Solar Power Tower

A solar power tower, also known as a central tower power plant or heliostat power plant, is a type of solar furnace that uses a tower to receive focused sunlight, concentrated by an array of flat, movable mirrors called heliostats that focus the sun rays upon a collector at the top of the tower. Early designs used the focused rays to heat water and used the resulting steam to power a turbine, while newer designs use liquid sodium or molten salts, typically a mixture of about 40 percent potassium nitrate and 60 percent sodium nitrate, as the working fluid. These working fluids have a high heat capacity, allowing the collected energy to be stored before it is used to boil water and drive turbines, which lets a solar power tower generate power continuously while the sun is shining and for several hours after it has set or been obscured by cloud.