Advancing sustainable bioeconomy: Integrative biorefinery pathways for circular valorization of agro-industrial residues

Global agro-industrial systems generate over one billion tonnes of lignocellulosic residues annually, yet systematic frameworks linking feedstock properties to conversion pathways and policy enablers remain absent. This study develops an integrative decision framework for industrial-crop biorefineries by coupling agronomic constraints—ash content (5–20 wt%), lignin syringyl/guaiacyl ratios (0.5–2.5), moisture levels (10–60 wt%), and wax barriers—with reactor-level intensification strategies and market-pull mechanisms. We analyzed three feedstock classes: cereal and oilseed residues (rice husks, wheat straw, sugarcane bagasse), dedicated perennial crops (switchgrass, miscanthus, short-rotation woody species), and oil/starch-bearing species (jatropha cake, cassava waste). These were systematically mapped to five modular conversion routes: deep-eutectic solvent pretreatment, electrified thermochemical upgrading, enzyme-directed saccharification with in-situ product removal, organic-solvent-lean separations, and precision fermentation for platform molecules. The framework yields two operational tools: first, a crop–process–product decision matrix categorizing pathways by Technology Readiness Level (TRL 6–9) and projected internal rate of return under carbon pricing scenarios (25–100 United States dollar (USD) per tonne carbon dioxide equivalent (CO₂e)); second, a technology-policy readiness map aligning conversion maturity with certification standards (Roundtable on Sustainable Biomaterials, International Sustainability and Carbon Certification), blending mandates (E10–E20, B7–B20), and production tax credits. Quantitative analysis identified primary conversion bottlenecks: ash-mediated enzyme inhibition reduces saccharification yields by 35–42%, while non-selective lignin depolymerization limits aromatic monomer recovery to below 28 wt%. Proposed mitigation strategies include mineral-scavenging additives (zeolites, activated carbon), tailored enzyme cocktails with enhanced cellulase/xylanase ratios (3:1–5:1), redox-balanced catalysts (nickel-ruthenium, copper-cobalt bimetallics), and electrified heat integration achieving 40–50% thermal energy reduction. Case validation across four bioeconomy models (Sweden forest-based cascade, Brazil sugarcane ethanol platform, Germany policy-integrated biorefinery clusters, United States precision agriculture systems) demonstrated that coherent policy design—combining green procurement (minimum 30% bio-based content), carbon floor pricing (≥50 USD per tonne CO₂e), and residue mobilization credits (15–25 USD per tonne)—functions as a design variable rather than external constraint. Life-cycle assessment integrated with techno-economic analysis showed that optimized industrial-crop biorefineries achieve net greenhouse gas reductions of 62–78% versus fossil-derived equivalents, residue valorization rates exceeding 92%, and levelized production costs competitive at crude oil prices above 65 USD per barrel. This framework provides a quantitative, evidence-based blueprint for advancing agro-industrial biorefineries from pilot-scale demonstration (TRL 6–7) to commercial deployment (TRL 8–9), ensuring alignment among environmental integrity, rural economic resilience, and market competitiveness. • Bioeconomy framed as crop–conversion–market system, not generic narrative. • Three crop classes mapped to modular, low-waste biorefinery pathways. • Decision matrix identifies bankable conversion routes and readiness gaps. • Agronomic traits coupled with reactor-level intensification strategies. • Tech maturity aligned with policy, carbon floors, and certification.