Description and Background: Curtailment of wind turbines during low wind speeds is a leading solution in reducing bat fatalities caused by collision with turbines. This method, often referred to as blanket curtailment, has been shown to significantly reduce fatalities at projects throughout North America. A threshold wind speed is established below which bat activity is likely to be highest and turbines are not allowed to operate. However, this can translate to a considerable loss of energy production and associated revenue. An alternative approach, often referred to as smart or informed curtailment, is to use additional data to curtail only when bats occur or are likely to be present within the rotor swept area and at risk of collision. Natural Power developed the EchoSense smart curtailment system, which combines wind speed and temperature data with bat acoustic data measured in real-time to determine when bats are present during the active season and to curtail appropriately under set conditions. This approach, which has been tested and operational for the past 3 years, provides comparable conservation benefits to blanket curtailment with lower energy losses. During a recent study, we compared EchoSense to blanket curtailment in terms of fatality rates and financial benefits. There was no significant difference in the number of fatalities between blanket and EchoSense curtailment. The reduction in energy loss associated with EchoSense compared to blanket curtailment ranged from 41% to 56%. Thus, the use of EchoSense in place of blanket curtailment at this site would be expected to translate into a considerable increase in annual revenue. The implications and benefits of using smart curtailment systems at wind projects that may be subject to additional mitigation measures because of sensitive bat species will be discussed.
