A Comprehensive Modeling Analysis of Formate‐Mediated Microbial Electrosynthesis

Mediated microbial electrosynthesis (MES) represents a promising strategy for the capture and conversion of CO2 into carbon‐based products. We describe the development and application of a comprehensive multiphysics model to analyze a formate‐mediated MES reactor. The model shows that this system can achieve a biomass productivity of ∼1.7 g L−1 h−1 but is limited by a competitive trade‐off between O2 gas/liquid mass transfer and CO2 transport to the cathode. Synthetic metabolic strategies are evaluated for formatotrophic growth, which can enable an energy efficiency of ∼21 %, a 30 % improvement over the Calvin cycle. However, carbon utilization efficiency is only ∼10 % in the best cases due to a futile CO2 cycle, so gas recycling will be necessary for greater efficiency. Finally, separating electrochemical and microbial processes into separate reactors enables a higher biomass productivity of ∼2.4 g L−1 h−1. The mediated MES model and analysis presented here can guide process design for conversion of CO2 into renewable chemical feedstocks. Model‐driven insight: Coupling electrochemical CO2 reduction to formate and microbial catalysis is a promising platform for sustainable chemical production. A comprehensive model capturing mass transport; electrochemical, acid/base, and microbial reaction kinetics and thermodynamics; temperature effects; and gas/liquid mass transfer was developed, revealing insights into performance limits for this system.