Destabilization of lithium hydride and the thermodynamic assessment of the Li–Al–H system for solar thermal energy storage

• Published in: RSC advances 2016-01, Vol.6 (97), p.94927-94933
• Main Authors: Javadian, Payam, Sheppard, Drew A., Jensen, Torben R., Buckley, Craig E.
• Format: Article
• Language: English
• Subjects: Aluminum; Cost engineering; Energy storage; Entropy; Lithium hydrides; Operating temperature; Solar heating; Thermodynamics
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C6RA16983J

Lithium hydride destabilised with aluminium, LiH–Al (1 : 1 mole ratio) was systematically studied and its suitability as a thermal energy storage system in Concentrating Solar Power (CSP) applications was assessed. Pressure composition isotherms (PCI) measured between 506 °C and 652 °C were conducted to investigate the thermodynamics of H 2 release. Above the peritectic temperature (596 °C) of LiAl, PCI measurements were not consistently reproducible, possibly due to the presence of a molten phase. However, below 596 °C, the hydrogen desorption enthalpy and entropy of LiH–Al was Δ H des = 96.8 kJ (mol H 2 ) −1 and Δ S des = 114.3 J (K mol H 2 ) −1 , respectively LiH (s) at 956 °C, Δ H des = 133.0 kJ (mol H 2 ) −1 and Δ S des = 110.0 J (K mol H 2 ) −1 . Compared to pure LiH, the Li–Al–H system has a reduced operating temperature (1 bar H 2 pressure at T ∼ 574 °C) that, combined with favourable attributes such as high reversibility, good kinetics and negligible hysteresis, makes the Li–Al–H system a potential candidate for solar thermal energy storage applications. Compared to pure LiH, the addition of Al can reduce the cost of the raw materials by up to 44%. This cost reduction is insufficient for next generation CSP but highlights the potential to improve the properties and cost of high temperature hydrides via destabilisation.