During a tour last month of Carleton College's 1.65 megawatt turbine in Northfield, Minn., project director Rob Lampa told a group of about 30 Winona County residents that the college had found no evidence of bird or bat kills in the first year of operating the 230-foot turbine, situated in a cornfield about 11/2 miles east of town.
As the group was leaving, Winona resident Marijo Reinhard pulled County Commissioner Dwayne Voegeli aside.
"Look," she said, pointing at the ground, where she had spotted a small, brown bat dead on the gravel below the slowly spinning turbine. A few feet away, she spotted another, also dead.
As a clean energy source, wind has long been championed by environmentalists. You don't have to worry about using up the wind, and turbines don't emit any pollutants.
But some wildlife advocates have been reluctant supporters, worried about the turbines' impact on birds. The American Bird Conservancy, for instance, supports the development of alternative energy sources, such as wind, but asserts that potential hazards to birds and bats should be evaluated through site analysis before the approval or construction of new turbines.
Much of the concern stems from reports that thousands of raptors are killed each year by large wind farms in northern California.
However, a recent study by the Government Accountability Office found that while turbines do kill some birds, the incidence is lower than previously thought. The report does point to the large number of bird kills in California and to a study that found 2,000 bats killed in one year at a West Virginia facility.
Some have suggested that the California kills are partly the result of thousands of turbines built along migratory bird routes on lattice-style towers that provide enticing perches for birds of prey.
New turbines, like Carleton's, have larger, slower-turning blades and are built on solid steel towers.
Jeff Cook-Coyle, the Rochester consultant heading the development study for a 2-megawatt turbine in Winona County, assured the group that the target sites in Mount Vernon Township, in the north of the county, would not be in the path of any migratory birds.