Thermal Storage


Sensible heat thermal storage is achieved by heating the storage medium (liquid sodium, molten salt or pressurised water) and increasing its energy content but not changing state during accumulation. Energy is released and absorbed by the medium as its temperature reduces and increases respectively. Sensible heat can be stored in either solid media (in packed beds, e.g. concrete, requiring a fluid to exchange heat) or in liquid media such as molten salt or pressurised water.


On the other hand, latent heat is associated with changes of phase. Energy required during charging is used to convert a solid material in a liquid material (such as paraffin wax), or a liquid material in to a gas. Phase change materials have the benefit of high thermal capacity but have the drawback of degrading performance after a number of freeze-melt cycles. In order to use latent heat storage, the storage material should have a melting temperature within the range of the charging and discharging temperatures of the Heat Transfer Fluid (HTF). As thermal storage has not been previously investigated for an industrial application, this limits the availability of suitable latent heat storage systems.


Similarly, endothermic chemical reactions require a specific temperature at which a chemical product is dissociated in a reversible chemical reaction and heat is retrieved when the synthesis reaction takes place. The development of such reactions is already at a very early stage and as the reaction temperature should lie within the charging and discharging temperature of the HTF, therefore the use of such technology needs to be case specific.


Hence, out of the options considered, it was most viable to use sensible heat storage, such as pressurised water and molten salt.


Pressurised Water






Molten Salt