800 Degree Heat From Solar Mirrors Frying Birds Mid Air

There is growing evidence that birds flying in the vicinity of a solar thermal power project in California's Mojave Desert are being injured and even killed either by the solar heat that's focused with mirrors on its three energy-collecting towers, or by colliding with the mirrors themselves.

Yet a task force set up to investigate the problem at the Ivanpah Solar Electric Generating System (ISEGS) has brushed aside several recommendations by the forensics laboratory of the U.S. Fish and Wildlife Service (FWS), according to the minutes of a meeting on the subject obtained by the Los Angeles public television station KCET.

The FWS had said wildlife mortality and injury at ISEGS may have been underrepresented because of inadequate searches for injured and dead animals, and it suggested ways to make those searches more thorough.

The panel - the Avian & Bat Technical Advisory Committee (TAC) - met in Nipton, Calif., on May 20, where it dismissed several FWS recommendations.

ISEGS is a solar thermal power generator that uses arrays of mirrors, called heliostats, that reflect and narrowly focus solar heat to "power towers" filled with water. The focused solar heat reaches a temperature of 800 degrees Fahrenheit, boiling the towers' water to generate electricity.

Dead and injured birds have been found at the plant site, having been burned, evidently by the reflected solar heat, or with other injuries because they evidently failed to recognize the mirrored heliostats as solid surfaces, much the same way that birds crash into windows.

The purpose of the May 20 meeting was to assess whether ISEGS presents a hazard to birds flying nearby and, if so, what could be done to mitigate the hazard. The TAC agreed to one FWS proposal, using specially trained dogs to find bird carcasses within the site's borders.

But the minutes of the meeting show that the TAC perfunctorily swept aside other suggestions that would have improved the accuracy of such surveys.

One proposal was to search for injured or dead birds outside the site. This was based on the observation of a large bird that had caught fire above ISEGS, become unstable in flight, but did not land until after it glided beyond the perimeter fence. That was rejected because the ecological consulting firm H.T. Harvey found that nearly 95 percent of singed birds were found at the plant, not outside it.

ISEGS is only one of three solar power plants in Southern California that are believed to be responsible for killing and injuring birds in flight. The other two are the Genesis Solar Energy Project in the state's Colorado Desert and the Desert Sunlight Solar Farm, which is still under construction.