Zero-waste cascading valorization of crop biomass residues for dual-purpose production of biofibers and bioenergy

• Cereal crop residues were evaluated for combined fiber production and energy use • Alkaline treatment produced 10.9-19.8% lignocellulosic fibers from tested biomass • Ash content in wheat straw decrease from 9.88% to 1.60% after fiber extraction • Post-extraction residues retained LHV of 14.36-16.97 MJ kg -1 for energy use Agricultural crop residues represent an abundant renewable resource that can be integrated into cascading biomass valorization systems. This study investigates the dual-purpose utilization of three cereal-based residues for the production of lignocellulosic fibers and energy: wheat straw, barley straw, and corn stalks. Biomass was subjected to alkaline pretreatment to extract natural fibers, followed by physicochemical and calorimetric characterization of the remaining solid residues. Fiber extraction yields ranged from 10.91% to 19.82%, depending on crop type, while the remaining solid residues accounted for 24.82-32% of the initial biomass. The extracted fibers exhibited densities between 1.2 and 1.6 g cm -3 , indicating their sustainability for lightweight composite reinforcement. Proximate analysis revealed a substantial reduction in ash content after fiber extraction. For example, in wheat straw ash content decreased from 9.88% to 1.60%, which significantly improves combustion characteristics. Although the lower heating values (LHVs) decreased slightly after fiber extraction, the residual biomass maintained LHV values between 14.36 and 16.97 MJ kg -1 , confirming its suitability for solid biofuel production. Compared with conventional single-purpose biomass utilization pathways, the proposed cascading approach enables the simultaneous generation of value-added fibers and energy from the same feedstock, thereby increasing overall biomass utilization efficiency and supporting circular economy strategies.