An object of the present invention is to provide a method and a system for implementing the method so as to alleviate the disadvantages of a reciprocating combustion engine and gas turbine in electric energy production. The invention is based on the idea of arranging a combustion chamber (10) outside a turbine (22) and providing compressed air from serially connected compressors to the combustion chamber in order to carry out a combustion process supplemented with high pressure steam pulses. The combustion chamber (10) is arranged to receive compressed air from each compressing stage of the serially connected compressors (24) for gradually increasing the amount of compressed air in the combustion chamber (10).