Scores of Birds Killed During Test of Solar Project in Nevada

A test of a solar power tower project in Nevada resulted in injuries to over one hundred birds, the federal government is reporting, though the project's owners say they've fixed the problem.

On January 14, during tests of the 110-megawatt Crescent Dunes Solar Energy Project near Tonopah, Nevada, biologists observed 130 birds entering an area of concentrated solar energy and catching fire. That's according to Rudy Evenson, Deputy Chief of Communications for Nevada Bureau of Land Management in Reno.

Evenson suggested that the birds may have been attracted by a glow the concentrated solar energy created above the project's sole tower.

The Crescent Dunes solar project, now in its final stages of construction and testing by owner SolarReserve, is set to go online in March. Its projected 110 megawatts of peak output will be sold to the utility NV Energy, which serves most of 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.

SolarReserve has confirmed to Rewire that birds were injured at the plant in January, but says that the mitigation measures Evenson described have allowed subsequent testing of the plant with less risk to wildlife -- which the company is touting as good news for management of power tower wildlife issues.

"We had some avian incidents during the week of January 11, in which there were a number of incidents, estimated at under 150 avian safety issues," SolarReserve CEO Kevin Smith told Rewire. "As a result, we stopped testing until we successfully developed mitigation procedures to address the identified avian safety issues."

Those mitigation procedures, developed by SolarReserve's engineers, include repositioning the plant's mirrors to reduce the intensity of the solar flux field.

"Over the last 30 days of commissioning activities, which includes extended periods of flux (sunlight) on the tower, the Crescent Dunes project has only experienced a single (one) avian fatality attributed to the solar facility," Smith said.

Though SolarReserve may well have found a way to test and operate the Crescent Dunes plant with lower risk to wildlife, another lesson from Tonopah in January may suggest that changes at other solar power tower plants are necessary as well. Rewire has learned via anecdotal accounts from another source that at least one of the birds injured January 14 was a common raven, which -- in the words of our source -- "turned white hot and vaporized completely." Asked to confirm that report, the BLM's Evenson said that his office didn't have a list of the species affected, but added that "that's what streamers are."

The U.S.'s one other solar power plant in operation, the Ivanpah Solar Electric Generating System, has been assessing that plant's risk to birds by monitoring the number of bird carcasses found on the power plant's grounds during routine operations and periodic surveys. If solar flux from the 110-megawatt Crescent Dunes plant is indeed capable of completely incinerating a large birds such as raven, which average more than two and a half pounds, then flux at the Ivanpah plant, whose three units are each slightly greater in output than Crescent Dunes, could arguably do the same.

And that means that looking for carcasses on the ground might not tell the whole story.