New rays of hope for solar power’s future

From five miles away, the Nevada Solar One power plant seems a mirage, a silver lake amid waves of 110 degree F. desert heat. Driving nearer, the rippling image morphs into a sea of mirrors angled to the sun.

As the first commercial “concentrating solar power” or CSP plant built in 17 years, Nevada Solar One marks the reemergence and updating of a decades-old technology that could play a large new role in US power production, many observers say.

“Concentrating solar is pretty hot right now,” says Mark Mehos, program manager for CSP at the National Renewable Energy Laboratory in Golden, Co. “Costs look pretty good compared to natural gas [power]. Public policy, climate concern, and new technology are driving it, too.”

Spread in military rows across 300 acres of sun-baked earth, Nevada Solar One’s trough-shaped parabolic mirrors are the core of this CSP plant – also called a “solar thermal” plant. The mirrors focus sunlight onto receiver tubes, heating a fluid that, at 735 degrees F., flows through a heat exchanger to a steam generator that supplies 64 megawatts of electricity to 14,000 Las Vegas homes.

Today the United States has 420 megawatts of solar-thermal capacity across three installations – including Nevada Solar One. That’s just a tiny fraction (less than 1 percent) of US grid capacity. But Nevada Solar One could signal the start of a CSP building boom.

Efforts to generate another 4,500 megawatts of solar thermal power are now in development across California, Nevada, Arizona, and New Mexico – all of which have the flat, near-cloudless skies most desirable for solar thermal, the Solar Electric Industries Association reports.

Photovoltaic panels that produce electricity directly from the sun’s rays work well on rooftops, but are still too costly for utility-scale power generation. Solar thermal, however, is nearing the cost of a natural gas-fired turbine power plant – making it a winner with several power companies that have signed long-term contracts to purchase solar-thermal power.

Desert land lures developers
In fact, there’s a land rush at the federal Bureau of Land Management. As of July, the BLM reported more than 125 applications to build solar power on about 1 million acres of desert, up from just a handful of proposals a few years ago.

“We think there’s a good market there,” says Travis Bradford, an expert at the Prometheus Institute, a Boston-based solar-energy market research firm. His firm sees 12,000 megawatts (12 gigawatts) of solar thermal installed by 2020 and maybe 20 times that in coming decades.

Dr. Mehos says perhaps 100,000 megawatts (100 gigawatts) could be built across the US Southwest over the next 30 years.

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