Thermodynamic Analysis and Performance Optimization of a Hybrid Solar–Thermal Energy Storage System Using Metal Hydrides and Phase‐Change Material

Thermal energy storage (TES) systems based on hydrogen offer a promising solution for efficient energy management and storage. By leveraging the latent heat of phase transitions, the incorporation of phase‐change materials (PCMs) improves their TES capabilities. This hybrid approach enables both effective energy storage and release by utilizing the high energy density of hydrogen and the thermal regulation capabilities of PCMs. Specifically, the synergistic interaction between hydrogen and PCMs addresses key challenges such as energy density, thermal stability, and heat‐transfer efficiency. Therefore, this approach makes the system a practical and versatile solution for important applications such as solar–TES and the integration of renewable energy sources across many thermodynamic applications. The proposed hydrogen and PCM–based TES system operates at temperatures of 293, 339, 423, and 453 K, which correspond to ambient temperature, regeneration temperature, storage temperature, and output temperature, respectively. The system’s performance is predicted using pressure–concentration isotherms of LaNi 4.7 Sn 0.3 –La 0.8 Ce 0.2 Ni 5 alloys. The maximum energy density ( ε ), second‐law efficiency ( η II ), and coefficient of performance (COP) are observed as 125.05 kJ/kg, 0.85, and 0.54, respectively. The study is further extended to predict the effect of operating temperature variations on system performance to determine the optimal operating temperature.