Scalable lignocellulosic biorefineries: Technoeconomic review for efficient fermentable sugars production

Sugars derived from lignocellulosic biomass represent an appealing and critical platform for advancing the bioeconomy. Attractive for the distinguished selectivity as well as green and sustainable features, enzymatic hydrolysis is a promising for sugars production. Despite the long-standing and ongoing interest and efforts in lignocellulosic sugar biorefining, extracting sugars from lignocellulose has not been widely adopted for the industrial-scale production because of inferior market competitiveness, driven by the high costs associated with each of the multiple intertwined stages of enzyme-mediated sugar production from field feedstock collection to factory product purification. While few reviews systematically discussed the entire process from an industrial perspective, considering the interconnections of constituent processes, along with overall profitability considerations. To fill this gap, a comprehensive discussion of key factors limiting scalable production such as feedstock and cellulase costs, alongside the efficiency in pretreatment and enzymatic hydrolysis is presented. Noteworthy is the examination of technical obstacles in enzymatic hydrolysis at high solid loadings, together with updates aimed at enhancing lignocellulosic sugar yields, quality and cost efficiency. More significantly, the interdependence among different steps is discussed; thus, economical full industry chain is recommended to improve the cost competitiveness of sugar production. Of particular importance is the need to maximize high value from by-products and explore more efficient feedstock supply logistics and on-site enzyme production technologies. Finally, technoeconomic analysis is emphasized as a valuable tool for assessing and optimizing feasibility of the proposed scheme.