Modeling and implementation of metal hydrides for hydrogen storage

This paper presents a mathematical model for a hydrogen storage system based on metal hydrides, developed within the broader context of decarbonizing shipboard auxiliary systems through hydrogen technologies. In the preliminary phase of the study, a critical literature review was conducted to assess the main hydrogen storage solutions currently under development or deployment. The outcomes of this comparative assessment led to the selection of metal hydrides – specifically LaNi5-based compounds – as the most promising option for shipboard integration, due to their safety, compactness, and thermodynamic compatibility with fuel cell systems operating in port conditions. Based on this choice, a dedicated mathematical model was developed adopting a lumped-parameter approach and implemented in a Fortran environment. The model describes the coupled heat and mass transfer phenomena, as well as the kinetics of hydrogen absorption and desorption, through a system of nonlinear differential equations. These equations are discretized and solved using an implicit finite element method to ensure stability and computational accuracy. The model was validated through comparison with numerical results from scientific literature and with experimental data reported in previous studies. Following validation, the model was encapsulated into a new TRNSYS Type, enabling its integration within a dynamic simulation framework for assessing the energy, economic, and environmental performance of hydrogen-based shipboard systems. Although a full case study is not included in the present work, future developments will focus on simulating and comparing different hydrogen storage configurations for different ships each equipped with a proton exchange membrane fuel cell system.