LIVERMORE, Calif.It's only 9 a.m., but the air already hangs hot and still. The sun has broken through the smoky haze created by two wildfires that have been burning since Labor Day, the Lick fire to the south and the Moonlight fire to the northeast. Of the hundreds of wind turbines that dot the surrounding hills, just one spins lazily.
I'm standing in the Altamont Pass Wind Resource Area, one of the oldest wind farms in the United States and most concentrated in the world. There are now some 5200 turbines crowded into this 4-by-6-mile rectangle of land, operated by about a dozen companies. The first rotors were installed in 1981, prompted by federal tax credits, and at the time no one knew much about how well, or even whether, they would work. What's more, no one had a clue how the turbines would interact with wildlife—more specifically, birds.
As it turned out, Altamont Pass could add to its list of pioneering superlatives this frightening title: deadliest wind farm in North America. More than 4700 birds are killed here each year, including 1300 raptors. Seventy golden eagles, a federally protected species, are also among them, even though the area is only big enough to support one mating pair. "A lot of adults come here looking for territory," says ecologist Shawn Smallwood, who has studied the pass extensively, "and very few make it out."
From the gravel parking lot in front of SeaWest Windpower's modest headquarters, I can see an olio of early turbine designs: 40- and 65-kilowatt models supported by metal lattices, 100-kw models atop tubular concrete towers. Some of the turbines are on mechanical yaw systems; others turn on simple ball bearings. Some have fat, rectangular blades; others are smoother, like butter knives. A few are missing blades altogether.
By checking 600 of these turbines every day (and many more on other companies's sites), Smallwood was able to identify the deadliest offenders: turbines on the ends of rows that sit low in valleys, where there are draws; that stand alone; or that are spaced far enough apart to create enticing gaps for birds. In Alameda County, companies must take down or relocate 7 percent of such turbines; in combination with other measures, this should reduce avian mortality by 50 percent in three years.
Perhaps more important, though, this research provides guidelines as to how farms can be built to reduce bird kills in the future, making wind power and wildlife more compatible concepts.
My next stop is the Buena Vista Wind Farm in Byron, Calif., which was repowered by Babcock & Brown in 2006. The company replaced 120-kw turbines, dating back to the 1980s, with 1-megawatt Mitsubishi models. By installing fewer, bigger turbines, the project's footprint shrunk from 2400 acres to 400 acres, with a power output five times that of before.
The turbines are enormous, though that's no doubt amplified by the fact that I'm craning my neck from directly beneath one. Whereas the towers at the SeaWest site are 18 meters high, the majority of towers here are 55 meters—above the range of most birds. Turbines lower in the valleys are even higher, on 60-meter towers. They are also sited slightly off the ridgelines, where raptors like to coast.
The wind has finally picked up, but the only sound is the aerodynamic swish of the blades as they cut through the air. (I'm told that if the wind had been blowing at the last site, I would have heard the turbines creak and moan.) The Mitsubishi's 100-ft.-long blades are moving at 140 mph. While that sounds fast, it may look slow to a raptor—no one knows. A different tactic, says Smallwood, would be to create a wall of small turbines, close together and spinning really quickly, so that birds could more easily identify it as a barrier.
George Hardie, Babcock & Brown's president, eyes the turbine before us—a $1.6 million investment—and likens it to a car: "You should be able to drive it around the world three or four times and only give it an oil change. Once you get it up, you don't want to take it down again." The American Wind Energy Association estimates that over 3000 mW of wind power will be installed in 2007. Hardie makes a good argument for figuring out how to put them up right.