Appalachian wind turbines are part of effort to develop clean source of energy, but they're killing thousands of bats.
Towering up to 228 feet above the Appalachian Mountain ridge, windmills are lined up like marching aliens from "War of the Worlds." Up close, they emit a high-pitched electrical hum. From a distance of a few hundred yards, their 115-foot blades make a steady whooshing sound as their tips cut through the air.
Owned by FPL Energy, a Florida-based company, they are part of the national effort to develop diverse and more environmentally friendly sources of energy. The problem is, they're killing thousands of bats a year.
"I can appreciate that we need other energy sources," said Jane Burch, who lives in neighboring Grant County, W.Va., where a large wind farm has been proposed. "But I don't like the look of them, and I don't want them behind my property, and I don't like what they do with the bat kills."
Though wind still generates less than 1 percent of the nation's electricity, the Department of Energy has set a goal of raising that to at least 5 percent by 2020. To reach that goal, the American Wind Energy Association estimates, it will require an increase from about 16,000 turbines nationwide now to more than 78,000 turbines.
About 600 of those turbines are planned for West Virginia and Pennsylvania. If they are built, more than 50,000 bats a year could be killed in these two states alone, said Merlin Tuttle, founder and president of Austin-based Bat Conservation International Inc.
He said there are no good estimates of how many bats would be killed nationwide if the association's projection of 78,000 turbines were reached, but he estimated that it would be far higher than 50,000.
"They can't sustain that kind of kill rate," Tuttle said, noting that bats are among the slowest-reproducing mammals, generally having one pup each year.
"Bats are just as important by night as birds are by day," he said. Indeed, bats play an important ecological role by eating mosquitoes and such crop-destroying insects as moths, locusts and grasshoppers.
Contrary to popular belief, bats have quite good vision. It's is enhanced by echolocation that helps them "see" in the dark and enables them to zero in on insects as small as a gnat.
A study conducted at FPL's Mountaineer Wind Energy Center this year indicated that its 44 turbines might have caused between 1,300 and 2,000 bat deaths in a six-week period. That study was led by Edward Arnett, a scientist with Bat Conservation International, and financed largely by the American Wind Energy Association and its 700 member companies.
During the study, one of the turbines at Mountaineer was out of service. It was the only turbine where no bat fatalities were recorded during the entire period. That led bat enthusiasts to conclude that bats are not colliding with stationary blades; they're being hit by moving blades, said Dan Boone, a wildlife biologist from Bowie, Md., who has joined the fight against new windmill farms on forested mountaintops.
A Government Accountability Office report in September showed that at wind farms outside the Appalachians, fewer than one to four bats were killed each year per turbine. But Arnett said the GAO report summarized studies that might have focused on birds and underestimated bat kills.
It's also unclear precisely why bats are killed by windmills. Among the theories: The windmills are located in the bats' migratory path; bats might be attracted by the turbines' humming sound, their flashing aircraft-warning lights or their tall masts suitable for roosting; the short range of the bats' echolocation does not give them time to avoid the blades.
The recent Mountaineer study has led to an impasse between bat conservationists and the wind power industry over what to do next. Conservationists have called for further studies that would disengage some turbines on nights when the wind speed is low and bats and their prey are more likely to fly. The wind power industry has rejected that suggestion. It has proposed studies of deterrent measures such as acoustics to discourage bats from approaching the turbines.
"We don't think it makes a whole lot of sense to be focusing on a solution that potentially could reduce the amount of power that is generated and potentially put stress on the machines," said Steve Stengel, an FPL Energy spokesman. "We think there needs to be a great deal of effort put into finding ways for bats and wind turbines to coexist."
Acoustical deterrent efforts currently are in the design stage and might be tested in the laboratory by early next year, Arnett said. If preliminary investigations show promise, field tests might take place next year. FPL Energy has offered to allow some of its facilities to be used for such tests.
But Arnett and Boone noted that acoustic efforts to rid houses of bats rarely work and said they do not believe that sound deterrents would be effective in shielding turbines.