Old ways can be the best ways
DESPITE its oppressive glow in much of the West, the sun has remained largely untapped as a source of electricity. The world's biggest solar farm, where more than 400,000 mirrors cover four square miles (10.3 square kilometres) of California's Mojave desert, was built in the 1980s and still churns out 354 megawatts of electricity, enough for 90,000 homes. But until recently no more large solar plants have been built, despite soaring demand.
Thanks to a confluence of factors—a federal tax credit, an uptick in federal funding for renewable energy R&D, the enactment of renewable electricity standards in many states and public antipathy toward greenhouse gas-belching coal-fired power plants—the sun is making a comeback. Concentrating solar power (CSP) is suddenly looking interesting again.
CSP systems capture and focus the sun's rays, using mirrors, to heat a working fluid to high temperatures and use it to drive a turbine. By contrast, photovoltaic solar power systems, mostly used on home rooftops, let light interact directly with semiconductor materials to generate power. As a source of large-scale power CSP is less expensive and more practical, not least because the technology can deliver power for hours after the sun sets using thermal storage. America's south-western deserts are an abundant source of sunshine that could meet the country's power needs several times over without releasing a molecule of carbon dioxide.
The first large CSP plant to be built since the 1980s went online in June in Nevada: it will generate 64 megawatts. Power companies have already signed long-term agreements with developers such as Stirling Energy Systems of Phoenix to buy up to 2,300 megawatts of CSP electricity from them. That is paltry compared with the nation's total electricity capacity of over 1m megawatts: but the Energy Department says at least 7,000 megawatts from CSP plants will be available by 2020. Meanwhile, large international CSP companies, such as Acciona Energy and Abengoa of Spain, and Solel of Israel, are busily setting up shop in America.
Electricity from the new plant in Nevada costs an estimated 17 cents per kilowatt hour (kWh), but projections suggest that CSP power could fall to below ten cents per kWh as the technology improves. Coal power costs just 2-3 cents per kWh. But that will rise if (as seems likely) regulation eventually factors in the environmental costs of the carbon coal produces. And CSP purveyors have a powerful friend: Harry Reid of Nevada, the Democratic leader in the Senate. Mr Reid recently declared that he will fight to prevent any new coal-fired plants in his state—or even nationwide.