When gas is burned, the oxygen in the air mixes with hydrogen and carbon from the gas. This interaction creates carbon dioxide, water, and a release of heat. The general composition of air is 21% oxygen, 78% nitrogen, and 1% miscellaneous gases. During combustion, nitrogen weakens the reaction thereby removing energy from the combustion's gaseous byproduct. Increasing the oxygen content in this type of system would prevent energy loss.
Oxygen-enriched combustion is a common practice in industrial furnaces in the glass-melting industry. To increase the oxygen content in the combustion air, liquid oxygen is used or pressure swing absorption devices operate to remove nitrogen. There is another option involving oxy-fuel burners in addition to standard burners to aid the process. In addition, there are combustion headers that use pure oxygen to increase the oxygen content in combustion air while others opt for mixing in the oxygen. Another alternative includes staging the combustion process and diversifying the oxygen content during various combustion stages. The final option involves artificially injecting oxygen into or near the fuel's flame to counteract the presence of the nitrogen.