An optimization framework for component sizing and energy management of hybrid electrolyzer systems considering physical characteristics of alkaline electrolyzers and proton exchange membrane electrolyzers

Abstract

This paper proposes to produce hydrogen using a hybrid electrolyzer system (HES) incorporating the alkaline electrolyzer (AEL) and the proton exchange membrane electrolyzer (PEMEL) technologies in the context of renewable energy sources (RESs). To solve the component sizing and energy management problems for the HES, this paper develops an optimization framework by taking into account the physical characteristics of AELs and PEMELs. In particular, the operating power range of the AEL is determined based on its hydrogen to oxygen (HTO) threshold (for the lower bound) and overloading capability (for the upper bound). The dynamic response characteristics of AELs and PEMELs as well as supercapacitors are considered in that their dynamic responses are parameterized as affine functions of the RES power fluctuations. The effectiveness of the proposed optimization framework is validated using a case study involving both offline and online simulations. Results show that the system revenue of the HES is the highest (1451.05 ¥) compared to the AEL-only (1411.84 ¥) and PEMEL-only (1254.36 ¥) configurations. The energy efficiency of the HES (108.05%) is significantly higher than that of the AEL-only system (95.97%). Therefore, the HES configuration is both technically and economically feasible and beneficial compared to the AEL-only and PEMEL-only configurations for hydrogen production.