Post-construction monitoring study, Criterion Wind Project, Garrett County, Maryland: April–November 2012

Published source details Young D.P.Jr, Nations C., Lout M. & Bay K. (2013) Post-construction monitoring study, Criterion Wind Project, Garrett County, Maryland: April–November 2012. Western EcoSystems Technology, Inc. (WEST) report.
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This study is summarised as evidence for the following.

	Action	Category
	Prevent turbine blades from turning at low wind speeds ('feathering') Action Link
	Increase the wind speed at which turbines become operational (‘cut-in speed’) Action Link

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

A before-and-after study in 2011–2012 at a wind energy facility in a forested area of Maryland, USA (Young et al 2013) found that preventing turbine blades from turning at low wind speeds (‘feathering’), along with increasing the speed at which turbines become operational (‘cut-in speed’), resulted in fewer bat fatalities than before the operational changes. Average bat fatality estimates were 62% lower after turbine blades were feathered below an increased cut-in speed of 5 m/s (11 bats/turbine) compared to the previous year without operational changes (29 bats/turbine). The difference was not tested for statistical significance. Five bat species were found across the site (see original report for details). In July–October 2012, all of 28 turbines at the facility were operated with feathering below an increased cut-in speed of 5 m/s. Weekly carcass searches were conducted along transects in circular plots (40-m radius) around 14 of the 28 turbines. Data for before the operational changes (blades rotated freely below a cut-in speed of 4 m/s) were collected in a previous study in July–October 2011. Carcass counts in both years were corrected to account for searcher efficiency and removal by scavengers.

(Summarised by: Anna Berthinussen)
Increase the wind speed at which turbines become operational (‘cut-in speed’)

A before-and-after study in 2011–2012 at a wind energy facility in a forested area of Maryland, USA (Young et al 2013) found that increasing the speed at which turbines become operational (‘cut-in speed’), along with preventing turbine blades from turning at low wind speeds (‘feathering’), resulted in fewer bat fatalities than before the operational changes. Average bat fatality estimates were 62% lower after the cut-in speed was increased to 5 m/s and turbine blades were feathered below this speed (11 bats/turbine) compared to the previous year without operational changes (29 bats/turbine). The difference was not tested for statistical significance. Five bat species were found across the site (see original report for details). In July–October 2012, all of 28 turbines at the facility were operated with an increased cut-in speed of 5 m/s with blades feathered below this speed. Weekly carcass searches were conducted along transects in circular plots (40-m radius) around 14 of the 28 turbines. Data for before the operational changes (blades rotated freely below a cut-in speed of 4 m/s) were collected in a previous study in July–October 2011. Carcass counts in both years were corrected to account for searcher efficiency and removal by scavengers.

(Summarised by: Anna Berthinussen)