Abstract: An elevated pressure power plant or system is disclosed that provides for cleanly and efficiently oxidizing or combusting a fuel, such as a fossil fuel, as follows. The fuel and an oxidant are passed to a reaction chamber, and the fuel is oxidized in the chamber at a pressure that is preferably substantially within a range of from approximately 700 psia to approximately 2000 psia and that is more preferably substantially within a range of from approximately 850 psia to approximately 1276 psia. A coolant is passed to the reaction chamber in a heat exchange relationship with the fuel and oxidant. The pressure of the reaction chamber is selected so that it is greater than or equal to a liquid-vapor equilibrium pressure of carbon dioxide at the temperature at which the coolant is passed to the reaction chamber.