WASHINGTON (AP) _ Wind farms could generate as much as 7 percent
of U.S. electricity in 15 years, but scientists want to spend more
time studying the threat those spinning blades pose to birds and
bats.
The towers appear most dangerous to night-migrating songbirds,
bats and some hunting birds. The risk is not well enough known to
draw conclusions, a panel of the National Research Council said
Thursday in a study requested by Congress.
Wind has powered sailing ships for thousands of years and has
long been important to turn windmills that move water and grind
grain. Only in recent years had the potential of the wind to
generate electricity been tapped.
Wind farms generate electricity by using the wind to turn giant
blades that rotate turbines to make power. The blades have
diameters ranging from 230 to 295 feet and are mounted on towers
between 197 and 295 feet tall. Some farms contain hundreds of
towers. The one at Altamont Pass, Calif., has more than 5,000.
Growing from almost nothing in 1980, wind powered turbines
generated 11,605 megawatts of electricity in the United States in
2006, though that was still less than 1 percent of the national
power supply.
Wind farms now operate in 36 states. The report says estimates
are that this source could generate from 2 percent to 7 percent of
the nation's electricity within 15 years.
By reducing the need to generate electricity from by burning
fossil fuels the turbines have been welcomed as a boon to the
environment. Others worry about the danger to birds and bats,
impacts on wildlife habitat and what some see as a blight on the
scenery.
Overall, the report noted, the benefits of wind-energy
development such as reductions in air pollutants benefit wide
areas, while the environmental costs, such as effects on the
ecology and increased mortality of birds and bats, occur locally.
The Research Council, as arm of the National Academy of
Sciences, concluded that:
_By the year 2020 wind generators could offset as much as 4.5
percent of emissions of the greenhouse gas carbon dioxide from
electricity production. The savings would be less in the
mid-Atlantic states where there is less regular wind.
_Wind generation in the mid-Atlantic highlands _ elevated
regions of Virginia, West Virginia, Maryland and Pennsylvania _ is
unlikely to reduce emissions of nitrous oxide and sulfur dioxide
because current and upcoming regulation will limit those emissions
in eastern states.
_In the mid-Atlantic highlands, preliminary studies indicate
that more bats are killed than expected based on experience with
bats in other regions. There is not enough information to determine
whether the number of bats killed will have overall effects on
populations. However, there has been a region-wide decline in
several species of bats in the eastern states, so the possibility
of population effects is significant.
_Turbines placed on ridges, as many are in the mid-Atlantic
highlands, appear to have a higher probability of causing bat
fatalities than those at many other sites
_At current levels of use, there is no evidence that fatalities
caused by wind turbines result in measurable demographic changes to
bird populations nationwide, with the possible exception of raptor
fatalities in the Altamont Pass area. However, data are lacking for
a many facilities.
_While aesthetic concerns often are the most heard about
proposed wind-energy projects, few decision processes adequately
address them.
_Other potential human impacts include effects on cultural
resources such as historic, sacred, archaeological and recreation
sites and the potential for electromagnetic interference with
television and radio broadcasting, cellular phones and radar.
_Building wind farms requires clearing land and soil disruption
and has the potential for erosion and noise.
_Regulation of wind farms is a developing area and better
technical guidance to the costs and benefits needs to be made
available. This guidance could be developed by state and local
governments working with groups composed of wind-energy developers
and non-governmental organizations representing all views of wind
energy, the committee said.
The National Academy is an independent organization chartered by
Congress to advise the government on scientific matters.
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