A recent trial of NRG Systems’ bat deterrent system at an EDF Renewables wind farm in Illinois yielded an overall reduction in bat fatalities of 67%, as well as greater reductions with species commonly affected by wind projects.
EDF, developer of the 175 MW Pilot Hill Wind Project, tested NRG’s ultrasonic acoustic system at the facility between August and October 2018. Fifteen out of the facility’s 103 turbines were outfitted with bat deterrent systems, and a 5.0 m/s cut-in speed curtailment was simultaneously applied at the deterrent-equipped turbines.
“Our goal with this trial was to gauge the efficacy of combining curtailment with NRG’s bat deterrent system to reduce bat mortality at wind turbines,” says Michael Azeka, director of environmental strategy at EDF Renewables. “The results of this trial are very encouraging and suggest that this approach to minimizing bat impacts is a compelling one for the wind industry.”
There are several bat species present at Pilot Hill, including multiple migratory tree species. The testing revealed a significant reduction of 72% with silver-haired bats, 71% with hoary bats and 94% with big brown bats. Eastern red bats proved harder to deter, with a 58% reduction in mortality for the two treatments together, reports EDF.
At the moment, raising cut-in wind speed is the most widely used method for reducing bat mortality at wind turbines, according to the partners, which add that although the method is effective, many wind plants in North America experience a significant loss of energy production.
Brogan Morton, senior product manager at NRG Systems, says, “The Pilot Hill trial is especially encouraging because it suggests that we can minimize bat impacts while increasing the amount of energy produced at wind plants struggling with this crucial issue. This is a win for all parties involved, including developers, conservationists and, most importantly, the planet.”
The trial was preceded by a two-year study at the Los Vientos Wind Energy Facility in Texas, which saw an overall reduction in bat fatalities of 54%. NRG’s system is currently available is North America, and the company also plans to hold trials of the technology in Europe this year.
Located in Kankakee and Iroquois counties, the Pilot Hill Wind Project, in operation since 2015, has a 20-year power purchase agreement with Microsoft Corp.