Moving horizon optimization for robust Power-to-Hydrogen design under inter-annual weather variability

Battery energy storage systems (BESSs) are essential for green hydrogen production via electrolysis, mitigating intermittent renewable inputs by storing energy during low demand and releasing it at peak times. This work addresses weather fluctuation impacts on green hydrogen plant design by improving a previously published sizing methodology. The approach determines the “overall optimum” capacities for a plant comprising solar photovoltaics, wind turbines, an electrolyzer, and a BESS. The optimization runs over 2000 fictitiously generated years, constructed by progressively shifting the daily starting dates of reference renewable profiles. This moving horizon technique ensures the optimum remains valid for years not included in optimization. Applied to California (2018–2024), the methodology identifies optimal capacities of 70 MW solar, 150 MW wind, 82.29 MW electrolyzer, and 116.98 MWh BESS, achieving levelized costs of hydrogen (LCOH) ranging from 3.12 to 3.64 USD/kg across weather scenarios. The configuration consistently meets the 8760 t/y production target for all validation years not used in optimization, with actual hydrogen production of 9020–10,222 t/y representing 3.0–16.4 % overproduction. This controlled overproduction demonstrates the methodology's robustness while maintaining economic competitiveness. The framework reveals how individual extreme weather days disproportionately impact BESS sizing, providing crucial insights for resilient infrastructure planning.