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Ultrasonic Bat Signal Will Protect Sensitive Species from Wind-turbine Blades

Yahya Modarres-Sadeghi

The U.S. Department of Energy (DOE) has issued a $250,000 grant, augmented by $62,500 from the Massachusetts Clean Energy Center, to a team led by researchers at UMass Amherst to develop a blade-mounted, ultrasonic whistle on wind turbines to deter and protect bat species. As air flows over the wind turbine blade, the device will produce a deterrence signal. The project will address the challenge of deterring bats across the entire wind-turbine rotor and test whether a pulsed noise, similar to a bat call, can act as an effective warning. The project, entitled “A Biomimetic Ultrasonic Whistle for Use as a Bat Deterrent on Wind Turbines,” was funded by the DOE’s Office of Energy Efficiency & Renewable Energy. Read related article: The announcement of funded proposals can be found at here.

Dr. Paul Sievert of the Department of Environmental Conservation at UMass Amherst will direct the project, while Principal Investigator Dr. Yahya Modarres-Sadeghi of the Mechanical and Industrial Engineering (MIE) Department at UMass and collaborator Dr. Michael Smotherman of the Biology Department at Texas A & M University will oversee activities in their respective programs. UMass Biology Professor Elizabeth Dumont and MIE Professor Matthew Lackner will serve advisory roles in connection with bat larynx modeling and whistle placement, respectively. Other members of the research team are UMass IGERT Student Fellows Zara Dowling and Daniel Carlson. This collaboration largely represents an outgrowth of the UMass Offshore Wind IGERT, a program, led by UMass MIE Professor Erin Baker, which brings together the Departments of Environmental Conservation, Mechanical & Industrial Engineering, and other fields, to address interdisciplinary problems in the area of offshore wind development.

The DOE noted that it issued “$1.75 million for five projects that will develop and demonstrate technologies to reduce the potential impacts of wind farms on sensitive bat species. A current challenge facing wind energy developers in the United States is how to protect wildlife while responsibly deploying and operating this reliable source of clean energy. As wind energy continues to grow as a major supplier of renewable electricity in communities throughout America, new mitigation techniques and technologies could help minimize its environmental impacts to bats and other sensitive wildlife.”

The UMass project will focus on design and manufacturing of a biomimetic ultrasonic pulse generator for use as a bat deterrent on wind turbines. As the UMass DOE proposal said, “We will design a whistle-like device based on a bat larynx, mechanically powered via air flow over the wind turbine blade. We will carry out an iterative process of whistle design alternating with laboratory testing on bats to create a series of devices which effectively induce a flight avoidance response for at-risk bat species. Ultimately, our goal is to provide a reliable, cost-effective means of alerting bats to the presence of moving turbine blades, reducing bat mortality at wind facilities, and reducing regulatory uncertainty for wind facility developers.” 

Specifically, the research team intends to create a biomimetic device that produces a short, broadband sound spanning the ultrasonic range in which hearing sensitivity is highest in the bats most impacted by wind turbines. The researchers will also conduct a series of laboratory and field experiments on at-risk bat species to evaluate flight response to acoustic stimuli, specifically identifying frequency ranges, intensity, and patterns of sound that induce avoidance responses across three Vespertilionid species. 

A series of iterative testing and modeling will be used to optimize acoustic features to evoke avoidance behavior in bats. Bandwidth, intensity, directionality and beam projection pattern of the device will be optimized for positioning on turbine blades.

“Because the source of sound generation will be mechanical in nature, these innovative devices will require no external power source, should require little maintenance, and will be small and cost-effective,” as the UMass proposal explained. “The small size of these devices will allow us to position them at intervals along the turbine blade, addressing the issue of rapid attenuation of ultrasound in the atmosphere, without reducing blade efficiency.”

The DOE announced that all the funded projects “build on the Wind Program’s work to remove barriers to wind power deployment and increase the acceptance of wind power technologies by addressing siting and environmental issues. These technologies, if successful, will protect wildlife and also provide the wind industry with new tools to minimize regulatory and financial risks.” (April 2015)