NOVELTY - Method of converting carbon dioxide produced during an industrial process to methane comprises: (a) preparing a culture of hydrogenotrophic methanogenic Archaea in a bioreactor; and (b) supplying an output gas from an industrial process to the bioreactor, where the output gas comprises carbon dioxide and 0.02-6.7% of oxygen (moles/volume of output gas) and the hydrogenotrophic methanogenic Archaea converts the output gas to continuously produce methane.    USE - The method is useful for converting carbon dioxide to methane, where the carbon dioxide is produced during an industrial process, which is coal gasification, biomass gasification or liquid fuel production by biomass fermentation (all claimed). The process is useful for reducing the carbon dioxide emissions from industrial processes including ethanol production, by using a bioreactor system that uses the emissions to produce methane (natural gas).    ADVANTAGE - The method exhibits high efficiency with greater than 95% conversion of carbon dioxide to methane at moderate temperatures.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a cascaded bioreactor comprising: a first reactor vessel; a second reactor vessel; a culture of hydrogenotrophic methanogenic Archaea, which is present in the first and second reactor vessels; a source of an output gas from an industrial process comprising carbon dioxide that feeds into the first reactor vessel; a source of hydrogen gas that feeds into the first reactor vessel; a gas feed from the first reactor vessel to the second reactor vessel; a feed to the first reactor vessel for providing fresh medium; a feed to the second reactor vessel for providing fresh medium; a feed to the first reactor vessel for removing the hydrogenotrophic methanogenic Archaea culture; and a feed to the second reactor vessel for removing the hydrogenotrophic methanogenic Archaea culture.    DESCRIPTION OF DRAWING(S) - The diagram shows the schematic representation of the carbon dioxide recapture and methane production plant.