Monday, July 19, 2010


Alex Tabarrok on bird death.

How Stuff Works on statistics of bird death. (Wind turbines 10,000-40,000; power lines 130-174 million...)

Altamont Pass is different for two main reasons: turbine location and turbine design.

There are more than 4,000 wind turbines at the Altamont Pass energy farm in California. It's one of the first wind farms in the United States, and its 20-year-old turbines are accordingly out-of-date. Their design has long since been abandoned: Latticework blades with small surface area are far from efficient for energy generation, and far from safe for birds. The lattice structure actually attracts large birds, because the frame makes for an excellent perch. Large birds like raptors are drawn to the blades, and collision rates are high as a result.

The other design issue is the blades' low surface area, because less surface area means the blades have to spin faster to turn the electricity-generating turbines. The faster the blades spin, the more dangerous they are to birds flying near them. It's unlikely that a bird that finds itself in the vicinity of the blades could ever make it through when they're spinning so fast.

As if this weren't enough to make old wind farms a bird nightmare, the Altamont Pass power plant was built smack dab in the middle of a major migratory route for large birds. The area also houses the world's largest single population of golden eagles [source: USA Today]. With thousands of dated wind turbines sprawling across a super-high-population bird area, it's inevitable that birds and turbines will meet. A current estimate puts the number of birds killed by turbines at Altamont Pass to be about 4,700 each year, several hundred of which are raptors [source: USA Today].

The Altamont Pass wind farm kills far more birds than any other farm in the United States. The total at that single wind farm with 4,000 turbines is 4,700 fatalities; the total for all wind farms in the United States, with more than 25,000 turbines in operation at any given time, is 10,000 to 40,000 per year [source: Reuters

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