Design of a solid-state hydrogen storage tank for application in the European Spallation Source (ESS)

Abstract

The European Spallation Source, located in Lund, Sweden, is one of the largest scientific and technological infrastructures currently under construction and will be the world’s most powerful neutron source. Its operation will be based on proton acceleration and scattering technology, giving rise to neutron beams up to 100 times brighter than those obtained by existing sources in Europe. In summary, a proton beam is produced by rapidly varying electromagnetic fields, heating hydrogen gas so that electrons evaporate from the hydrogen molecules. The beam will then be accelerated until it hits a target made of stainless steel and containing bricks of tungsten, generating scattering neutrons used in various scientific instruments. However, there is a problem related to the storage of the hydrogen gas used in producing the proton beam. Initially, a cylinder containing 5 liters of H2 at 150 bar pressure was designed, but local regulations state that the pressure cannot exceed 1.45 bar. In this scenario, hydrogen storage in the solid state through metal hydrides would be an excellent alternative for storing the required volume of hydrogen at a much lower pressure level and with a higher volumetric density. Therefore, the goal of this work was to design a tank for solid-state hydrogen storage, ensuring a pressure level below 1.45 bar. For this, a multicomponent alloy was selected through results reported in the literature and compositional adjustments based on a thermodynamic model that allows the prediction of PCT (Pressure-Composition-Temperature) diagrams. Furthermore, calculations were performed for the tank sizing, and its components were selected and analyzed, resulting in two project options. Next, a cost projection for the tank production was elaborated, involving the costs of raw materials to produce the selected alloy and the components chosen to compose the tank. Finally, a prototype and proof-of-concept tests were proposed to verify essential properties for this project, such as the H2 flow rate reached.