Concentrating Solar Power Systems
Concentrating solar power technologies convert solar energy into electricity by using reflective surfaces such as mirrors to focus concentrated sunlight onto a receiver. The technologies concentrate sunlight from 80 to 3,000 times normal, producing high temperatures at the receiver. The receiver then transfers the heat to a device that converts the heat into electricity.
These technologies can be used to generate electricity for a variety of applications, ranging from remote power systems as small as a few kilowatts up to grid-connected power plants of 10's to 100's of megawatts. More than 350 megawatts of concentrating solar power systems were installed in California in the 1980's, during an era of significant federal and state support, which continue to operate providing power into the southern California grid.
Concentrating solar power systems must point directly at the sun and track it as it moves across the sky, so they rely on the light streaming directly from the sun, called direct radiation. This limits their use to sunny, arid locations, including the U.S. desert southwest. Because of the economies of scale and the cost of operation and maintenance, they work best in large power plants, and usually use a fossil fuel such as natural gas as a backup heat source. Because of this feature, the plants are dispatchable to the power grid, operate at high annual efficiencies, and are easily integrated into the power grid.
There are two main types of concentrating solar power systems:
A third type of concentrating solar power system, called a "solar power tower," has been demonstrated on a pilot scale but is not currently being pursued for use in the United States.