Tuesday, December 6, 2011

Solar farms: the newest crop in the desert southwest

Gail Overton
Senior Editor
Laser Focus World

In the dusty little corner of the planet--the lower Mojave desert--that I call home, it's time to start raiding the just-picked lettuce and broccoli fields for the abundant leftovers. Broccoli soup, wilted lettuce, and wedge salads will be commonplace at my house for the next few months; after all, I live just next door to Yuma, AZ, the winter lettuce capital of the world. But sprouting from the ground with concrete footers and rows of metal posts rather than green shoots are fields of silicon, steel, and glass structures that are harnessing the sunlight to power our homes rather than fill our stomachs. The latest crop in the desert southwest today is not a vegetable.

Utility scale solar photovoltaic and concentrating solar power (CSP) installations in southern California and Arizona are the latest cash crop. The small town of Gila Bend, AZ is home to three separate solar farms, most located/to be located on former agricultural fields to fast-track environmental assessments (tortoises must be moved!).

One of the largest solar fields in Gila Bend is the 280 MW Solana Solar Project, which is using CSP technology from Abengoa Solar (Sevilla, Spain). The image above, courtesy Gunther Portfolio, shows the support structures being "planted" for Abengoa's proprietary parabolic trough technology. Parabolic mirrors focus the sun on a heat transfer fluid that can reach 735 degrees Fahrenheit. The hot fluid transfers its energy to water to create steam that runs conventional steam turbines. Large "thermos-like" buildings containing the molten salt hat transfer fluid are located next to the steam boilers. At select times, instead of immediately creating steam, the heat transfer fluid will heat the molten salt. Electricity can be created immediately, or from heat energy that was created up to six hours earlier--a real benefit when the sun is not shining. The YouTube "marketing" video below gives a decent overview of the Solana Solar Project:

Another solar field in California that will also use Abengoa Solar equipment is the 280 MW Mojave Solar Project--currently underway thanks to a $1.2 billion dollar loan guarantee from the U.S. Department of Energy, which comprises the bulk of the overall $1.6 billion total investment for the San Bernardino County installation. Yes, a government loan guarantee is resulting in actual hardware and actual energy generation; it’s a shame that the Solyndra scandal is getting all the headlines.

In addition to CSP-based solar farms, photovoltaic (PV) panels from First Solar (Tempe, AZ) will comprise the 550 MW Desert Sunlight Project near Desert Center, CA (operational by Q1 2015) and the 290 MW Agua Caliente Solar Project near Dateland, CA. First Solar continues to be one of the most profitable thin-film PV manufacturers, with its cadmium telluride (CdTe) recipe competing against conventional crystalline silicon PV modules. Another alternative is solar thermal power, which will be implemented in the 392 MW Ivanpah project by BrightSource (Oakland, CA).

Sadly, solar energy still accounts for less than 1% of all the energy sources used worldwide today. But rather than dwelling on this fact, I'd rather remain optimistic that renewable energy will be the savior of our planet. Scientists are improving the optical-to-electrical energy conversion efficiency parameters daily, and solar energy is available TODAY unlike some other yet-to-be-proven energy methods such as laser fission/fusion via the National Ignition Facility. As huge swaths of arid desert land lay fallow due to lack of water and cheaper produce from Mexico and South America, why not plant a solar farm instead?

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