Dynamic Modelling of a PEM Electrolyser and Metal Hydride Hydrogen Storage System

Abstract

Renewable deployment requires hydrogen storage decoupling production from demand, and metal hydride systems offer a safe, low-pressure, high-density option. Within the EU REMEDHYS project, a solid-state storage system based on an intermetallic alloy produced from recycled European metals is coupled to a 2 MW proton exchange membrane electrolyser. This paper presents a modular, equation-based Modelica model of the balance of plant of both subsystems, comprising eleven control loops, measured pressure-composition isotherms and a pseudo-twodimensional discretisation of the hydride bed. A 2 MW to 1 MW load step, a full absorption-desorption cycle, a sensitivity analysis and a coupled scenario feeding twenty cassettes are simulated. The hydrogen delivered per cycle falls from 4281 to 3292 g as the delivery pressure rises from 1 to 5 bar and doubles between 50 and 70 ◦C. Coupled to the electrolyser, a cassette charges in 6.6 h and stops discharging at a state of charge of 0.24, limited by the alloy equilibrium pressure.