In what's turning into a public relations headache for the solar industry, news has emerged that a recent test of the 110-megawatt Crescent Dunes Solar Energy Project in Nevada resulted in some 130 birds catching fire, when they flew into an area of highly concentrated solar energy.
As KCET's Rewire is reporting, the incident happened last month, but the news is only emerging now. According to Rudy Evenson, Deputy Chief of Communications for Nevada Bureau of Land Management in Reno, the birds were likely drawn to a glow created by the concentrated solar energy above the project's sole tower.
As noted by E&E reporter Phil Taylor, plants like this one are a huge problem for birds. He describes the Ivanpah Solar Electric Generating System, a similar but larger plant in California's Mojave Desert:
The 45-story "power towers" shine with sunlight reflected by 350,000 heliostat mirrors spread across an area four times the size of New York's Central Park. Receivers atop the towers heat to nearly 1,000 degrees Fahrenheit, boiling water to turn turbines that crank out 392 megawatts — power for more than 100,000 houses.
This intense heat would incinerate any bird that flies within the "flux field" between the mirrors and the towers.
The smaller Crescent Dunes plant includes 17,500 heliostat mirrors that collect and focus the sun's thermal energy to heat molten salt flowing through a 54o-foot (16 meter) tower.
Rewire describes the recent incident in Nevada:
According to Evenson, workers testing the plant moved approximately a third of the project's ten thousand mirrors to focus sunlight on a point 1,200 feet above the ground, approximately twice the height of the power tower at Crescent Dunes.
The test started at 9:00 a.m. on January 14, Evenson told Rewire. By 10:30, biologists working on the site began noticing what have become known as "streamers," trails of smoke and water vapor caused by birds entering the field of concentrated solar energy (a.k.a. "solar flux") and igniting.
By the time the test ended for the day at 3:00 p.m., biologists had counted 130 such "streamers." A subsequent test on January 15 reduced the number of mirrors aimed at the focal point above the tower, said Evenson, and that apparently ended the injuries to birds.
The ensuing mitigation procedures, which include repositioning the plant's mirrors to reduce the intensity of solar flux, has allowed the subsequent testing of the plant, and with less risk to wildlife.
Looking ahead, and given the future potential of these concentrated arrays, the solar industry is going to have to tread very carefully. Killing or maiming most bird species, whether it's deliberate or inadvertent, is illegal under the Migratory Bird Treaty Act.
Image of Crescent Dunes Solar Energy Project: Amble/CC