ShareThisThe butterfly effect suggests the flapping of a tiny insect's wings in Africa can lead to a tornado in Kansas.
Call this the bat effect: A bat killed by a wind turbine in Somerset, Pa., can lead to higher tomato prices at the Wichita, Kan., farmers market.
Bats are something of a one-species stimulus program for farmers, every year gobbling up millions of bugs that could ruin a harvest. But the same biology that allows the winged creatures to sweep the night sky for fine dining also has made them susceptible to wind turbines.
The 420 wind turbines now in use across Pennsylvania killed more than 10,000 bats last year -- mostly in the late summer months, according to the state Game Commission. That's an average of 25 bats per turbine per year, and the Nature Conservancy predicts as many as 2,900 turbines will be set up across the state by 2030.
This is a bad time to be a bat.
It may seem like a good thing to those who fear the flying mammals, but the wind farm mortality rate is an acute example of how harnessing natural energy can lead to disruptions in the circle of life -- and the cycle of business. This chain of events mixes biology and economics: Bat populations go down, bug populations go up and farmers are left with the bill for more pesticide and crops, which accounts for those pricey tomatoes in Kansas.
Wind industry executives are shelling out millions of dollars on possible solutions that don't ruin their bottom line, even as wind farms in the area are collaborating with the state Game Commission to work carcass-combing into daily operations.
"If you look at a map and see where the mountains are, everything funnels through Somerset," said Tracey Librandi Mumma, the wildlife biologist who led the March commission report on bird and bat mortality.
Bats are nature's pesticide, consuming as many as 500 insects in one hour, or nearly 3,000 insects in one night, said Miguel Saviroff, the agricultural financial manager at the Penn State Cooperative Extension in Somerset County.
"A colony of just 100 little brown bats may consume a quarter of a million mosquitoes and other small insects in a night," he said.
If one turbine kills 25 bats in a year, that means one turbine accounted for about 17 million uneaten bugs in 2010.
Bats save farmers a lot of money: About $74 per acre, according to an April report in Science magazine that calculated the economic value of bats on a county-by-county basis.
Initially, the "Economic Importance of Bats in Agriculture" article was meant to attract attention to the white-nose fungus virus that is wiping out entire colonies of bats across the country.
"We were getting a lot of questions about why we should care about white-nose syndrome," said author Justin Boyles, a post-doctoral fellow in bat research at the University of Tennessee. "Really, it's the economic impact that makes people listen."
The white-nose syndrome is compounding the wind turbine problems, having killed more than a million bats in the northeastern United States since 2006.
Technology is being developed on sound generators that would deter the creatures from getting too close with a high-pitched noise only heard by bats. Some studies suggest that a slowdown in blade speed would reduce mortality.
But new technology is expensive and a blade slowdown would reduce the number of megawatts produced.
Bats suffer from a condition called barotrauma. It's the bat equivalent of the "bends" that scuba divers can suffer if they surface too quickly.
The rapid drop in air pressure around the blades causes the bats' lungs to burst, and they collapse with no ostensible lacerations or scars on the body.
Barotrauma in bats was discovered in 2008, when a Canadian biologist thought to dissect one of the unblemished carcasses turning up at wind farms across North America.
Contact Erich Schwartzel at eschwartzel(at)post-gazette.com. For more stories visit scrippsnews.com
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