The development of NRG’s Bat Deterrent System was a years-long process that involved extensive testing carried out by leading energy and environmental experts. The data and knowledge collected during this time were crucial to bringing a viable and effective product to market.

While our deterrent technology has been commercially available for well over a year, NRG continues to look for new ways to optimize our product to protect more bats at wind turbines. However, this continuous improvement relies heavily on our understanding of how bats behave in relation to the technology.

Bats are notoriously difficult to study due to their small size, nocturnal habits, and penchant for hiding during daylight hours. Therefore, we were particularly excited when researchers from the National Renewable Energy Laboratory (NREL) asked NRG to take part in an innovative study exploring how bats interact with ultrasonic acoustic deterrents.

The "open air" flight cage. Image courtesy of Texas State University.

The study, launched in the fall of 2019 at Texas State University, involved constructing an “open air” flight cage with NRG’s acoustic deterrent devices mounted on either end. Thermal video and acoustic detectors are used to record the behavior of bats around the deterrent systems. The data collected from these observations will help the research team gain a better understanding of how bats are responding to ultrasonic acoustic deterrents. They are also hoping to quantify the relationship between bats and sound pressure level at different frequencies, observe potential seasonal differences in behaviors, and determine whether bats change their echolocation characteristics in the presence of deterrent signals.

Sara Weaver, a Senior Ecologist and Project Manager at Bowman Consulting who led critical field studies of our Bat Deterrent System and is currently involved in the NREL flight cage study, said, “We know that deterrent effectiveness varies by species, with deterrents being highly effective for some bat species and not for others. The flight cage allows us to observe species-specific behaviors around deterrents to better understand why there are differences. Having this knowledge may help us refine the current system to increase effectiveness for more species. There are still many questions to be answered regarding ways to advance the technology, and this collaboration is a vital step in the process.”

The first trial at the flight cage involved 30 cave myotis bats and 12 Brazilian free-tailed bats. One bat was released into the flight cage at a time, allowing the team to closely monitor its behavior. Unlike the pond tests and wind turbine trials NRG participated in during product development, the flight cage allows us to control which bats are observed so that we can form more concrete assumptions about species-specific interactions with our deterrents. When testing in nature, there is less certainty around which species are present. A second trial targeting more species, such as tricolored, eastern red, and evening bats, was scheduled to take place at the flight cage in spring 2020 but has been postponed until Autumn 2020 due to COVID-19.

NRG Systems is thrilled to be a part of this study and we are eager to apply the insights gathered at the flight cage to improve the effectiveness of ultrasonic acoustic deterrents for as many bat species as possible.

Interested in learning more about this innovative technology? Head to the Bat Deterrent System product page on our website. An in-depth article about this study can also be found on the Office of Energy Efficiency and Renewable Energy’s website.

Study Uses NRG’s Bat Deterrent Systems to Analyze Bat Behavior

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