Sustainable thermal energy storage in a cylindrical solar pond with calcium chloride stratification

This study designed and operated a calcium chloride‐based solar pond (CMSP) with a 2.35 m diameter and 1.80 m depth to collect and store solar heat. The pond used CaCl 2 solutions of varying densities to establish stable thermal stratification. Hourly temperature data were recorded for a year using a 16‐channel system, and a parallel COMSOL Multiphysics model was developed for validation. The study addresses the need for efficient, low‐cost, long‐term solar thermal energy storage to mitigate solar intermittency and fossil fuel dependence. The annual stored energy was 7040.35 MJ experimentally and 7450.19 MJ numerically, with a 5.50% deviation, confirming good model accuracy. This energy corresponds to CO 2 emission reductions of 240.22 kg (experimental) and 254.20 kg (numerical). Maximum thermal efficiencies occurred in December—49.18% experimentally and 43.32% numerically—indicating effective summer‐to‐winter heat utilization. Strong agreement between experimental and numerical results verified the model's predictive capability. The CMSP maintained stable stratification and demonstrated the suitability of CaCl 2 as a working salt for heat storage. Payback periods were 6.35 years (experimental) and 5.90 years (numerical), confirming both technical and economic feasibility. Overall, CaCl 2 ‐based solar ponds provide a reliable, low‐cost, and sustainable solution for seasonal thermal storage and carbon mitigation, offering strong potential for renewable heating applications.