a first steam as a result of a charging operation of the thermochemical heat storage unit in a second step the first steam is fed to a heat exchanger in a third step the first steam with an at least partial release of its thermal energy is at least partially condensed into water by means of the heat exchanger in a subsequent fourth step the water is pressurized in other words the pressure of the water is increased in the fourth step furthermore in a fifth step the pressurized water may be returned to the heat exchanger in a sixth step with an at least partial absorption of the thermal energy previously released in the third step the pressurized water is at least partially evaporated into second steam in a seventh step the second steam is at least partially stored in a steam storage unit recuperative cooling of the steam that forms during charging first steam thus takes place the first steam which is at least partially liquefied is subsequently pressurized that is to say the pressure is increased and furthermore with the at least partial absorption of the thermal energy released during the recuperative cooling again heated or superheated in a recuperative manner as a result steam second steam is produced at an elevated pressure level compared to the first steam some embodiments include.