Four newly designed solar power collection dishes called SunCatchers were unveiled at Sandia’s National Solar Thermal Test Facility. The new dishes are the next-generation model of the original SunCatcher system. Engineers say they are designed for high-volume production, ease of maintenance and cost reductions, and could be in commercial service by 2010.
The modular solar-thermal power SunCatcher uses precision mirrors attached to a parabolic dish to focus the sun’s rays onto a receiver, which transmits the heat to a Stirling engine. The engine is a sealed system filled with hydrogen. As the gas heats and cools, its pressure rises and falls. The change in pressure drives the piston inside the engine, producing mechanical power, which in turn drives a generator and makes electricity.
The new dishes are an improvement over the original SunCatcher system. “Six first-generation SunCatchers built over the past several years at the NSTTF have been producing up to 150KW [kilowatts] of grid-ready electrical power during the day,” says Chuck Andraka, the lead Sandia project engineer. “Every part of the new system has been upgraded to allow for a high rate of production and cost reduction.”
The new SunCatcher is about 5,000 pounds lighter than the original, is round instead of rectangular to allow for more efficient use of steel, has improved optics, and consists of 60 percent fewer engine parts. The revised design also has fewer mirrors — 40 instead of 80. The reflective mirrors are formed into a parabolic shape using a stamped sheet metal technique, similar to that used to form the hood of a car. The mirrors are made by using automobile manufacturing techniques. This approach, according to SNL and its partner, Stirling Energy Systems, allows high-volume production, cost reductions and easier maintenance.
“The new design of the SunCatcher represents more than a decade of innovative engineering and validation testing, making it ready for commercialization,” says Steve Cowman, CEO of SES. “By utilizing the automotive supply chain to manufacture the SunCatcher, we’re leveraging the talents of an industry that has refined high-volume production through an assembly line process. More than 90 percent of the SunCatcher components will be manufactured in North America.”
The new SunCatcher minimizes both cost and land use and has numerous environmental advantages, Andraka says. “They have the lowest water use of any thermal electric generating technology, require minimal grading and trenching, require no excavation for foundations and will not produce greenhouse gas emissions while converting sunlight into electricity.”