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

JOURNAL OF ALLOYS AND COMPOUNDS

卷:858

Article

Griffond, Arnaud C. M.¹  Sofianos, M. Veronica^1,2  Sheppard, Drew A.¹  Humphries, Terry D.¹  Sargent, Anna-Lisa³  Dornheim, Martin³  Aguey-Zinsou, Kondo-Francois⁴  Buckley, Craig E.¹ 

[1] Curtin Univ, Fuels & Energy Technol Inst, Phys & Astron, GPO Box U1987, Perth, WA 6845, Australia

[2] Univ Coll Dublin, Sch Chem & Bioproc Engn, Dublin 4, Ireland

[3] Helmholtz Zentrum Geesthacht, Dept Nanotechnol, Inst Mat Res, Max Planck Str 1, D-21502 Geesthacht, Germany

[4] Univ New South Wales, Sch Chem Engn, Merlin Grp, Sydney, NSW 2052, Australia

关键词: Metal hydride;    Thermal energy storage;    Calcium hydride;    Thermodynamics;    Destabilisation;   

DOI  :  10.1016/j.jallcom.2020.158229

来源: Elsevier

【 摘 要 】

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 degrees 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) H-2) was lower compared to the experimentally determined value (154 +/- 4 kJ mol(-1) H-2). This mismatch was mainly due to the formation of CaO and a CaSi solid solution in addition to the desired Ca5Si3 phase. (C) 2020 The Author(s). Published by Elsevier B.V.

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