Editorial: Emerging Feedstocks & Clean Technologies for Lignocellulosic Biofuel

The United Nations Sustainable Development Goals (SDGs) include the availability of affordable and clean energy (Goal 7) for attaining peace and prosperity for all (Sustainable Development Goals, 2022).The other SDGs "Sustainable Cities and Communities" (Goal 11), "Responsible Consumption and Production" (Goal 12), and "Climate Action" (Goal 13) also warrant the search for sustainable feedstock and clean technologies for the production of renewable fuel.Lignocellulosic biomass is one of the prominent and emerging feedstocks being investigated as a source for biofuel production.The yearly global production of lignocellulosic biomass in nature is estimated to be 181.5 billion tons.Of this, just 8.2 billion tons of biomass is said to be currently utilized of which 7 billion tons originates from forest, agriculture and grasses and 1.2 billion tons is supplied from agricultural residues (Ashokkumar et al., 2022).The traditional utilization of such biomass is for cooking, heating, construction material, and production of paper, cardboard, and textiles.With the advancement in technologies and biomass management this valuable lignocellulosic biomass can be directed towards production of renewable biofuels.Moreover, the cellulose, hemicelluloses, and lignin material could be valorized to other useful industrial bioproducts and biochemicals (Ashokkumar et al., 2022).Lignocellulosic biomass comprises of lignin, cellulose, and hemi-cellulose and is abundant globally.Cellulose is the most abundant organic material available in nature followed by lignin.The percent composition of cellulose, hemicellulose, and lignin vary in lignocellulosic materials such as softwood, hardwood, agricultural residues, and grasses.Lignocellulosic biomass comes from a wide variety of feedstocks such as sugar crops, starch crops, agricultural residues, herbaceous biomass, woody biomass, oilseeds, and microalgae (Yuan et al., 2018).Carbohydrate present in the cellulose and hemicellulose components of lignocellulosic biomass are considered suitable for the production of biofuels.However, the lignocellulosic material is recalcitrant as the lignin in the lignocellulosic biomass inhibits the saccharification and hydrolysis of carbohydrate present in the biomass and thus poses challenges in biofuel conversion.The major challenge in the conversion of polymer to monomer from the lignocellulosic biomass is attributed to the strong covalent and non-covalent bond in its structure, crystallinity, and lignin incrustation that needs to be overcome for its utilization as a material for biofuel production (Preethi et al., 2021).The recalcitrance nature of the lignocellulosic material is overcome by pre-treatment steps that disorders the lignin component in the biomass.Thereafter, the cellulose and hemi-cellulose could be subjected to enzymatic hydrolysis.The pre-treatment methods can be physical, chemical, physiochemical or biological.Pre-treatment leads to fragmentation of the lignocellulosic material, further enhancing its surface area and solubility, and lowering the crystallinity of cellulose and lignin content in the biomass (Hoang et al., 2021;Kumar et al., 2022).