Thermal Energy Storage technologies for the optimal management of metal hydride hydrogen storage systems

Abstract

Hydrogen is an excellent energy carrier that could enable the energy transition, however, storing it in a proper and effective way is one of hydrogen key issues. Storing hydrogen via metal hydrides (MH) can be considered a potential solution to avoid problems (safety, pressurization/liquefaction costs) related to conventional storage systems. A thermal energy storage could be coupled to the MH one, to store the heat obtained from the hydrogen absorption reaction and subsequently to release it to start and support the desorption reaction. This technology allows not to use external sources of heat or of compression, guaranteeing significant energy savings. In this work a MH hydrogen storage system (coupled to a 1 MW electrolyser used in an industrial use case) is studied, focusing on its thermal management supported by a Latent Heat Thermal Energy Storage (LTES) via Phase Change Materials (PCM). The study analyses three different metal hydrides, namely LaNi5, TiFe, TiMn1.5, and phase change materials produced by Rubitherm® Technologies GmbH. A model representing a specific electrolyser case study is then built up, enabling the evaluation of the hourly behaviour of the integrated system, the sizing of the thermal energy storage and to conduct a sensitivity analysis towards the identification of most relevant geometry parameters which affect the techno-economic performances of the system, whose are reported in the concluding part of the paper.