H2 gas-liquid mass transfer: A key element in biological Power-to-Gas methanation

Power-to-Gas technologies are considered essential for a green transition of the global energy system by producing fossil-free fuel from renewable electricity and CO2. Biological methanation can be used as a Power-to-Gas technology by harnessing hydrogenotrophic methanogenic archaea to produce CH4 from CO2 and electricityderived H-2. Advancing biological Power-to-Gas methanation technologies to full-scale requires a dedicated focus on H-2 gas-liquid mass transfer, which generally limits the conversion of H-2 to CH4. Process and reactor design and operation have accordingly received much research attention in recent years, but technology development is still characterized by a broad investigation of various system configurations and operational conditions, mainly in lab-scale. This review gives an extensive summary of the current biological methanation capacities of different reactor types in the context of Power-to-Gas and critically examines the influence of operational parameters on H-2 gas-liquid mass transfer based on the two-film theory. The review provides a basis for critical comparison of reactor performances among biological methanation studies, which often vary in key process parameters that have a direct influence on H2 gas-liquid mass transfer and, therefore, product gas quality. The review hereby compiles knowledge essential to realize the microbial potential for biological Power-to-Gas methanation and support the technology's development to an industrially relevant scale.

Automated summary

Power-to-Gas technologies, particularly biological methanation, are essential for a green transition of the energy system. Advancing biological methanation technologies to full-scale requires a focused on H2 gas-liquid mass transfer. While there has been significant research attention on process and reactor design and operation, technology development still mainly focuses on lab-scale investigations of various system configurations and operational conditions.