Thursday, May 5, 2011

good basic primer on Concentrating Solar Thermal Power

Solar power is used synonymously with solar energy or more specifically to refer to the conversion of sunlight into electricity. This can be done either through the photovoltaic effect or by heating a transfer fluid to produce steam to run a generator.

Solar energy technologies harness the sun's energy for practical ends. These technologies date from the time of the early Greeks, Native Americans and Chinese, who warmed their buildings by orienting them toward the sun. Modern solar technologies provide heating, lighting, electricity and even flight.

Concentrated sunlight has been used to perform useful tasks from the time of ancient China. A legend claims Archimedes used polished shields to concentrate sunlight on the invading Roman fleet and repel them from Syracuse in 212 BC. Leonardo Da Vinci conceived using large-scale solar concentrators to weld copper in the 15th century. In 1866, Auguste Mouchout successfully powered a steam engine with sunlight, the first known example of a concentrating solar-powered mechanical device. Over the following 50 years, inventors such as John Ericsson, and Frank Shuman developed solar-powered devices for irrigation, refrigeration and locomotion. The progeny of these early developments are the concentrating solar thermal power plants of today.

Concentrating Solar Thermal (CST) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. This is then used to generate electricity. Moreover, the high temperatures produced by CST systems can be used to provide process heat and steam for a variety of secondary commercial applications (cogeneration). However, CST technologies require direct insolation to function and are of limited use in locations with significant cloud cover. The main methods for producing a concentrated beam are the solar trough, solar power tower and parabolic dish; the solar bowl is more rarely used. Each concentration method is capable of producing high temperatures and high efficiencies, but they vary in the way they track the sun and focus light.

 

Monty Bannerman

ArcStar Energy

646.402.5076

www.arcstarenergy.com

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