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The proposed Palen Solar Project in the Riverside County desert should be considerably scaled back from the planned two 750-foot, 250 MW solar towers fed by 170,000 heliostats to just a single tower, concluded a California Energy Commission siting committee overseeing the project. Instead of 3,000 acres, the committee proposes 1,900 acres of heliostats. The reduced acreage is “a superior alternative” to the proposed project because it “feasibly lessens most of the environmental impacts while attaining most of the project’s objectives,” according to a Sept. 15 proposed decision. The document is a revision of a proposed decision originally issued in December 2013. Then, it indicated the siting committee was against permitting the project due largely to concerns over the project’s “solar power tower” technology impact to birds. Last year and in January, the committee argued for denying the solar thermal project on the basis that the impacts of the project outweigh the benefits. However, project owner BrightSource bought itself some time by stating it would look at bird mortality rates at its similar Ivanpah solar project in the Mojave Desert. That project consists of three power blocks with 459-foot towers surrounded by 170,000 mirrored heliostats. Bird mortality rates associated with BrightSource solar towers became a significant issue last year because in the second half of 2013, dozens of birds were found dead at the Ivanpah site. In the newly-released revised decision, the siting committee states it came to the conclusion that an alternative plan utilizing just one solar tower is preferable to the proposed BrightSource plan of two towers. The siting committee admitted that the reduced acreage alternative would still cause unmitigated environmental impacts, but it was determined that the benefits of the project would outweigh the impacts to birds and the environment. The project “would not create significant adverse direct, indirect or cumulative effects upon energy supplies or resources, require additional sources of energy supply, or consume energy in a wasteful or inefficient manner,” the proposed decision states. The Palen certification process began in 2009, when previous owner Solar Millennium filed a certification application. Parabolic trough technology was the planned source of generation. The application was approved in 2010. But in 2012, after a change of ownership, BrightSource subsidiary Palen Solar Holdings filed an amendment to switch from parabolic trough to solar power tower technology. Parabolic trough technology uses specially curved mirrors to concentrate the sun’s rays onto a pipe running the length of the mirrors. Fluid running through the pipe is heated by the rays and creates steam. Solar power tower technology, on the other hand, uses a large array of mirrors to concentrate the sun’s rays on a receiver atop a tower. The concentrated rays turn water pumped through the tower into steam, which drives a turbine. The proposed decision is not final. It must go through a 30-day public comment period. A committee conference on the proposal is scheduled for Oct. 6. The full Energy Commission is expected to decide the fate of the project, which is halfway between the Riverside County cities of Indio and Blythe, Oct. 29. If approved, construction and startup testing would take about 28 months, according to BrightSource.

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