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Bat Deterrent Systems

Bat Deterrent Systems

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NRG Systems is currently developing a pioneering new technology that will help support bat conservation – one of the most pressing issues facing the wind industry today.

As White-Nose Syndrome continues to ravage the populations of many hibernating bat species, the wind industry remains committed to lessening its impact on wildlife, including contributing to bat fatalities. While it is well researched that wind turbines cause mortality to bats, successful minimization methods have been implemented. Presently, the most effective techniques involve curtailment, which requires a reduction in energy generation. NRG Systems understands that this is not an ideal option for wind plant operators, so we have set out to develop Bat Deterrent Systems that could significantly reduce bat take without curtailment, meaning operators can produce more renewable energy more of the time while keeping all bats out of harm’s way.

The video above shows a pond test of NRG's Bat Deterrent Systems. The Deterrents were turned on for 5 minutes and then off for 5 minutes multiple times. The left-hand side shows the bats’ flight paths (green dots) when the Deterrents were off, while the right-hand side shows the bats’ flight paths (red dots) when the Deterrents were on. As seen in the video, there was a significant reduction in the amount of bat activity when the Deterrents were on.

HOW IT WORKS

NRG Systems’ Bat Deterrent Systems discourage bats from flying within a turbine’s rotor swept area by emitting an ultrasonic acoustic field that matches their natural calling frequencies. This effectively jams their echolocation systems and discourages them from the airspace, keeping them at a safe distance from the rotor.

Early trials have yielded positive results and NRG Systems is currently field testing Bat Deterrent Systems with a variety of wind plant operators. We expect our Bat Deterrent Systems to be commercially available in early 2018.

Bat Deterrent System FAQs

As bats approach the turbine, the intensity of the ultrasonic noice gradually increases, leading them away from the areas where sound levels could affect their hearing.

Because bats have very good directional hearing and the ultrasonic noise gradually increases as they approach the turbine, they are able to avoid any airspace where they would completely lose the ability to orient themselves. During field testing of the Bat Deterrent Systems, which was conducted on ponds where bats congregate, the bats immediately move in the opposite direction of the ultrasonic noise and did not become disoriented.

Our Bat Deterrent Systems only cover the rotor swept area of the 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 40m above ground level, bats foraging below this level are completely unaffected and will not be pushed out of their natural habitat.

When wildlife get used to an unnatural visual or acoustic disturbance that is meant to keep them out of an area it is called habituation (imagine a bird perched on a scarecrow).  Luckily, our Bat Deterrent Systems are not meant to simply annoy or frighten bats—the ultrasonic noise they emit actually interferes with their ability to orient and forage. Because bats rely so heavily on echolocation, they know to avoid any area that compromises this capability.

We thoroughly considered the unintended consequences of using ultrasonic noise for our Bat Deterrent Systems. There is no evidence that birds can hear ultrasound or that they are repelled by it, so we do not believe that our Systems will have an effect on any wildlife besides bats. During some of the field testing that we have conducted on ponds, herons and ducks have flown into and stayed in the areas covered by our deterrent devices, while the bats stayed away.

The current version of our Bat Deterrent System affects bat species whose call frequencies are between 20 kHz and 50 kHz. This covers all of the bat species found in North America, including endangered myotis species, and a vast majority of bats found in Europe.