Carbon Sequestration Through Syngas Biomethanation Coupled with H2 Supply for a Clean Production of Natural Gas Grade Biomethane

Biomass gasification generates a gas mixture (syngas) that constitutes rich source of carbon and energy for the production second-generation renewable fuels such as biomethane. However, produced syngas composition (H2/CO/CO2) cannot be converted to natural grade biomethane due stoichiometric limitations, waste stream CO2 is released unexploited in atmosphere. The present study introduces concept biomass coupled biomethanation with in-situ exogenous H2 supply complete sequestration carbon, valorization excess electricity from wind solar power satisfying criteria injection grid. Syngas was executed by mixed microbial consortia trickle bed reactor at 37 °C 60 °C. assessment effects net inlet performed according hereby proposed quality index ( $$SQI$$ ), which based on content compounds able act electron donors stoichiometry methane production. SQI stoichiometrically ideal 4. Values below 4 correspond carbon-moles while values above electron-moles excess. It demonstrated switching supplied 1.44 3.67 increased CH4 outlet 30 72%, accompanied an least 1.2-fold increase productivity. A 4.78 (> 4) resulted significant deterioration high (52–54%) unconverted because thermodynamic limitations carboxydotrophic hydrogenogenesis thermophilic conditions. Maximal shown feasible = 3.98