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This paper reports on an energy/exergy analysis of a standalone solar-hydrogen system with a metal hydride (MH) system thermally managed using a phase change material (PCM). This is a self-contained thermal management arrangement that stores the heat released from the MH unit, when it is being charged and transfers it back to the MH while discharging hydrogen. The first and second laws of thermodynamics were used to develop a mathematical model in MATLAB to simulate this system and quality its performance from the energy and exergy viewpoints. The model was then applied on a passive standalone house, with ∼3.8 MWh/year electricity demand, located in southeast Australia. The exergy efficiencies of the solar PV, electrolyser, fuel cell and the whole solar hydrogen system were found to be 6.5%, 88%, 50.6%, and 3.74%, respectively. The paper also provides the detailed entropy generation and exergy analysis on the MH hydrogen storage unit together with its PCM-based thermal management arrangement. The results show that the annual entropy generation, exergy destruction and exergy efficiency of the MH hydrogen storage unit were 173 Wh/K, 51.5 kWh, and 98.8%, respectively. • Exergy analysis of phase change material used for metal hydride thermal management in solar hydrogen system. • The energy and exergy efficiencies of the solar PV are around 6.1% and 6.5%, respectively. • Energy and exergy of solar-hydrogen system were 3.48% and 3.74%, respectively. • Exergy efficiency of the MH thermal management using PCM was 98.8%. [ABSTRACT FROM AUTHOR]

• Metal hydride (MH) thermal management in a solar-hydrogen system was modelled. • A phase change material (PCM) was used for thermal management of MHs. • Low conductivity of PCMs was a major challenge for thermal management of MHs. • Using PCM offers an energy saving equivalent to about 15% of the total yearly hydrogen production. In this paper, a model of a metal hydride thermal management using phase change material in the context of a standalone solar-hydrogen system is proposed and investigated. The HOMER software is used to simulate the optimal system architecture and yearly power profiles of the electrolyser and fuel cell stacks used in a case study of a remote household in southeast Australia. A dynamic theoretical model of a phase change material arrangement for thermal management of the metal hydride hydrogen storage unit is then built in MATLAB environment to study the performance behaviour of the hydrogen storage system in this context. Based on the case used for this study, it was found that approximately equivalent to ~12% of total energy content of the hydrogen generated by the electrolyser can be saved annually by replacing an external energy thermal management system with the proposed phase change material thermal management solution. It was also found that the conductivity of phase change materials must be improved to a minimum of 1.5 W/mK, in order to make this thermal management arrangement more practical. [ABSTRACT FROM AUTHOR]