A power generation system and method in which a fuel gas is introduced into a combustor and at least a portion of the fuel gas is combusted in the combustor, producing an exhaust gas having no appreciable available oxygen. The exhaust gas is introduced as a working fluid into a gas turbine, thereby generating power. Cooling of the power generation system is accomplished using a cooling fluid selected from the group consisting of synthesis gas, natural gas, natural gas/steam mixture, flue gas, flue gas/steam mixture, and mixtures thereof.