Concentrated solar power (CSP) technology is one of two major solar power technologies, the other being photovoltaic (PV).
CSP encompasses several distinct design technologies that all use thermal heat to produce electricity; PV, by contrast, generates electricity directly from the sun’s light. CSP plants concentrate solar irradiation (sunlight) by means of mirrors. The concentrated irradiation is aimed on a receiver that is heated to very high temperatures. Flowing through the receiver is a heat-transfer fluid that carries the heat to a steam generator, where water is converted into superheated steam. This steam runs a turbine, which puts an electric generator in motion, just as in a conventional fossil-fuel power plant.
The two most common CSP configurations are parabolic trough and solar tower. A third, less common configuration is the parabolic dish.
Parabolic trough plants use rows of trough-shaped reflectors that focus the solar irradiation on to absorber tubes that are located in the focal line of the reflectors. Flowing through the absorber tubes is the heat-transfer fluid.
Central tower plants consist of several hundred to several thousand heliostats located around a tower. At the top of the tower is a receiver that receives the irradiation reflected by the heliostats. The heat-transfer fluid flows through the receiver.
An important advantage of CSP over PV is that heat can be stored much more easily than electricity. If power generation after sunset is required, a system to store the hot heat-transfer fluid can be incorporated into the plant. After sunset, or other periods without direct sunlight, the stored heat-transfer fluid can power the steam turbine for continued power generation. CSP plants require lots of direct sunlight and large sites in order to produce electricity at utility scale. As such, Abu Dhabi is ideally suited to host CSP plants.
There are more parabolic trough systems in operation around the world than any other type of CSP technology. This is due to several benefits of this technology:
Parabolic trough technology allows for single-unit solar power plants of larger rated output than other CSP technologies. The highest capacity single-unit parabolic trough plants currently in operation are the 80 MW SEGS plants, which use the same technology as Shams 1.
Parabolic trough technology has a commercial and operational track record of almost two decades, including nine plants in California, and more than 12 billion kWh of electricity generated. The historical data of this technology’s operating performance gives parabolic trough a commercially proven annual plant efficiency of more than 14% (net electrical output to solar radiation).