Steam reactivation of spent CaO/CaCO3 for thermochemical energy storage

• Published in: Solar energy Vol. 255; pp. 138 - 145
• Main Authors: Hu, Yingchao, Chen, Yingjie, Fu, Ruicheng, Yan, Shuiping, Li, Hailong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-05-2023
• Subjects: CaO/CaCO3; Hydration treatment; Steam reactivation; Thermochemical energy storage; Thermochemical energy storage; CaO/CaCO3; Steam reactivation; Hydration treatment
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2023.03.019

•Steam hydration effectively improved the microstructures of spent CaO.•Hydrated calcium materials showed greatly enhanced energy storage density.•Decayed energy storage performance could be repeatedly improved via multi-hydration treatment.•Hydration treatment was also good at reactivating spent calcium pellets.
Calcium looping process exhibited great prospects for thermochemical energy storage due to high working temperatures, high energy density, good thermal conductivity, cheapness and non-toxicity of raw materials. However, progressive performance decay of CaO/CaCO3 density with cycles lay on the way to its practical application. This study proposed hydration treatment to reactivate spent calcium materials to regain the reactivity. It was found that steam hydration effectively enhanced the energy storage density of spent calcium powder. With the hydration degree of 150%, the reactivated CaO showed high density of 1920 kJ/kg, over twice as high as that of the deactivated materials. The enhancement was attributed to the mitigated sintering, increased surface area and enriched porosity. Although the reactivated calcium materials still showed performance decay trend, multi-hydration was demonstrated effective to repeatedly improve the performance of spent materials. In addition, for a more practical application, the effectiveness of steam hydration in reactivating spent calcium pellets was also investigated. It was indicated the reactivation effectiveness is as satisfying as that in the modification of spent powder.