Modelling of thermal management in metal hydride-based hydrogen storage for stationary applications

Achieving the greenhouse gas emissions reductions needed to meet commitments under the Paris Agreement and the EU's climate neutrality objective requires a fundamental shift towards clean and sustainable energy systems, while promoting innovation in renewable energy technologies. In the transition towards renewable sources for energy production towards, hydrogen is emerging as a key energy vector, enabling efficient storage and transport of energy. However, due to the intermittent nature of renewable energy sources, reliable and flexible hydrogen storage solutions are required to ensure energy stability. This study is part of the broader field of innovative technologies for hydrogen storage and transport, as well as its transformation into derivatives and e-fuels. Among the various hydrogen storage technologies, this study focuses on metal hydrides, which store hydrogen through a chemisorption process. This method offers significant advantages over conventional storage techniques, particularly in terms of high volumetric energy density and enhanced safety due to the solid-state containment of hydrogen. However, the absorption of hydrogen in metal hydrides is an exothermic reaction, making effective heat dissipation a critical factor in ensuring optimal performance. The practical implementation of metal hydride storage systems requires addressing these thermal management challenges. This thesis presents the development of a mathematical model aimed at supporting the scale-up of a hybrid hydrogen storage system. The design of metal hydride storage requires analysis based on its thermophysical properties such as activation/deactivation energy, enthalpy of formation, equilibrium pressure, reaction kinetics and external thermal management system. The model is designed to be applicable to different metal alloys and boundary conditions. It provides the temperature profiles as a function of the hydrogen flow rate analysing the heat fluxes through the reactor. In particular, the case of a cylindrical reactor placed between an electrolyser and a fuel cell for stationary application was examined. It was observed that, for the proposed reactor geometry, the hydrogen inlet flow rate must be reduced compared to the maximum allowable rate dictated by reaction kinetics alone, to ensure proper thermal regulation. The proposed technology represents a promising solution for scalable, efficient, and safe hydrogen storage, with potential applications in stationary civil and industrial energy systems. The findings indicate that while reaction kinetics do not inherently limit the hydrogen absorption process, effective heat management remains a critical factor in ensuring system efficiency. Further optimization of the tank geometry and operational parameters could enhance performance, making metal hydride-based storage an even more reliable option for future hydrogen energy systems.