News from Ecosa

Reducing the impact of wind turbines on bats

23 July 2013

ECOSA has been involved in a number of on-shore wind farm projects, conducting Ecological Impact Assessments (EcIA) for our renewable energy clients. These projects include surveys of bat activity on site and analysis of bat activity in relation to turbine locations both at height and at ground level.

Following concerns about dead bats found underneath wind turbines in North America and Europe, a report^* promoted by Bat Conservation International offers new insight into the potential to reduce bat fatalities on wind farms. The report synthesises data from ten operational mitigation studies on wind energy developments in North America. Its conclusions show that the fatalities can be reduced by as much as 70% when certain operational parameters are applied, including:

• Increasing wind turbine cut-in speed;
• Feathering turbine blades at or below the cut-in speed, when turbines are producing no electricity into the power grid; and
• Applying these adjustments when bats are likely to be more active, for example by temperature, time of night and seasonal bat activity.

It is to be hoped that where such measures can be automated and shown to result in an output loss of less than 1% as the report suggests, the benefits of wind energy will be diluted less by the issue of associated bat mortalities.

^*Arnett, E. B., G. D. Johnson, W. P. Erickson, and C. D. Hein. 2013. A synthesis of operational mitigation studies to reduce bat fatalities at wind energy facilities in North America. A report submitted to the National Renewable Energy Laboratory. Bat Conservation International. Austin, Texas, USA.