The solar tower is a renewable-energy power plant for generating electricity from solar energy.
The solar tower, also known as ‘central tower’ power plants or ‘heliostat’ power plants or power towers, is a type of solar furnace using a tower to receive the focused sunlight. It uses an array of flat, movable mirrors (called heliostats) to focus the sun’s rays upon a collector tower (the target). Concentrated solar thermal is seen as one viable solution for renewable, pollution-free energy.
Early designs used these focused rays to heat water, and used the resulting steam to power a turbine. Newer designs using liquid sodium have been demonstrated, and systems using molten salts (40% potassium nitrate, 60% sodium nitrate) as the working fluids are now in operation. These working fluids have high heat capacity, which can be used to store the energy before using it to boil water to drive turbines. These designs also allow power to be generated when the sun is not shining.
- Some Concentrating Solar Power Towers are air-cooled instead of water-cooled, to avoid using limited desert water.
- Flat glass is used instead of the more expensive curved glass.
- Thermal storage to store the heat in molten salt containers to continue producing electricity while the sun is not shining.
- Steam is heated to 500 °C to drive turbines that are coupled to generators which produce electricity.
- Control systems to supervise and control all the plant activity including the heliostat array positions, alarms, other data acquisition and communication.
- Generally, installations use from 150 hectares (1,500,000 m2) to 320 hectares (3,200,000 m2).