Federal Lab Offers Grim Look at Solar Harm to Wildlife

Yellow-rumped warbler with solar flux damage to feathers | Photo: National Fish and Wildlife Forensics Laboratory

A report just made public by the U.S. Fish and Wildlife Service documents a disturbing amount of bird injuries at three large California desert solar power plants, and says that there are no easy fixes to the issue.

The report, compiled by the USFWS's National Fish and Wildlife Forensics Laboratory, describes the results of examinations of 233 carcasses of birds found at the Ivanpah Solar Electric Generating System (ISEGS) south of Las Vegas, the Desert Sunlight facility near Joshua Tree National Park, and the Genesis Solar project west of Blythe in Riverside County.

The occasionally gruesome report indicates that injuries from concentrated solar flux and from impact with mirrors or photovoltaic panels constitute the two largest solar facility threats to wild birds, and suggests that the limited scope of carcass surveys at solar projects may be obscuring the true magnitude of bird mortalities they cause.

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ISEGS is a 392-megawatt concentrating solar power tower facility operated by NRG Energy for partners BrightSource Energy and Google. NextEra Energy Resources owns both the Genesis Solar project, a 250-megawatt parabolic trough concentrating solar project, and Desert Sunlight, a 550-megawatt photovoltaic project being built by First Solar. The report thus examines one of each of the main technology types used in large desert solar projects.

Of the bird carcasses studied, significantly more than half came from one project: 141 out of the 233 carcasses examined by the National Fish and Wildlife Forensics Laboratory team came from ISEGS. Two thirds of the remainder, or 61, came from Desert Sunlight, with 31 provided by the operators of the Genesis Solar project.

Those proportions may or may not represent each project's relative risk to wildlife: the majority of the carcasses provided were "incidental" finds, discovered as workers were performing other tasks. And it's worth noting that the number of birds examined from Genesis Solar totaled less than half the number of carcasses project owner NextEra told the CEC it found on the site in August 2013.

But taking the numbers at face value, the report's authors conclude that Desert Sunlight may pose the greatest risk of the three projects to water birds, and that ISEGS, the only project of the three to use solar power tower technology, constitutes a unique threat to wildlife due to the highly concentrated solar energy -- "solar flux" -- around its boilers.

A third cause of death among the birds studied, predation by other animals, likely results from birds having been injured or stranded at the facilities by solar flux, impact trauma, or other injuries, where opportunistic meat-eaters such as ravens, coyotes, or desert kit foxes then take advantage of the easy prey.

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The black bands on this peregrine falcon's feathers absorbed more energy from the solar flux, and were thus more badly damaged. | Photo: National Fish and Wildlife Forensics Laboratory

The ISEGS solar flux portion of the National Fish and Wildlife Forensics Lab report is notably striking, even distressing. 47 of the 141 bird carcasses provided the lab by ISEGS showed clear signs of solar flux injury, with feather damage ranging from singeing to charring, and a few instances of skin burns.

Also distressing, though for different reasons: the authors mention that ISEGS' owners have failed to provide them with information on the project's solar flux operating temperatures "despite repeated requests," forcing them to compile data from other sources.

One bird not examined by the lab, but which the authors cite as evidence that current carcass search strategies may be woefully inadequate, was a bird of prey that flew through the zone of solar flux at ISEGS during an October inspection by USFWS :

Damage to feathers that impedes flight generally means the bird in question can't feed, escape predators, or regulate its body temperature, say the authors.

One other description of the scene at ISEGS during that October visit is especially chilling, and confirms ReWire's speculation that ISEGS may function as a huge "ecological trap" endangering an entiire food chain:

The authors suggest that ISEGS and other proposed power tower facilities may have a "significant impact on monarch populations in the desert southwest."

The report also offers a bit of grisly jargon used by ISEGS workers to describe the effect of the solar flux on wildlife that flies into it:

The authors recommend a number of measures at the different facilities to lessen mortalities, including netting off evaporation ponds at Desert Sunlight to discourage water birds from landing there. Also suggested: clearing all vegetation inside the fenceline at Ivanpah to reduce the attractiveness of the site to predators, who might be attracted to the presence of disabled birds and themselves fall prey to solar flux injures or other harms.

The report may well have ramifications beyond the three power plants examined: the California Energy Commission will soon be considering whether to proceed with the Palen Solar Electric Generating System, a much larger version of Ivanpah proposed for the Chuckwalla Valley in Riverside County. That project's backers have agreed to provide avian mortality data from Ivanpah to use as a way to assess Palen's likely damage to wildlife, a main concern of the CEC's when it proposed to deny the project late last year.

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

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