Based on the analysis of cost models for different energy storage systems, the total cost and unit energy storage cost of each energy storage system were calculated, and the economic efficiency of different energy storage systems was compared. Sensitivity analysis was used to evaluate the impact of different influencing factors on the unit energy storage cost, and the importance of the main influencing variables in different energy storage systems was obtained. This provides a reference for the selection of cost reduction paths for each energy storage system. The main research findings are summarized as follows:
(1) Through energy storage cost calculation and comparative analysis of dual tank molten salt energy storage system, high-temperature concrete energy storage system, phase change packed bed energy storage system, and sensible latent heat combined packed bed energy storage system, it is found that the unit energy storage cost of traditional dual tank molten salt energy storage system is relatively high, and the sensible latent heat combined packed bed energy storage system is an ideal alternative solution.
(2) For the sensible latent heat combined packed bed energy storage system, the influence of different concrete volume fractions on the system cost and thermal storage performance was analyzed. Taking into account investment costs, unit energy storage costs, and energy storage efficiency, the use of a 50% concrete volume ratio in the sensible latent heat combined packed bed energy storage system is an overall optimal choice. Under the same conditions, compared to the dual tank molten salt energy storage system, the use of the C-X1 energy storage system can reduce the unit energy storage cost by 30.1%, and the cost savings are largely attributed to the reduction of costs related to the tank body.
(3) Through sensitivity analysis of the main influencing factors on the unit energy storage cost of different energy storage systems, it was found that the material cost of the tank body is the most sensitive parameter in the dual tank molten salt energy storage system. By reducing the material cost of the tank body by 20%, the unit energy storage cost of the system can be reduced by 11.5%. In high-temperature concrete energy storage systems, due to the high cost of insulation materials, the unit energy storage cost of the system is most sensitive to its impact. The high-temperature phase change energy storage system is most affected by the price of phase change materials. For other phase change packed bed energy storage systems, the packaging cost of phase change materials is the most sensitive factor affecting the unit energy storage cost of the system. Reducing packaging cost is an effective way to reduce the unit energy storage cost of the system.
(4) For the C-X1 energy storage system, sensitivity analysis of the main influencing factors on the unit energy storage cost of the system reveals that the cost of tank materials is the most significant factor affecting the unit energy storage cost of the system. Compared to the phase change packed bed energy storage system, although the energy storage of the system has been reduced, the unit energy storage cost is relatively low, and the energy storage rate of the system is relatively high, making it an optimal energy storage solution.