Understanding the\nFlexibility Challenges of a Plant\nfor Microbial CO<sub>2</sub> Electroreduction with Hexanoic Acid Recovery

CO<sub>2</sub> electroreduction driven by renewable energy\nis a\npromising technology for defossilizing the chemical industry, but\nintermittency challenges its operation. This work aims to understand\nthe impacts of intermittency on the design, volume flexibility, and\nscheduling of a microbial electrosynthesis (MES) plant that converts\nCO<sub>2</sub> to hexanoic acid. A battery and a storage tank were\nconsidered to buffer the intermittency. Explorative case studies showed\nthat batteries were economically unfavorable. Restricted by the downstream\nprocessing (DSP) flexibility, a storage tank with optimized size combined\nwith optimal scheduling, under the assumed conditions in this work,\nimproved the plant’s volume flexibility only by 10%. The carbon\nfootprint became 3 times lower when switching from grid to renewable\nelectricity, but the levelized production cost of hexanoic acid increased.\nHence, coupling with renewable electricity was not economically but\nenvironmentally favorable. Developing more flexible DSP technologies\nor synthesizing higher-purity chemicals are needed to enhance MES’s\nattractiveness.