Thermochemical Biomass Conversion for Sustainable Hydrogen Production: A Review of Techno-Economic Performance and Decarbonization Potential

Hydrogen is a strategic energy carrier for decarbonizing hard-to-abate sectors; however, current production remains fossil-based, while the economics and utilization of renewable electrolysis depend strongly on the availability and variability of low-carbon electricity. Thermochemical biomass conversion offers a complementary route because biomass can be stored, dispatched, and sourced from residues, wastes, and bioeconomy streams. This study systematically reviews the thermochemical pathways for sustainable hydrogen production, integrating technical performance, feedstock suitability, process upgrading, techno-economic feasibility, life-cycle impacts, and decarbonization potential. Following a PRISMA-based methodology, 111 core studies were included in the systematic review, while 26 review articles were analyzed separately as the supporting literature. Unlike previous reviews that primarily centered on technology- and reactor-level comparisons, the present synthesis places particular emphasis on the economic and deployment conditions governing biomass-to-hydrogen feasibility, including LCOH, plant scale, feedstock logistics, purification boundaries, and carbon-management assumptions. Gasification appeared in 96 core studies and showed the strongest maturity evidence among the reviewed thermochemical pathways, including pilot-scale integrated operation with downstream gas cleaning, water–gas shift, and hydrogen purification, although numerical TRL values were not consistently reported. Reported H2 concentrations ranged from approximately 8–16 vol% in conventional air/oxygen gasification and 30–60 vol% in steam-based gasification. Advanced capture-assisted systems achieved 78–81.1 vol% H2, while pilot-scale purification reached 98.6 vol%. Reported economic values varied substantially across metric definitions, plant scales, currencies, and system boundaries. Accordingly, LCOH, minimum selling price, and hydrogen production cost were treated as distinct metrics, and original currencies and economic reference years were retained when available rather than pooled into a single cross-study cost range.