Bat Barotrauma and Wind Turbines
Aug. 25th, 2008 01:37 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
webfarmerCanadian researchers are now reporting that it may not be the wind turbine blades that kill bats, at least exclusively so, but rather the change in air pressure as they go from the high pressure area ahead of the turbine (where the air slows down - a bit like a large flowing football crowd as it gets close to a stadium) and then is exposed to the low pressure area behind the turbine (lower pressure because the flow has been slowed and expanded by the aerodynamic power extraction effect of the rotor blades).
Looks like the alternatives are to run the turbines when migrations are not on-going, during low wind periods when the bats tend to be in the air or find some way of making the bats avoid the turbines (emitting some kind of sound or light they might not like). They've already had some success in mitigating bat kills by changing the cut-in (turn on) wind speed for the turbines.
Wind Turbines Kill Bats Without Impact - Discovery News - 25 Aug 08
"All species are susceptible to death by sudden change in air pressure, Baerwald said. 'But the larger the animal is, the bigger the air pressure drop has to be. We know that four kilopascals [a unit of pressure] is enough to kill a rat. Bats are much smaller. We found that these wind turbines produce a five to 10 kilopascal drop.'
Birds are less vulnerable to the drop, because they have rigid, tubular lungs, compared to the balloon-like structures of bat lungs, which are much like human lungs."
Wind Turbines Make Bat Lungs Explode - New Scientist - 25 Aug 08
"Why bats - who echolocate moving objects - are killed by turbines has remained a mystery until now. The research council thought the high-frequency noise from the turbines' gears and blades could be disrupting the bats' echolocation systems.
In fact, a new study shows that the moving blades cause a drop in pressure that makes the delicate lungs of bats suddenly expand, bursting the tissue's blood vessels. This is known as a barotrauma, and is well-known to scuba divers. 'While searching for bat carcasses under wind turbines, we noticed that many of the carcasses had no external injuries or no visible cause of death,' says Erin Baerwald of the University of Calgary in Canada."
Looks like the alternatives are to run the turbines when migrations are not on-going, during low wind periods when the bats tend to be in the air or find some way of making the bats avoid the turbines (emitting some kind of sound or light they might not like). They've already had some success in mitigating bat kills by changing the cut-in (turn on) wind speed for the turbines.
Wind Turbines Kill Bats Without Impact - Discovery News - 25 Aug 08
"All species are susceptible to death by sudden change in air pressure, Baerwald said. 'But the larger the animal is, the bigger the air pressure drop has to be. We know that four kilopascals [a unit of pressure] is enough to kill a rat. Bats are much smaller. We found that these wind turbines produce a five to 10 kilopascal drop.'
Birds are less vulnerable to the drop, because they have rigid, tubular lungs, compared to the balloon-like structures of bat lungs, which are much like human lungs."
Wind Turbines Make Bat Lungs Explode - New Scientist - 25 Aug 08
"Why bats - who echolocate moving objects - are killed by turbines has remained a mystery until now. The research council thought the high-frequency noise from the turbines' gears and blades could be disrupting the bats' echolocation systems.
In fact, a new study shows that the moving blades cause a drop in pressure that makes the delicate lungs of bats suddenly expand, bursting the tissue's blood vessels. This is known as a barotrauma, and is well-known to scuba divers. 'While searching for bat carcasses under wind turbines, we noticed that many of the carcasses had no external injuries or no visible cause of death,' says Erin Baerwald of the University of Calgary in Canada."
