An air separation unit separates air into an oxygen-rich and oxygen-deficient gas. Fuel gas and the oxygen-rich gas are preheated at heat exchangers through which hot flue gas flows. Combustion of the preheated fuel and oxygen-rich gases result in the hot flue gas. The hot flue gas is cooled at the heat exchangers and flows through a waste heat boiler. Water and/or steam flowing through the waste heat boiler absorbs energy from the cooled flue gas thereby producing heated steam. The heated steam flows through a turbine to produce power. The power is transferred to the air separation unit, thus reducing a power requirement of the air separation unit needed to separate the air.