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bats and wind turbine blades....follow up
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Daniel J. Alberts
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Oct 13, 2005 11:06 PDT
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The following is an excerpt from the final research report by Jessica Kerns
and Wally Erickson, dated June 2005:
Thermal images indicated that bats are attracted to and investigate both
moving and nonmoving blades. Thermal images of bats attempting to land, or
actually landing on stationary blades and turbine masts, suggest possible
curiosity about potential roosts or use for gleaning insects. Images of bats
chasing turbine blades rotating at slow speeds suggest possible attraction
to movement out of curiosity. However, most of the observed collisions (7 of
8) were between bats and fast-moving (17 rpm) turbine blades. Thermal
imaging observations of bat and insect activity support the conclusion that
fatality occurs primarily on low wind nights, but when blades are pitched
into the wind and powered to rotate, which may be at or near their maximum
speeds of 17 RPM, despite modest or no power production.
This is potentially valuable information for protecting bats in Michigan's
UP. Since the Bowling Green wind farms maintain their turbines a constant
16.8 rpm for compatibility with grid transmission, we may be able to operate
wind turbines in the UP at a similar speed with minimal impacts.
I believe that if turbines are to be allowed in the UP, especially within a
mile of bat hibernacula, the state should require a study to confirm the
impacts of blade speed and pitch on bat fatalities, and then require that
blades be kept below the threshold for causing significant harm.
Kerns and Erickson's final report is now available at
http://www.batcon.org/wind/research.html.
Daniel Alberts
Lawrence Tech's Wind Energy Delphi
www.ltu.edu/engineering/mechanical/delphi_wind.asp
dja1-@nethere.com
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