Over recent months we’ve looked at various small-scale battery systems that are suitable for domestic use. This time we’re going large-scale and looking at Concentrated Solar Thermal power (CST) – a method of generating electricity that also enables solar energy to be stored in the form of heat. You’re not likely to have one of these systems on your roof any time soon, but CST has huge potential for large-scale generation and storage.
How it works
A CST power station typically consists of an array of sun tracking mirrors (‘heliostats’) that concentrate sunlight by focusing it onto a target at the top of a tower. Some towers heat water directly to create steam to drive turbines, while others heat molten salt. Molten salt towers work by pumping ‘cold’ salt (about 280°C) up to the top of the tower where it is heated, and then it is pumped back down the tower for storage or immediate use. The advantage of molten salt is that the energy from the heat can be stored and used at a later time, or released immediately into a heat exchanger that produces steam to power a standard steam turbine. The molten salt has a 30+ year life span and can be repurposed as a high grade fertiliser.