The design of a cellulosic ethanol process for maximum utilization of both pentose and hexose sugars in the most productive way is still an unsolved puzzle. Based on the current technologies, either SHCF or SSCF may result in the best cellulosic ethanol productivity. SSCF may be more economically feasible in setting up a bio-refinery as it requires less number of unit operations. However, for a continuous ethanol production process, the following guidelines are considered in setting up a bio-refinery:

• Reusability of chemicals (for a pretreatment process)

• Recirculation of enzymes for enzyme hydrolysis and cell biomass for ethanol fermentation

• Generation of potential market valued by-products such as lignin

• Maximum utilization of energy generated during the process

• Minimal waste generation