The energy transition will deeply transform the current energy system. On the one hand a massive exploitation of various renewable energy sources will be necessary, not only to generate “clean” electricity but also carbon-free heating, cooling and fuels. On the other hand, this shift of production will inevitably increase the sector dependency on weather conditions, with their inherent variability and low predictability. In this context Thermal Energy Storage (TES), together with other forms of storage and flexibility, is expected to play a crucial role to decouple the demand of energy from its generation, ensuring the security of supply while maximizing the exploitation of the installed capacity.