During operation of a power generating plant, which essentially comprises a gas turbogroup, a compressed air accumulator, an air turbine which is equipped with at least one generator, the compressed air which is extracted from the compressed air accumulator is directed through a heat exchanger, which acts on the outflow side of the gas turbogroup, and is thermally conditioned there. This compressed air then charges the air turbine, wherein during a “black out” or other shutdown of the power generating plant, the electric current energy which can be obtained by means of the thermally conditioned compressed air in the air turbine, via a power line is used directly for start-up of the gas turbogroup.