Solar furnace
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A solar furnace is a structure used to harness the rays of the sun in order to produce high temperatures. This is achieved by using a curved mirror (or an array of mirrors) acting as a parabolic reflector to concentrate light (Insolation) on to a focal point. The temperature at the focal point may reach up to 3,000 degrees Celsius, and this heat can be used to generate electricity, melt steel or make hydrogen fuel.
The solar furnace at Odeillo in the Pyrenees of France was opened in 1970 and is the largest in the world. It employs an array of plane mirrors to gather the rays of light from the sun and reflects them on to a larger curved mirror. The rays are focused on to an area the size of a cooking pot and can reach up to 3,000 degrees Celsius.
The first modern solar furnace is believed to have been built in France in 1949 by Professor Félix Trombe. It is still in place at Mont Louis, near to Odeillo. The Pyrenees were chosen as the site for these furnaces due to the weather being sunny for up to 300 days a year. [1]
It has been suggested that solar furnaces could be used in space to provide energy for manufacturing purposes, although their reliance on sunny weather means that they are unlikely to be used as a major source of renewable energy on Earth.
The ancient Greek / Latin term "heliocaminus" literally means "solar furnace" - A glass-enclosed sunroom intentionally designed to become hotter than the outside air temperature.[2] Today, the term "solar furnace" has evolved to refer to solar concentrator heating systems using parabolic mirrors or heliostats. 1,000 degrees Fahrenheit (538 degrees Celsius) is now being commonly achieved. The theoretical maximum is the 5778 degree Kelvin surface temperature of the sun [3], although the practical limit (due to atmospheric absorption and rapid heat transfer at high temperature differentials) is much lower.
During the Second Punic War (218 - 202 BCE), the Greek scientist Archimedes is said to have repelled the attacking Roman ships by setting them on fire with a "burning glass" that may have been an array of mirrors. An experiment to test this theory was carried out by a group at the Massachusetts Institute of Technology in 2005. It concluded that although the theory was sound for stationary objects, the mirrors would have been unlikely to concentrate sufficient solar energy to set a ship on fire under battle conditions.[4]
The solar furnace principle is being used to make inexpensive solar cookers, solar-powered barbecues, and for solar water pasteurization. [5][6] [7] A prototype Scheffler reflector is currently being constructed in India for use in a solar crematorium. This 50 m² reflector will generate temperatures of 700 °C and displace 200-300 kg of firewood used per cremation.[8]
[edit] See also
[edit] References
- ^ http://www.promes.cnrs.fr/ Odeillo Solar Furnace official website, retrieved 12 July 2007
- ^ MEEF Roman Architectural Glossary
- ^ Sun Fact Sheet
- ^ 2.009 Product Engineering Processes: Archimedes
- ^ Solar Cookers International (Solar Water Pasteurization
- ^ Coming to a garden near you - the solar-powered barbecue | the Daily Mail
- ^ http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5090399.PN.&OS=PN/5090399&RS=PN/5090399 US patent for solar barbecue granted in 1992.
- ^ DEVELOPMENT OF A SOLAR CREMATORIUM. Solare Brüecke. Retrieved on 2008-05-20.
[edit] External links
- Article about the Odeillo and Mont Louis solar furnaces
- Page including an animation of a solar furnace
- BBC News article about the solar power station serving Seville, Spain
- Build a solar furnace
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