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A Concentrating Solar Power (CSP) system uses mirrors to concentrate (focus) light energy from the sun, transforming it into heat and steam to generate electricity.
FREMONT, CA: CSP technology takes advantage of concentrated sunlight. By employing mirrors to focus and concentrate the sun's energy into high-temperature heat, CSP plants produce electricity. The plants are divided into two sections: one that gathers solar energy and transforms it into heat; the other transforms the heat energy into electricity. After that, a typical generator receives the heat. On the Department of Energy's Solar Energy Technologies website, there is a brief video demonstrating the operation of concentrating solar power using a parabolic trough system as an example.
CSP plants have been successfully running for over 15 years within the US. When used to generate energy at a commercial scale, all CSP technical approaches necessitate enormous areas for solar radiation gathering.
The CSP technology uses three technologies: trough, power tower, and dish/engine systems.
Trough systems use sizable, U-shaped (parabolic) reflectors (focusing mirrors) with oil-filled pipes running along the center or focal point. A mirror reflector pointing toward the sun heats the oil inside the pipes up to 750°F. In order to power traditional steam turbines and generators, the hot oil has to boil water.
Power tower systems, also known as central receivers, track the sun and direct its beams onto a receiver using many big, flat mirrors called heliostats. The receiver is perched atop a tall tower where intense sunlight heats a fluid to 1,050°F, such as molten salt. The hot liquid can be kept for later use or utilized immediately to create steam for energy production. Since molten salt effectively holds onto heat, it can be kept for days before being used to generate power. So, it is possible to generate electricity during high demand, even on overcast days or several hours after sunset.
Mirrored dishes about ten times larger than a backyard satellite dish are used in dish/engine systems to focus and concentrate sunlight onto a receiver. At the dish's focal point, the receiver is mounted. The dish assembly follows the sun as it moves across the sky as much as possible in order to absorb solar energy. A highly efficient "external" combustion engine houses the receiver. The engine's four-piston cylinders are connected by thin tubes that enter the cylinders and hold hydrogen or helium gas. The receiver is exposed to concentrated sunlight, which heats the gas in the tubes to extremely high temperatures and causes the heated gas to expand inside the cylinders. The pistons are propelled by expanding gas. A single, integrated assembly is installed at the focal point of the mirrored dish and contains the receiver, engine, and generator.
