Agricultural waste valorization for sustainable biofuel production

Biofuels are considered as one of the possible solutions to reduce transportation emissions and human dependence on fossil fuels, as they are renewable and carbon neutral. Lignocellulosic agricultural wastes are promising feedstocks for the biofuel industry, because they are generated on a large scale, inedible, and currently not widely utilized. Technologies developed so far to produce liquid biofuels from lignocellulosic biomass follow two distinct pathways: one is biological, involving enzymatic hydrolysis and microbial fermentation of polysaccharides in the cell wall, and the other is thermochemical, utilizing pyrolysis or liquefaction of the biomass in an oxygen-free environment. Production of ethanol or a mixture of acetone, butanol, and ethanol are mature biotechnologies. Thermal processes to produce partially upgraded biocrudes are now in their final stage of commercialization. There are strong technological developments in both fields that will decrease production costs and provide more competitive biofuels for the transportation industry. This chapter provides a review of recent trends and innovations of lignocellulosic agricultural waste valorization to produce sustainable liquid biofuels.