Solar power towers, also called heliostat power plants are facilities that use the heat from concentrated sunlight to produce electricity. Sunlight is reflected by mirrors and sent to a small region at a central tower. There it can heat water which drives a steam turbine. More recent designs heat molten salts (mixtures of potassium nitrate and sodium nitrate) instead of water. The salts are then used to boil water. The big advantage of using molten salts is that it can store heat in order to boil water even when the sun is not shining.
Some bigger solar power towers (several GWh annually) are now in operation in the United States and in Spain. More will certainly follow, as concentrated solar power is seen as a viable solution for high efficient use of solar energy.
Mini versions of solar power towers are called Dish Stirlings or Solar Stirling Plants. They consist of a stand-alone parabolic reflector that concentrates light onto a receiver positioned at the reflector’s focal point. A Stirling engine is used to generate power. Solar Stirling Plants can even be built at home for personal use.
Instead of producing electricity, concentrated solar thermal systems can also be used for cooking. In that case food is heated instead of a liquid that drives an engine.
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