Methane is a potent greenhouse gas and at the same time an important renewable energy source. The study of methane formation is, therefore, of great relevance for basic and applied science. Microbes called methanogens produce half of the methane on our planet. Most methanogens use hydrogen and CO2 in a process called hydrogenotrophic methanogenesis to generate methane. Scientists at the Max Planck Institute for Terrestrial Microbiology in Marburg together with collaborators at the Max Planck Institute of Biophysics in Frankfurt have now shown how methane generation and CO2 fixation are connected. The work can potentially improve future attempts to reduce atmospheric methane levels as well as to generate methane as a renewable energy source. This work was recently published in the international journal Science.