Concentrating Solar Water Heater
Concentrating Solar power plants produce electricity by using mirrors to focus sunlight. This focused sunlight heats a fluid that will run an engine that drives a generator or it will spin a turbine.
Research is under way using Molten Nitrate Salt as a fluid because of its superior heat transfer and heat storage capabilities. 
A parabolic dish of mirrors reflects sunlight onto a thermal receiver to produce electricity. The dish is mounted on a structure that tracks the movement of the sun to capture as much energy as possible. The power is converted using a Thermal Receiver and an Engine Generator. The thermal receiver can be a bank of tubes containing Hydrogen or Helium used as a heat transfer fluid. Alternate Thermal receivers use heat pipes where boiling and condensing of an intermediate fluid transfers the heat to the engine. The most common engine used here is the Sterling Engine, which uses the heated fluid to move pistons and create mechanical power. The Solar fields have a large number of collectors set in parallel rows in a north/south orientation to take advantage of year round Solar Energy. Using a single axis tracking system the collectors follow the sun from east to west to get the most exposure. The linear systems currently used in the U.S. are the Parabolic Trough system. The receiver tube is placed in the path of the reflector.The transfer fluid is heated to steam and sent directly to the turbine. These systems produce about 80 megawatts of power. New systems are being developed that can create as much as 250 MW. Click here if you would like to visit the NREL site. Concentrating Solar.
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