Friday, December 6, 2013

Wind Turbines and Bats

A better idea will be to mount sound devices on the blades that emit in the sound range used by bats for navigation.  Such an effect would make the local environment impossible to use and the bats would be forced to avoid it.  We also may want to try something like that to fend of birds while we are at it.  This should turn out to be possible.

These wind turbines have turned out to be far better killers of birds than we had ever expected.  The problem is big enough to now take seriously and solve.

Sonic devices certainly recommend themselves provided they operate outside our own hearing range.  If not then they have to be narrowly constrained perhaps along the leading edge.

Wind turbines are giant killers of bats


Alternative forms of energy, such as solar power that relies on arrays of mirrors in the desert that focus beams of sunlight to drive a generator, or wind turbines, have been shown to have a significant environmental impact in some cases. A solar energy complex located between Los Angeles and Las Vegas has been blamed for actually singeing off the wings of migrating birds that were unlucky enough to fly through the focused sunbeam. In another cases, wind turbines have been dubbed ‘bird Cuisinarts’ for supposedly shredding birds caught in the propellers that catch air currents and turn generators.

A new study shows that wind turbines may also be a menace for bats.  Mark Hayes, a researcher at the University of Colorado Denver said of the results of his study, "The development and expansion of wind energy facilities is a key threat to bat populations in North America." He added, "Dead bats are being found underneath wind turbines across North America. The estimate of bat fatalities is probably conservative." According to the study, more than 600,000 bats were killed by wind energy turbines in 2012. Bats, while they often get a bad rap, are prodigious eaters of flying insects such as houseflies and mosquitoes, while they also serve as pollinators of economically important crops.

Hayes, who is an expert in integrated biology, said that cities such as Buffalo, Tennessee and Mountaineer, West Virginia in the Appalachians had the highest rate of fatalities for bats. However, according to UCD, little is known so far about bat deaths attributable to wind turbines west of the Rocky Mountains and the Sierra Nevada range. The bats most represented in the study are the hoary bat, eastern bat and the silver-haired bat. There are currently forty-five known bat species in the lower 48 states of the U.S. 

The study shows that hapless bats become victims when they fly into the spinning blades of wind turbines, which can rotate at 179 mph. Their blades can reach 130 feet. Before the study emerged, the estimate of bat mortality ranged from 33,000 to 880,000. Hayes said that the number of bat fatalities could be as high as 900,000.

UCD noted that Hayes’ estimates may be conservative. Hayes chose the minimum estimate for bat mortality when a range of deaths was reported. Also, the amount of mortality came from estimates for only the migratory period for bats. Bats largely migrate during the autumn months in North America.

Hayes said his estimates are likely conservative for two reasons. First, when a range of fatality estimates were reported at a wind facility, he chose the minimum estimate. Secondly, the number of deaths was estimated for just migratory periods, not the entire year, likely leaving out many other fatalities.

Researcher Hayes suggests that bat mortality could be lessened if wind turbines are activated only when there are higher wind speeds and thus during periods when bats are not likely to fly. "A lot of bats are killed because the turbines move at low wind speeds, which is when most bats fly around," said Hayes, who has studied bats for 15 years, according to UCD. A decrease of operational speeds for wind turbines from 10 mph to 18 or 20 mph could drop the fatalities by 40 to 90 percent.

Hayes was philosophical about the likelihood that more bats will die as more wind turbines pop up. Said Hayes, "I am not against wind energy. It's clean, it reduces pollution and it creates jobs. But there are negative impacts," he said. "Still, I think this is a problem we can solve."

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