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December 11, 2018

The Ultrasonic Technology is Poised to Change How the Wind Industry Manages Bat Conservation


NRG Systems, Inc., a designer and manufacturer of smart technologies for a range of wind, solar, and meteorological applications, has announced that a trial of its ultrasonic acoustic Bat Deterrent System reduced overall bat fatalities at the Los Vientos Wind Energy Facility in Starr County, Texas, U.S.A., by 54 percent. The results of the test prove that NRG Systems’ technology is an effective tool for reducing mortality of certain species of bats caused by wind turbines.

The Bat Deterrent System is based on “jamming” the echolocation capabilities of bats, which they rely on for orienting, foraging, and communication, while causing no harm to wildlife that encounter the treated airspace. The Bat Deterrent System emits an ultrasonic acoustic field in the same range as bats’ natural calling frequencies (20 kHz and 50 kHz). This interferes with their ability to receive and interpret their own echolocation calls and creates a disorienting airspace that is difficult to navigate. By jamming their echolocation systems in such a way, bats are discouraged from entering the treated airspaces and roosting locations. This concept is very similar to the practice of using white noise machines to mask unwanted sounds. The Bat Deterrent System only covers the rotor swept area of the wind turbine, so the intensity of ultrasonic noise beyond this region does not affect the bats. Since the rotor tips of modern wind turbines do not swing below 40 meters above ground level, bats foraging below this level are completely unaffected and will not be pushed out of their natural habitat. NRG thoroughly considered the unintended consequences of using ultrasonic noise for their Bat Deterrent System. There is no evidence that other species that frequent a wind turbine’s rotor swept area can hear ultrasound or that they are repelled by it, so NRG does not believe that its Bat Deterrent System will have an effect on any wildlife besides bats.

The test at the Los Vientos Wind Energy Facility was led by researchers from Texas State University in partnership with Bat Conservation International (BCI), and involved installing NRG’s Bat Deterrent Systems on 16 of the facility’s 255 turbines. Brogan Morton, Senior Product Manager at NRG Systems, said, “It is no secret that wind turbines cause mortality to bats. This has become an increasingly critical issue as bat populations across North America continue to decline. NRG set out to develop a technology that would allow wind developers and operators to protect bats while creating more energy more of the time. We are incredibly pleased to say that we are well on our way to making this a reality.” Sara Weaver, doctoral candidate at Texas State University, and biology lecturer at A&M, San Antonio, who led the Los Vientos study, said, “Our results from a robust, two-year study at an operational wind energy facility in Texas indicate NRG’s acoustic deterrents significantly reduce Brazilian free-tailed bat and hoary bat fatalities. Based on these results, the technology is a promising tool for reducing bat fatalities at wind turbines.”

While 2018 marks three years of testing for NRG’s Bat Deterrent System, research around using ultrasonic acoustic deterrents to reduce bat fatalities at wind turbines has been underway for over a decade. This was led by The Bats and Wind Energy Cooperative (BWEC), an organization that BCI helped launch and continues to coordinate. Established in 2003, other founding members of BWEC include the US Fish and Wildlife Service, the American Wind Energy Association (AWEA), and the National Renewable Energy Laboratory of the US Department of Energy (NREL).

“Bat Conservation International is proud to partner with companies like NRG Systems – entrepreneurs looking to reduce bat fatalities at wind turbine sites,” said Mylea Bayless, Senior Director of Network & Partnerships at BCI.  “We hope that future testing shows continued mortality reduction in additional species and that NRG’s Bat Deterrent System will serve as a highly effective tool for wind developers and operators looking to minimize their impact on bat populations.”

NRG’s Bat Deterrent System will be commercially available in North America in 2019. Currently, NRG’s Bat Deterrent System has only been tested in North America. NRG plans to hold trials of the technology in Europe in the near future, and looks forward to learning more about their Bat Deterrent System’s effectiveness in this region, which is home to its own unique bat population.

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