Portfolio selection and optimal planning for hydrogen energy storage systems composed of heterogeneous electrolyzer and fuel cell technologies in industrial park multi-energy systems

As photovoltaic (PV) deployment expands and demand in industrial park multi-energy systems (INP-MESs) intensifies, hydrogen energy storage systems (HESSs) offer a viable solution by balancing the supply-demand mismatch and enabling park-level autonomy. However, integrating diverse electrolyzers (ELs) and fuel cells (FCs), while assessing how their operational flexibility and waste heat recovery potential affect technology mix and sizing, remains challenging. This study integrates three ELs and four FCs into an electrochemical hydrogen-water conversion system (EH2W), proposing a coordinated planning model. Firstly, a capacity-pool-based relaxed clustered unit commitment (CP-RCUC) method is proposed to construct a unified operational model for heterogeneous EL and FC clusters, efficiently solving large-scale mixed-integer problems. The model is then embedded into a long-term high-resolution planning framework for INP-MES enabling a comparative assessment of HESS and battery energy storage system (BESS) in terms of cost and renewable energy curtailment. Furthermore, based on differences in efficiency, cost, flexibility, and heat recovery among ELs and FCs, this research realizes the optimal portfolio selection and sizing for EH2W. A 2050 case study in Gansu demonstrates that HESS integration reduces year-round PV curtailment and cuts costs by up to 43.57 %. Although certain ELs and FCs are more cost-effective, the system prefers higher-efficiency technologies. Sensitivity analysis reveals that a 10 % efficiency gain or cost reduction in proton exchange membrane fuel cell (PEMFC) increases its capacity share from 23.46 % to 41.42 % and 43.27 %, respectively, underscoring its scalability under improved techno-economic conditions