Advancing biomass residue valorization for sustainable energy and material production

This review provides a critical comparative analysis of biomass residue valorization pathways, addressing the fragmented knowledge between energy-focused and material-focused conversion. Thermochemical processes (pyrolysis, gasification, combustion) offer higher energy densities and are suited for dry lignocellulosic feedstocks, while biochemical routes (anaerobic digestion, fermentation) perform better for wet organic wastes. Key advances include: (1) solar-assisted pyrolysis of rice husk achieving 48–165× lower global warming potential than grid electricity; (2) co-digestion increasing methane yield by 23–64%; and (3) supercritical CO2 extraction enabling dual-function pretreatment for bio-oil upgrading. Techno-economic assessment reveals that modular decentralized systems (TRL 5–7) reduce transportation costs by 30–40% while enabling high-value products such as biochar-based lubricant additives, which improve tribological performance and increase product value by 200–300%. Life-cycle assessment confirms that renewable energy integration and co-product recovery are critical for achieving carbon-negative status. This review bridges the gap between fundamental biomass conversion science and industrial deployment by systematically linking synthesis parameters, environmental metrics, and technological readiness. The practical implication is that hybrid biorefineries combining thermochemical and biological routes with high-value material production offer the most viable path toward commercial circular bioeconomy implementation, supported by decentralized modular systems and consistent policy incentives.