Continuous biomethanation of flue gas-carbon dioxide using bio-integrated carbon capture and utilization.

Biomethanation of carbon dioxide (CO) from flue gas is a potential enabler of the green transition, particularly when integrated with the power-to-gas chain. However, challenges arise in achieving synthetic natural gas quality when utilizing CO from diluted carbon sources, and the high costs of CO separation using amine-based solutions make large-scale implementation unfeasible. We propose an innovative continuous biomethanation system that integrates carbon capture and CO stripping through microbial utilization, eliminating expenses with the stripper. Stable continuous biomethane production (83-92 % methane purity) was achieved from flue gas-CO using a biocompatible aqueous n-methyldiethanolamine (MDEA) solution (50 mmol/L) under mesophilic and hydrogen-limiting conditions. MDEA was found to be recalcitrant to biodegradation and could be reused after regeneration. Demonstrating the microbial ability to simultaneously strip and convert the captured CO and regenerate MDEA provides a new pathway for valorization of flue gas CO.