Current status of research on microbial electrocatalytic CH₄ production for biogas upgrading and challenges

Biogas is a renewable and clean energy source that can replace fossil fuels. However, its practicality as fuel is limited by the high concentration of carbon dioxide. Biogas upgrading is an advanced process that removes carbon dioxide from biogas and converts it into biomethane, which has higher commercial value. Microbial electrocatalysis technology offers a sustainable and cost-effective method for biogas upgrading by utilizing electrogenic and methanogenic microorganisms to convert carbon dioxide into methane (CH₄). This comprehensive review provides a comprehensive overview of the principles of microbial electrocatalytic methane production, extracellular electron transfer pathways, and the current status of microbial communities. It also highlights the latest advancements in biogas upgrading techniques, including the use of different three-dimensional electrode materials, various electric stimulation methods, and hydrogen-assisted approaches. Additionally, several strategies for achieving efficient CO₂ conversion are emphasized, including determining the composition and expression levels of key proteins through multi-omics analysis, utilizing synthetic biology for artificial regulation to generate more efficient-microbial communities, designing novel electrode materials, and optimizing key parameters for efficient CO₂ conversion. These insights will drive further exploration of microbial electrocatalysis-driven biogas upgrading to address the global energy crisis and challenges of climate change associated with fossil fuel usage.