Concentrated Solar Thermal: Collecting heat from the sun Current technologies for large-scale thermal power plants can be distinguished in the way they collect and concentrate solar radiation. As diffuse light can not be focused, only locations with a high proportion of direct light will be suitable for this technology. Target locations include Southern Spain and many parts of the U.S. where annual energy yield is above 2,000kWh/m².

Parabolic Trough Several parallel rows of collectors, 20 - 400m in length, are made of parabolic reflectors. They focus the light onto a specially coated absorber tube that runs along a caustic line. Solar radiation heats up a heat-transfer fluid, which is subsequently used in a heat exchange. The troughs track the sun over the course of the day along the central axis as the sun travels from East to West. This is the most mature CST technology with a concentration ratio of around 100x. An example is the solar thermal power plant, Andasol, in Andalusia, Spain (2008 - 2011) with a collector surface of 512,000 m2.