Location, Location and Surface Area
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In the past couple of decades, turbine designs have changed dramatically. Turbine blades are now solid, meaning no lattice structure to attract birds looking to perch. Also, the blades' surface area is much larger, so they don't have to spin as fast to generate power. Slower-moving blades mean fewer bird collisions.
Perhaps the biggest change in wind-farm safety, though, has to do with location. Now, all new turbine proposals are reviewed for ideal, bird-friendly placement. Wind farms cannot be built in migratory pathways, in areas with high bird populations, or in areas with special features that could possibly attract high bird populations in the future. Also, the growing trend toward offshore turbine construction bodes well for birds, since offshore wind farms have fewer bird collisions than land-based farms.
Turbines and Bats
Bats have many of the same habits and habitats as birds. They just come out at night instead of day. It logically follows that bats would have run-ins with wind turbines, too; and they do, more often than birds at some locations. Still, most experts see the numbers as negligible compared to bat deaths by other forms of human intervention. According to the American Wind Energy Association, it's not just pollution and habitat destruction. People accidentally waking bats from their daytime sleep kills far more bats than wind turbines ever could. Apparently, sleep disruption messes up bats' metabolism, causing many of the little guys to starve in winter [source: AWEA].
Possibly the greatest indicator that wind turbines are not, in fact, bird-o-matics, is the growing number of endorsements by bird conservation groups. The American Bird Conservancy supports wind power with the caveat that bird-friendly placement and design be primary factors in construction [source: ABC]. The Wisconsin Bird Initiative states that wind turbines have a "low impact" on avian mortality compared to window glass and communication towers [source: WBCI]. And in 2006, the Audubon Society gave its figurative seal of approval to the American Wind Energy Association. The president of the national organization is quoted by Renewable Energy World as stating, "When you look at a wind turbine, you can find the bird carcasses and count them. With a coal-fired power plant, you can't count the carcasses, but it's going to kill a lot more birds" [source: REW].
Of course, zero turbine-related bird deaths would be the best-case scenario, but as far as energy production goes, that seems to be an unrealistic goal. The best we can hope for is smarter placement of wind turbines and more bird-friendly design in order to further reduce the number of bird deaths resulting from one of the best alternative energy sources available right now. Altamont Pass, for its part, is in the process of slowly replacing its turbines with newer models.
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