The production of colorless, gaseous, inflammable hydrocarbons with living organisms: "Methanogenesis is the formation of methane from microbes that exist in fresh-water or marine sediments, in the intestinal tracts of animals, or in places constructed by humans; such as, sludge in sewage or biomass digesters all of which come from the anaerobic microbial food chain."

"In biotechnology, methanogenesis is the last step in the artificial production of methane, during which hydrogen and bicarbonate are processed into methane."