Concentrated Solar Power (CSP) plants generate electricity by using mirrors or lenses to concentrate sunlight onto a small area, which produces high temperatures. This concentrated heat is then used to generate steam, drive a turbine, and produce electricity. There are several common types of CSP systems, each with its own way of concentrating sunlight and converting it into electrical power:
Parabolic Trough Systems: In parabolic trough systems, long curved mirrors, shaped like troughs, focus sunlight onto a receiver tube that runs along the focal line of the trough. A heat transfer fluid (often a synthetic oil) flows through the receiver tube, absorbing the concentrated sunlight's heat and reaching temperatures up to several hundred degrees Celsius. This heated fluid is then used to generate steam, which drives a turbine connected to an electricity generator.
Solar Power Tower Systems: In solar power tower systems, a large field of mirrors, known as heliostats, tracks the sun and reflects sunlight onto a receiver mounted on top of a tall tower. The receiver, often containing a heat transfer fluid or molten salt, absorbs the concentrated sunlight and reaches extremely high temperatures. The heat transfer fluid can be used to generate steam and power a turbine-generator system, similar to parabolic trough systems.
Linear Fresnel Reflector Systems: Linear Fresnel reflectors use flat mirrors that move to track the sun and focus sunlight onto a linear receiver. The receiver, similar to parabolic troughs, contains a heat transfer fluid that absorbs the concentrated sunlight's heat and generates steam to drive a turbine.
Dish Stirling Systems: These systems use a parabolic dish with a Stirling engine at the focal point. The dish concentrates sunlight onto the Stirling engine, which operates based on the temperature difference between the hot and cold ends of a gas-filled chamber. As the gas expands and contracts, it drives a piston, which generates mechanical energy that is converted into electricity.
Solar Chimneys (Updraft Towers): This concept involves a large greenhouse-like structure with a tall chimney/tower in the center. Sunlight heats the air inside the greenhouse, and the hot air naturally rises towards the tower, creating an updraft. The updraft drives wind turbines located at the base of the tower, producing electricity.
CSP plants are often used in conjunction with thermal energy storage systems, allowing them to store excess heat during sunny periods and continue generating electricity during cloudy periods or at night when the sun is not available. This integration improves their capacity to provide consistent power and grid stability.