Sunday, October 28, 2012

Energy Generation: Solar Stirling Engines

The Solar Dish Stirling system is shaped much like large satellite dishes (approximately 37’ in diameter) and covered with curved mirrors. These solar dishes are programmed to always face the sun and focus that energy on a collector in much the same way that a satellite dish focuses radio waves on a tuner. This collector is connected to a Stirling engine which uses the thermal power generated by the focused solar energy to heat liquid hydrogen in a closed-loop system. The expanding hydrogen gas creates a pressure wave on the pistons of the Stirling engine which spins an electric motor creating electricity with no fuel cost or pollution. This technology is referred to as solar thermal or concentrating solar power.

The SES (Stirling Energy Systems) Solar Dish Stirling technology is well beyond the research and development stage, with more than 20 years of recorded operating history.  The equipment is well characterized with over 25,000 hours of on-sun time.  Since 1984, the Company's solar dish Stirling equipment has held the world's efficiency record for converting solar energy into grid-quality electricity.



In addition to reducing air pollution, how else does a solar Stirling Dish benefit the environment?
Dish Stirling Systems create no adverse environmental consequences. First, with the exception of antifreeze used in the cooling system and the small amount of oil lubricant used in the Stirling engine, there are no toxic chemicals. The hydrogen gas used is sealed inside the engine; although small amounts will escape over time, hydrogen is a non-toxic substance that will diffuse rapidly into the atmosphere. Third, the only fuel used is the sun. Fourth, the only water used is that used to periodically wash the mirrors, only 4.4 gallons per MWh of energy produced (much less than traditional power generation usage). Fifth, since the Stirling engine does not use internal combustion, it is remarkably quiet, emitting less than 66 dB at full load. Sixth, a Stirling solar plant will have no significant biological or cultural/paleontological/geological impacts. The system has a support post structure that is only about 18 inches in diameter, the result being comparable to the planting of a tree. The primary impact, after construction, is to provide shade. Finally, a Dish Stirling solar plant requires only about one acre per 8 systems. Further, the solar plant will normally be located in underutilized land that is far from urban areas.

Is a Stirling Solar Dish new technology?
This is well-established, reliable technology. The SES dish system was initially developed by McDonnell-Douglas in the mid 1980's. Since 1998 SES and Boeing have been under contract with the Department of Energy’s Sandia National Laboratories for a Dish-Engine Critical Components (DECC) program. Phase I of that program incorporated design enhancements to the Stirling Dish System to increase performance and decrease and maintenance costs. Phase II, aimed at system integration and a business and marketing component has been successfully completed. Independent reviews of the DECC program have concluded that there are no serious obstacles to commercialisation of this technology and that this, and other concentrating power technology, could contribute significantly to the U.S. supply of electricity from domestic sources.

What about fuel costs and emissions?
Solar has zero fuel costs and zero emissions.

What geographical areas are best suited for a solar dish farm?
The southwest region of the United States is ideally suited for this. In fact, a solar farm 100 miles by 100 miles could satisfy 100% of the America’s annual electrical needs. Solar technology primarily addresses the peak power demands facing utility companies in the Southwest U.S. and other solar-rich areas.

For more information see http://www.stirlingenergy.com

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