Renewable energy vs. wildlife conservation - Solar, Wind and Land: Conflicts in Renewable Energy Development - page 87

Mitigation strategies for protecting bats near wind farms
In light of the aforementioned challenges, what can wind energy devel-
opers and operators do to prevent massive killings of bats on their projects
while still generating wind power? To date, researchers have been able to
uncover relatively few answers to this question. At least one study suggests
that painting wind turbines purple could be an onsite mitigation strategy
capable of reducing fatalities to bats, 97 although few developers have
actually tried it.
The most promising mitigation technique for protecting bats seems to
be the practice of increasing turbine “cut-in speeds” during night hours
when bats are most likely to be in the air. Typically, commercial wind
turbines are designed and programmed to begin rotating and generating
electricity when wind speeds reach eight to nine miles per hour. 98 A 2009
study co-sponsored in the United States by the Bats and Wind Energy
Cooperative and the Pennsylvania Game Commission concluded that
increasing the cut-in speed on one Pennsylvania wind farm's turbines to
approximately 11 miles per hour resulted in dramatic reductions in bat
fatalities. 99
Unfortunately, many operators of wind farms are not likely to view the
approach of increasing turbine cut-in speeds as an appealing solution to
this problem. The reductions in bat deaths in the Pennsylvania study were
likely attributable to the fact that, due to the increase in cut-in speeds, the
turbines involved in the study rotated less frequently. In other words, the
turbines were not generating power when wind speeds were between 8 and
11 miles per hour, even though they would have been generating power at
such wind speeds under normal operations. The Pennsylvania study was
conducted during relatively low-wind-speed months, so overall decreases in
energy production from the technique were relatively modest. 100 However,
any strategy that requires a major reduction in energy generation is costly
to wind farms and thus bound to be less popular with the wind energy
industry.
A case study of clashes between bats and wind farms: Animal Welfare
Institute v. Beech Ridge Energy LLC
The 2009 case of Animal Welfare Institute v. Beech Ridge Energy LLC 101
illustrates the inherent tension between protecting bats and promoting wind
energy. The defendants in the case, Beech Ridge Energy LLC and Invenergy
Wind LLC, were wind energy developers of a wind farm in Greenbrier
County, West Virginia, in the United States. Multiple plaintiffs filed suit
against the developers to enjoin operation of the project on the ground that
the project would otherwise result in the incidental “taking” of numerous
Indiana bats—a species of bat appearing on the endangered species list and
thus protected under the ESA.