Environmental Engineering Reference
In-Depth Information
An emerging market for wind turbines is the recent development of
small wind turbines that can be attached to a rooftop and can generate
electricity at home in winds as low as 2 miles per hour.
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In urban and
suburban settings, the high density of nearby buildings and trees tends
to block the higher wind speeds needed by conventional turbines that
must be mounted on the ground. Ninety percent of the wind sources in
North America are lower than 10 miles per hour. Each small turbine
generates 2 kilowatts of power (much more than is needed by an average
household) and sells for $4,500, with an additional installation cost of
$1,500.
Onshore versus Offshore
Winds are generally stronger and more consistent offshore than onshore
because there are no topographically high areas in the sea to block the
moving air. A report by the Interior Department in 2006 said that wind
energy within 50 miles of the U.S. coast has the potential to provide
900 gigawatts of power, close to the total currently installed electrical
capacity in the United States. And 78 percent of the nation's electricity
is used in areas touching oceans or the Great Lakes. By comparison,
the best wind sites on land tend to be in rural areas in the middle of
the country.
Locating an energy source near the coast would relieve some of the
burden on long-distance transmission lines. A study by the University of
Delaware and Stanford University concluded that the wind resource off
the mid-Atlantic coast alone could supply the energy needs of nine states
from Massachusetts to North Carolina, with enough left over to support
a 50 percent increase in future energy demand.
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Despite these assess-
ments, there are no offshore wind farms along the coastline of the United
States, although the Department of the Interior has approved construc-
tion of a large wind farm offshore of Cape Cod, Massachusetts. There
are at least eleven other offshore wind projects in development. Offshore
wind installations are common in Europe. They occur in offshore Britain,
Ireland, Sweden, Denmark, and the Netherlands.
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Total offshore capac-
ity in Europe grew from 40 megawatts in 2000 to more than 1,200
megawatts in 2007.
All current offshore wind farms are in shallow water, but facilities
farther offshore to better wind locations are possible because of techno-
logical innovations by the oil industry drilling in deep waters in the Gulf
of Mexico.
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Floating offshore wind turbines may be erected in the
future, although they are not economical at present.
