The Arizona-based Stirling Energy Systems (SES) is about to deploy the 1.5 megawatt demonstration site, known as Maricopa Solar; it is set to begin operations early January 2010. The solar module - the SunCatcher - looks like a well-known concentrator but includes a Sterling engine as the power producing unit. Introduced in 1816, the Sterling engine has efficiency theoretically approaching that of the most efficient Carnot cycle. However, such features as the external source of heat and many moving parts have made it notoriously unpractical. Can these features make it one of the most attractive candidates for "green" power generation? Read "Are Engines the Future of Solar Power?" by Cynthia Graber in Scientific American (December 30, 2009).

Nearly 200 years after their invention, and decades after first being proposed as a method of harnessing solar energy, 60 sun-powered Stirling engines are about to begin generating electricity outside Phoenix, Ariz., for the first time. …

… The 1.5 megawatt (MW) demonstration site, known as Maricopa Solar,

is set to begin operations early January 2010, with units provided by the Arizona-based Stirling EnergySystems (SES). …

…First invented by Robert Stirling in 1816, the engines use a heat source to warm gas, which expands and is pushed into another chamber. When the gas cools and contracts, it flows back. The expansion and contraction pushes a piston, which in turn produces electricity. …

… Stirling engines are significantly more efficient at converting sunlight into energy than most photovoltaic panels or concentrating solar power plants, whether parabolic trough or tower designs. The test units have reached 31 percent efficiency, compared to 16 percent for parabolic troughs and about

14-18 percent for PV panels in use today …

… Proponents of the technology point to the advantages it has over other forms of solar power, particularly concentrating solar power (CSP), which also captures the sun’s heat. Most CSP systems require significant amounts of water, which has proven to be a challenge in desert regions of the U.S. where solar power is most attractive, while Stirling engines require none other than small amounts for cleaning the mirrors.

… Maricopa Solar also represents just one scalable module; each multi-megawatt field will be grouped first in 60-engine units that come together to generate 1.5 MW, then those larger units are linked to each other to produce up to 9 MW …

… Tessera Solar, SES’s sister company in charge of development, is renegotiating contracts with utilities in California but expects to supply power at or below the cost of other solar technologies, and they plan to break ground on bigger solar Stirling engine power plants in Texas and California in 2010. …

Full story – at http://www.scientificamerican.com/article.cfm?id=are-engines-the-future-of-solar-power

Related articles:

“Sandia, Stirling Energy Systems set new world record for solar-to-grid conversion

efficiency”

"The Stirling Engine” http://electron9.phys.utk.edu/phys136d/modules/m3/m3ex1.htm

"How Stirling Engines Work”