Ultrasonic noise emissions from wind turbines: potential effects on bat species

The impact that wind turbines have on the environment, particularly with respect to wildlife such as bat species, has generated increasing concern over the last decade. Although the harnessing of wind power is becoming much more widespread as a clean, renewable energy resource, the increasing global turbine mortality rates for bats are thought to be significantly detrimental to susceptible species. Much research is still needed to fully understand the ways in which turbines affect bats, since they rely on echolocation and audible cues to hunt and navigate, therefore having a unique acoustic perspective of objects in their vicinity. Here we present an overview of what is currently known regarding ultrasonic emissions from operational wind turbine structures, including noise generated from the gearing mechanism, rotor, or through blade defects, and how such noise may be perceptible to some bat species in the local turbine habitat

Wind turbines and bat mortality: interactions of bat echolocation pulses with moving turbine rotor blades.

Wind power is a rapidly growing energy technology, popular for being a clean, reliable and cost-efficient renewable energy source. However, recently concern has been growing over the impact of wind turbines on flying wildlife, with both birds and bats found dead around turbine bases and observed collisions with moving turbine rotors. This phenomenon is widespread and has received enough attention to warrant investigation into how and why these collisions occur. In this paper we investigate the acoustic interaction of bats with wind turbines, in particular the interpretation of reflected sound pulses (echolocation) used by bats to navigate. This paper focuses on the effects of moving turbine rotor blades on reflected acoustic pulses, analogous to what might be presented to an echolocating bat approaching an operational turbine at rotor height. High frequency, simulated FM bat pulses were used to assess reflected echo properties from microturbines (experimentally and in simulation) in order to investigate what interaction rotor movements had with incoming pulses and the potential consequences for an echolocating bat near a moving wind turbine