of the oxide layer and is optimized with regard to power and efficiency furthermore by way of example information about the local composition of the combustion gas in the turbine can be taken into consideration it being possible for this information to be obtained for example with the aid of emission analysis a further exemplary embodiment is illustrated in fig3 unlike in the exemplary embodiment illustrated in fig1 the working medium is liquefied through dissipation of heat in a co 2 liquefier 10 and a pump 9 which transfers the liquid working medium to the combustion chamber 2 is used instead of the compressor in this example stepped compression and expansion processes with intervening supply or dissipation of heat can be provided in order to limit the maximum operating pressure a final exemplary embodiment is illustrated in fig4 in this case ch 4 is reacted with o 2 in a membrane reactor 11 supplied with compressed air by a compressor 1 one side of the membrane being purged with a sweep gas 13 which comprises the hot co 2 h 2 o mixture described above with a low o 2 content the membrane reactor 11 is thereby integrated in the sweep cycle of the gas.