You can’t have both. Roughly 600,000 bats were killed in 2012 by wind turbines, a structure that creates sustainable energy in the U.S. The turbines, which spin up to 179 miles per hour and rise hundreds of feet, are killing bats mid-air. Ironically, the scary creatures have been helping the environment for year by eating a large number of flying insects and helping pollinate crops. And considering many bat carcassses are taken by animals before researchers could find them, the numbers are probably conservative, biologist Mark Hayes noted. Even worse, it’s unlikely the species will repopulate quickly, considering bats give birth just one time every year.