Solar towers and heliostats
Nowadays, solar towers are the favoured technology for generating high-temperature heat in the range from 500 degrees Celsius to over 1,000 degrees Celsius. This form of energy can be stored highly efficiently and in large quantities and is equally suitable for generating electricity, chemical fuels or supplying industrial processes.
Solar tower systems consist of one or more central towers surrounded by a large number of reflecting heliostats. The heliostats are biaxially movable mirrors that direct the sunlight precisely onto a receiver at the top of the tower.
On this solar receiver, the sunlight is bundled by a factor of approximately 1,000 and absorbed as high-temperature thermal energy, usually by a heat transfer fluid, and stored in a thermal energy store for further energy utilisation as required.
Alternatively, the thermal energy can also be used directly in a thermochemical reactor to produce a fuel, such as hydrogen.
Up to hundreds of thousands of heliostats in commercial systems
Commercial systems today are mostly solar tower power plants with one tower and tens or hundreds of thousands of heliostats. Molten salt is often used as a heat transfer fluid and also to store the thermal energy at a temperature level of 560 to 600 degrees Celsius. A steam power plant uses this to generate electricity on-demand in the order of 100 megawatt per solar tower.
