Potentials of absorption thermal energy storage systems in seasonal application.

Sorption thermal energy storage systems hold potential to enable seasonal storage of solar energy. These systems utilize absorption mechanisms to store energy as chemical potential, thereby minimizing long-term energy dissipation. This study investigates the theoretical thermodynamic limitations of the closed absorption process. Key system parameters, including source and sink temperatures, are varied to evaluate their significant impact on energy storage density (ESD). The analysis incorporates a newly developed Python library absorptionlib for absorption-pair thermophysical properties, including aqueous solutions of NaOH, LiCl, LiBr, and CaCl2. NaOH achieves the highest theoretical ESD, exceeding 450 kWh/m3 for a 10K lift and 300 kWh/m3 for 20K. CaCl2 shows the lowest potential at 150 kWh/m3 for 10K, while being inoperable at a 20K lift. Despite promising ESD values, technological bottlenecks limit practical application. Alternative process designs, such as processes allowing crystallization, should be explored to enhance ESD and improve feasibility for sorption energy storage in seasonal applications.