 Stirling Energy Systems of Phoenix, Ariz., plans commercial production of the Dish Stirling System based on technology it describes as the "most efficient solar powerplant ever built."
The Dish Stirling System integrates a solar concentrator developed by McDonnell Douglas and engine/generator power conversion unit developed by Kockums in Sweden. The power conversion unit produces 25 kilowatts per hour of solar energy. SES acquired the rights from a Swedish defense contractor to manufacture the Stirling PCU in this country. The unit includes the Stirling engine, an electrical generator, a solar receiver, cooling system, and an electronic command and control system. Efficiency record The 4-95 Stirling PCU holds the world's efficiency record for converting solar energy into grid-quality electricity (30 percent at 1,000 watts per square meter). The unit has accumulated more "on sun" operational time (16,000 hours) than any other Stirling PCU unit, according to Beverly Pardo, SES utility marketing representative.
Southern California Edison and Georgia Power tested the Dish Stirling system for several years at their solar test site near Barstow, Calif. The systems generated more than 100 megawatthours of grid-quality electricity. In addition, bench-scale Dish Stirling PCUs have operated for more than 100,000 hours with conventional hydrocarbon fuels. Utilities targeted SES initially plans to market to utilities, according to Pardo. The Dish Stirling system can also provide power for communities or commercial operations not connected to a utility grid, and the power modules can be combined to meet incremental load capacity growth. When the sun is not available, the system operates on conventional fuels. SES systems also are applicable to irrigation pumping in rural areas. PCU electric generator output can be directly coupled to one or more submersible pump motors. A nonsolarized version of the engine can be powered by almost any fuel, including natural gas or biomass, and can produce hot water from its waste heat. Ideal initial market applications include small businesses, apartments, and hotels.
|
||||||
The SES solar parabolic concentrator, which focuses the sun's energy, is 38 feet in diameter and has 82 mirror facets the size of car hoods. The mirror facets direct solar radiation to a solar receiver that encloses the heater head of the Stirling engine. The PCU is cantilevered 24 feet in front of the mirrors. The solar radiation heats hydrogen gas in the heater head tubes, which expands and creates pressure on the pistons to rotate a crankshaft that drives the electric generator.
