SDG&E has committed to delivering 20% of its electricity from renewable sources by 2010. The utility also announced the purchase of approximately 4MW of energy and capacity from a local biogas landfill project.

The contract marks the second major deal recently for SES. In early August, SES announced a contract with Southern California Edison that will result in the development of a 500MW 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, is to be constructed during a four-year period.

The Stirling Solar Engine

The SES dish technology converts solar thermal energy to electricity by using a mirror array to concentrate the sun’s rays on the receiver end of a Stirling engine. (This type of approach to solar generation is termed Concentrating Solar Power (CSP), as opposed to photovoltaic (PV).

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.

Resources:

• Sandia National Labs: Concentrating Solar Power and SunLab