In 2022, the scale of China’s energy storage lithium battery industry chain will exceed 200 billion yuan, of which the scale of the electric energy storage industry chain will increase to 160 billion yuan, and the scale of household energy storage will increase to 40 billion yuan.
Globally, the “blue ocean” of the lithium battery energy storage track has become a “red ocean”. Lithium battery energy storage focuses on three elements: long life, low cost, and high safety. Long life is relatively easy to achieve (Guoxuan high-tech energy storage battery cycle has reached 12,000 times), low cost will gradually be solved as the scale increases, and the most difficult problem to solve is safety.
The lithium battery energy storage system consists of a large number of battery cells connected in series and parallel. A 20-foot 3.44MWh liquid-cooled energy storage container requires more than 3,840 280Ah batteries.
A large number of batteries are integrated and used in the battery compartment, which will continue to generate heat during charging and discharging. The optimal operating temperature of lithium-ion batteries for energy storage is 25°C-40°C. Long-term high-temperature operation may have an irreversible impact on the efficiency, performance, and life of the energy storage system, or cause thermal runaway risks and safety accidents.
According to incomplete statistics, since May 2017, more than 70 lithium-ion battery energy storage safety accidents have occurred in the global energy storage field. The main cause of the accident is the internal thermal runaway of the energy storage lithium battery. Safety issues have actually affected people’s personal and property safety.
On the other hand, in recent years, energy storage cells have become bigger and bigger, and the capacity of the cells is moving from 280Ah to 300Ah+. In 2022, EVE launched the LF560K energy storage battery with a capacity of 560Ah. The energy of a single battery reaches 1.792kWh, which is known as the energy storage battery with the largest capacity.
In 2022, Haichen Energy Storage, Trina Energy Storage, Envision Power, Penghui Energy, Haiji New Energy, Ripu Lanjun, Chuneng New Energy, Honeycomb Intelligent Storage, Guoxuan Hi-Tech, BYD, and Narada Power More than a dozen energy storage cell companies have successively launched cell products with a capacity of 300Ah and above.
The capacity of batteries is getting bigger and bigger, and the heat generated when a large number of batteries are integrated is increasing, and the safety risk is increased. How to better control the temperature of the batteries, reduce the energy consumption of the energy storage system, and improve the safety of the energy storage system are proposed by the industry. One of the solutions is to upgrade the energy storage thermal management system (transition from air-cooled heat dissipation through cold-plate liquid-cooled heat dissipation to fully-immersed liquid-cooled heat dissipation).
The development of energy storage thermal management systems can be roughly divided into three stages. Air-cooled heat dissipation dominates, cold-plate liquid-cooled heat dissipation emerges suddenly, and full-immersion liquid-cooled heat dissipation emerges.
In the first stage, before 2021, the energy storage market basically presents a situation in which air-cooled heat dissipation dominates.
Air-cooled heat dissipation technology uses air as the cooling medium, and there are two types: natural air cooling (without mechanical devices such as fans and air conditioners) and forced air cooling (with mechanical devices such as fan air conditioners).
In the second stage, from 2021 to the present, the cold plate liquid cooling technology has suddenly emerged, and its market share has continued to increase.
The cold plate liquid cooling heat dissipation technology uses liquids such as ethylene glycol aqueous solution as the cooling medium. By integrating and arranging the cells in the battery pack on the liquid cold plate to work, the cooling medium flows through the liquid cold plate to dissipate heat.
In 2020, CATL and other leading enterprises successively launched cold-plate liquid-cooled energy storage products, and continued to update and iterate. Ningde era will launch the outdoor system EnerOne product based on liquid-cooled CTP electric box technology in 2020, and achieve batch delivery in 2021, and launch the upgraded product EnerC.
At present, there are a large number of energy storage companies deploying cold plate liquid cooling technology, including Kehua Data Energy, Sungrow Power, Yiwei Lithium Energy, Cairi Energy, Xingyun Times, HyperStrong, Haichen Energy Storage, Zhongtian Technology, Dozens of energy storage companies such as Shanghai Electric Guoxuan, Trina Energy Storage, Ashite, and Shenghong Co., Ltd. cover diverse scenarios such as grid-level energy storage, industrial and commercial energy storage, and household energy storage.
In the third stage, cold plate liquid cooling and air cooling are divided into two parts, and full immersion liquid cooling is emerging.
The fully submerged liquid cooling technology uses various cooling insulating liquids such as ultrapure water, mineral oil, polyolefin, and fluorine-containing fire extinguishing agent as the cooling medium, and immerses the battery system as a whole in the cooling insulating liquid to dissipate heat directly through liquid circulation
At present, enterprises that deploy fully-immersed liquid cooling technology include Chuneng New Energy, China Southern Grid Energy Storage, Foshan Joan, Easytech, Kechuang Energy Storage, Narui Jibao, Energy Storage Online, etc.
Full immersion liquid cooling energy storage technology, as the name suggests, in the energy storage system, the battery cell is directly immersed in the cooling liquid, completely isolated from air, moisture, etc., and the direct contact between the battery cell and the cooling liquid is used to achieve rapid and sufficient temperature control.
Figuratively speaking, if the air-cooled heat dissipation is likened to a blowing fan, and the liquid-cooled heat dissipation of the cold plate is compared to sticking to ice, then the fully immersed liquid-cooled heat dissipation is a collective “cold bath” of the battery cells.
In actual operation, the battery is directly immersed in the coolant in the cabin to achieve direct, rapid and sufficient cooling of the battery, which ensures that the battery operates within the optimal temperature range, effectively prolongs the service life of the battery, and improves the overall efficiency of the energy storage power station. safety performance.
Wang Zhiqiang, chairman of China Southern Power Grid Energy Storage Technology Co., Ltd. once said to Meizhou Baohu Energy Storage Power Station: “The successful development of the submerged liquid-cooled battery energy storage system has realized the iterative upgrade of electrochemical energy storage safety technology, and the battery heat dissipation efficiency is higher than that of traditional methods. Increased by 50%. Meizhou Baohu energy storage power station can realize that the temperature rise of batteries does not exceed 5 degrees Celsius, and the temperature difference between different batteries does not exceed 2 degrees Celsius.”
On the whole, compared with air cooling and cold plate liquid cooling, full immersion liquid cooling has the advantages of high temperature control efficiency and high system security. The disadvantage is that the current system cost and operation and maintenance cost are high, and the current stage The large-scale commercial application model is not yet fully mature and is in the initial trial stage.
In December 2022, the “Jianmo” battery system pioneered by Chuneng New Energy was officially released. The newly developed fire-fighting system of this system can use liquid fire-fighting media to burn the liquid within 3 minutes after the battery energy storage system receives a thermal runaway alarm signal. The cold PACK box is completely submerged, which can effectively improve the safety of the energy storage battery system.
The principle of action is that the thermal runaway battery is inhibited by rapid cooling and local suffocation, making it difficult to react further, the heat spread between the cells and the PACK is blocked, the thermal runaway is difficult to continue to deteriorate, and the safety of the battery energy storage system is improved.
At present, a number of fully submerged liquid-cooled energy storage projects have been started and put into use in my country.
On March 6, 2023, the world’s first submerged liquid-cooled energy storage power station, China Southern Power Grid Meizhou Baohu Energy Storage Power Station, was officially put into operation, marking that the cutting-edge technology of submerged liquid cooling has entered the field of new energy storage engineering. the application stage.
It is reported that the total scale of the project is 70MW/140MWh, of which the fully submerged liquid-cooled energy storage system is 15MW/30MWh. According to the calculation of 1.75 times of charge and discharge per day, it can generate nearly 81 million kWh per year and reduce carbon dioxide emissions by more than 45,000 tons.
On December 27, 2022, the independent battery energy storage project on the grid side of Nanhai Power Grid in Foshan, Guangdong Province, was officially launched. On April 28, 2023, the project’s 75MW/150MWh submerged cabin level management liquid-cooled energy storage system integration began to invite bids.
It is reported that the construction scale of the project is 300MW/600MWh, mainly composed of a 300MW/600MWh energy storage system, related auxiliary equipment, and a smart energy storage digital operation management and control platform. It is expected to be completed and put into operation in 2023.
The cost of fully submerged liquid-cooled energy storage systems is relatively high at this stage, and it is difficult to apply them in cost-sensitive energy storage scenarios.
However, for those scenarios that attach great importance to safety and are not so sensitive to cost, such as public facilities, data centers, commercial buildings, airports, ports, rail transit and other fields, fully submerged liquid-cooled energy storage systems have broad prospects.
In the future, with the further iteration of the fully submerged liquid-cooled energy storage technology, large-scale and standardized applications will be formed, and the cost will be greatly reduced. Combined with its overwhelming advantages of high safety, its penetration rate in the energy storage system will be explosively improved .
