 An Experimental Study of the Decomposition and Carbonation of Magnesium Carbonate for Medium Temperature Thermochemical Energy StorageDaniel Mahon,
Gianfranco Claudio and
Philip Eames
Energies, 2021, vol. 14, issue 5, 1-23 Abstract: To improve the energy efficiency of an industrial process thermochemical energy storage (TCES) can be used to store excess or typically wasted thermal energy for utilisation later. Magnesium carbonate (MgCO 3 ) has a turning temperature of 396 °C, a theoretical potential to store 1387 J/g and is low cost (~GBP 400/1000 kg). Research studies that assess MgCO 3 for use as a medium temperature TCES material are lacking, and, given its theoretical potential, research to address this is required. Decomposition (charging) tests and carbonation (discharging) tests at a range of different temperatures and pressures, with selected different gases used during the decomposition tests, were conducted to gain a better understanding of the real potential of MgCO 3 for medium temperature TCES. The thermal decomposition (charging) of MgCO 3 has been investigated using thermal analysis techniques including simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC), TGA with attached residual gas analyser (RGA) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (up to 650 °C). TGA, DSC and RGA data have been used to quantify the thermal decomposition enthalpy from each MgCO 3 .xH 2 O thermal decomposition step and separate the enthalpy from CO 2 decomposition and H 2 O decomposition. Thermal analysis experiments were conducted at different temperatures and pressures (up to 40 bar) in a CO 2 atmosphere to investigate the carbonation (discharging) and reversibility of the decarbonation–carbonation reactions for MgCO 3 . Experimental results have shown that MgCO 3 .xH 2 O has a three-step thermal decomposition, with a total decomposition enthalpy of ~1050 J/g under a nitrogen atmosphere. After normalisation the decomposition enthalpy due to CO 2 loss equates to 1030–1054 J/g. A CO 2 atmosphere is shown to change the thermal decomposition (charging) of MgCO 3 .xH 2 O, requiring a higher final temperature of ~630 °C to complete the decarbonation. The charging input power of MgCO 3 .xH 2 O was shown to vary from 4 to 8136 W/kg with different isothermal temperatures. The carbonation (discharging) of MgO was found to be problematic at pressures up to 40 bar in a pure CO 2 atmosphere. The experimental results presented show MgCO 3 has some characteristics that make it a candidate for thermochemical energy storage (high energy storage potential) and other characteristics that are problematic for its use (slow discharge) under the experimental test conditions. This study provides a comprehensive foundation for future research assessing the feasibility of using MgCO 3 as a medium temperature TCES material. Future research to determine conditions that improve the carbonation (discharging) process of MgO is required. Keywords: thermochemical energy storage; magnesium carbonate; thermal energy storage; industrial waste heat; thermal analysis (search for similar items in EconPapers) Downloads: (external link) Related works: Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:14:y:2021:i:5:p:1316-:d:507936 Access Statistics for this article Energies is currently edited by Ms. Agatha Cao More articles in Energies from MDPI |
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