System suitable for producing hot water and/or steam, comprising a high-temperature reservoir (2.2) for a gas turbine power plant, and suitable for feeding the hot water and/or steam in an open process for injection into a fluid flow between the compressor and the turbine and/or the turbine of the gas turbine power plant, wherein - the high-temperature reservoir has a reservoir material heatable by internal and/or external energy sources, wherein - the high-temperature reservoir (2.2) has connections for direct and/or indirect charging of the reservoir material, o connections (5.1, 5.2) are connected to at least one external energy source for indirect charging and heating of the reservoir material to a temperature T3>T2 and/or o connections for direct charging and heating of the reservoir material to a temperature T3'>T2 are coupled to at least one external energy source and/or o connections of the high-temperature reservoir (2.2) for its indirect charging and the heating of the reservoir material to a temperature T3">T2 are coupled to at least one external energy source providing electrical energy, - at least one channel leads through the high-temperature reservoir (2.2) with the reservoir material located therein, which channel has an inlet (4.1) for water or hot water with an inlet temperature, and in that the channel has an outlet (4. 2) from the high-temperature reservoir, through which the hot water and/or the steam emerges with an outlet temperature (T2>T1) of at least 100°C and a pressure of at least 1 bar, since a heat transfer takes place from the reservoir material to the water or hot water supplied to the high-temperature reservoir, - and wherein the reservoir material consists of o solids in the form of metals, cast iron, building materials, concrete, reinforced concrete, ceramic materials or combinations of the aforementioned materials and/or o liquid in the form of oil, commercially available synthetic heat carriers, liquid metals, liquid sodium and/or o phase change material in the form of metals, in particular lead or tin, nitrates, hydroxides, chlorides, carbonates, fluorides or combinations of the aforementioned materials including necessary auxiliary materials. - the high-temperature reservoir has a reservoir material heatable by internal and/or external energy sources, wherein - the high-temperature reservoir (2.2) has connections for direct and/or indirect charging of the reservoir material, o connections (5.1, 5.2) are connected to at least one external energy source for indirect charging and heating of the reservoir material to a temperature T3>T2 and/or o connections for direct charging and heating of the reservoir material to a temperature T3'>T2 are coupled to at least one external energy source and/or o connections of the high-temperature reservoir (2.2) for its indirect charging and the heating of the reservoir material to a temperature T3">T2 are coupled to at least one external energy source providing electrical energy, o connections (5.1, 5.2) are connected to at least one external energy source for indirect charging and heating of the reservoir material to a temperature T3>T2 and/or o connections for direct charging and heating of the reservoir material to a temperature T3'>T2 are coupled to at least one external energy source and/or o connections of the high-temperature reservoir (2.2) for its indirect charging and the heating of the reservoir material to a temperature T3">T2 are coupled to at least one external energy source providing electrical energy, - at least one channel leads through the high-temperature reservoir (2.2) with the reservoir material located therein, which channel has an inlet (4.1) for water or hot water with an inlet temperature, and in that the channel has an outlet (4. 2) from the high-temperature reservoir, through which the hot water and/or the steam emerges with an outlet temperature (T2>T1) of at least 100°C and a pressure of at least 1 bar, since a heat transfer takes place from the reservoir material to the water or hot water supplied to the high-temperature reservoir, - and wherein the reservoir material consists of o solids in the form of metals, cast iron, building materials, concrete, reinforced concrete, ceramic materials or combinations of the aforementioned materials and/or o liquid in the form of oil, commercially available synthetic heat carriers, liquid metals, liquid sodium and/or o phase change material in the form of metals, in particular lead or tin, nitrates, hydroxides, chlorides, carbonates, fluorides or combinations of the aforementioned materials including necessary auxiliary materials. o solids in the form of metals, cast iron, building materials, concrete, reinforced concrete, ceramic materials or combinations of the aforementioned materials and/or o liquid in the form of oil, commercially available synthetic heat carriers, liquid metals, liquid sodium and/or o phase change material in the form of metals, in particular lead or tin, nitrates, hydroxides, chlorides, carbonates, fluorides or combinations of the aforementioned materials including necessary auxiliary materials.