Rotor-mounted Bat Impact Deterrence System

Frontier Wind, supported by grants from the California Energy Commission (CEC) and the US Department of Energy (DOE), is developing a system to deter bats from flying/foraging near the blades of wind energy generators.... [ view full abstract ]

Frontier Wind, supported by grants from the California Energy Commission (CEC) and the US Department of Energy (DOE), is developing a system to deter bats from flying/foraging near the blades of wind energy generators. Frontier Wind designed and will study the effectiveness of a bat impact deterrence system that utilizes ultrasound transmitters mounted on a wind turbine rotor. Prior attempts at ultrasound deterrents only mounted the transmitters to the tower or nacelle were limited due to the rapid attenuation of ultrasonic frequencies and their ability to ensonify the full rotor swept area. Coverage is estimated at 5-20 meters, leaving a substantial area of the rotor as well as high and low pressure areas around the rotor blades unprotected. Frontier Wind’s innovative approach will mount a minimally invasive array of ultrasound transmitters along the length of the turbine blades, providing coverage of the entire rotor envelope and as well as a buffer zone beyond the envelope.

The goal of the project is to develop and demonstrate an effective bat impact deterrence system which will reduce curtailment at wind farms and allow for expansion of wind farm generation. Specific objectives of this project include designing and fabricating the deterrence system, assessing the effectiveness of the installed system in reducing bat fatalities at operating wind turbines, creating processes for installation on the population of operating turbines and new turbines, and creating system controller settings optimized for a range of bat species.

The project will field a system that meets the bat mitigation requirements for the turbine operating life in a matter that is cost effective in both system fabrication and installation while not negatively impacting turbine operations. Frontier Wind developed and tested an acoustic model utilizing the wind turbine blade design/dimensions to determine the optimal configuration of transmitters to provide sound transmission coverage across the turbine rotor swept volume.

Pattern Energy has agreed to partner with Frontier Wind to allow testing of the deterrent system to occur at Pattern’s Hatchet Ridge Wind Facility (HRWF) in California on 13 of the farm’s 44 turbines. Bat carcass data collected from the field study benefits from and will expand upon work from previous deterrent studies. The research will indicate the system’s effectiveness in reducing bat fatalities, relative to control turbines that will operate normally and without deterrents. Frontier Wind has partnered with experienced bat specialists known in the industry to plan and conduct the bat impact study.

The proposed research will be conducted over an eight-week period in August and September during 2016 and 2017. This time frame overlaps with the fall migration period for bats at HRWF. This also targets the period when the majority of bat fatalities at wind energy facilities have occurred. During 3 years of previous carcass monitoring at HRWF, 64.2% carcasses were collected in August and September.

Introducing this technology to the market will have the broad impact of reducing curtailment activities at wind farms as well as increasing the rate of additional wind farm development across the country.