Advances in second-generation biofuel production from rice straw and barley straw

Abstract

This review critically examines recent advances in the use of rice straw and barley straw as lignocellulosic feedstocks for second-generation biofuel production. A comprehensive analysis of their chemical composition, including cellulose, hemicellulose, lignin, and ash content, reveals how these intrinsic properties affect the efficiency of conversion to bioethanol, biogas, and bio-oil. Pretreatment methods including steam explosion, ionic liquids, alkaline treatments, and microwave-assisted ammoniation are evaluated for their effects on sugar release, microbial digestion, and thermal degradation. Comparative analysis highlights the differing processing needs and biofuel yields of rice straw and barley straw, with discussion of catalytic systems, reactor configurations, and integration strategies. Logistical challenges in residue collection, storage, and transport are explored, along with emerging solutions such as decentralized biorefineries and digital optimization through Industry 4.0 technologies. The review concludes that the strategic integration of biochemical and thermochemical pathways, tailored to regional biomass characteristics and supported by policy and infrastructure, is essential to unlock the full potential of rice and barley straw as sustainable bioenergy resources.