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BrightSource Walks Away From Rio Mesa 'For Now'

Artist's conception, Rio Mesa solar project | Image courtesy California Energy Commission

BrightSource Energy, which had called its planned 500-megawatt Rio Mesa concentrating solar project a crucial step in developing reliable solar power generation, now says it's putting that project on hold. Citing mounting obstacles to the project, the company has backed out of a controversial contract to sell energy from the plant to Southern California Edison (SCE), and says it will be focusing its efforts on the nearby proposed Palen Solar Power plant in Riverside County.

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The firm made its announcement by way of an interview with reporter K Kaufmann in the Palm Springs Desert Sun on Saturday. Joe Desmond, BrightSource's vice president for government affairs, told Kaufmann that demands for further study of the project's likely environmental and economic impacts meant BrightSource "could no longer meet the commercial terms of our agreement for the project." The plant would have needed approval from the California Energy Commission by June in order to meet the terms of its power purchase agreement with SCE.

The project, proposed for 4,070 acres of open desert south of Blythe, would have generated a maximum of 500 megawatts of electrical power by way of two 250-megawatt steam turbines mounted atop 750-foot towers. Each tower would have been surrounded by tens of thousands of mirrored heliostats which would have focused solar energy on the turbines' boilers.

The Rio Mesa project has been beset by one obstacle after another over the past few months. In early 2012 news got out that surveyors had found what has turned out to be a world-class Ice Age fossil deposit on the site, with finds including mammoth ivory and what appears to be an entire fossilized desert tortoise burrow, complete with unhatched eggs.

In October, the California Public Utilities Commission (CPUC) approved just one of two power purchase agreements between BrightSource and SCE for power from Rio Mwsa, citing the high projected cost of power as its reason for denying the other:

The [Rio Mesa 1 and 2] projects compare poorly on price and value relative to other solar thermal projects offered to SCE at the time the amended and restated PPAs were being negotiated and executed. SCE had the option to choose from 18 of 19 solar thermal projects totaling over 2,300 MW in combined capacity resulting from its 2011 RPS Solicitation that were all materially higher in value than the Rio Mesa 1 and Rio Mesa 2 projects.

As we reported in October, the CPUC approved one of the Rio Mesa power purchase agreements, rather than vetoing both, in an effort to lend support to BrightSource's development of solar thermal storage technology. In thermal storage plants, solar heat is used to melt a substance, usually a salt, which can then heat fluid in a boiler well after the sun sets. In a meeting with ReWire in October, BrightSource's Joe Desmond characterized his firm's planned thermal storage technology as a likely solution to renewable energy's pesky intermittency problem -- the fact that solar panels stop producing power when the sun goes down, just as people start turning on their electric lights.

Rio Mesa would not have incorporated thermal storage technology, but Desmond told ReWire in October that BrightSource would be approaching that technology by increment, with Rio Mesa one of the steps along the way. "We can't just jump into building thermal storage without experience with the second phase of our technology, which we've planned for Rio Mesa," Desmond said. When the CPUC approved one of Rio Mesa's power purchaser agreements, it was with the explicit understanding that this was a ratepayer investment in thermal storage technology, which BrightSource hoped to implement in a planned 540-megawatt plant, Sonoran West, northwest of Rio Mesa.

Though paleontology and expensive power were definitely stumbling blocks for BrightSource, the biggest obstacle to Rio Mesa was very likely concern over the plant's impact on wildlife, especially of the flying variety. For months, wildlife advocates including the U.S. Fish and Wildlife Service have asked pointed questions about the effect of concentrated solar energy, called "solar flux," from the projects' thousands of mirrors on birds, bats and insects who fly into the path of the concentrated energy. The mirrors themselves also pose a potential threat, likely appearing as open water or sky and suggesting the possibility that animals would fly into the mirrors and be injured. Fish and Wildlife recently weighed in with an extensive list of concerns over insufficient data by which to gauge threats from the Rio Mesa project to local wildlife, either living in the adjacent desert or visiting from the nearby Cibola National Wildlife Refuge.

Much of the concern over mirror collisions and solar flux injury has been directed equally toward Rio Mesa and its near-twin, BrightSource's proposed Hidden Hills project east of Death Valley. The issues shared by the two proposals were similar enough that California Energy Commission combined proceedings on the two projects as regards wildlife issues. The impact on Hidden Hills of the Rio Mesa back-burnering remains to be seen. Though Hidden Hills doesn't have an adjacent National Wildlife Refuge, it does host a significant avian population due to nearby springs, sky-island mountain ranges and the Amargosa River.

BrightSource says that the company's focus post-Rio Mesa will be on getting its Palen project up and running, which almost certainly involves setting the clock back on getting the firm's "phase two" technology field tested. BrightSource bought Palen in 2012 from the bankrupt German firm Solar Millennium, and is redesigning the project from the solar trough thermal Solar Millennium had planned to BrightSource's power tower technology. That redesign will certainly mean months of agency processes to catch up with where Rio Mesa was prior to this week, meaning likely delays in BrightSource's implementation of its thermal storage technology at Sonoran West.

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About the Author

Chris Clarke is a natural history writer and environmental journalist currently at work on a book about the Joshua tree. He lives in Joshua Tree.
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