energy Association, are North Dakota, Texas, Kansas,
South Dakota, Montana, Nebraska, Wyoming, Oklahoma,
Minnesota, and Iowa. In fact, if we developed the wind
energy in North Dakota, Texas, and Kansas to their full
potential, we could supply enough electricity to meet the
current needs of the entire United States! Wind power
projects are under way in these and many other states.
Currently, wind energy is captured and placed into
regional electricity grids. Deploying wind energy on a na-
tional scale—for example, wind energy produced in Texas
and used in New York City—requires the development of
new technologies for storing and distributing energy.
Wind produces no waste and is a clean source of en-
ergy. It produces no emissions of sulfur dioxide, carbon
dioxide, or nitrogen oxides. Every kilowatt-hour of elec-
tricity generated by wind power rather than fossil fuels
prevents as much as 1 kg (2.2 lb) of the greenhouse gas
CO 2 from entering the atmosphere.
Although the use of wind power doesn’t cause major
environmental problems, one concern is the deaths of
birds and bats. The California Energy Commission esti-
mated that several hundred birds turned up dead in the
vicinity of the 7000 turbines at Altamont Pass in Califor-
nia during a two-year study; most had collided with the
turbines. Studies later determined that Altamont Pass is
a major bird migration pathway. Wind power sites have
implemented technical “fixes” such as painted blades and
anti-perching devices, or have shut down operations dur-
ing peak bird migration periods. Developers of future wind
farm sites currently conduct voluntary wildlife studies and
try to locate sites away from bird and bat routes.
Not all people welcome wind power projects with
open arms. The Maple Ridge Wind Farm in upstate
New York has almost 200 windmills. Many local resi-
dents appreciate the extra money that wind-farm leases
provide to the local economy. However, others think
the wind turbines ruin their view of the Adirondack
Mountains. A similar dispute is occurring over the
proposed Nantucket Sound wind farm off the coast of
Massachusetts. This 130-turbine wind farm, if built, will
be the first offshore wind project in the United States.
Massachusetts has some of the highest electricity costs
in the nation, and proponents of the wind farm point
out that wind energy will help lower energy costs. How-
ever, many people are concerned that the wind farm
will adversely affect the local economy because tourists
will find it offensive.wind energy
Electric energy
obtained from surface
air currents caused
by the solar warming
of air.