Meta-analysis of solar-thermal catalytic reforming of biomass for green hydrogen production: Evaluating kinetic synergy and carbon neutrality potential

Solar-driven hydrogen production from biomass represents a promising pathway toward carbon-neutral energy systems by integrating concentrated solar thermal energy with catalytic biomass reforming. This meta-analysis synthesizes forty-two empirical studies published between 2015 and 2025 to evaluate the kinetic interaction between intensified solar heat and catalytic performance in hydrogen generation from diverse biomass feedstocks. Using random-effects modeling in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 framework, the pooled standardized mean difference in hydrogen yield was 0.76 (95% confidence interval: 0.60–0.92; heterogeneity index = 61.2%). Lignocellulosic biomass outperformed agricultural residues, with standardized mean differences of 0.88 and 0.57, respectively. Meta-regression identified solar concentration ratios between 10 and 150 suns and nickel-based catalysts promoted with noble metals as key determinants of performance. However, more than half of the residual heterogeneity remained unexplained, likely due to reactor-scale geometric and flow-field variations. Solar-assisted reforming reduced activation energy from 180–210 to 65–95 kilojoules per mole, corresponding to a kinetic synergy factor of 2.1–2.9. Carbon assessment indicated potential greenhouse gas emission reductions of 3.2–4.8 kilograms of carbon dioxide equivalent per kilogram of hydrogen, while sensitivity analysis incorporating indirect land-use change effects identified a threshold of 8–10 kilograms beyond which carbon-positive performance may occur. Catalyst deactivation from coke deposition remains a technical constraint, with regeneration intervals of 50–150 operating hours. Fluidized-bed reactors achieved 18–24% higher hydrogen selectivity than fixed-bed systems but experienced mass-transfer limitations under high solar flux. These findings underscore the need for durable catalysts and adaptive reactor designs to improve scalability and long-term operational stability.