It's a big week for mirrors in the desert—with two big southwestern projects putting a spotlight on a form of big-scale solar energy that its most ardent advocates believe has the best chance of expanding the nation's share of electricity from renewable sources.
Today, Arizona's largest utility, Arizona Public Service, is announcing plans to build the world's largest "concentrating solar power" plant, a $1 billion project to spread parabolic mirrors over a 3-mile-square stretch of desert 70 miles southwest of Phoenix. To be designed and built by the Spanish firm Abengoa, it would generate 280 megawatts of electricity, or enough to power 70,000 homes.
That makes it four times as large as Nevada Solar One, near Boulder City, Nev., which last summer became the first CSP plant to open in the United States in more than 17 years. Tomorrow, Nevada Solar One's developer, a rival Spanish company, Acciona, plans a star-studded dedication ceremony for the facility, with speakers including former astronaut Sally Ride, Apple cofounder Steve Wozniak, and actor/activist Ed Begley Jr. The dedication, says Acciona Energy North America chief executive Peter Duprey, is meant to get the word out that concentrating solar "is a reality today, and we need to be developing it and exploiting it."
Unlike the solar energy that most people know, CSP doesn't use expensive semiconductor material to transform the sun's energy into electricity. CSP relies on mirrors to focus sunlight onto a heat transfer fluid, which in turn heats water into steam, which turns turbines to generate power. The big Arizona plant, which will be called Solana Generating Station, will take the technology an exciting step forward by using molten salt to store solar energy for up to six hours. "When the suns sets, this plant keeps on ticking," says Arizona Public Service President Don Brandt. "We'll have solar energy in the dark."
The big issue with solar energy has been the cost. Brandt says the Solana plant is expected to generate electricity at 12 cents to 14 cents per kilowatt-hour, which is about 20 percent more than the cost of the other electricity that APS generates with its mix of nuclear, natural gas, and coal. But Brandt notes that since the price of the fuel is free, it's a 30-year contract with one big source of risk eliminated. If natural gas prices increase or if coal-fired power is made more expensive because of climate-change legislation, the CSP power could end up being one of the lowest-priced forms of electricity in the utility's portfolio. "Any business wants to diversify its sources of supply," Brandt says. "That's why we feel right now the price is attractive. And you factor in the possibility of natural gas prices rising or any carbon legislation, and I think we'll look back in five years and think this was an absolute grand-slam home run."
In the late 1970s, it was the U.S. government that spurred research and development of CSP technology through a series of experimental projects in the Mojave Desert—one of which has been generating power for years, operated by Florida Power & Light. But in recent years, European companies have taken the lead in big-scale renewable energy projects, spurred by aggressive government incentives.
Duprey of Acciona says his company is building four more CSP plants in Spain and has a number in development in the United States. He says all will be two or three times the scale of Nevada Solar One, which was a $226 million project. "This plant is on the smaller side, because we wanted to see how it would work," he says. "We had to start out with all new suppliers and build out this industry. It's like an infant—we have to nurture it and bring it along.
"We believe the technology is proven, it's a matter of getting more suppliers and getting competition among suppliers and driving the cost down," he says.