In addition to energy consumption, substrate cost in a fermentation– PV coupled process also poses major constraints on a
commercial production scale. In conventional ABE production by fermentation, substrate cost accounts for up to 79% of the solvent production cost (Green, 2011; Pfromm et al., 2010). An increase of yield in the fermentation–PV coupled process would decrease substrate consumption, as a result, the overall solvent production cost would decrease. Thus, the economic capacity of ABE production from renewable resources could be significantly improved in continuous fermentation–PV coupled process