Development of a CO2-biomethanation reactor for producing methane from green H2†
Abstract
“Power-to-Methane” approaches allow the storage and transport of green methane, produced from renewable energy and any CO2 source. In nature, some microorganisms, namely methanogens, can grow on CO2 and H2 and produce pure methane via an ancestral process, the methanogenesis, under mild conditions (temperature, pressure, aqueous solvents…). These microorganisms are able to perform efficiently the Sabatier reaction (4H2 + CO2 → CH4 + 2H2O), using H2 and CO2 as sole energy and carbon sources. Here, we developed a biomethanation reactor to culitvate a pure culture of Methanococcus maripaludis, a mesophilic methanogen growing rapidly at ambient temperature. A modular scalable and frugal 2 L-bubble column bioreactor was constructed to operate efficiently and autonomously for several weeks under a wide range of conditions. High H2 conversion and methane yield higher than 90% could be reached. This high-performance, modular and robust bioreactor shows its potential for integration in outdoor systems coupling the conversion of alternative sources of green H2 to fossil-free methane.