Optimal sizing for an integrated energy system considering degradation and seasonal hydrogen storage

Highlights: • An optimal sizing method with selection of typical days is presented in this paper. • The degradation process of PEMFC, PEMEL and BAT is considered in this paper. • A life cycle cost scheme of IES is proposed. • The results show the effect of degradation processes on system sizing. • The benefits of seasonal hydrogen storage are discussed. In order to analyze the feasibility and economy of island integrated energy system combined power-hydrogen-heat-cooling cogeneration in detail, this paper proposes a two-level optimal sizing method. First, a cost scheme of the integrated energy system based on the life cycle is proposed, and the degradation, remaining life, and replacement of proton exchange membrane fuel cell, proton exchange membrane electrolyzer and battery are considered. Then, considering the randomness and correlation of various environmental data and loads during the sizing process, a clustering and scenario generation method based on eigenvalues is designed. Finally, an optimal sizing method based on the random-trigonometric grey wolf optimizer and mixed integer linear programming is proposed and tested. The performance of the two-level optimal sizing method is verified by benchmarks and a case in Ningxia, China. The scheduling results and economics based on the sizing results are elaborated and analyzed in detail. In particular, the degradation cost accounts for 13.1% of the total life cycle cost, and the seasonal hydrogen storage provides 1.4317 × 10⁵ kWh of energy for the system at a lower cost compared with battery, which reveal the necessity of considering system degradation and the economic advantages of the integrated energy system with seasonal hydrogen storage.