By: Joe Castaldo

Image is everything, and that applies to renewable energy, too. The entire industry is premised on being clean and environmentally friendly, and so it’s not an insignificant public relations problem for wind power producers that turbines kill hundreds of bats and birds each year. But now a new report proposes a way to reduce fatalities.

Critics have thrown the animal casualties issue at the wind industry from time to time, and some commentators griped last year that the 500 dead ducks (later discovered to total more than 1,500) found in Syncrude’s tailings pond in Alberta caused a PR nightmare for the oil sands giant, while comparatively little attention has been paid to the flying wildlife felled by wind turbines each year. (One study found 2,092 bats were killed over seven months at a single wind farm in West Virginia, along with more than 200 birds.)

The question of why bats are more susceptible than birds was a bit of a mystery up until last year. Wind farm operators for TransAlta in Alberta had noticed an abundance of dead bats, and the company initiated a study with the University of Calgary to find out why. The research team found that the sudden drop in air pressure created by wind turbines causes bat lungs to balloon and blood vessels to burst. Bird lungs can more easily withstand changes in air pressure—although they still cannot contend with the turbine blades, which can spin as fast as 80 metres per second.

But the Bats and Wind Energy Cooperative in the U.S. (yes, it’s for real) released a report recently about how to avoid this problem. Unsurprisingly, the method is simple: turn the turbines off. The group undertook a three-month long study at a wind farm in Pennsylvania and experimented with raising the “cut-in speed,” the minimum wind speed necessary for turbines to become operational. That means they don’t spin at lower wind speeds, which reduced bat deaths by 53% to 87% during the study period.

The trade-off, of course, is that wind energy producers have to contend with lower output—and profits. But the study found that annual energy output would be reduced by 1% at most, not an unbearable inconvenience to help alleviate an unpleasant effect of wind power. BWEC is also investigating other ways to mitigate fatalities without have to reduce operations, such as installing devices that interfere with the echolocation bats use to navigate in order to deter them from wind farms altogether.