Energy storage has become a main topic in the last years, growing in importance with the increase of renewables penetration in the energy mix and the new energy efficiency policies. Indeed, a storage permits to absorb the renewable production peaks and release this energy when it is requested by the users, giving flexibility to renewables. In particular, thermal energy storage (TES) technologies can be adopted in a wide range of applications: they can be used for the recovery of waste heat increasing the efficiency of the process involved, or coupled with renewables, mainly solar power, for a daily or seasonal storage.