In the electrochemical energy storage project, the battery of the energy storage element needs to be replaced many times during operation because of the small number of cycles, which results in the cost of replacing the energy storage battery and equipment (Replacement cost). Under normal circumstances, the service life of batteries and equipment is shorter than the project cycle of the energy storage system, so the replacement cost of the battery needs to be considered during the operation cycle of the project, including the purchase cost of updated materials and equipment, installation costs, and worker compensation costs. Replacement costs are considered variable costs, and their magnitude depends primarily on the age of the battery and how often it is used. If calculated according to the 6,000 cycle life of lithium-ion batteries (lithium iron phosphate) and charging and discharging twice a day, the batteries need to be replaced every 10 years. When the energy storage battery exceeds the service life, it is uneconomical and not environmentally friendly to replace all the batteries.
Therefore, in actual operation, a certain capacity is added every year according to the annual decay rate of the battery to ensure the available capacity of the energy storage system. The cost of replacing energy storage batteries and equipment can be calculated from the annual cost of battery replacement, the capacity of the energy storage device, and the conversion efficiency of the energy storage device. Among them, the factors that affect the annual cost of battery replacement include replacement cost, replacement cycle, return on investment period, discount rate, number of battery charge and discharge cycles, and annual operating days of the battery. Due to the limited number of battery charge and discharge cycles, the battery capacity will gradually decay, and the battery needs to be replaced frequently during the operation of the energy storage system. Therefore, the cost of battery capacity decay and the time value of funds need to be considered. However, because different types of energy storage batteries have different life cycles, and their actual life is related to factors such as charge and discharge depth and charge and discharge times, there is uncertainty. Therefore, this parameter is determined according to its influencing factors in actual use.