Wind farms can kill bats in large numbers. A six week study of two United States wind farms in 2004 noted 4500 bat fatalities due to collisions with turbines. in
Britain and the US will be using wind power to supply as much as ten percent of their power in the next decade.
Bats in the US also face a spreading fungal disease.
http://www.examiner.com/examiner/x-6180-Birmingham-Science-News-Examiner~y2009m6d13-Holy--Batman--Bats-dying-of-unknown-fungus
University of Aberdeen scientists Barry Nicholls and Paul Racey, funded by the People's Trust for Endangered Species have found that an electromagnetic signal from a small portable radar unit with a fixed antenna reduced the foraging activities of bats within 90 feet of the unit. The bats came back when the radar unit was turned off.
Further refinement in frequency, pulse length, pulse length to pulse rate and power could keep the bats out of the turbines
Bats eat their weight in insects every day. No bats and we will be knee deep in bugs.
Noting the serendipitous nature of discovery, Nichols and Racey got their first clue about the effectiveness of radar in removing bats from a strong radar on a lighthouse in Utgrunden Sweden. Radar on at night kept bats away from the lighthouse on an island with a large nighttime bat population.
This is a simple and inexpensive solution that protects endangered animals as well as the investment in wind powered energy.
http://wwwphysorg.com/news166978013.html
One hint to the frequency needed may come from the work of several scientists who have found that tiger moths ultrasonic emitted a chirp that jam a bat's ability to zero in on its target by echolocation. Bats can see but not well. Bats rely on echolocation to locate prey and to fly without crashing into objects in their path.
Science, 2009. DOI: 10.1126/science.1174096