WASHINGTON • Construction should begin within a month on a “waterless” 700-megawatt solar power project in Maricopa County that won a $359.1 million conditional loan guarantee this week from the Department of Energy.
Energy Secretary Steven Chu said the loan guarantee would cover a significant portion of the estimated half-billion-dollar cost for the first phase of San Diego-based Sempra Generation‘s Mesquite Solar plant, located on old farm land about 40 miles west of Phoenix.
The Sempra project uniquely situated to Arizona because it is a photovoltaic system, which uses little or no water.
“This is a really good choice for water-constrained areas,” said Sempra spokesman Scott Crider.
Many large-scale projects are concentrating-solar power plants, which use hundreds of thousands of gallons of water a year to generate steam that moves turbines or to cool the system.
Photovoltaic systems — the dark panels your neighbors might have on their roof — usually use small amounts of water to clean the solar panels, but they generally haven’t been efficient enough for large-scale projects.
A 55-megawatt capacity operation by First Solar and Sempra in Boulder City, Nev., is the largest U.S. photovoltaic project in operation, according to a Solar Energy Industries Association report.
Crider said the Nevada power plant hasn’t used any water yet. Rain has been sufficient to clean the panels so far.
The first phase of the plant will have a capacity of 150 megawatts, enough to power 56,000 homes, according to the company.
Sempra is building the Mesquite Solar project near its Mesquite Power Generating Station, a 1,250-megawatt natural gas power plant that’s been in full operation since December 2003.
The location allows the company to plug into existing transmission lines that it has already upgraded. Sempra could potentially bring power on line, 10 megawatts at a time, as construction is going on, said Crider.
Pacific Gas and Electric, a California utility, has a 20-year contract to purchase all the electricity generated in the first phase of the Mesquite Solar project. The California Public Utilities Commission approved the deal April 14.
Electricity generated by subsequent phases of the project may be available for Arizona utilities’ use. Pacific Gas and Electric serves central and northern California.
The Department of Energy could not disclose what conditions Sempra must meet in order to get the loan guarantee.
_ Sempra Generation: www.semprageneration.com
_ U.S. Department of Energy: www.energy.gov
_ Solar Energy Industries Association: www.seia.org