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High-temperature thermochemical energy storage using metal hydrides: Destabilisation of calcium hydride with silicon

High-temperature thermochemical energy storage using metal hydrides: Destabilisation of calcium hydride with silicon Thumbnail


Contributors

Griffond, Arnaud C. M.
Other

Sofianos, M. Veronica
Other

Sheppard, Drew A.
Other

Humphries, Terry D.
Other

Sargent, Anna-Lisa
Other

Aguey-Zinsou, Kondo-Francois
Other

Buckley, Craig E.
Other

Abstract

The thermochemical energy storage properties of calcium hydride (CaH2) destabilised with either silicon (Si) or CaxSiy compounds at various molar ratios, were thoroughly studied by a combination of experimental and computer assisted thermodynamic calculations. Particularly, the destabilisation effect of Si on CaH2 at five different molar ratios (1:1, 1:2, 2:1, 3:4, 5:3 CaH2 to Si) was extensively investigated. Theoretical calculations predicted a multi-step thermal decomposition reaction between CaH2 and Si forming CaxSiy at varying temperatures, which was confirmed by in-situ synchrotron X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and mass-spectroscopic measurements. The most suitable destabilisation reactions between CaH2 and Si or CaxSiy that meet the criteria of a thermal energy storage system for the next-generation of concentrated solar power (CSP) plants were identified. The CaH2 and CaSi system (in a 2:3 molar ratio of CaH2 to CaSi) showed desirable operating conditions with a decomposition temperature of 747 ± 33 °C at a hydrogen pressure of 1 bar. Pressure composition isothermal measurements were conducted on this system to determine its practical enthalpy of decomposition to form Ca5Si3. The calculated value (107.3 kJ mol−1 H2) was lower compared to the experimentally determined value (154 ± 4 kJ mol−1 H2). This mismatch was mainly due to the formation of CaO and a CaSi solid solution in addition to the desired Ca5Si3 phase.

Citation

(2021). High-temperature thermochemical energy storage using metal hydrides: Destabilisation of calcium hydride with silicon. Journal of Alloys and Compounds, 858, Article 158229. https://doi.org/10.1016/J.JALLCOM.2020.158229

Journal Article Type Article
Acceptance Date Dec 6, 2020
Online Publication Date Dec 10, 2020
Publication Date Mar 25, 2021
Deposit Date Oct 24, 2024
Publicly Available Date Oct 24, 2024
Journal Journal of Alloys and Compounds
Print ISSN 0925-8388
Electronic ISSN 1873-4669
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 858
Article Number 158229
DOI https://doi.org/10.1016/J.JALLCOM.2020.158229
Public URL https://nottingham-repository.worktribe.com/output/34872523
Publisher URL https://www.sciencedirect.com/science/article/pii/S0925838820345928?via%3Dihub

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