Microbial electrosynthesis from CO2: forever a promise?

• Published in: Current opinion in biotechnology Vol. 62; pp. 48 - 57
• Main Authors: Prévoteau, Antonin, Carvajal-Arroyo, Jose M, Ganigué, Ramon, Rabaey, Korneel
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2020
• Subjects: carbon dioxide; carbon monoxide; electric potential difference; electrochemistry; electrolytes; electrosynthesis; energy conversion; ethanol; fermentation; hydrogen; hydrogen production; products and commodities
• ISSN: 0958-1669; 1879-0429; 1879-0429
• DOI: 10.1016/j.copbio.2019.08.014

•MES was proposed as a route to convert CO2 to commodities.•Performance indicators of MES are plateauing and far from economic competitiveness.•Effective water electrolysis in microbial-compatible electrolytes is challenging.•Severe trade-off between production rate and energy conversion efficiency.•Improvement of MES, applicability and possible directions are discussed. Microbial electrosynthesis (MES) is an electrochemical process used to drive microbial metabolism for bio-production, such as the reduction of CO2 into industrially relevant organic products as an alternative to current fossil-fuel-derived commodities. After a decade of research on MES from CO2, figures of merit have increased significantly but are plateauing yet far from those expected to allow competitiveness for synthesis of commodity chemicals. Here we discuss the substantial technological shortcomings still associated with MES and evoke possible ways to mitigate them. It appears particularly challenging to obtain both relevant production rates (driven by high current densities) and energy conversion efficiency (i.e. low cell voltage) in microbial-compatible electrolytes. More competitive processes could arise by decoupling effective abiotic electroreductions (e.g. CO2 to CO or ethanol; H2 evolution) with subsequent fermentation processes.