Wednesday, August 5, 2009

How Solar Thermal Power Works - Stirling Energy SunCatcher News - Popular Mechanics

How Solar Thermal Power Works - Stirling Energy SunCatcher News - Popular Mechanics: "Solar Stirling Engine: Each Stirling Energy SunCatcher dish can produce 60,000 kilowatt-hours of electricity a year—enough to power a dozen U.S. homes. (Photograph by Jamey Stillings)

Planted in the New Mexico desert near Albuquerque, the six solar dish engines of the Solar Thermal Test Facility at Sandia National Laboratories look a bit like giant, highly reflective satellite dishes. Each one is a mosaic of 82 mirrors that fit together to form a 38-ft-wide parabola. The mirrors’ precise curvature focuses light onto a 7-in. area. At its most intense spot, the heat is equivalent to a blistering 13,000 suns, producing a flux 13 times greater than the space shuttle experiences during re-entry. “That’ll melt almost anything known to man,” says Sandia engineer Chuck Andraka. “It’s incredibly hot.”

The heat is used to run a Stirling engine, an elegant 192-year-old technology that creates mechanical energy from an external heat source, as opposed to the internal fuel combustion that powers most auto­mobile engines. Hydrogen gas in a Stirling engine’s four 95 cc cylinders expands and contracts as it is heated and cooled, driving pistons to turn a small electric generator. The configuration of the dish and engine represent the fruit of more than a decade of stea"

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