A thermodynamic analysis of electron production during syngas fermentation

► The Gibbs free energy of reaction for electron production from CO is thermodynamically favorable for typical conditions. ► The Gibbs free energy of reaction for electron production from H2 can be thermodynamically favorable or unfavorable. ► Electron production from CO is always more thermodynamically favorable compared to electron production from H2. ► It is unlikely that H2 can be utilized in favor of CO for electron production when both species are present. ► CO conversion efficiency will likely be sacrificed during syngas fermentation.