Published at the Journal for Energy Storage – Improving the thermal energy storage performance of calcium hydride via vacancy defects for next-generation concentrating solar power

<p><strong><a href="https://www.solarpaces.org/wp-content/uploads/2026/04/o.png"><img alt="" class="alignnone size-full wp-image-30482" height="611" src="https://www.solarpaces.org/wp-content/uploads/2026/04/o.png" width="750" /></a><br />
Abstract:</strong><br />
Although the metal hydride CaH2 possesses a remarkably high hydrogen-based energy storage density, its application in thermal energy storage systems for next-generation concentrated solar power plants presents a challenge due to its 1100 °C decomposition temperature. These plants are expected to operate within a range of 600 to 800 °C, which makes CaH2 unsuitable for use as a reversible hydrogen storage medium. To mitigate the limitations of calcium hydride&#8217;s thermal stability, this research uses advanced computational modeling to explore the impacts of calcium vacancy formation on decomposition temperature. Computations were conducted using the Korringa-Kohn-Rostoker method alongside the coherent potential approximation used to model disordered systems. The findings reveal that increasing the concentration of calcium defects in the material correlates with a significant rise in formation enthalpy from −184.5 kJ·mol−1H₂ at 0% calcium defect concentration to −106.9 kJ·mol−1H₂ at 15% calcium defect concentration, along with a marked reduction in decomposition temperature from 1127 °C (0%) to 538 °C (15%). The findings also reveal a significant increase in storage capacity of CaH2 as Ca vacancies are increased, from 4.789 (0%) to 5.586 wt% (15%). Moreover, increasing concentrations lower the activation energy, which enhances hydrogen diffusion and facilitates efficient hydrogen release.</p>
<p><em><strong>Soufiane Bahou, Improving the thermal energy storage performance of calcium hydride via vacancy defects for next-generation concentrating solar power, Journal of Energy Storage, Volume 153, Part A, 2026, 120885, ISSN 2352-152X, <a href="https://doi.org/10.1016/j.est.2026.120885" rel="noopener" target="_blank">https://doi.org/10.1016/j.est.2026.120885</a></strong></em></p>
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