Kinetic models relating redox potential control to ethanol fermentation have been proposed [9, 10]. Liu et al. developed a kinetic model by incorporating ethanol toxicity concentration and VHG conditions into consideration [10]. Various operating diagrams were then designed, making it easy to choose different combinations of fermentation operating conditions when needed. According to their simulated results, the best operation condition under redox potential-controlled VHG fermentation was to control redox potential level at -140 mV along with 275 g glucose/l feed, where 133.2 g ethanol/l could be obtained.