Electrochemical methanation of carbon dioxide: Advances, challenges, and perspectives for biogas upgrading

The electrochemical conversion of carbon dioxide to methane is emerging as promising strategy for both mitigating CO2 emissions and enabling renewable energy storage in a chemically stable, energy-dense form. Among the possible products of CO2 electroreduction, methane stands out due to its high volumetric energy density, compatibility with existing natural gas infrastructure, and potential for direct integration into current energy systems. This review provides a comprehensive overview of the recent advancements in the electrochemical CO2to-CH4 conversion, with particular focus on catalyst development, cell configurations, and system-level performance under industrially relevant conditions. Key challenges such as low selectivity, limited current densities and long-term operational stability are critically discussed. In addition, the review also explores the technoeconomic aspects of electrochemical methanation, highlighting pathways toward scalable and sustainable deployment. Special emphasis is then placed on the potential application of this technology for biogas upgrading, which offers a unique advantage by utilizing an already CO2-rich feedstock without the need for additional separation steps. Finally, we outline future directions for research aimed at making electrochemical biogas upgrading a viable component of circular carbon and renewable energy strategies.