Abstract: A storage device for thermal energy includes a thermo-vector unit, and a thermo-accumulator unit. The thermo-vector unit includes one or more flow ducts for a working fluid. The thermo-accumulator unit includes a thermal storage material configured to operate in a thermal exchange relationship with the working fluid and for storing and releasing thermal energy due to a thermal exchange with the working fluid. The thermo-accumulator unit has a thermal diffusivity comprised between 10 and 150 mm2/s.