Apologies for duplicate postings.--tm
Subj: [GWTF] [CONS-SPST-GLOBALWARM-TF] Proposed Texas offshore wind farm ruffles a few feathers
Date: 6/8/2006 4:50:17 PM Central Daylight Time
From: [log in to unmask] (Arthur D Unger)
Sender: [log in to unmask] (Global Warming/Clean Energy Task Force)
Reply-to: [log in to unmask] (Global Warming/Clean Energy Task Force)
To: [log in to unmask]
Making the wind machine blades motionless during migration "could be done at some economic cost"; according to Paul Gipe, author of several books on wind energy.
Art
----- Original Message -----
From: "Dan Boone" <[log in to unmask]>
To: "Vivian Newman" <[log in to unmask]>
Sent: Tuesday, June 06, 2006 6:15 PM
Subject: Re: Fw: Proposed Texas offshore wind farm ruffles a few feathers
> Hi Vivian,
>
> Stopping the turbines during peak migration periods may help avoid
> collision risk to larger birds (like hawks, waterfowl and herons),
> which take more time to pass through the rotating blades. It also may
> be a potential mitigation measure for reducing impact to migrating
> bats.
>
> It seems that bats may be disproportionately killed by wind turbines
> because they may be attracted to them as potential roost (big trees!)
> or foraging sites. Anecdotal evidence indicates that non-working
> (i.e., stationary) turbines may kill far fewer of these migratory bat
> species, which mainly concentrate to fly south in late summer and early
> fall (when wind energy production by turbines is at its lowest).
>
> In fact, for over 2 years bat experts have identified as a top priority
> for research the strategy of keeping turbines from spinning much during
> periods of peak migration. Unfortunately, Florida Power and Light
> Energy - which owns about half of all the windpower projects in the US
> - has stymied this research - see:
> http://www.vawind.org/Assets/Docs/Articles/FPL-Stops-Bat-Research-060805.pdf
> . They don't want to have the turbines stopped during even a limited
> time for a variety of reasons that reflect politics more than
> economics.
>
> However, for nocturnally migrating birds, which include the majority of
> smaller songbirds. There is inconclusive evidence that stationary
> turbines would be significantly less of a collision risk than turbines
> with rotating blades - though at least one simulation model indicates a
> slightly lower risk if blades are not moving. Also, the non-moving
> blades would not create strong eddies of turbulence, which are known to
> cause birds to fall to the ground when they hit this "wake".
>
> The collision risk of a wind energy project to nocturnal migrant
> songbirds may be roughly proportional to the cumulative cross-sectional
> areas of all the turbines that the birds may encounter (which includes
> the tower, nacelle and the 3 huge blades). Songbirds don't have
> evolutionary experience with avoiding 400 foot high obstacles -
> especially when flying along the coasts.
>
> Nonetheless, the risk of collision would be much greater during periods
> of fog or inclement weather, when visibility is low and more birds are
> forced to fly below a low cloud ceiling (concentrating them). Lighting
> of the turbines over water may exacerbate the risk.
>
> Alot is unknown.
>
> Hope this helps!
>
> Dan
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