Stirling Energy Systems (SES; Phoenix, Arizona, U.S.) has signed an agreement with Edison International subsidiary Southern California Edison (SCE), the nation's leading purchaser of renewable energy, that will result in construction of a 4500-acre solar generating station in Southern California. When completed, this power station will be the world's largest solar facility, capable of producing more electricity than all other U.S. solar projects combined.

“At a time of rising fossil-fuel costs and increased concern about greenhouse gas emissions, the SES project would provide enough clean power to serve 278,000 homes for an entire year,” notes SCE Chairman John Bryson.

The signed 20-year power purchase agreement, which is subject to California Public Utilities Commission approval, calls for the development of a 500-MW solar project in the Mojave Desert northeast of Los Angeles using SES' Stirling dish technology. The agreement includes an option to expand the project to 850 MW. Initially, SES would build a 1-MW test facility using 40 of the company's 37-ft (11-m) diameter dish assemblies. Subsequently, a 20,000-dish array will be constructed during a four-year period.

The SES dish technology converts thermal energy to electricity by using a mirror array to focus the sun's rays on the receiver end of a Stirling engine. The internal side of the receiver then heats hydrogen gas, which expands. The pressure created by the expanding gas drives a piston, crank shaft and drive shaft assembly, much like those found in internal combustion engines but without igniting the gas. The drive shaft turns a small electricity generator. The entire energy-conversion process takes place within a canister the size of an oil barrel. The process requires no water and the engine is emission-free.

Although solar Stirling dish technology has been tested for 20 years, the SES -SCE project represents its first major application in the commercial electricity generation field. Experimental models of the SES dish technology have undergone more than 26,000 hours of successful solar operation. A six-dish model SES power project is currently operating at the Sandia National Laboratories in Albuquerque, New Mexico.

“This solar dish Stirling facility employs the world's most efficient sun-to-electricity conversion technology,” says SES General Manager Robert Liden. “This power purchase agreement is quite complex and took many months to hammer out but represents an excellent beginning for both companies' long-term relationship.”