Solar thermal energy

Solar thermal energy is a way of producing electricity in which the Sun's energy is concentrated by mirrors or lenses to either heat a fluid-filled pipe or drive a Stirling engine. The oil which is hot is circulated into a water storage system where it is used to change water into superheated steam, that then turns a turbine to generate electricity. The heat that is produced through this process powers a Stirling engine. The Stirling engine provides electricity and mechanical energy by having the fluid from within a cylinder expand, which then drives a piston that turns a shaft.

Solar thermal energy is primarily used domestically for space heating, hot water, and in some cases air conditioning. Solar thermal energy is renewable and no fuels are required during the process to generate electricity or mechanical energy. It is also carbon free except for production and transportation, otherwise it is non-polluting. Solar thermal can also be combined with photovoltaics (PVs), in highly efficient cogeneration systems. Some downsides are that solar thermal generates low grade energy, installation and construction costs are very high, it is expensive compared to conventional water heaters, and is hard to compete against cheap natural gas. An example of a Solar Thermal Electric Generation Plant is the Ivanpah Solar Electric Generating System that uses 300,000 computer-controlled mirrors, that focuses sunlight to the top of 459-foot towers, where water is turned into steam to power turbines.

Solar Thermal Energy Media

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  Roof-mounted close-coupled thermosiphon solar water heater.

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  The first three units of Solnova in the foreground, with the two towers of the PS10 and PS20 solar power stations in the background.

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  MIT's Solar House#1 built in 1939 used seasonal thermal energy storage (STES) for year-round heating.

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  Unglazed, "transpired" air collector

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  Building integrated unglazed transpired solar air collector with grey walls and white canopy/collection ducts

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  Solar Evaporation Ponds in the Atacama Desert.

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  The Solar Bowl above the Solar Kitchen in Auroville, India concentrates sunlight on a movable receiver to produce steam for cooking.

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  Part of the 354 MW SEGS solar complex in northern San Bernardino County, California.

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  The solar furnace at Odeillo in the French Pyrenees-Orientales can reach temperatures up to 3,500°C (6300°F).

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  Sketch of a parabolic trough design. A change of position of the sun parallel to the receiver does not require adjustment of the mirrors.