As the digitalization process continues to accelerate, data centers and 5G networks have developed rapidly, but at the same time they have also brought huge energy consumption. From 2017 to 2020, the power consumption of data centers above designated size has increased by an average annual rate of 28%.
Currently, the annual electricity consumption of data centers accounts for more than 2% of the total electricity consumption in society. It is expected that by 2026, the annual power consumption of 5G base stations will also rise to 2% of the total electricity consumption in society. According to statistics, electricity expenses account for 95% of the annual operating costs of data centers.
Huge electricity costs and increasingly stringent carbon emission regulations have put more pressure on the development of the information and communications industry. Therefore, it is imperative to achieve green development of the information and communications industry. As a flexible power resource regulation method, energy storage configuration can reduce electricity costs and improve green energy consumption capabilities, thereby effectively solving the problem of green development in the information and communication industry.
Development status of communication energy storage systems
According to the energy storage technologies, energy storage can be divided into three categories: mechanical energy storage, chemical energy storage, and electromagnetic energy storage.
Among them, mechanical energy storage mainly includes pumped hydro energy storage, compressed air energy storage, flywheel energy storage, gravity energy storage, etc. Electrochemical energy storage mainly includes lead-acid batteries, lithium-ion batteries, sodium-ion batteries and flow batteries. Electromagnetic energy storage mainly includes supercapacitor energy storage, superconducting energy storage, etc.
Considering the construction site conditions and construction scale, electrochemical energy storage will be the mainstream method of energy storage application in the communications industry.
Currently, in the communications industry, energy storage is the mainstream application method as a backup power supply. It is mainly used for short-term emergency power supply after the mains power is cut off and before the oil generator is started. In this method, energy storage batteries are used as isolated components and lack effective interaction with the power grid, resulting in the failure to fully realize the value of energy storage resources. Moreover, backup batteries are generally lead-acid batteries, which mainly work in a float-charge state and have a small number of cycles.
As lithium-ion battery technology matures and costs decline, major operators have begun to try to apply new energy storage technologies represented by lithium ion battery energy storage. For example, a 1.2 MWh lithium battery energy storage project was built in a city’s information park, and a 5G base station energy storage project was implemented in cooperation with a county power supply company.
Implementation methods of communication energy storage systems
1. Income methods
The benefits of energy storage generally include energy storage construction subsidies, energy storage demand-side response, and arbitrage of peak and valley price differences in electricity charges. Energy storage construction subsidies mainly rely on local policies.Â
Demand-side response is generally divided into agreed response and real-time response, but there are certain restrictions on response time and scale. At present, demand-side response faces problems such as collaborative dispatch and pilot limitations.
There is no market-oriented mechanism yet, so the benefits are highly uncertain. The main income from building energy storage comes from peak-to-valley price difference arbitrage. Taking lithium battery energy storage as an example, the construction cost is about 1.8 yuan/Wh, and the peak-to-valley price difference of electricity charges of 0.7 yuan is the economic inflection point of energy storage construction (as the cost decreases, the inflection point also will be gradually reduced). Based on 2 charges and 2 discharges per day, the single-day electricity bill income is calculated as follows:
T=2×P×η×DOD×ΔP
In the formula, P is the energy storage capacity, η is the energy storage charge and discharge efficiency, DOD is the energy storage charge and discharge depth, and ΔP is the peak-to-valley electricity price difference.
2. Architecture and technical parameters of energy storage system
Energy storage systems generally consist of battery units, battery management systems (BMS), energy management systems (EMS), cooling systems, detection units, and energy storage converters. Taking the 100 kW/215 kWh lithium battery energy storage system as an example, the battery unit generally uses 280 Ah cells, forming a single lithium ion battery pack according to 1P16S, and 10 identical battery packs are connected in series to form 1P240S, forming a battery cluster.
Suggestions for communication energy storage systems
1. Energy storage safety
From the comprehensive consideration of multiple factors such as industrial scale, system cost, energy and power characteristics, and recyclability, lithium-ion batteries currently have outstanding advantages and are the mainstream energy storage method.
Although lithium battery energy storage is generally equipped with three levels of protection measures: PACK level, battery cluster level, and container level, and is equipped with a complete battery management system and energy management system, safety risks are still a factor that cannot be ignored, and operation and maintenance pressure is high. .
In order to reduce the pressure on operation and maintenance, it is recommended to adopt the contract energy model in the early stage, with a third-party professional energy company responsible for the construction, operation and maintenance of the energy storage system, and sharing the energy storage income with communication operators.
2. Energy storage economics
Data centers and communication equipment rooms are basically used for industrial and commercial electricity, and their electricity costs include capacity electricity charges. However, energy storage construction requires charging of energy storage battery units. When the load fluctuation is not large, the capacity electricity fee will be increased, resulting in a decrease in revenue.
Therefore, energy storage construction should comprehensively consider load fluctuations and energy storage capacity, and choose an appropriate capacity billing method to ensure the highest energy storage income.
In addition, the government also needs to promote the demand-side response marketization mechanism, such as the form, depth, revenue model and corresponding regulation strategies of energy storage systems participating in grid dispatching, so as to stimulate the enthusiasm of communication energy storage to participate in grid dispatching, thereby maximizing energy storage system benefits.
The future development of communication energy storage
With the continuous optimization and improvement of energy storage technology and the continuous improvement of industry policies, energy storage in the communications industry will become an important part of industrial and commercial energy storage system, which will help further improve the level of energy conservation and consumption reduction and help achieve the dual carbon goal.
In the future, digital and intelligent technologies can also be used to realize the deep integration of distributed energy storage and loads in a large number of data centers, communication offices, base stations, etc., to form a “virtual power plant” to provide support for the development of new power systems.
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