Optimized Design and Economic Evaluation of a Renewable Hydrogen Refueling Station for Public Transport on Elba Island

<div>The aim of this study is to develop a methodology to significantly reduce emissions in bus fleet renewal scenarios by investigating both technical and economic aspects. This work presents a case study based on Elba Island, Italy, which investigates optimal solutions for replacing existing Diesel buses through a total cost of ownership analysis. The investigation is carried out for four different potential scenarios: renewing the fleet with Diesel buses, renewing the fleet with electric buses, adopting fuel cell buses, and implementing a hybrid solution. The latter represents a synergistic solution that integrates fuel cell buses with the development of a hydrogen refueling station driven by a proton exchange membrane electrolyzer, unlocking the techno-economic potential of self-producing green hydrogen for bus refueling. The novelty of this study is its integrated methodology that combines a total cost of ownership analysis with a tailored design of a green hydrogen production network optimized for continuous fleet operation. A constrained optimization algorithm was employed to determine the optimal configuration of key plant components, including the proton exchange membrane electrolyzer system size, the amount of photovoltaic panels and wind turbines, and the capacity of the hydrogen storage tank. The grid-based alternative offers a simple payback period under 4 years and a total cost of ownership of 6 M€, making it more cost-effective than the 6.5 M€ electric and 7.5 M€ Diesel options. These results provide a scalable, replicable roadmap for accelerating sustainable public transport adoption in similar contexts.</div>