Techno-economic assessment of high-solid simultaneous saccharification and fermentation and economic impacts of yeast consortium and on-site enzyme production technologies

An efficient simultaneous saccharification and fermentation (SSF) at high-solid loading are keys to the successful commercialization of lignocellulose-based process. In the present work, technological and economical potentials of high-solid SSF for sugarcane bagasse-to-ethanol conversion process [6] was analyzed based on process flowsheet simulation for an estimation of the minimal ethanol selling price (MESP). Based on techno-economic assessment a high-solid SSF process platform for a low-cost lignocellulosic ethanol production was designed composing of (1) yeast consortium for C5 and C6 sugars co-fermentation and (2) cellulase/on-site hemicellulase enzyme mixtures acting synergistically for efficient saccharification. Implementing the integrated SSF process with on-site enzymes and yeast consortium, the MESP could be reduced to as low as 15.7 Baht/L equivalent to 1.66 USD/gal which is a 6% lower than the current market selling price of 1.76 USD/gal. Thus, the on-site enzymes together with cellulase-hemicellulase synergism to lower enzyme demand as well as the yeast consortium technology to increase ethanol titer from C5/C6 co-fermentation would provide economic feasibility for the future cellulosic ethanol production in the industrial scale. Such process platform is also an important strategy for the development of low-cost biorefinery industry that can outperform the current sugar-based process for the production of biofuels.