The Status of and Key Barriers in Lignocellulosic Ethanol Production: a Technological Perspective

The development of biorefineries to produce fuel ethanol and commodity chemicals from lignocellulosic biomass is a potential alternative to current reliance on non-renewable resources. However, many technological barriers remain despite research progress in the past several decades. This article examines the major process barriers in biochemical conversion of biomass to cellulosic ethanol. We review the key pretreatment processes, including a process recently developed by the authors for biomass conversion, and the technical potentials for commercialization. The importance of feedstock physical size reduction and issues related to size-reduction energy consumption and substrate size characterization are also discussed. The article also analyzes and compares enzymatic conversion of cellulose from different feedstocks and the recovery of hemicellulose sugars from different pretreatments. Finally, we discuss the commercial viability of the existing processes in terms of the availability of commercially proven capital equipment.