Thermal energy storage (TES)

Concentrated solar power plants (CSP plants) use the thermal energy produced from solar radiation in order to generate electricity. Therefore, they are only capable of generating electricity as long as the sun is shining unless they can resort to thermal energy from other sources.

The storage of energy is one of the biggest challenges when it comes to balancing the power supply grids. It is still much easier and more cost efficient today to store energy in the form of thermal energy than in the form of electric energy. Depending on the profile of the local current demand, it makes sense to equip CSP plants with thermal storage units. Thermal molten salt storage devices ensure a considerable increase in the annual operating hours and, as a result, of the annually produced electricity output, too.

During the construction phase of the Andasol 1, 2 and 3 power plants, TSK Flagsol gained experience in the construction and operation of thermal storage units that can be used for the scalable operation of a power plant. The necessary thermal energy is stored in a mixture of molten salt. The storage system consists of two tanks with molten salt, pumps, and oil/salt heat exchangers. For charging of the storage system, the molten salt in the cold storage tank having a temperature of approximately 290°C is pumped to the heat exchanger. Here it is heated to approximately 390°C with the help of the heat transfer fluid (HTF) from the solar field and is fed into the hot storage tank. Discharging of the storage unit is done in the opposite direction. A full storage unit can drive the turbine up to eight hours at full load, thus making it possible to operate
power plants almost 24 hours a day in the summer months.
Energy Storage