A module based oxy-fuel boiler system comprising a first boiler (112) configured as a main boiler and a second boiler (216) configured as a reheat boiler, said first boiler including: plurality of first boiler tubes (T) for carrying water, the tubes forming at least one water wall, a feedwater inlet line (230) in flow communication with said plurality of first boiler tubes (T), said feedwater inlet line (230) configured to be connected to an external source of water, a steam outlet line (246) in flow communication with said plurality of first boiler tubes and configured to be connected to a first turbine (238), said turbine (238) having a steam outlet that is configured to be coupled to a reheat line (248) of said second boiler (216), the first boiler (212) configured to substantially prevent the introduction of air, a first boiler oxygen supply (218) for supplying oxygen having a purity of greater than 21 percent; a first boiler carbon based fuel supply (220) for supplying a carbon based fuel; at least one first boiler oxy-fuel burner system (222) coupled to said first boiler oxygen supply (218) and said first boiler carbon based supply (220), the first boiler oxy-fuel burner system (222) configured to feed the oxygen and the carbon based fuel into the first boiler (212) in a near stoichiometric proportion to one another to limit an excess of either the oxygen or the carbon-based fuel to a predetermined tolerance, a first boiler flue gas exit line (213) for discharging exhaust gas generated as a result of the combustion in said first boiler (212), wherein the first boiler tubes (T) are configured for direct, radiant energy exposure for energy transfer to the water to produce steam; a second boiler (216) having a a reheat inlet line (248) in flow communication with the steam outlet of said turbine (238); a reheat steam outlet line (250) in flow communication with a second turbine (240), a second boiler flue gas exit line (217) for discharging exhaust gas generated as a result of the combustion in said second boiler (216), wherein the second boiler(216) is configured to carry out a different energy transfer function than the first boiler (212) and is configured to substantially prevent the introduction of air; a second boiler supply (218) for supplying oxygen having a purity of greater then 21 percent; a second boiler carbon based fuel supply (20, 120) for supplying a carbon based fuel; at least one second boiler oxy-fuel burner system(226), the second boiler oxy-fuel burner system (226) configured to feed the oxygen and the carbon based fuel into the second boiler (216) in a near stoichiometric proportion to one another to limit an excess of either the oxygen or the carbon based fuel to a predetermined tolerance.