San Diego Signs Up for 300 Megawatts of Solar Thermal Power

September 14, 2005

A photo of a field of dish Stirling systems, each composed of nearly 100 mirrored squares combined into a dish shape and mounted on a pillar, reflecting the sky and clouds.
An arm of metal gridwork extends from the center of each mirror and holds the Stirling engine, a dark metal cylinder.

The new solar facility in California's Imperial Valley will consist of a field of dish Stirling systems.
Credit: Randy J. Montoya, Sandia National Laboratories

San Diego Gas and Electric (SDG&E) announced on September 7th that it has signed a 20-year power purchase agreement with Stirling Energy Systems for 300 megawatts of solar power, to be generated by Stirling solar dishes in a three-square-mile array in California's Imperial Valley. The installation, to be called "SES Solar 2," will require new transmission lines to carry the power to SDG&E customers. SDG&E also has options for another 600 megawatts of solar thermal power that could be built in two future phases of the solar power project. See the SDG&E press release.

Stirling solar dish technology converts solar thermal energy to electricity by using a dish-shaped array of mirrors to focus the sun's rays on the receiver end of a Stirling engine. The internal side of the receiver then heats hydrogen gas, causing it to expand. The expanding gas creates pressure that drives a piston, which turns a small electricity generator. To learn more about the technology, see the SunLab Web site.

The announcement is the second in as many months for Stirling Energy Systems, which could quickly become the leading source of solar power in the United States. In early August, Southern California Edison signed a similar agreement with the company for 500 megawatts of solar power, with an option to expand the project to 850 megawatts. See the article from the August 17th edition of this newsletter.