System for the production of methane from CO2

A method of converting carbon dioxide produced during an industrial process to methane comprising:

• a) contacting a culture comprising hydrogenotrophic methanogenic archaea with H2 gas, CO2 gas and an output gas from an industrial process in a bioreactor, wherein the output gas comprises CO2 gas, carbon monoxide gas and between 0.1% to about 32% air by volume;
• b) supplying an amount of H2 gas to maintain a redox potential in the bioreactor under −100 mV or less, wherein no additional constituent other than the H2 gas is added to the bioreactor to maintain the redox potential in the bioreactor under −100 mV or less;
• and
• c) maintaining the redox potential of −100 mV or less,
• wherein the hydrogenotrophic methanogenic archaea continuously produces methane in the presence of oxygen.