Thermal Power Heats Up Nevada

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Acciona / PR NewsFoto

Acciona's Nevada Solar One concentrating solar power plant.

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That last point has held up solar thermal in the past. Though the basics of the technology are over 100 years old, NS1 is the first major solar thermal project to be built in over 16 years. Unlike solar photovoltaics, which can be useful on a house-by-house basis, solar thermal really only becomes competitive once it reaches utility-scale. It's all or nothing, and in building the plant, Acciona stuck out its neck. "No one was taking the risk to develop this technology," said Acciona CEO Jos Entrecanales. "We had no real evidence, no real certainty of efficiency."

But Nevada was a good place to try. The American Southwest receives plentiful sunshine and doesn't lack for the sprawling space solar thermal plants need; plus, the state implemented aggressive policies in support of renewable energy, requiring at least 5% of its power to come from solar by 2015. (Nevada now leads the U.S. in solar energy.) Without that renewable portfolio standards, Entrecanales says, it's unlikely Acciona would have been able to build NS1. "It would have been a very risky venture."

With the success of NS1, Acciona is planning on adding an additional 500 megawatts of solar thermal power in the U.S. by 2011. That's just a fraction of the new power capacity a growing America will need over the coming years, but there's a chance that with the right federal policies, solar thermal could contribute far more. Its proponents believe that alone among major renewables, solar thermal has the capacity to displace fossil fuels on the utility scale, perhaps eventually taking up a quarter or even half of the national power supply. A study published in Scientific American in January sketched out a grand plan where by 2050 similar solar thermal plants would cover 30,000 square miles of the mostly empty American Southwest. To provide power at nighttime, excess energy produced during the day would be stored using compressed air or molten salt. (In the former, solar power is used to compress air in an underground cavern, which is released as needed to power turbines; in the latter, the sun heats salt, which retains its heat for hours, enough to keep the plants running at night.) The authors estimate solar could supply 69% of U.S. electrical needs by 2050, enough to free the country from its reliance on coal and foreign oil. To get there, however, the government will need to put a price on carbon and implement reliable subsidies for the solar industry, so companies like Acciona can invest for years ahead.

For now, that future is still a desert mirage. Less than 400 megawatts of solar thermal have been deployed in the U.S., and Entrecanales worries that a lack of water could limit the growth of the technology in the very desert areas that receive the most sun. It also hurts that the federal investment tax credit on solar power is due to expire at the end of the year, and it's not clear that a distracted Congress will renew it in time. But even on a cloudy day in Nevada, the future looks bright for solar thermal. "This is a wonderful technology," said Begley Jr. "We're headed in the right direction. We're getting there."

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