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Solar thermal plant approved for California

by Bob Morris, published

The 250-megawatt Beacon Solar Energy Project has been approved by the California Energy Commission. When built, it will be the first large-scale solar thermal plant in the US in over 20 years and will generate enough power for 100,000 homes. This is first of many such solar thermal projects planned for the Mojave area. Twelve more may be approved by the end of the year with a total of 34 being planned. If they all are built, then 300,000 acres of the Mojave Desert will be used to generate 2.4 gigawatts of electricity, which could power nearly one million homes.

Solar thermal uses rows of parabolic trough mirrors to focus heat on liquid-filled tubes to create steam to run turbines, thus generating electricity.  The liquid in the pipes can be water as well as other fluids. Some solar thermal plants store excess heat in molten salt to be used to create power when the sun isn't shining. The Beacon Project appears to not store excess heat and does not use water in its pipes.  It will however use a startling amount of water, over 500 million gallons a year, for cooling.  Yikes. Initially the water was going to be pumped out of freshwater wells. However opposition to this environmentally noxious scheme forced a change and now the water will be reclaimed sewage water piped in from nearby towns. However, it's not clear what happens to the water after beacon uses it. Will it be piped back to the towns, into aquifers, or something else?

If all the projects are built - and we're talking being built in a desert here - then where will all the needed water come from? And why isn't excess heat being stored for later use? This would not only make the plants more efficient, it would also cut down on the amount of water used for cooling. While we certainly need renewable energy, California faces a perpetual water shortage. If the Beacon plant is roughly 1/10 the size of all the proposed sites and will use 500+ million gallons a year, and the other sites use equal amounts of water, then  the total will be nearly 5 billion gallons a year. Such water will have to be reclaimed and reused; it simply cannot be wasted.

The approval process for Beacon took 2 ½ years.  That seems overly slow and pokey, especially considering that federal incentives for such power expire at the end of 2010 and the three investor-owned utilities in California must get 20% of their power from renewable sources by the end of the year too. Many of the other proposed projects would be sited on Bureau of Land Management land and thus require federal as well as state approval. This will only slow down the process even more, even as the year-end deadlines mean time is not on the side of developers.

California Unions for Renewable Energy says the plant won't be built "anytime soon" because it has no agreement to sell power to a utility company, but management says they are negotiating one now. "Build it and they will come" seems applicable here, especially when the big utilities must make that 20% renewable mark.

Renewable energy is still more expensive than coal or nuclear. But it doesn't produce enormous amounts of greenhouse gases like coal or have disposal problems like nuclear. Perhaps one day, the bulk of power for California will come from solar, wind, and geothermal. It certainly has the resources to do so.

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