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 CO 2 emissions and enabling renewable energy storage in a chemically stable, energy-dense form. Among the possible products of CO 2 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 CO 2 -to-CH 4 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 techno-economic 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 CO 2 -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.