Bats and wind turbines
Credit: IN WISCONSIN REPORTS, wpt2.org, Thursday, March 4, 2010
Here’s a mystery, why would bats known for stealth flying skills, that allows them to sense something as small as a human hair have a problem avoiding huge wind turbines? New research reveals what’s happening. Reporter Jo Garrett talks with one of Wisconsin’s leading bat experts who is helping to unravel the mystery.
Patty Loew:
This week we start with a mystery unraveling on the Wisconsin landscape. It’s a mystery surrounding deadly collisions between high-tech wind turbines and high flying bats. Wind power might be an ecofriendly source of alternative energy, but as “In Wisconsin” reporter Jo Garrett discovers, it’s killing bat populations across the state and in Dodge County.
Man:
The wings look good.
Jo Garrett:
These wings make up one of the most amazing flying machines ever.
Man:
The echolocation speeds up so fast it just sounds like a little buzz.
Jo Garrett:
Our fellow mammal, the bat, is the only mammal that can fly, and they’re stellar, so stellar that the US Air Force has actually funded a study on bat flight. They’re interested in developing micro air vehicles, based on the bat. Wisconsin bat researcher Dave Redell shows us the animal’s wing; some call it a “hand wing.”
Dave Redell:
Neat thing with these wings is that’s analogous to our thumb up here. And then these finger bones, that would be our, you know, index finger down to the pinkie right here. There’s the elbow.
Jo Garrett:
Bats evolved separately from birds. This elongated hand, skin stretched between the fingers, makes for a perfect air foil. Unlike an airplane or bird wing, it’s bendable, curving and changing as they fly. Stealthy bats can turn on a dime, think complex maneuvers in a cluttered environment, trees, branches and even other bats. They dodge. They dart. It’s said that these aerialists can read a spiderweb on the landscape, whip turn, and avoid it. So why are they colliding with these? Why are they running into wind turbines?
Dave Redell:
It’s amazing, you know, with the echolocation, able to sense something as fine as a human hair, you’d think something as big as a 747 would be a little easier to see. But that’s why it surprised all of us that they actually got affected.
Jo Garrett:
Redell works as a bat ecologist for the Wisconsin department of natural resources. He and other bat researchers around the world had noticed an alarming increase in bat mortality associated with wind farms.
Dave Redell:
Angela is checking the guidelines.
Jo Garrett:
Back in 2005, Redell and the DNR saw an opportunity to help them figure out why. A new wind farm was scheduled to be built in Wisconsin.
Dave Redell:
There’s been 12 studies with wind farms and bats, but they’ve been all after the wind farms have been built.
Jo Garrett:
This study would document, look at bat life.
Dave Redell:
We’re trying to fill in gaps of what altitude do they migrate at, forage, and commute.
Jo Garrett:
Before and after the introduction of a wind farm.
Dave Redell:
We really need to see the pre and the post together before you can draw any conclusions for the future. So we’re trying to develop tools here to look in the future.
Jo Garrett:
It’s a future that will be full of wind farms.
Dave Redell:
Renewables are the current push in the United States, as well as other parts of the world.
Jo Garrett:
Redell’s work and that of others could provide input for this growing industry on where to put their turbines, how to place them, build them, run them, to coexist with this other winged creature on the landscape.
Dave Redell:
It could be an attraction maybe associated with weather.
Jo Garrett:
Most importantly, they want to cut down on collisions between these tiny creatures and these massive turbines.
Dave Redell:
Some people looking at the physics of sound and echolocation are looking at the curvature of the blades.
Jo Garrett:
This mystery of bat mortality took an interesting turn last year. Bat researchers in Canada found out why some bats are dying. It has to do with the turbine blades. But there’s an interesting twist.
Dave Redell:
When you see them on the landscape, because they’re so big, it looks like they’re actually spinning quite slow, but out at the tip, that can be going 180, 200 miles an hour.
Jo Garrett:
And for many bats the problem seems to be not the blade, but what’s behind it.
Dave Redell:
What they found up in Canada was many of the bats weren’t actually hitting the turbine blades themselves, but were getting caught up with that pressure change behind the blade. Because of the aerodynamics of the blade coming through the air, it creates a pressure drop behind the blade and the bats flying through that, their internal organs aren’t set up to withstand that drastic pressure drop.
Dave Redell:
She could be producing lots of sound right now, we just can’t hear it.
Jo Garrett:
They are, like us, mammals with balloon-like lungs. When faced with this severe pressure drop, capillaries burst and fill the lungs with fluid. The bats drown as they fly.
Dave Redell:
Similar to the bends for divers, but I guess you could call it the “bat bends.”
Jo Garrett:
The phenomenon is called barometric change trauma or barotrauma. Birds, because they have a more rigid lung system, don’t get the bends. Another study on bats out of Pennsylvania points to a possible solution.
Dave Redell:
Changing the speed at which the turbines begin spinning to generate electricity.
Jo Garrett:
Bats like to fly at low wind speeds. When turbines aren’t generating much electricity. So…
Dave Redell:
If we can change it so they begin spinning after the wind speed picks up to a higher level, they’ve shown in these other studies that it can drastically reduce the number of fatalities by, say, anywhere from 60% to 80 some percent.
Jo Garrett:
Redell’s research continues, informed by these new findings. He hopes that Wisconsin will soon provide more information to help other researchers, regulators and wind farm owners to do their best by bats.
Patty Loew:
Last week, Jo Garrett reported on another threat facing bats nationwide, the deadly white nose syndrome that’s wiping out entire bat colonies out east. The concern? It will spread to Wisconsin. If you’d like to learn more, just go to our website at wpt.org and click on “In Wisconsin.” You’ll find several of our reports about Wisconsin’s bats.
Tags: Wind power, Wind energy, Bats, Video
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