Solar Product Supplier
Apr 23, 2021
The whole life cycle process of an electrochemical energy storage power station includes the project construction phase and the project operation phase. On the one hand, it is necessary to analyze the cost composition of the electrochemical energy storage power station; on the other hand, it is necessary to analyze the influence parameters of various cost calculations.

1.1  Construction cost

The construction cost of an energy storage power station, also known as the system cost, refers to the cost of an energy storage system per unit capacity. It is mainly composed of equipment installation cost (including battery cost) and construction cost (excluding land cost).

Energy storage equipment includes energy storage batteries, battery management systems, energy storage inverters, and power distribution systems. The purchase cost of these equipment constitutes the equipment installation cost. Construction costs mainly include construction engineering fees, installation engineering fees, and equipment and facility design and commissioning expenses. The battery cost accounts for a large proportion of the equipment cost. At the same time, the battery operation and maintenance and fault replacement are highly professional. In order to reduce the financial burden of one-time investment and the difficulty of battery operation and maintenance, the investor adopts the method of leasing to the battery manufacturer The lease of the battery is ten years; the battery manufacturer is responsible for daily operation and maintenance and free replacement of the faulty battery during the lease period, and the investor pays the battery cost annually. In the process of calculating the construction cost of energy storage, the declining proportion of total construction cost, unit energy construction cost and energy storage capacity parameters should be considered.

1.2 Charging cost

The charging cost of an energy storage power station refers to all costs incurred during the charging process. During charging, the energy conversion efficiency cannot reach 100%, resulting in the cost of energy loss. Therefore, this part of the cost mainly depends on the energy conversion efficiency. For example, the charging electricity fee is 1 unit price per kWh, and for an energy storage device with an efficiency of 75%, the total energy cost is: 1/75%=1.33/kWh. To calculate the cost of energy storage charging, it is necessary to consider the charging price, equipment utilization efficiency, the annual discharge capacity of the energy storage system, and energy conversion efficiency parameters.

1.3 Operational labor cost

In some cases, the operation of energy storage equipment may require labor. Within a certain range, the fixed labor cost has nothing to do with the size of the stored electricity, and the total cost is constant. Variable labor costs are directly proportional to the frequency and duration of storage usage. In many cases, the calculation of labor costs for battery energy storage power stations is mainly based on the size of the energy storage equipment and storage capacity, and there is no clear value standard for the time being. According to research by Yang Haibo and others, the operating labor cost of energy storage power station can be calculated through unit labor cost and the number of employees.

1.4 Operation and maintenance cost

The operation and maintenance cost of the energy storage power station is the cost required to maintain the energy storage power station in a good standby state. This cost includes cleaning costs for photovoltaic panels, power station management, and maintenance costs. No matter how much storage is used, the fixed maintenance costs are the same. Variable maintenance costs are directly proportional to the frequency and duration of storage usage. The operation and maintenance cost is generally obtained by multiplying the initial investment by the transportation inspection rate. Considering the limited service life of the ESS, a certain amount of loss will occur during the operation of the system, resulting in system life loss costs. Therefore, when calculating the operation and maintenance costs of energy storage power stations, it is necessary to comprehensively consider parameters such as the total construction cost reduction ratio, operation and maintenance rate, unit energy construction cost, and energy storage capacity.

1.5  Plant electricity cost for energy storage purposes

The cost of auxiliary electricity for energy storage is the cost of electricity used by the energy storage power station for energy storage. The cost of outsourcing electricity costs incurred by the power plant to maintain the operation of the energy storage power station, including electricity purchase fees, self-use electricity fees, and related salaries and management fees. In the process of calculating the cost of auxiliary power for energy storage purposes, it is necessary to consider parameters such as the average annual power consumption rate, the proportion of the power used by the energy storage power station for energy storage purposes in the power consumption of the factory, the charging power price, and the energy storage capacity.

1.6   Replacement of energy storage battery and equipment cost

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, resulting in the replacement of the energy storage battery and equipment cost (Replacement  cost). Under normal circumstances, the service life of batteries and equipment is less than the energy storage system project cycle. Therefore, the battery replacement cost should be considered during the project operation cycle, including the purchase cost of updated materials and equipment, installation costs, and worker salaries. The replacement cost is regarded as a variable cost, and its size mainly depends on the battery life and frequency of use. If calculated on the basis of a lithium-ion battery (lithium iron phosphate) cycle life of 4000 cycles and two charge and discharge per day, the battery needs to be replaced every 5.56 years. When the energy storage battery exceeds the service life, it is not economical and environmentally unfriendly 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 usable 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. The factors that affect the annual cost of battery replacement include replacement cost, replacement cycle, investment payback period, discount rate, battery charge and discharge cycle cycles, and battery annual operating days. 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 the depth of charge and discharge and the number of charge and discharge, there is uncertainty, so this parameter is determined according to its influencing factors in actual use.

1.7 Assessment cost

From the point of view of life cycle cost, the assessment cost that is not considered in the traditional cost electricity price model is a part that cannot be ignored. According to the "Shandong Power Grid Photovoltaic Power Station Dispatching Management Regulations (Trial)", the daily power generation dispatching plan curve and dispatching instructions issued by the provincial government should be strictly implemented, and the active power output should be adjusted in time. The deviation of the actual power output from the dispatching plan should follow the curve. Breach assessment. The evaluation cost calculation should consider such parameters as the evaluation cost of dispatching, the penalty price of electricity, the planned output of the optical storage power station, and the grid-connected power of the optical storage.

1.8 Disposal cost

When the life of each part of the energy storage system is exhausted, it needs to be treated in a harmless manner, and the capital invested is the disposal cost. The cost is mainly divided into two aspects: environmental protection expenses and equipment residual value. The cost of recycling the battery is the cost of environmental protection, and the initial investment cost and the recovery factor will determine the size of the residual value of the equipment. At present, my country's battery recycling industry has not yet taken shape and is under development. For this reason, most of the waste components have not been effectively disposed of, and these wastes will pose a great threat to the natural environment and human health. The existing disposal methods of waste batteries mainly include solidification and deep burying, storage in waste mines, and resource recycling. According to foreign experience, the decommissioning costs associated with any storage system cannot be ignored. After the end of life, the battery must be disassembled to remove chemical substances. Ideally, the disassembled battery and its chemical substances can be recycled, which can offset the loss caused by partial disassembly and disposal of hazardous substances, but the final disposal-related costs should be included in the total cost of the energy storage power station.

In the foreseeable future, the impact of recycling value on the economics of battery energy storage will become greater and greater due to the establishment and improvement of energy storage battery recycling mechanisms. For example, lead-carbon batteries, with the development and progress of lead recycling technology, the current lead-carbon batteries can achieve 100% recycling, and the residual value of the equipment can reach 20% of the initial investment. The recycling of waste lithium batteries is faced with many problems. Its recycling technology is complex and costly. There is currently no good recycling program, and there is no clear recycling value. The residual value of the equipment can be regarded as zero. Therefore, the unit capacity purchase price, the rated capacity of the energy storage system, the unit power energy storage inverter price, the unit power auxiliary equipment cost and the residual value rate parameters should be considered in the calculation of the energy storage disposal cost.

1.9 Other costs

The cost of energy storage power station also includes other costs such as financial costs and taxes. The financial cost is mainly the interest expense incurred by the long-term loan of the energy storage power station. The calculation of interest expenses should consider the loan ratio, scheduling period, repayment period, loan interest rate and initial investment parameters. Tax expenditures should be considered during the operation of energy storage power stations. Taxes mainly include value-added tax, income tax and sales tax surcharges. Among them, sales tax surcharges include urban maintenance and construction tax and education surcharges.

Concluding remarks

With the reduction of the cost of energy storage, energy storage can be applied on a large scale in all aspects of power system transmission, distribution and utilization, and can play a large-scale role in peak shifting and energy management. This article analyzes the cost of electrochemical energy storage projects from the perspective of overall life cycle, and quantifies the various costs of electrochemical energy storage projects. The cost is divided into construction costs and total operating costs. The total operating costs mainly include charging costs, labor costs, operation and maintenance costs, plant electricity costs for energy storage purposes, and the cost of replacing energy storage batteries, as well as equipment costs and disposal costs. , Assessment costs, financial costs, taxes, etc. Clarifying various costs and specific impact parameters can provide a basis for the lean cost management of electrochemical energy storage power stations.

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