Power station and method for operating the same

A method for generating heat energy in a power plant by burning a carbonaceous fuel in a combustion chamber of the power plant and a system for carrying out the method is described. A combustion chamber is fluidly connected to a membrane chamber that includes a membrane operating at a temperature between 600 and 1000° C. The combustion chamber receives a cleaned flue-gas oxygen mixture for combustion from the membrane chamber. Oxygen from heated air passes through the membrane in the membrane chamber to the permeate side of the membrane, where it is mixed with cleaned heated flue gas and the resulting gas mixture is fed to the combustion chamber. Flue gas removed from the combustion chamber are cooled, cleaned and heated as described herein and recirculated to the membrane chamber.