In recent years, environmental awareness has been increasing in countries around the world, and China has also proposed to achieve the “dual carbon goal”. Energy storage systems have gradually come into people’s view. Many people have heard of the concept of energy storage, but what exactly is an energy storage system? Is it just a large upgraded version of a “power bank”?
Simply put, an energy storage system refers to a system that stores energy when it is abundant and releases the stored energy for use when energy demand peaks. The storage system can store excess thermal energy, kinetic energy, electrical energy, chemical energy, etc., and can change the output capacity, output location, output time, etc. of energy.
Existing energy storage systems are mainly divided into five categories: mechanical energy storage, electrical energy storage, electrochemical energy storage, thermal energy storage and chemical energy storage.
My country’s battery energy storage, especially lithium battery energy storage industry, is developing rapidly, and battery energy storage is the main form of electrochemical energy storage. This article will focus on battery energy storage and share relevant information using container energy storage systems as an example.
What container energy storage system?
The container energy storage system (CESS) is an integrated energy storage system developed for the needs of the mobile energy storage market. It adopts a standardized design and uses containers as carriers. Its core components are battery cabinets, lithium battery management systems (BMS), power conversion systems (PCS) and EMS control cabinets.
Internal structure
From a design point of view, the container energy storage system is mainly divided into battery warehouses and equipment warehouses
Battery warehouse
Batteries, battery racks: The types of batteries can be iron-lithium batteries, lithium batteries, lead-carbon batteries and lead-acid batteries. Batteries need to be equipped with corresponding BMS management systems.
Cooling air conditioners: Cooling air conditioners are adjusted in real time according to the temperature in the warehouse.
Monitoring cameras: Monitoring cameras can remotely monitor the operating status of equipment in the warehouse. A remote client can be formed to monitor and manage the operating status and battery status of equipment in the warehouse through the client or app.
Equipment warehouse
Power conversion system (PCS): PCS can control the charging and discharging process, perform AC/DC conversion, and directly supply power to AC loads without a power grid.
EMS control cabinet: In terms of distribution network, EMS mainly collects the real-time power status of the power grid and monitors the changes in load power in real time through communication with smart meters. Control automatic power generation and evaluate the power system status.
Taking the 1MW/1MWh container energy storage system as an example, the system is generally composed of energy storage battery system, monitoring system, battery management unit, special fire protection system, special air conditioner, energy storage converter and isolation transformer, and is finally integrated in a 40-foot container.
Application field
In terms of use, it is mainly used in the following three aspects
Peak shaving and valley filling – Peak shaving refers to reducing the power demand of users during the peak load period of the power grid, valley filling refers to increasing the power demand of users during the low-valley period of the power grid, and peak shaving and valley filling refers to transferring the user demand of peak load to the low-valley load period. For example: when the equipment power demand is large during the day and the power grid output pressure is large, the energy storage cabinet can release electricity for supplement.
Peak-valley arbitrage – Simply put, it is to charge the energy storage system with cheap valley electricity at night and discharge it during the peak period when the electricity price is high during the day to reduce the company’s electricity cost.
Used as a backup power source
The specific application areas can be divided into the following areas:
Power supplement: In areas with imperfect power infrastructure, container energy storage systems can be used as energy storage and transmission equipment to provide local residents with a stable power supply.
Distributed energy: In cities, islands and other areas, container energy storage systems can be combined with renewable energy such as solar energy and wind energy to form a distributed energy system to improve energy utilization efficiency.
Emergency power supply: When a disaster occurs, it may destroy the traditional power system. At this time, the container energy storage system can be used as an emergency power supply to ensure the power supply of important facilities and rescue sites.
In recent years, with the favorable development of new energy, the demand for energy storage equipment at home and abroad has generally increased, and the export volume of energy storage cabinets in my country has also continued to rise. The transportation demand for container energy storage cabinets is increasing, so what risks are worth noting during transportation?
From the previous introduction, we learned that container energy storage cabinets include batteries, heat dissipation devices, fire extinguishing systems, PCS, EMS, BMS systems, etc. According to the International Maritime Dangerous Goods Code, many of its components are listed as dangerous goods. For example: lithium-ion batteries with cell power exceeding 20W and battery power exceeding 100W are all classified as Class 9 dangerous goods; fire extinguishers in the fire extinguishing system are classified as Class 2.2 dangerous goods; refrigeration systems with freon are classified as Class 2.2 dangerous goods, etc.
Risks faced by container energy storage cabinets during transportation:
Energy storage cabinets usually contain lithium batteries. Due to the characteristics of batteries, there is a potential risk of combustion and explosion.
The size and weight of energy storage cabinets are large, and there is a high risk of falling, impact, and vibration during loading and unloading during transportation.
Energy storage cabinets require a certain enclosed space to store electrical energy, and the existence of enclosed spaces may also increase the internal pressure of the energy storage cabinet, resulting in problems such as leakage and short circuit.
How to deal with risks faced during transportation?
Choose the right mode of transportation: When choosing a mode of transportation, you should consider the size, weight, destination and other factors of the energy storage cabinet. At present, sea transportation is the most commonly used mode of transportation.
Protect the equipment well: Before transportation, the equipment should be inspected to ensure that the equipment is in good condition, and necessary measures should be taken to avoid or reduce damage to the equipment during transportation.
Communicate fully in advance: Before the energy storage cabinet is exported by sea, you should communicate with the shipping company in advance to understand the transportation progress and possible problems during transportation, so as to take timely measures to deal with the problems.
Tracking equipment status: During transportation, the status of the energy storage cabinet should be tracked in real time to ensure that the equipment does not have any failure or leakage during transportation. After the transportation is completed, the equipment should be inspected to ensure that the equipment is in good condition.
Future development
At present, container energy storage systems have gradually been widely used around the world, especially in Asia and Africa. The application in Africa and Southeast Asia has achieved remarkable results. With the continuous upgrading of technology, it is expected that the container energy storage system will show the following development direction in the future:
More efficient battery technology: Lithium-ion batteries are currently the mainstream, but new battery technologies such as magnesium-ion batteries and solid-state batteries will gradually mature in the future, which will further improve energy storage efficiency and safety.
Materials with higher energy density: The volume of container energy storage systems is limited, so increasing the energy storage capacity of a single box is a problem that needs to be solved in the future, which requires exploring more materials with higher energy density in the future.
Green and environmental protection: In the future, the design of container energy storage systems will pay more attention to sustainable development and environmental protection requirements, such as adopting recycled materials, energy-saving design and other measures to reduce the impact on the environment.
