Reassessing Risk using Acoustic Exposure Results Summary

This study was funded by the Renewable Energy Wildlife Research Fund to assess the relationship between acoustic bat activity and fatality rates on wind farms.

Wind turbine curtailment is a reliable and widely used method to reduce turbine-related bat mortality. However, the practice also reduces the amount of energy that turbines can generate. Focusing curtailment strategies on periods when risk to bats is greatest can reduce energy losses associated with curtailment, but requires reliable information on when and under what conditions bats are active in the rotor-swept zone of turbines. Data from turbine-mounted acoustic detectors can be used to calculate acoustic exposure — a metric of how many bat passes were detected when turbine rotors were spinning — allowing wind energy facility operators to measure how effectively curtailment strategies prevent turbine operation when bats are active and compare alternative strategies. Such feedback is critical for balancing the simultaneous needs to reduce turbine-related impacts to bats and increasing renewable energy generation. This project explored the relationship between acoustic exposure and fatalities and demonstrated how acoustic exposure can be used to compare curtailment strategies. By assessing how height, season, wind speed influence simulated exposure, we can better understand how these factors influence fatality risk and how to best manage this risk by using curtailment strategically.