Comparisons of thermal performance and cost for three thermal energy storage systems utilized in supercritical CO₂ Brayton cycle

There are few studies focus on thermal energy storage (TES) system coupled with S-CO2 power cycle. In this paper, a dynamic model is built to analyse the thermal performance and cost of the TES systems and compare the thermodynamic performance of the S-CO2 power cycles integrating the corresponding TES. The TES systems include the two-tank, sensible-packed bed thermocline (PBT), and latent-PBT. Results show that sensible-PBT has the smallest stored thermal energy and effective discharging time by the effect of the thick thermocline, which are 203 MWhth and 11.1 h, respectively. The latent-PBT owns the largest stored thermal energy and effective discharging time, which are 222 MWhth and 12.6 h, respectively. The power cycle integrating the sensible-PBT operates with the designed conditions during most of the time and has the smallest total work output, which is 110 MWhe. The power cycle integrating the latent-PBT has a large total work output, which is 118 MWhe, but operates with the off-designed conditions for a while. The study on the capital cost of TES system shows the two-tank has the largest TES cost (54 $/kWhth), followed by sensible-PBT (52 $/kWhth) and latent-PBT (37 $/kWhth), and some suggestions are provided to effectively reduce the TES cost. Results are useful to the performance optimization in concentrating solar power.