Oxy-combustion has emerged as one of the most appealing combustion technologies. The fuel and recycled flue gas are combusted with oxygen-enriched air, resulting in a flue gas primarily composed of CO2 and water vapor. Oxy-combustion can provide benefits such as increased efficiency, lower emissions, improved temperature stability, and heat transfer, increased productivity, improved ignition characteristics, and lower risk. Distillation, adsorption, and membranes are three technologies that have been developed to meet high concentrations of oxygen in order to improve combustion efficiency. A single pass through membranes can increase the oxygen concentration in the air by 35%, and a double pass through membranes can increase the concentration by 50%. Increased oxygen flux improves the combustion process slightly and raises the maximum temperature inside the reaction zone slightly. Furthermore, increasing the concentration of oxygen in combustion air allows for a reduction in fuel consumption. When the oxygen concentration rises from 21% to 40%, energy savings of up to 60% are possible.