San Diego Gas & Electric signs solar power deal

PHOENIX, Sept. 7, 2005 — Stirling Energy Systems (SES) has announced a contract with San Diego Gas & Electric (SDG&E) to provide between 300 and 900 MW of solar power, approximately 30 times more solar power than is now being generated in the San Diego region. This contract represents the second record-breaking solar project signed by the SES in the past month, which may surpass the earlier contract to become the world’s largest solar installation.

Under this contract, SDG&E will buy the electrical energy produced from this plant from SES Solar Two LLC, an affiliate of Arizona-based Stirling Energy Systems, Inc. SES and SDG&E have agreed to an initial 20-year contract to purchase all the output from a 300 MW solar power plant, which consists of 12,000 Stirling solar dishes on approximately three square miles in the Imperial Valley of Southern California. SDG&E has options on two future phases that could add up to 600 MW of additional renewable energy and capacity to SDG&E’s resource mix. This contract is subject to approval by the California Public Utilities Commission (CPUC).

“SDG&E has pledged to supply 20 percent of its customers energy needs from renewable resources like solar and wind by 2010,” said Edwin A. Guiles, chairman and chief executive officer of SDG&E. “With this purchase, SDG&E continues to demonstrate its commitment to bring more renewable energy to its customers.”

Last year, the California Public Utilities Commission approved SDG&E’s long-term resource plan, which relies on a balanced mix of resources to meet the growing energy needs of San Diego. That mix includes increased emphasis on energy efficiency and more renewable energy resources, as well as additional baseload generation plants and more transmission lines. All phases of the Stirling projects will require additional transmission facilities to be built to deliver the energy to SDG&E customers.

Second Major Contract for SES in 2005
Early last month, SES announced a contract with Southern California Edison that will result in construction of a massive, 4,500-acre solar generating station in Southern California.

The signed 20-year power purchase agreement, which is also subject to CPUC approval, calls for development of a 500-MW solar project in the Mojave Desert northeast of Los Angeles, with an option to expand the project to 850 MW. The first 500 MW phase, consisting of a 20,000-dish array, will be constructed during a four-year period.

How the Technology Works
The SES dish technology converts thermal energy to electricity by using a mirror array to focus the sun¹s 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 is connected to 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.

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The Clarion Energy Content Team is made up of editors from various publications, including POWERGRID International, Power Engineering, Renewable Energy World, Hydro Review, Smart Energy International, and Power Engineering International. Contact the content lead for this publication at

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