Page 615 - Environment: The Science Behind the Stories

according to the U.S. Environmental Protection Agency.
The amount of carbon pollution that all U.S. wind turbines
together prevent from entering the atmosphere is equal to the
emissions from nearly 10 million cars, or from combusting
the cargo of a 750-car freight train of coal each and every day.
Under optimal conditions, wind power appears efficient
in its energy returned on investment (EROI; pp. 541–542,
590–591). Most studies find that wind turbines produce roughly
20 times more energy than they consume. This EROI value is
better than that from most other energy sources. Wind farms
also use less water than do conventional power plants.
Wind turbine technology can be used on many scales,
from a single tower for local use to farms of hundreds that
supply large regions. Small-scale turbine development can
Figure 21.15 More and more wind farms are being devel- help make local areas more self-sufficient, just as solar
oped offshore. Offshore winds tend to be stronger yet less energy can. For instance, the Rosebud Sioux Tribe of Native
turbulent.
Americans set up a single turbine on its reservation in South
Dakota. The turbine has been producing electricity for 200
homes and brings the tribe $15,000 per year in revenue. The
tribe has now developed a 30-megawatt wind farm nearby, and
Offshore sites hold promise 20 more turbines are slated to be added soon.
Wind speeds on average are 20% greater over water than over Another benefit of wind power is that farmers and ranch-
land, and air is less turbulent over water. For these reasons, ers can lease their land for wind development. A single large
offshore wind turbines are becoming popular (Figure 21.15). turbine can bring in $2000 to $4500 in annual royalties while
Costs to erect and maintain turbines in water are higher, but occupying just a quarter-acre of land. Most of the land can still
the stronger, less turbulent winds produce more power and be used for agriculture. Royalties from the wind power com-
make offshore wind potentially more profitable. Today’s off- pany provide the farmer or rancher revenue while also increas-
shore wind farms are limited to shallow water, where towers ing property tax income for their rural community.
are sunk into sediments singly or using a tripod configura- Wind power involves up-front expenses to erect tur-
tion. In the future, towers may also be placed in deep water on bines and to expand infrastructure to allow electricity dis-
floating pads anchored to the seafloor. tribution, but over the lifetime of a project it requires only
Denmark erected the first offshore wind farm in 1991, maintenance costs. Unlike fossil-fuel power plants, wind
and soon more came into operation across northern Europe, turbines incur no ongoing fuel costs. Startup costs of wind
where the North Sea and Baltic Sea offer strong winds. Once farms generally are higher than those of fossil-fuel plants,
Germany raised its feed-in tariff rate for offshore wind from but wind farms incur fewer expenses once they are up and
9 cents to 15 cents per kilowatt-hour in 2009, many projects running. Moreover, advancing technology is driving down
began construction and today several are operating. By 2013, the costs, per unit of electricity produced, of wind farm
over 1800 wind turbines were operating in 65 wind farms in construction.
the waters of 10 European nations. Finally, just as solar energy creates job opportunities,
In the United States, no offshore wind farms have yet so does wind power. Roughly 85,000 Americans and nearly
been constructed, but development of the first was approved 700,000 people globally are now employed in the wind indus-
in 2010 after nine years of debate. The Cape Wind offshore try. More than 100 colleges and universities now offer pro-
wind farm, if constructed, will feature 130 turbines rising grams and degrees that train people in the skills needed for
from Nantucket Sound 8 km (5 mi) off the coast of Cape Cod jobs in wind power and other renewable energy fields.
in Massachusetts. In announcing the government’s approval,
U.S. Interior Secretary Ken Salazar predicted that it would be
“the first of many projects up and down the Atlantic coast.” Wind power has some downsides
Indeed, as of 2013, eight offshore wind developments were in Wind is an intermittent resource; we have no control over
the planning stages off the Northeast coast, one off the Texas when it will occur. This is a major limitation in relying on
coast, and one in Lake Erie. wind as an electricity source, but it is lessened if wind is one
of several sources contributing to a utility’s power generation.
Wind power has many benefits Pumped-storage hydropower (p. 592) can help to compensate
during windless times, and batteries or hydrogen fuel (p. 621)
Like solar power, wind power produces no emissions once the can store energy generated by wind and release it later when
equipment is manufactured and installed. As a replacement for needed.
fossil fuel combustion in the average U.S. power plant, run- Just as wind varies from time to time, it varies from place
ning a 1-megawatt wind turbine for 1 year prevents the release to place; some areas are windier than others. Global wind
of more than 1500 tons of carbon dioxide, 6.5 tons of sulfur patterns combine with local topography—mountains, hills,
614 dioxide, 3.2 tons of nitrogen oxides, and 60 lb of mercury, water bodies, forests, cities—to create local wind patterns.

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