Synthesis of Bat Curtailment Studies

Bat fatalities at wind energy facilities have been widely known since 2003. To reduce bat fatalities operational minimization strategies have been developed and implemented with successful results. In 2015, voluntary... [ view full abstract ]

Bat fatalities at wind energy facilities have been widely known since 2003. To reduce bat fatalities operational minimization strategies have been developed and implemented with successful results. In 2015, voluntary operational practices aimed at reducing bat fatalities from wind turbines by up to 30 percent were established by the wind power industry. These strategies will adjust the operation of wind turbines during the fall migration season when bats are at the highest risk of collision with moving turbine blades. Adjusting turbine blade rotation by changing cut-in speed (“turbine curtailment”) does potentially reduce energy generation and therefore leads to monetary losses to wind energy companies, as well as losses in generated renewable energy which must then be generated by other means.

Here we provide an updated synthesis of results from publicly available turbine curtailment studies designed to reduce bat fatalities at wind energy facilities since 2009. Summaries and evaluations of the studies are provided. A synthesis of the results shows strong correlation between all bat fatality reductions with increasing cut-in speeds at operational facilities in North America. Additionally, studies that include feathering of turbine blades below the normal cut-in wind speed are evaluated and summarized. We provide examples of different curtailment strategies employed at different wind energy facilities and a summary of lessons learned from the most recent curtailment studies to be used for future operational wind facilities.