National‐scale impacts on wind energy production under curtailment scenarios to reduce bat fatalities

Abstract

Wind energy often plays a major role in meeting renewable energy policy objectives; however, increased deployment can raise concerns regarding the impacts of wind plants on certain wildlife. Particularly, estimates suggest hundreds of thousands of bat fatalities occur annually at wind plants across North America, with potential implications for the viability of several bat species. One approach to reducing bat fatalities is shutting down (or curtailing) turbines when bats are most at risk, such as at night during relatively low wind speed periods throughout summer and early autumn.While curtailment has consistently been shown to reduce bat fatalities, the lost power production reduces revenues for wind plants. This study conducted simulations with a range of curtailment scenarios across the contiguous United States to examine sensitivities of annual energy production (AEP) loss and potential impacts on economic metrics for future wind energy deployment. We found that AEP reduction can vary across the country from less than 1% to more than 10% for different curtailment scenarios. From an estimated 2891 gigawatts (GW) of simulated economically viable wind capacity (measured by a positive net present value), we found the mid curtailment scenario (6.0 m/s wind speed cut-in from July 1 through October 31) reduced the quantity of economic wind capacity by 274 GW or 9.5%. Our results indicate that high levels of curtailment could substantially reduce the future footprint of financially viable wind energy. In this context, future work that illuminates cost-effective strategies to minimize curtailment while reducing bat fatalities would be of value.

Seasonal patterns of bird and bat collision fatalities at wind turbines

“…This suggests a nearly 5-months-long period during which bat fatalities at wind facilities in the U.S. are elevated. Region-specific curtailment requirements would shorten the duration of curtailment at any individual facility, which at present is typically instituted during some period of time from July–October [ 24 ]. However, complicating translation of our results into practice is the finding that the timing of carcass discoveries varied by location and year.…”

“…Nonetheless, we think that variation in curtailment regimes is unlikely to affect our results or conclusions. Curtailment in the U.S. is usually imposed during a specific window of time when bat fatalities are expected to be greatest, typically July–October [ 24 ]. If effective, curtailment should depress seasonal peaks in fatality counts but will not introduce spurious peaks in carcass counts.…”