Accelerating Renewables While Reducing Impacts

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Duke Energy plans to grow its renewables portfolio to 16,000 megawatts by the end of 2025. While these clean energy sources are emissions-free, they can still face environmental hurdles – and the company is taking a leading role in getting ahead of this challenge.

For example, hundreds of thousands of bats die every year at North American wind farms. Ultrasonic deterrents were seen as one potential solution, but very few field studies had been conducted at utility-scale facilities. When Duke Energy’s environmental scientists learned of a promising new technology in need of a host site, they offered to facilitate a study at the company’s Los Vientos wind farm in south Texas.

In partnership with Texas State University, Texas Parks & Wildlife, Bat Conservation International, Vestas, and NRG Systems, the technology’s developer, researchers tested a device that emits highfrequency sounds on 16 of the site’s 255 wind turbines.

In partnership with Texas State University, Texas Parks & Wildlife, Bat Conservation International, Vestas, and NRG Systems, the technology’s developer, researchers tested a device that emits high-frequency sounds on 16 of the site’s 255 wind turbines. This ultrasonic sound essentially disrupts the bats’ echolocation capabilities – their system for navigation and finding food. It does not harm the bats but since they cannot echolocate, they leave the area around the turbine’s blades. The sound is above human hearing range, dissipates quickly and does not impact other wildlife or livestock.

Over the course of a two-year study, the system was found to reduce bat fatalities by 50 percent overall, and by nearly 80 percent for the hoary bat, a species of conservation concern. The results were significant enough that Duke Energy committed to add the technology to all 255 Los Vientos turbines – the first commercial-scale installation in the continental United States.

Such measures aren’t limited to bats. At other wind farms, Duke Energy has implemented innovative eagle protection systems and facilitated research into their effectiveness; one recent study demonstrated an 82 percent reduction in eagle fatalities. By sharing this third-party analysis, the company hopes its leading-edge approach will help accelerate renewable energy growth nationwide.