Fewer bats dying after Alberta wind turbines tweaked
 
 
September 25, 2009

 
"Given that more bat fatalities occur in low wind speeds and the 
relative ease of manipulating operation of turbines, we examined 
whether reducing the amount that turbine rotors turn in low wind speeds 
would reduce bat fatalities."
 
"Given that more bat fatalities occur in low wind speeds and the 
relative ease of manipulating operation of turbines, we examined 
whether reducing the amount that turbine rotors turn in low wind speeds 
would reduce bat fatalities."
Photograph by: Courtesy of Hydro-QuÈbec.,

CALGARY — University of Calgary researchers say they've discovered a 
simple way to drastically reduce the number of bats killed near wind 
turbines in southern Alberta.

The study, published in the Journal of Wildlife Management, found that 
slowing the turbine blades in the area of Pincher Creek, Alta., during 
periods of light wind reduced migratory-bat mortality by up to 60 per 
cent.

Pincher Creek is about 200 kilometres south of Calgary.

The findings come on the heels of previous research that blamed the 
sudden changes in air around the wind turbines for killing large 
numbers of bats every year, as the mammal's respiratory system wasn't 
able to withstand the pressure.

TransAlta initiated the followup study to figure out how to reduce the 
number of deaths without significantly reducing the wind energy the 
turbines generate.

Researchers began with the premise that the tiny bats don't like to fly 
in high winds, said U of C biology professor Robert Barclay, who co-
authored the paper.

"The idea was, if most of the bat activity is when the wind isn't 
blowing all that hard and most of the energy is produced when the wind 
is blowing hard, perhaps there's a way of modifying how the turbines 
operate when the wind's not very strong, thereby reducing the 
fatalities," Barclay said.

Most of the bats dying near the turbines are migratory, including the 
silver-haired and hoary species. The bats apparently move to Alberta 
for the summer to give birth, then fly down south for the winter, 
Barclay said.

It's during their migration period that they become most vulnerable to 
the wind turbines.

The efforts to reduce the deaths factored in the wind speeds bats tend 
to fly in, and the turbines' mechanical capabilities, said study co-
author Erin Baerwald.

"Given that more bat fatalities occur in low wind speeds and the 
relative ease of manipulating operation of turbines, we examined 
whether reducing the amount that turbine rotors turn in low wind speeds 
would reduce bat fatalities," she said.

TransAlta operators made a simple adjustment to the amount of wind 
speed needed to start the blades turning, said Barclay.

The efforts proved successful, he said, with researchers recording a 60 
per cent drop in the fatality rate with minimal impact to the energy 
operation.