Bird Deaths Mount at Ivanpah Solar

Ivanpah's Unit 3 achieves flux August 11, two days before a burned bird is found | Photo: 49er Girl/Flickr/Creative Commons License

The owners of the Ivanpah Solar Electric Generating Station filed their monthly report with the California Energy Commission (CEC) this weekend, and the news is unsettling for anyone concerned with the plant's effect on desert wildlife. The project's owners reported seven birds found dead at the plant in August, at least one of them with burn injuries that may have been caused by the plant's concentrated solar energy.

As ReWire reported last week, similar mortalities are already being reported from September. A peregrine falcon was found injured in the first week of September, and ReWire has now heard unconfirmed reports that six total bird mortalities were recorded at the plant in that week. According to those reports, four of the dead birds had charred or melted feathers when found.

According to compliance reports filed with the CEC by BrightSource Energy, reported bird mortalities have been climbing steadily since January 2013. August's seven birds followed eight mortalities in July and five in June. With six mortalities unofficially reported for just the first week of September as the facility nears completion, the effect of the Ivanpah solar facility is raising significant concern among wildlife advocates -- especially considering the implications for BrightSource's proposed Palen Solar project, which would be much larger than Ivanpah.

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BrightSource co-owns the 377-megawatt project next door to the Mojave National Preserve with NRG Energy and Google. The project is being built by Bechtel, and is expected to go online by the end of the year.

Bird mortalities at Ivanpah are sometimes hard to pin on a particular cause: the carcasses have often been dead for some time before they're found, and the desert is full of animals anxious to eat dead things, from insects on up in size. An adult Cooper's hawk was found dead and partly scavenged on the site in February, for instance, with the consulting biologist opining that it may have been carried onto the site by a kit fox.

But reading Ivanpah's compliance reports from January on reveals a pattern. In early 2013, one or two birds were reported dead each month at most, with the apparent causes of death mainly collisions with either power lines or vehicles.

As the year progressed, more birds with severe apparent trauma were described in the reports -- predictable given increasing installations of the thousands of mirrored heliostats that now surround the project's three power towers.

August's compliance report contains a first: a description of a mortality that seems likely to have resulted from exposure to the plant's concentrated "solar flux," or the energy from the sunlight that the project's heliostats focus on the boilers atop the power towers. Bird feathers are made of keratin, a class of protein that can degrade if heated above 160°C (320°F), and actually catch fire not much hotter than that.

ReWire went into the science of solar flux and keratin in some detail in March, in a discussion of BrightSource's abandoned Hidden Hills project. In March, there was disagreement between CEC staff and BrightSource's hired consultants whether that project's solar flux posed an actual threat to birds. Like Palen, Hidden Hills would have had considerably larger generating capacity than Ivanpah, with taller power towers that allowed more closely packed heliostats surrounding them -- and thus the potential for stronger solar flux.

August's apparent solar flux mortality, and those that we've learned followed in early September, will likely be seen by many as empirical evidence supporting the CEC staff's arguments. The description of the August mortality's injury in the just-filed August compliance report is disturbing:

Though the swallow drank readily and appeared energetic, according to the compliance report, it died August 16 at a rehab facility.

When the burned bird was found, Ivanpah's Unit 3 had been "achieving flux" daily for eight days. That's the company's term for having enough of the unit's heliostats aimed at the power tower to create heat in the boiler.

Among the other birds found dead during August were a white throated swift and a lazuli bunting that apparently both died after colliding with heliostats, as well as two ravens, a lesser nighthawk, and a loggerhead shrike. One of the ravens' deaths was seen by a construction worker, and was attributed to electrocution after landing on a power transformer. The other birds' deaths were not explained in the compliance report.

Hence the pattern: as Ivanpah nears completion, the number of deaths seemingly resulting from collisions with heliostats rises; now, solar flux is apparently becoming an issue even though at the September 20 filing of the August compliance report, two-thirds of the plant had not been creating flux for months. Unit 2 last reached flux in May, and Unit 1 in June. If flux injuries are mounting when one third of the plant is firing up as part of daily tests, an ominous question presents itself: what happens when all three units are creating as much flux as possible every day?

And what happens if the Palen project, now being evaluated by the CEC and the BLM, subjects birds to even higher intensities of solar flux?

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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