A method of using electricity to produce methane includes maintaining a culture comprising living methanogenic microorganisms at a temperature above 50° C. in a reactor having a first chamber and a second chamber separated by a proton permeable barrier, the first chamber comprising a passage between an inlet and an outlet containing at least a porous electrically conductive cathode, the culture, and water, and the second chamber comprising at least an anode. The method also includes coupling electricity to the anode and the cathode, supplying carbon dioxide to the culture in the first chamber, and collecting methane from the culture at the outlet of the first chamber.