Production of low cost sugars from biomass: Progress, opportunities, and challenges

Lignocellulosic biomass (e.g., agricultural and forestry residues, waste paper, and woody and herbaceous crops) is an abundant low-cost resource that can be used to produce commodity fuels, chemicals, and materials while providing substantial environmental, economic, and strategic advantages. For biologically based conversion technologies, a key need is to produce low-cost sugars from the cellulose and hemicellulose fractions of biomass that together make up about two thirds to three quarters of the feedstock. Technologies have substantially improved that break down recalcitrant biomass into sugars and realize high product yields from the five sugars released. As a result, several firms are now pursuing commercial processes to make ethanol from biomass. Advanced pretreatment and hydrolysis process configurations may be able to further reduce biomass processing costs so that neat fuels are not competitive. Understanding the mechanisms involved in cellulose and hemicellulose hydrolysis will support such advancements and accelerate scale-up of biological processing technologies at lower costs. Development of coproducts to fully utilize the substrate will also improve process economics.