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Providing evidence to improve practice

Individual study: Altering turbine speed reduces bat mortality at wind-energy facilities

Published source details

Arnett E.B., Huso M.M.P., Schirmacher M.R. & Hayes J.P. (2010) Altering turbine speed reduces bat mortality at wind-energy facilities. Frontiers in Ecology and the Environment, 9, 209-214


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Increase the wind speed at which turbines become operational (‘cut-in speed’) to reduce bat fatalities Bat Conservation

A randomized, replicated, controlled study in 2008–2009 at a wind farm in a forested area of Pennsylvania, USA (Arnett et al. 2010) found that increasing the wind speed at wind turbines become operational (‘cut-in speed’) resulted in fewer bat fatalities than at conventional wind turbines. Average bat fatalities were lower at turbines with increased cut-in speeds (5 m/s: 0.3–0.7 bats/turbine; 6.5 m/s: 0.5–0.6 bats/turbine) than at turbines with conventional cut-in speeds (3.5 m/s: 2 bats/turbine). In July–October 2008 and 2009, two treatments (cut-in speed increased to 5 m/s or 6m/s) and one control (cut-in speed of 3.5 m/s) were randomly assigned to three groups of four turbines for 25 nights/treatment. Daily carcass searches were conducted along transects in 120 x 126 m plots centred on each of 12 turbines. If applied to the entire wind farm (23 turbines), annual power output losses were projected to be 0.3% with cut-in speeds increased to 5 m/s, and 1% with cut-in speeds increased to 6.5 m/s.

(Summarised by Anna Berthinussen)