Posted: Saturday, May 30, 2015 12:15 am
BY MICHAEL PARR | 2 comments
When the Department of Energy released a report last week championing the construction of larger, more-powerful wind turbines, the wind industry unsurprisingly greeted the news with enthusiasm.
By extending the “hub-height” of turbines up to 360 feet, the chief executive of the American Wind Energy Association said, wind energy could expand to all 50 states.
Less ardent was the association’s response to well-documented concerns over the half-million birds that die each year from collisions with existing turbines: Some migrating birds, a spokesman said, fly too high to be harmed by rotor blades.
Indeed. Some birds do fly very high in the sky. But far more travel at the very altitudes that would put them at greatest risk of colliding with these taller turbines. The risk is especially high during spring and fall, when migrating birds take to the skies in billions, many traveling vast distances between their wintering and breeding grounds.
A new report this month from the U.S. Fish and Wildlife Service calls into question the wind industry’s assertion that birds fly well above wind turbines’ rotor blades. Using radar, researchers examined fall migration at two locations in Michigan. They found that the greatest density of birds and bats migrating at night occurred from 300 to 500 feet above ground. That’s almost directly at hub-height for the new generation of giant turbines.