TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The culture is a substantially pure culture of one hydrogenotrophic methanogenic Archaea species. The hydrogenotrophic methanogenic Archaea species is Methanothermobacter thermautotrophicum, Methanosarcina barkeri, Methanococcus maripaludis, Methanocaldococcus fervens, Methanocaldococcus indicus, Methanocaldococcus infernus, Methanocaldococcus vulcanius (all preferred), Methanobacterium alcaliphilum, Methanobacterium bryantii, Methanobacterium congolense, Methanobacterium defluvii, Methanobacterium espanolae, Methanobacterium formicicum, Methanobacterium ivanovii, Methanobacterium palustre, Methanobacterium thermaggregans, Methanobacterium uliginosum, Methanobrevibacter acididurans, Methanobrevibacter arboriphilicus, Methanobrevibacter gottschalkii, Methanobrevibacter olleyae, Methanobrevibacter ruminantium, Methanobrevibacter smithii, Methanobrevibacter woesei, Methanobrevibacter wolinii, Methanothermobacter marburgensis, Methanothermobacter thermoflexus, Methanothermobacter thermophilus, Methanothermobacter wolfeii, Methanothermus sociabilis, Methanocorpusculum bavaricum, Methanocorpusculum parvum, Methanoculleus chikuoensis, Methanoculleus submarinus, Methanogenium frigidum, Methanogenium liminatans, Methanogenium marinum, Methanosarcina acetivorans, Methanosarcina mazei, Methanosarcina thermophila, Methanomicrobium mobile, Methanocaldococcus jannaschii, Methanococcus aeolicus, Methanococcus vannielii, Methanococcus voltaei, Methanothermococcus thermolithotrophicus, Methanopyrus kandleri or Methanothermobacter thermoautotroiphicus.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Method: The method comprises: contacting a culture comprising hydrogenotrophic methanogenic Archaea with hydrogen gas and an output gas from an industrial process comprising carbon dioxide gas in a bioreactor, where the culture is present in a first and second reactor vessel; supplying fresh medium to the first and second reactor vessels through a first medium feed line attached to the first reactor vessel, and a second medium feed line attached to the second reactor vessel; supplying hydrogen gas to the first reactor vessel through hydrogen gas feed line; supplying an output gas from an industrial process to the first reactor vessel, through an output gas feed line; and transferring at least a portion of gas in the first reactor vessel to the second reactor vessel by a first gas feed line. The method further comprises: supplying fresh medium to the third reactor vessels through a third medium feed line attached to the third reactor vessel; transferring a portion of gas in the second reactor vessel to the third reactor vessel by a second gas feed line, where the hydrogenotrophic methanogenic Archaea culture in the third reactor converts hydrogen gas and carbon dioxide gas to produce methane. In the method, no sulfur is present in the process other than the sulfur present in the culture medium. The conditions include temperature of 35-37 degrees C, 60-65 degrees C or 80-100 degrees C. The hydrogen is supplied to maintain a redox potential in the bioreactor under -100 mV or less, and where no additional constituent other than the hydrogen gas is added to the bioreactor. Preferred Components: The cascaded bioreactor further comprises: a third reactor vessel; a culture of hydrogenotrophic methanogenic Archaea, which is present in the third reactor vessel; a gas feed from the second reactor vessel to the third reactor vessel; a feed to the third reactor vessel for providing fresh medium; and a feed to the third reactor vessel for removing the hydrogenotrophic methanogenic Archaea culture.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The industrial output gas comprises at least 0.8% (preferably 3.4-6.7%) of oxygen (moles/volume of output gas). The industrial output gas further comprises carbon monoxide (at least 8%, preferably 60% by volume). EXAMPLE - Methanococcus maripaludis was grown at 37 degrees C in modified McCas medium (comprises potassium chloride (0.335 g), magnesium chloride hexahydrate (2.75 g), magnesium sulfate heptahydrate (3.45 g), calcium chloride dihydrate (0.14 g), ammonium chloride (0.5 g), sodium carbonate (8.4 g), sodium chloride (22 g), dipotassium hydrogen phosphate (0.14 g), ferrous sulfate heptahydrate (9.5 mg), resazurin (1 mg), casamino acids (2 g), cysteine hydrochloric acid hydrate (0.5 g), sodium citrate hydrate (21 mg), manganese sulfate dihydrate (5 mg), cobalt chloride hydrate (1 mg), zinc sulfate hydrate (1 mg), copper sulfate pentahydrate (0.1 mg), aluminum potassium sulfate (0.1 mg), orthoboric acid (0.1 mg), sodium molybdate dihydrate (1 g), nickel(II)chloride hexahydrate (0.25 mg), sodium selenite (2 mg), vanadium(III)chloride (0.1 mg), sodium tungstate (1 mg), biotin (0.02 mg), folic acid (0.02 mg), pyridoxine hydrochloric acid (0.10 mg), thiamine hydrochloric acid (0.05 mg), riboflavin (0.05 mg), nicotinic acid (0.05 mg), DL-calcium pantothenate (0.05 mg), vitamin B12 (0.001 mg), p-aminobenzoic acid (0.05 mg) and lipoic acid (0.05 mg)). After autoclaving and before inoculation, the medium was reduced by the addition of sodium sulfide (0.5 g/l) from a 50x anaerobic, sterile stock solution to yield an oxidation-reduction potential (ORP) of the medium below -100 mV. The medium was equilibrated prior to inoculation with a gas phase containing 0.2 atmosphere partial pressure of carbon dioxide to yield a pH of 7.2-7.3. The initial medium used to start the culture contained the sodium acetate trihydrate (1.4 g/l), in addition to the components, but the medium reservoir used in continuous culture conditions lacked the addition of acetate. The fresh medium (1 l) was initially inoculated with Methanococcus maripaludis (5 ml) in a stationary phase, and methane production was monitored over time. A gas feed of 4:1 hydrogen:carbon dioxide was provided at a culture of pH 7.33 and an ORP of -140 mV.