Concentrating Solar Power
Concentrating Solar Power: How Does It Work?
The technology is vast when it comes to harnessing solar energy, storing it, and distributing it at a later time. Concentrating Solar Power is one of those technologies. Concentrating solar power (CSP) plants use mirrors to concentrate the sun’s energy to drive traditional steam turbines or engines that create electricity. The thermal energy concentrated in a CSP plant can be stored and used to produce electricity when needed, day or night.
Concentrating solar power technology
There are four types of concentrating solar power systems: Parabolic Trough Systems, Linear Fresnel Systems, Power Tower Systems, and Parabolic Dish Systems. The trough systems were the first used, and as of 2017, the power tower is the fastest growing system. For each of these, there are various design variations, configurations, and depending on whether thermal energy storage is included – differing methods used to store solar thermal energy.
Parabolic Trough Systems
Parabolic Trough Systems use parabolically curved, trough-shaped reflectors to concentrate the sun’s energy onto a receiver pipe, which runs along the inside of the curved surface. The temperature of the heat transfers fluid flowing through the pipe, usually thermal oil, which is increased from 293ºC to 393ºC. The heat energy is then used to generate electricity in a conventional steam generator.
Linear Fresnel Systems
Linear Fresnel Systems use a series of long, narrow, and shallow curved mirrors to focus light onto one or more linear absorbers that are positioned above the mirrors. These are typically aligned in a north-south orientation to maximize energy collection. The mirrors are laid flat on the ground and reflect the sunlight to the pipe above. Like trough and tower, Fresnel can also incorporate thermal storage, or generate steam for direct use.
Power Tower Systems
Power Tower Systems utilize sun-tracking mirrors called heliostats to focus sunlight onto a receiver at the top of a tower. A heat transfer fluid heated in the receiver at around 600ºC is used to generate steam, which is then used in a conventional turbine-generator to produce electricity.
Parabolic Dish Systems
Parabolic Dish Systems consist of a parabolic-shaped point focus concentrator in the form of a dish that reflects solar radiation onto a receiver mounted at the focal point. These concentrators are mounted on a structure with a two-axis tracking system to follow the sun. The collected heat is typically utilized directly by a heat engine mounted on the receiver moving with the dish structure.