A smart curtailment approach for reducing bat fatalities and curtailment time at wind energy facilities

  • Published source details Hayes M.A., Hooton L.A., Gilland K.L., Grandgent C., Smith R.L., Lindsay S.R., Collins J.D., Schumacher S.M., Rabie P.A., Gruver J.C. & Goodrich-Mahoney J. (2019) A smart curtailment approach for reducing bat fatalities and curtailment time at wind energy facilities. Ecological Applications, 29, e01881.


This study is summarised as evidence for the following.

Action Category

Automatically reduce turbine blade rotation when bat activity is high

Action Link
Bat Conservation
  1. Automatically reduce turbine blade rotation when bat activity is high

    A replicated, randomized, controlled study in 2015 at a wind energy facility in an agricultural area of Wisconsin, USA (Hayes et al 2019) found that using automated ‘Smart Curtailment’ operating systems that reduced turbine blade rotation speed resulted in 74–91% fewer fatalities of five bat species compared to conventionally operated turbines. Total fatality estimates were lower at automated turbines than conventionally operated turbines for eastern red bats Lasiurus borealis (automated: 34 fatalities; conventional: 220 fatalities); hoary bats Lasiurus cinereus (automated: 11; conventional: 59); silver-haired bats Lasionycteris noctivagans (automated: 5; conventional: 55); big brown bats Eptesicus fuscus (automated: 8; conventional: 31); and little brown bats Myotis lucifugus (automated: 3; conventional: 35). Twenty turbines were randomly selected (10 operated by automated systems, 10 conventionally operated). At automated turbines, fatality risk was calculated by a predictive model using real-time bat activity and wind speed data every 10 minutes. If fatality risk was high (wind speed <8 m/s and >1 bat call detected in the previous 10 minutes), rotor blades were rotated out of the wind and slowed (to ≤1 rpm) for 30 minutes. Conventionally operated turbines were ‘feathered’ to rotate slowly below a cut-in speed of 3.5 m/s. Daily carcass searches were conducted along transects in  plots (80 x 80 m) centred on each of the 20 turbines in July–September 2015. Carcass counts were corrected to account for searcher efficiency and removal by scavengers. Electricity generation was reduced by 90 MWh/turbine at automated turbines during the study period.

    (Summarised by: Anna Berthinussen)

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