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Turning Glare Into Watts

New York Time
Published: March 6, 2008

BOULDER CITY, Nev. — At first, as he adjusted pumps and checked temperatures, Aaron Boucher looked like any technician in the control room of an electrical plant. Then he rushed to the window and scanned the sky, to check his fuel supply.

Especially in areas of intense sun, an array of reflectors can concentrate sunlight, heating a fluid to create steam and power.

Mr. Boucher was battling clouds, timing the operations of his power plant to get the most out of patchy sunshine. It is a skill that may soon be in greater demand, for the world appears to be on the verge of a boom in a little-known but promising type of solar power.

It is not the kind that features shiny panels bolted to the roofs of houses. This type involves covering acres of desert with mirrors that focus intense sunlight on a fluid, heating it enough to make steam. The steam turns a turbine and generates electricity.

The technology is not new, but it is suddenly in high demand. As prices rise for fossil fuels and worries grow about their contribution to global warming, solar thermal plants are being viewed as a renewable power source with huge potential.

After a decade of no activity, two prototype solar thermal plants were recently opened in the United States, with a capacity that could power several big hotels, neon included, on the Las Vegas Strip, about 20 miles north of here. Another 10 power plants are in advanced planning in California, Arizona and Nevada.

On sunny afternoons, those 10 plants would produce as much electricity as three nuclear reactors, but they can be built in as little as two years, compared with a decade or longer for a nuclear plant. Some of the new plants will feature systems that allow them to store heat and generate electricity for hours after sunset.

Aside from the ones in the United States, eight plants are under construction in Spain, Algeria and Morocco. Another nine projects are in various stages of planning in those countries as well as Israel, Mexico, China, South Africa and Egypt, according to a count kept by Frederick H. Morse, formerly in charge of solar energy at the Energy Department and now a consultant.

Mr. Morse and others say that solar thermal plants could meet most of the galloping growth in power demand in Phoenix, Las Vegas and the rest of the southwestern United States. In fact, experts say enough sunshine hits the deserts of the Southwest that such plants could theoretically power the entire United States. But that is a far-off dream, since it would require big new transmission cables.

The workability of solar thermal power was established in the 1980s, when developers in California built a series of plants in the Mojave Desert, eventually reaching 354 megawatts of capacity. A megawatt is enough electricity to run 1,000 room air-conditioners at once.

The California plants grew more sophisticated and costs shrank as the project progressed. But then the price of a competing fuel, natural gas, collapsed in the 1990s and building new solar plants became uneconomic.

Today, natural gas prices are much higher, and political opposition is rising to construction of new coal-burning power plants. Many states, including California, are imposing mandates for renewable energy. All of that is reviving interest in solar thermal plants.

The power they produce is still relatively expensive. Industry experts say the plant here produces power at a cost per kilowatt- hour of 15 to 20 cents. With a little more experience and some economies of scale, that could fall to about 10 cents, according to a recent report by Emerging Energy Research, a consulting firm in Cambridge, Mass. Newly built coal-fired plants are expected to produce power at about 7 cents per kilowatt-hour or more if carbon is taxed.

The solar plants receive a federal tax subsidy, like other types of renewable energy, which makes the economics work for builders but also feeds skepticism about the technology’s long-term potential. "Unless there’s a subsidy involved, it doesn’t seem like a very attractive technology," said Revis James, a renewables expert at the Electric Power Research Institute, a utility industry consortium.

Still, solar plants do tend to produce peak power during the hottest part of the day, when demand is highest and electricity is costly, so at certain times they are already competitive with plants using natural gas. And they have an advantage over the other widely available form of renewable power, wind turbines: they are more predictable.

With California utilities struggling to meet a state quota of 20 percent renewable power by 2010, the state has grown interested in solar plants. Pacific Gas and Electric has committed to building several plants and is expected to make announcements about new solar plants soon.

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