Optimal design of grid-connected green hydrogen plants considering electrolysis internal parameters and battery energy storage systems

The use of water electrolysis to produce green hydrogen from renewable energy resources has attracted a significant attention, where hydrogen could be utilized as a reliable energy carrier and clean fuel. Yet, Green Hydrogen Plants (GHPs) are categorized as complex and high -cost systems and thus their mass deployment and integration with power grids necessitate the development of appropriate design models. As such, this paper introduces a novel mathematical formulation to optimize the design of grid -connected GHPs. The formulated optimization model aims to find (i) the rated powers of the electrolysis, power converters, and compressor units, (ii) specifications of the internal parameters of the electrolysis stacks (membrane thickness, cell area, and cathodic pressure), and (iii) capacities of the local hydrogen storage tank and an optional battery energy storage system (BESS). The objective of the design is to minimize the Levelized Cost of Hydrogen (LCOH) considering two scenarios for hydrogen production: pure green from renewable generation and dull green from a mix of renewable and conventional power sources. The proposed formulation also accounts for the PEME degradation cost and the recently announced clean hydrogen subsidies by different governments. In addition it takes into account the PEME safety constraints. The proposed model has been numerically validated using the IEEE 30 bus transmission test system and the results show that the consideration of PEME internal parameters in the optimization model has achieved up to 20% reduction in the LCOH and 29% reduction when combined with the BESS. Further, the results show that ignoring the PEME safety constraints leads to improper GHP design and PEME parameters selection. The results also show that clean hydrogen subsidies significantly change the GHP design and the selection of the PEME internal parameters.