Life cycle assessment of hydrogen production from biomass residues via steam gasification: Comparative analysis of citrus peels and Posidonia oceanica

The conversion of biomass residues into bioenergy carriers through thermochemical processes represents a key pathway toward sustainable energy systems. In this study, hydrogen-rich syngas production from two Mediterranean biomass feedstocks—citrus peels (CP) and Posidonia Oceanica (PO)—was evaluated using steam gasification. Aspen Plus simulations, validated against experimental data, were employed to model process performance under varying steam-to-biomass ratios (S/B = 0, 0.5, 0.75, and 1.0). The simulation results provided the basis for a gate-to-gate life cycle assessment (LCA), enabling the comparison of the environmental performance of both biomass residues. The findings indicate that increasing the S/B ratio mitigates environmental differences between CP and PO across most impact categories. Global warming potential (GWP) decreased by 63.5 % for CP and 67.6 % for PO when increasing S/B from 0 to 1.0. Overall, CP exhibited higher environmental burdens, while PO gasified at S/B = 1.0 achieved the best performance, combining the highest hydrogen yield with an 11.8 % lower GWP compared to CP under identical conditions. This work highlights the role of agricultural and marine biomass residues as renewable feedstocks for hydrogen production via steam gasification, contributing to the advancement of bioenergy technologies and circular economy strategies.