Why did the fire at an energy storage power station in the United States not go out for several days? The security alarm bell is ringing again

Interface News

2024-05-24 20:24Published on the official account of Shanghai Jiemian News

Interface News Reporter |

The safety of energy storage has once again aroused discussion in the industry.

On the afternoon of May 15, local time, the 250-megawatt Gateway energy storage power station, the world's largest lithium battery energy storage power station, was found to be on fire.

The fire has also aroused great concern in the domestic industry. Why did the fire at the energy storage power station last for several days? On May 23, Tian Qingjun, senior vice president of Envision Group and president of Envision Energy Storage, revealed three major reasons in an interview with Jiemian News and other media.

First of all, the energy storage system uses ternary lithium cells.

The U.S. energy storage power station that caught fire was operated by LS Power, NEC ES System Integration of Japan, and ternary lithium batteries provided by LG Chem of South Korea.

According to Tian Qingjun, the above-mentioned energy storage system will be connected to the grid in 2020, when the technology is relatively lagging behind, and ternary lithium batteries are relatively easy to thermal runaway, and the temperature application range is relatively different from that of lithium iron phosphate.

The temperature of thermal runaway of ternary lithium battery is generally between 120-140 °C, and the temperature of thermal runaway of lithium iron phosphate is 250-300 °C.

Thermal runaway refers to the phenomenon of overheating, fire and explosion caused by the rapid change of the rate of self-temperature rise of the battery caused by the chain reaction of battery heat release.

After the ternary lithium battery is thermally runaway, a large amount of combustible gases such as hydrogen and oxygen will be generated, and once burned, it will be more violent. Lithium iron phosphate batteries do not produce oxygen after thermal runaway, and can isolate the air by isolation to prevent misfire.

The San Diego Union Tribune report also said that one of the reasons the fire at the plant is difficult to extinguish is that the materials used in lithium-ion batteries produce oxygen on their own, and although water-based fire extinguishing agents can cool overheated batteries, they do not always completely extinguish the fire.

"Thermal runaway management of lithium iron phosphate batteries is simpler and easier to operate than ternary lithium." Tian Qingjun said.

According to public information, from 2011 to 2021, there were 32 fire and explosion accidents in energy storage power stations around the world, of which 25 accidents used ternary lithium batteries.

The advantages of ternary lithium batteries are that they have a relatively large energy density and long life, and are mostly used in new energy vehicles with long battery life. The total capacity of the vehicle is smaller than that of large-scale energy storage.

However, ternary lithium batteries are also often regarded as the culprits of spontaneous combustion of new energy vehicles, and their performance is unstable, and they are prone to short circuits when hit or the temperature is too high.

LG Chem's batteries, which are used in the above-mentioned energy storage systems, have been frequently exposed to potential safety hazards in recent years. From 2020 to 2022, LG has had a large-scale recall of related models due to battery defects.

As of September 2023, LG Energy has reported 73 battery thermal runaway incidents worldwide, according to the Battery 100 Committee. On February 5 this year, the Australian Competition and Consumer Commission also issued a document proposing a mandatory recall of LG energy storage batteries that pose safety risks.

Tian Qingjun said that in comparison, the critical point of thermal runaway of domestic lithium iron phosphate batteries is much higher than that of ternary lithium batteries.

In addition to the battery cells, Tian Qingjun said that the safety design and thermal runaway management of the energy storage system in the United States are not in place, and the design of the stacked building is unreasonable, which is far from the current multiple protection and box-type structure in the industry.

"With a building-style stacked layout, large-capacity batteries are concentrated in a confined space, once the fire-fighting agent is exhausted, only water can be added to the inside, or water can be sprayed from the outside, resulting in the entire monitoring system is also in a state of failure, and the internal environment is invisible and uncontrollable, resulting in the re-ignition and even spread of the entire system, making the fire last for several days." Tian Qingjun said.

Third, the means of operation and maintenance of the above-mentioned system are relatively simple, and there are many blind spots. According to Tian Qingjun, the energy storage power station where the accident occurred was not highly intelligent when it was connected to the grid, the design was not in place, and the early warning was not done.

"In addition to enterprises, local governments in China are also very concerned about this incident." Tian Qingjun said that in the past two years, China's large-scale operation of new electrochemical energy storage has brought a lot of challenges to safety management.

In the past two years, China's energy storage industry has been in a stage of rapid development, especially new energy storage based on lithium batteries. In 2023, China will put into operation 21.5 GW/46.6 GWh of new energy storage capacity, with a year-on-year increase of more than 150% in both power and energy scale, and China has completed the "14th Five-Year Plan" new energy storage installation target ahead of schedule.

The rapid decline in the price of energy storage systems has brought many contributions to the prosperity of the industry, but it has also brought many hidden dangers to the industry. The industry has frequently called for energy storage to adhere to the bottom line of "safety".

Tian Qingjun said that in the past two years, the industry has made rapid technological progress, and some of the products that have been launched before have not done well enough in terms of cell quality and fire protection design, and during the outbreak of the industry, too many "cross-border players" have entered under the impetus of capital, resulting in uneven product and technical quality. In the past few years, many power stations have not actually been used, the risks have not yet appeared, and new technologies have not been verified throughout the life cycle, which is a big hidden danger for the domestic market.

Tian Qingjun also mentioned the problem of unfair competition in the industry. Some unknown enterprises have proposed that they must be equipped with their energy storage products just because they have wind and solar resources in their hands, and some investors have sacrificed the requirements of energy storage safety in order to obtain more wind and solar resources and assets. Second, local protectionism also has a certain impact.

In 2021, China experienced a sensational fire and explosion at the Dahongmen energy storage power station in Beijing.

On April 16 of that year, a fire broke out in the southern area of the energy storage power station in the Dahongmen shopping mall of Jimei Home Furnishing outside Yongwai South Fourth Ring Road, Fengtai District, Beijing. In the process of disposing of the southern area of the power station, the northern area suddenly exploded without warning, resulting in 1 person killed, 2 firefighters killed, 1 firefighter injured, and the direct property loss of 16.6081 million yuan in the fire.

The above-mentioned power station uses Guoxuan Hi-Tech (002074.SZ) lithium iron phosphate battery. The final report shows that the accident was caused by an internal short circuit fault in the lithium iron phosphate battery, which caused the battery to catch fire due to thermal runaway.

Tian Qingjun said that the Dahongmen energy storage power station is equivalent to user-side energy storage, and once an accident occurs, the social repercussions are very strong, which has also caused great harm and a worse impact on the energy storage industry. This is the inevitable price to pay and the tuition fee that the industry needs to pay in the process of growth and development. From the perspective of enterprises, once such a vicious event occurs in the industry, it is necessary to do serious analysis and research and reflect on itself.

In order to avoid more energy storage safety accidents in the future, Tian Qingjun suggested that the industry needs to do self-inspection and self-correction of old power stations in the past, especially those that have been in operation for more than three years and are non-lithium iron phosphate in the early years.

For power stations that have not been used under the "strong allocation and storage" before, it is recommended that each investor or asset owner do a comprehensive inspection to prevent problems before they occur.

In addition, Tian Qingjun also pointed out the need to pay special attention to the safety of industrial and commercial energy storage.

"The safety of industrial and commercial energy storage is generally not as good as that of large storage." He suggested that industrial and commercial energy storage should be legal and compliant in construction, and the design of energy storage power station systems should introduce more safety perspectives, including monitoring systems, safety monitoring and early warning, etc.

According to the application scenarios, energy storage can be roughly divided into large storage (power generation side, grid side), medium storage (industrial and commercial) and small storage (household storage, portable storage). Large storage is mainly used to match the use of large-scale power stations.

At present, the domestic industrial and commercial electric energy storage standards are not clear enough. But most of these power stations are in commercial or densely populated areas. For the purpose of reducing the land occupation, most of them are arranged relatively closely, which is not conducive to safety. Tian Qingjun called for the introduction of relevant policies as soon as possible to stipulate the requirements and standards for the spacing of industrial and commercial energy storage arrangements.

In terms of the safety design of the product itself, Tian Qingjun said that the shape, layout, and deployment of the entire cable of energy storage equipment products need to be comprehensively considered, and it is not recommended to build a stacked building type of energy storage.

The core essence of energy storage safety is the problem of battery cells. Enterprises can add safety isolation pads between battery cells, add aerosols, etc., if a single cell has thermal runaway, it can ensure that it does not spread in the future, and can block the air.

If the thermal runaway continues to the Pack level, the automatic fire protection will be activated immediately, and the overall system safety will not be affected. Upgraded to the entire system level, additional fire protection systems will also ensure that there will be no impact on surrounding fires or impact on the power grid.

In addition, in product design, artificial intelligence and other methods can also be used to perceive and accurately extinguish fires in advance.

Tian Qingjun believes that the safety of electrochemical energy storage is manageable and controllable. Lithium battery power stations can be controlled and managed from a design perspective. Cost and security are not inherently contradictory. In the future, energy storage is confident that it will have the same life as wind and solar assets, and the energy storage industry can propose more solutions and properly handle safety issues, hoping to give the industry more patience.

At the same time, he pointed out that once the energy storage power station catches fire, it will become a public incident and need to be strictly managed. But don't be "one size fits all", you can't deny the safety of the entire business or product because of the problem of one power station.

In addition to the domestic energy storage market, Tian Qingjun also mentioned overseas markets.

Different from domestic ones, most overseas energy storage projects need to provide services for the whole life cycle. The domestic warranty period is generally 3-5 years, and most reaches 7 years. Once the cycle is exceeded, the assets are handed over to the purchaser, and the equipment provider no longer bears the economic losses and risks caused by the quality of the products.

Tian Qingjun said that it is not excluded that the operation and maintenance of energy storage in China in the future will also be handed over to the equipment provider, and only enterprises that continue to invest in energy storage technology and research and development and are deeply involved in the industry can coexist with their partners for a long time.

Previously, overseas battery manufacturers had fewer choices, and there was still a market for LG batteries even if they had frequent problems. Chinese energy storage companies have just begun to go overseas in recent years, and have not yet been verified by long-term cooperation, and many overseas customers have an attitude of trying to cooperate.

Tian Qingjun said that Envision Energy will expand overseas this year, on the one hand, through the global cell factories to obtain local support and recognition, and on the other hand, through regional marketing to expand customers.

According to the long-term plan, developed regions such as Europe and North America will become the most important markets in the future. Considering that these regions have more reasonable gross margins, Envision will invest large-scale strategic resources here.