Harnessing the potential of lignocellulosic biomass for biofuels production.

Currently, fossil fuels are the main and dominant sources for producing fuels and commodity chemicals. The rising demand for fossil fuels continues to entrench global dependency on non-renewable sources creating the climate risk, the economic instability and sustainability challenges. Hence, there is a need to shift towards globally available, sustainable and renewable resources such as lignocellulosic biomass (LCB) that offers a sustainable pathway for producing biofuels and chemicals. Though various technologies are available for LCB conversion to biofuels and chemicals, scaling up of biorefineries remains stifled by its recalcitrance nature and volatile supply chain economics. LCB processing often requires pretreatment to disrupt the rigid lignin-hemicellulose barrier and decrystallize cellulose. This structural opening is essential to maximize the enzymatic hydrolysis and sugar yields for biofuel production. The pretreatment process is energy-intensive and expensive accounting for 40% of the overall biofuel production cost followed by hydrolysis using expensive enzyme cocktails. These economic barriers currently limit the adoption of LCB as a cost-competitive fuel resource. The promising strategy for low cost LCB derived ethanol production is to adopt integrated biorefinery approach utilizing physical, chemical and biological processes. The integrated biorefinery approach tackles the high costs of second generation ethanol production by mimicking traditional petroleum refineries. It valorizes all three LCB components to marketable fuels and high-value chemicals maximizing the overall process profitability. This review discusses on the latest developments in biofuels production processes especially in relation to ethanol and butanol production. KEY POINTS: Importance of lignocellulosic biomass (LCB) for biofuels production.The promotion of circular bioeconomy through integrated biorefineries. Need for solutions to LCB preprocessing challenges such as Pretreatment, enzyme production.Need for developing alcohol-producing microbes with capabilities to produce LCB-degrading enzymes.