Comprehensive study of a volcanic-based hydrated salt thermochemical energy storage composites for buildings heating in China's low-latitude plateau region: Development, characterisation, and analysis

Thermochemical energy storage technologies can be integrated with building heating to promote the application of renewable energy. In this study, to address the challenges between the substantial heating demand and the imbalanced supply for buildings in the low-latitude plateau regions of China, a novel and cost-effective hydrated salt composite has been developed based on volcanic from TengChong. The composite was prepared by impregnating acid-treatment volcanic into a 20 % concentration of a 1:1.5 mass ratio MgCl₂-CaCl₂ solution. The BET results revealed that acid treatment increased the pore volume and the proportion of mesopores in the volcanic, which resulted in better absorption of the hydrated salts. The water adsorption capacity of the acid treatment's composites at 25 °C and RH 90 % reached 0.79 g/g. The energy storage density of the volcanic acid-treatment adsorbed hydrated salt (VAS) was 601.33 kJ/kg through DSC testing. VAS can achieve 84.15 % of the energy storage density at 68 % of the cost of MgCl₂-CaCl₂-zeolite-13×. Based on the subsequent environmental and economic analyses, the new composite was found to have significant potential for energy savings and carbon emission reduction if employed in building heating systems.