Degradation-aware design and lifetime evaluation of hydrogen hybrid marine energy systems

Abstract

Hydrogen fuel-cell and battery systems can reduce ship emissions, but their early-stage design requires the simultaneous consideration of component sizing, operational dispatch, hydrogen production pathway, onboard storage, and component degradation. This study proposes a degradation-aware two-stage optimisation framework for the design and assessment of hydrogen hybrid marine energy systems. The first stage applies mixed-integer linear optimisation to determine the fuel-cell and battery capacities and their mission-level power allocation, while the second stage evaluates the resulting operation using fuel-cell voltage-loss and battery-ageing models. The framework is demonstrated for the retrofit of an 89.9 m short-sea cargo vessel over a representative 194 h mission. For electrolytic hydrogen produced using proton-exchange-membrane electrolysis, the selected fully electrified configuration comprises five 150 kW fuel-cell units and three 100 kWh battery modules and consumes 7189 kg of hydrogen per mission. Under the adopted accounting boundary, the system reduces mission emissions by 92.4% relative to the diesel reference case. However, hydrogen storage represents 87.0% of the total capital cost at a storage-specific cost of USD 700 kg⁻¹, while the required fuel volume is approximately 300 m³ for compressed hydrogen at 350 bar or 103 m³ for liquid hydrogen. At three missions per month, the fuel-cell health indicator reaches its prescribed limit after approximately 31 months, whereas the battery retains 93.0% of its initial capacity. The results identify hydrogen storage and fuel-cell degradation as the principal constraints governing the technical and economic feasibility of hydrogen-powered ship retrofits.