Abstract
Decarbonization of hydrogen-intensive industrial clusters is essential to meet the European Union's net-zero targets. Although hydrogen can replace fossil-based feedstocks and fuels in refineries and chemical industries, its production remains largely dependent on natural gas. Therefore, cost-effective and low-emission supply routes require a system-level approach that integrates regional resources, technologies, and industrial demand. This study applies a multi-objective optimization framework to design a low-carbon hydrogen supply system for Galicia (northwestern Spain), addressing two gaps in regional energy system modeling: model transferability across regions and integration of social criteria beyond techno-economic assessment. The model quantifies trade-offs between total system cost and greenhouse gas emissions, and an employment indicator is integrated via post-processing using TOPSIS. The results show that meeting 100% of the projected 2030 demand (105 kt H2/a) yields a single feasibility-limited solution dominated by biomass gasification (69% of hydrogen production). When the demand was reduced to 60% coverage (63 kt H2/a), 28 non-dominated solutions were obtained. The top-ranked compromise combines 55% PEM electrolysis and 45% biomass gasification, supported by a wind-dominated electricity mix, under equal weighting of economic, environmental, and social criteria. When either emissions or employment is prioritized, this compromise remains top-ranked, while the cost prioritization shifts preference to a solution with hydrogen production from PEM (51%) and alkaline (3%) electrolysis and biomass gasification (46%).