Study

Reducing bat fatalities at wind facilities while improving the economic efficiency of operational mitigation

  • Published source details Martin C.M., Arnett E.B., Stevens R.D. & Wallace M. (2017) Reducing bat fatalities at wind facilities while improving the economic efficiency of operational mitigation. Journal of Mammalogy, 98, 378-385.

Actions

This study is summarised as evidence for the following.

Action Category

Prevent turbine blades from turning at low wind speeds ('feathering')

Action Link
Bat Conservation

Increase the wind speed at which turbines become operational (‘cut-in speed’)

Action Link
Bat Conservation
  1. Prevent turbine blades from turning at low wind speeds ('feathering')

    A replicated, randomized, controlled study in 2012–2013 at a wind farm in a forested area in Vermont, USA (Martin et al 2017) found that preventing turbine blades from turning at low wind speeds (‘feathering’), along with increasing the wind speed at which turbines become operational (‘cut-in speed’) at temperatures above 9.5°C, resulted in fewer bat fatalities than at conventional turbines. The average number of bat fatalities was 62% lower at wind turbines when cut-in speeds were increased to 6 m/s at temperatures >9.5°C and the blades were feathered below this speed (0.5 bats/turbine) compared to conventional control turbines (1.4 bats/turbine). Three bat species were found (see original paper for details). In June–September 2012 and 2013, eight of 16 turbines were randomly assigned the treatment (cut-in speed increased to 6 m/s at temperatures >9.5°C and blades feathered below this speed) for a total of 60 nights. The other eight turbines were unaltered (cut-in speed of 4 m/s without feathering). Daily carcass searches were conducted along transects in rectangular plots (3,629–5,746 m2) centred on each of the 16 turbines. If applied to all turbines, it was estimated that the operational changes would result in annual energy losses of 1%.

    (Summarised by: Anna Berthinussen)

  2. Increase the wind speed at which turbines become operational (‘cut-in speed’)

    A replicated, randomized, controlled study in 2012–2013 at a wind farm in a forested area in Vermont USA (Martin et al 2017) found that increasing the wind speed at which turbines become operational (‘cut-in speed’) at temperatures above 9.5°C, along with preventing turbine blades from turning at low wind speeds (‘feathering’), resulted in fewer bat fatalities than at conventional turbines. The average number of bat fatalities was 62% lower at wind turbines when cut-in speeds were increased to 6 m/s at temperatures >9.5°C and the blades were feathered below this speed (0.5 bats/turbine) compared to conventional control turbines (1.4 bats/turbine). Three bat species were found (see original paper for details). In June–September 2012 and 2013, eight of 16 turbines were randomly assigned the treatment (cut-in speed increased to 6 m/s at temperatures >9.5°C and blades feathered below this speed) for a total of 60 nights. The other eight turbines were unaltered (cut-in speed of 4 m/s without feathering). Daily carcass searches were conducted along transects in rectangular plots (3,629–5,746 m2) centred on each of the 16 turbines. If applied to all turbines, it was estimated that the operational changes would result in annual energy losses of 1%.

    (Summarised by: Anna Berthinussen)

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