Agency Staff: 'Hidden Hills Solar Will Kill Eagles'

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Golden eagle | Photo: kamerakamote/Flickr/Creative Commons License

ReWire reported on Monday on the dispute between the California Energy Commission (CEC) and BrightSource Energy over the risk to wildlife from the concentrated solar energy at BrightSource's proposed Hidden Hills Solar Electric Generating System, and we promised you an update on CEC scientific staff testimony when the transcript of a particularly groundbreaking hearing was made available. CEC made that transcript available today, and it's a doozy. According to CEC scientific staff, the Hidden Hills project will "almost certainly kill or injure" eagles and "other special status" species of birds.

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The hearing, held thursday March 14 in Shoshone, covered threats to birds from the facility's concentrated solar energy directed at boilers atop 750-foot tall towers by thousands of mirrored heliostats. As we mentioned Monday, concentrated "solar flux" can injure birds if it raises the temperature of their feathers past 160°C, at which point the keratin protein in those feathers begins to denature. As birds rely on their feathers not only for insulation and camouflage but for their ability to fly, damaging those feathers can cause serious harm to the bird that wears them -- either immediately, as the bird finds itself unable to fly at 1,000 feet above the ground, or more slowly due to more subtle impairments in speed and agility.

With the information we had available yesterday, we wrote that CEC staff had proposed a safety solar flux exposure threshold one tenth what is being advocated by BrightSource, saying that the firm's proposed 50 kilowatt-per-square meter (kW/m2) limit, 50 times the intensity of unaugmented sunshine, should be cut down to 10 kW/m2. That intensity threshold would mean that birds flying into a danger zone about 2,000 feet wide around each tower at Hidden Hills would run the risk of injury from solar flux.

That was before we saw the transcript of the March 14 hearing. According to the transcript, CEC staff actually advocates a 5 kW/m2 threshold, one-tenth what was proposed by BrightSource.

As one might expect, there's tension between BrightSource and the CEC staff on this and related matters. Here's how the CEC's Rick Tyler, a senior mechanical engineer with the California Energy Commission, started his hearing testimony on March 14. After introducing other CEC staff and experts who'd be offering testimony, Tyler said:

Artist's rendition, Hidden HIll solar plant | Image courtesy California Energy Commission

After a bit of a technical discussion of risk assessment and an introduction to staff's assumptions about modeling the complexities involved in how birds and their feathers interact with the air and solar flux, Tyler continued:

As for the safe threshold level of exposure to the solar flux, Tyler was unsparing of the scientific claims of BrightSource and its contractor CH2M Hill, based on CH2M Hill's experiments with dead birds photos of which have been kept from the public by BrightSource:

After some discussion of the dimensions of the solar flux field that Hidden Hills would create and the speed at which birds would likely fly through that field, Tyler concluded with a bleak assessment of Hidden Hills' likely deleterious impact on golden eagles and other birds, and a reminder that not all fatal injuries caused by the solar flux would show up right away:

That phrase "significant impact" is, well, significant. Under the California Environmental Quality Act (CEQA), the CEC would have to deliberately override the provisions of CEQA to approve Hidden Hills if any of the project's environmental impacts are found to be "significant." The CEC is no stranger to overriding CEQA provisions: They've done so for many of the desert solar projects they've approved so far. But the Commission has taken heat for it, and BrightSource increasingly seems the least favored solar developer among California regulators. The company has been slapped down by the CPUC of late, for instance. If there's a single developer for whom the CEC's commissioners might be tempted not to override CEQA, BrightSource is likely that company. And having the CEC fail to approve Hidden Hills would be one more setback for a company that's already had one setback too many.

So as you might expect, BrightSource -- whose very existence might actually be threatened by the solar flux and birds issue -- objected to this line of testimony. We'll discuss BrightSource's answers to CEC staff in Part 3 of this series.

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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