TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: The ratio of partial pressure of hydrogen to the partial pressure of carbon dioxide is 7:1-30:1. The method further involves at least one cell growth phase, wherein in the at least one cell growth phase the ratio of the partial pressure of hydrogen to the partial pressure of carbon dioxide inside the reaction vessel is maintained at a ratio different from the ratio in the at least one methane production phase. The ratio of partial pressure of hydrogen to the partial pressure of carbon dioxide in at least one cell growth phase is maintained at a ratio lower than the ratio in the at least one methane production phase. The ratio of partial pressure of hydrogen to the partial pressure of carbon dioxide in the cell growth phase is 0.5:1-4:1, preferably 4:1 or less. The methanogenic microorganisms are maintained in cell growth phase until the cell growth of the methanogenic microorganisms in the reaction vessel stagnates or reaches at least a concentration of 3 g biomass/l. The methanogenic microorganisms are switched from at least one cell growth phase to at least one methane production phase by adjusting or maintaining the ratio of partial pressure of hydrogen and carbon dioxide inside the reaction vessel. The carbon dioxide and/or hydrogen is derived from an industrial process, off-gas, real gas or their mixture. The industrial process includes biogas or biomass fermentation, anaerobic digestion, electrolysis of water or brine, methanogenesis by methanogenic archaea, oxygen combustion or gasification, and/or their combinations, where energy for the industrial process is derived from renewable energy source. The method involves maintaining oxidation reduction potential inside the reaction vessel in the methane production phase is -400 mV to -700 mV, preferably -350 mV, and in cell growth phase is -300 mV to -500 mV, preferably -300 mV. The pH of reaction vessel is 5-8. Preferred Microorganism: The methanogenic microorganism is methanogenic archaea chosen from Methanosarcina barkeri, Methanococcus maripaludis, Methanobacterium thermoautotrophicus, Methanothermobacter thermautotrophicus, Methanocaldococcus jannaschii, M.marburgensis, and their mixtures. EXAMPLE - No suitable example given.