How is solar energy used?
(continued)

Concentrating solar power systems

Concentrating solar power devices focus or concentrate the thermal energy of the sun to drive a generator or heat engine. They do so by means of mirrors arranged in a tower, trough or dish configuration.

• Power tower systems (also known as “central receiver” systems) use a field of large, flat mirrors to track and reflect sunlight onto a receiver mounted at the top of a tall tower. As the receiver collects heat, this heat is transferred to a fluid (synthetic oil or molten salt) pumped through the receiver. The fluid’s heat, reaching about 500°C, is then used to make steam to generate electricity in a conventional steam generator.
  
  
• Solar trough systems use a series of curved mirrored troughs to focus the sun’s energy on a pipe filled with a heat exchange fluid (oil). This fluid is heated to temperatures of about 400°C. The heat is then used to turn a steam generator to generate electricity in a central plant.
  
  
• Solar dish systems use a mirrored dish to track the sun and focus solar energy onto a receiver, mounted at the focal point of the dish. Fluid in the receiver absorbs the energy and heats up to 750°C to 1,000°C. This hot fluid is transferred to a small engine, which converts the heat energy to electricity.
  
  

Solar power tower system
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Solar trough system
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Dish system
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