Wind farms generate power, but may kill birds, bats
WASHINGTON — Wind farms could generate up to 7 percent of U.S. electricity in 15 years, but scientists want more study of the threat the spinning blades pose to birds and bats.
The towers appear most dangerous to night-migrating songbirds, bats and some hunting birds such as hawks and eagles. The risk is not understood enough to draw conclusions, a National Research Council panel said Thursday in a study requested by Congress.
“The human impacts of wind farms can be both positive and negative,” said Paul G. Risser of the University of Oklahoma, who was chairman of the committee that prepared the report.
Clearly the farms provide jobs and in some cases can be a recreational attraction, he said. But they can also affect property values, and reflections off the rotor blades can be distracting to some people, said Risser, who is currently acting director of the Smithsonian’s National Museum of Natural History.
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 feet to 295 feet and are mounted on towers 197 feet to 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 wind farms could generate 2 percent to 7 percent of the nation’s electricity within 15 years.
“There is a great diversity of opinion on how much there is going to be a ramping up of wind energy,” said report co-author Mary English of the University of Tennessee.
By reducing the need to generate electricity 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.
But the committee declined to say whether the benefits outweigh costs or vice versa, saying that decision is up to state and local officials and the public.
Frank Maisano, a spokesman for the wind developers in the mid-Atlantic area, said his industry has worked with conservation groups, regulators, environmentalists and community officials to find ways to ease the impact on wildlife, including birds and bats.