Methods to convert lignocellulosic waste into biohydrogen, biogas, bioethanol, biodiesel and value-added chemicals: a review

In the context of climate change and the circular economy, there is an urgent need to develop biofuels and value-added chemicals from lignocellulosic waste such as agricultural waste that amounts to about 1 million tons annually. Here, we review lignocellulosic feedstocks for the generation of biofuels, biogas, and biohydrogen. Pretreatment technologies include chemical treatments such as acidic and alkaline, organosolv and ionic liquid-based treatments, deep eutectic solvents-based treatments, physical treatments such as steam explosion and supercritical fluid, and biological pretreatment. We present feasible ways to dissolve complex organic materials into monomeric units using advanced methods for lignocellulosic biomass pretreatment. Techno-economic aspects of biomass valorization are discussed. Moreover, this review aims at using biorefinery technologies in order to develop economically viable lignocellulosic chemicals and products