Metal hydrides for thermochemical energy storage applications

Due to the depletion of natural energy resources, worldwide, solar energy is accepted as an emerging energy source because it is free, endless and can be convertible to other forms, but it is intermittent. Therefore, in the present study, different energy storage techniques, that is, sensible heat, latent heat and thermochemical heat storage techniques, suitable to store solar thermal energy are discussed and compared. Based on the energy storage density, reaction kinetics, operating temperature range and volume of storage material, the metal hydride-based thermal energy storage (MH-TES) system is observed to be the most promising for thermochemical energy storage applications. In continuation, the current work enlightens on the screening of MHs best-suited to the MH-TES, which results in the alloy pairs of MmNi(4.15)Fe(0.85)-TiCrMn and LaNi4.85Al0.15-MmNi(4.6)Fe(0.4), working on high-pressure and low-pressure sides, respectively. The thermodynamic performances are observed to be 140.25 and 188.16 kJ of heat generation with a coefficient of performance of 0.47 and 0.50 for MmNi(4.15)Fe(0.85)-TiCrMn and LaNi4.85Al0.15-MmNi(4.6)Fe(0.4) pairs, respectively, working at a temperature range of 403 (storage), 298 (ambient), 373 (regeneration) and 423 K (heat output). The study is extended to investigate the influence of operating temperatures on system performance and observed that the heat generation may be reduced by similar to 5% by increasing heat output temperature by 20 K due to reduction in mass transfer.