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Stirling SunCatcher with "Heat Engine" Technology

by LiveModern Webmaster last modified Jan 04, 2012 02:08 AM
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by Alex Wilson last modified Apr 29, 2010

Those of us who have tracked solar energy innovations for several decades will likely have heard about Stirling engines. This sealed "heat engine" technology has been around a long time--since 1816, in fact--when it was invented by the Scottish cle... To understand why I'm excited about the Stirling SunCatcher you have to understand how a Stirling engine differs from steam engines and steam turbines. Stirling engines are closed-cycle engines (sometimes called "external-combustion" engines) in which an external heat source heats air or another gas, such as helium or hydrogen, in one of the cylinders. The expanding gas pushes a piston, which compresses gas in the cooler portion of the engine. The SunCatcher uses hydrogen in an advanced, four-cylinder design. Concentrated heat from the sun is the external heat source to drive the process. No water or steam is involved--which has very significant implications, since places with a lot of sunlight where CSP applications are most cost effective are also usually very dry. In January, 2010, four months after breaking ground, Stirling Energy partner company Tessara Solar completed the 1.5 MW Maricopa Solar power plant in Peoria, Arizona, just outside Phoenix. The power plant is comprised of 60 SES SunCatchers. The Maricopa plant is considered a demonstration plant; Tessara hopes to break ground on much larger plants in California and Texas, totaling 1,500 MW of capacity, later this year. The Stirling engine SunCatcher isn't the only solar-thermal power-generation system that is ramping up in a big way across the desert Southwest these days. A different dual-axis-tracking technology, from BrightSource Energy , is going to be used in a 392-MW Ivanpah solar power plant in the Majave Desert, with groundbreaking planned for later this year. The U.S. Department of Energy recently announced a $1.37 billion load guarantee to support this project. BrightSource has contracts with Southern California Edison and Pacific Gas & Electric to supply a total of 2,600 MW of electric capacity over the next several years, though all of these projects are pending final permits. The Stirling SunCatcher differs from BrightSource technology--and that of a somewhat different technology that is used in the Solar Energy Generating Stations (SEGS) plants that have been operating since the early 1980s--in how the heat is converted into electricity. Most CSP systems, including BrightSource, uses the heat to boil water, creating high-pressure steam that then spins a steam turbine. Thus, these CSP systems require water to operate. The SunCatcher does not consume water, since the Stirling engine uses sealed, hydrogen-filled cylinders to convert thermal energy into electricity. One thing is for sure: the next year will be an exciting period for large-scale solar thermal plants. Keep watching! For more information: Stirling Energy Systems Scottsdale, Arizona 602-957-1818 Tessara Solar Houston, Texas 713-554-8484 I invite you to share comments on this blog. Alex Wilson is the executive editor of Environmental Building News and founder of BuildingGreen, LLC. To keep up with his latest articles and musings, you can sign up for his Twitter feeds . Photos of SunCatcher dish collectors at the Maricopa solar power plant. Source: Stirling Energy Systems. See more on this product in the GreenSpec Guide






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