text: One limitation is the energy loss in methane-producing bioelectrochemical systems. This occurs as a result of overpotentials occurring at the anode, membrane, and biocathode. The energy loss reduces efficiency significantly. Another limitation is the biocathode. Because the biocathode is so important in electron exchange and methane formation, its make-up can have a dramatic effect on the efficiency of the reaction. Efforts are being made to improve the biocathodes used in electromethanogenesis through combining new and existing materials, reshaping the materials, or applying different "pre-treatments" to the biocathode surface, thereby increasing biocompatibility.