With an offshore wind farm of 200 turbines proposed for the Delaware coast, concerns for bird safety are hitting home.
But according to one Danish scientist, a properly planned wind farm will not decimate bird populations.
Mark Desholm of Aarhus University in Denmark, received his doctorate for wind farm mortality on birds. Denmark, which has several offshore wind farms already up and running, had Desholm and a team of researchers go out and study the issue.
While California’s land-based wind farm Altamont Pass has been known for killing scores of hawks and eagles every year, many other farms support Desholm’s studies, which post very low mortality rates.
Desholm —- who spoke at a University of Delaware College of Marine and Earth Studies public workshop on wind power —- has studied avian behaviors around two of Denmark’s offshore wind farms for three years before construction and another three afterwards.
Through Desholm findings, he and his team were able to create a probability model for the two Danish wind farms as having a collision risk of only .02 percent for birds.
According to Desholm, the location of an offshore wind farm is very important when it comes to bird populations.
With regular flight paths and migration routes located in close proximity to coastlines, planners must make sure they build away from such areas.
Desholm and his team conducted aerial and radar surveys before the farms’ construction to get a better knowledge of what species of and how many birds were habitually traveling through the proposed sites.
Desholm said that for his study, he narrowed the avian species of interest list down to water birds, like ducks and gulls, and birds of prey.
He excluded song birds from his survey, despite the fact that they were present in small numbers.
Desholm said that those people looking to construct an offshore wind farm in Delaware should, as he did, pare down the number of species they intend to study.
According to him, two factors should be noted when reviewing which species to survey: A species’ relative abundance and its elasticity of adult survival —- how well it adapts.
According to his aerial studies, Desholm said that large populations were not regularly found in the proposed sites. He was finding that birds were actually turning almost two miles before they were at the turbines.
He said that with another round of aerial surveys, radar and a Thermal Animal Detection System —- similar to a camera and attached directly to turbines —- even fewer birds were found traveling through the farms after construction.
Some flocks still flew through the wind farm, though. Desholm said that during the day, the flocks would generally pass under the rotors, while at night they went over them.
John Sherwell of Maryland’s Department of Natural Resources has reviewed the mortality concerns with multiple wind farms proposed in the state’s mountainous western region.
Sherwell, who also spoke at the workshop, said it is not bird populations that are being reduced by wind farms in neighboring Pennsylvania and West Virginia —- it is bats.
He said the Maryland proposals are highly contested by some environmental groups.
“The environmental community itself is divided,” Sherwell said.
According to him, some see wind power as a good alternative to fossil fuel generated power, while others are concerned over potentially detrimental effects on local flora and fauna.
In Delaware, one environmental group has given its blessing to the offshore wind farm proposal.
According to the Delaware Audubon Society’s statement on off-shore wind energy, the organization supports the offshore wind farm proposal.
Its position paper, which actually quotes Desholm’s study, says that it is the “only reasonable, cost-effective and environmentally beneficial alternative.”
By Daniel Divilio
25 February 2007
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