Frequent Energy Storage Accidents Drive Growing Demand for Fire Safety in ESS
Electrochemical energy storage is a highly energy-intensive chemical integrated device. If battery abuse occurs, such as overcharging, over-discharging, overcurrent, thermal runaway, and internal short circuit, it will easily lead to heat accumulation inside the battery. Once the critical point is exceeded, thermal runaway will occur, and thermal runaway will spread rapidly, spreading among battery modules, battery cabinets, and even energy storage battery compartments. The flammable gases released when the battery burns will further prolong the combustion time, increase the difficulty of extinguishing, and even cause an explosion, ultimately leading to serious economic and personal damage.
Battery Type Proportions in Energy Storage Accidents (Unit: %)
Accidents at energy storage power stations occur frequently, and energy storage safety issues need to be addressed urgently: According to incomplete statistics from the International Energy Network, a total of 37 energy storage power station explosions occurred worldwide from 2011 to January 2022, of which 4 occurred in China. On April 16, 2021, an energy storage power station accident at Beijing Guoxuan Fuweis Solar Storage and Charging Technology Co., Ltd. caused one death, two firefighters died, one firefighter was injured, and direct property losses of 16.61 million yuan were caused; from the perspective of new energy vehicle accidents, according to data released by the Fire and Rescue Bureau of the Ministry of Emergency Management, in the first quarter of 2022, a total of 640 new energy vehicle fires were reported in China, an increase of 32% over the same period last year; from the perspective of accident battery type, 82% of energy storage accidents were caused by ternary lithium batteries, mainly because the decomposition temperature of the positive electrode material of the ternary lithium battery is only 200°C, which is prone to thermal runaway and thus fire.
Early Warning: The First Line of Defense for ESS Safety, Evolving with Stricter Thermal Runaway Requirements
Early warning: The requirements for thermal runaway are increasing, which puts higher requirements on early warning technology. Thermal runaway early warning technology mainly integrates battery safety failure mechanism with big data artificial intelligence technology to establish safety early warning models for various failure modes. Commonly used ones include battery internal short, lithium deposition, capacity abnormality, etc. These abnormal changes in the battery are manifested as abnormalities or abnormal trajectories of voltage, temperature, current and other data in the battery operation data. Through multi-dimensional analysis of voltage, current, temperature and other data recorded by BMS during battery operation, the fault information of the battery can be identified, and the battery safety risk can be judged to achieve the purpose of early warning. With the continuous improvement of the industry’s requirements for thermal runaway, the thermal runaway target has been increased from the original 5min to 30min, 60min, and even more than 24h without open fire/no spread, which puts higher requirements on the thermal runaway protection and suppression technology of the power battery system.
In the future, it is still necessary to develop more sensitive and reliable sensors on the existing basis and reduce their costs, and at the same time explore whether there are more effective early warning methods to further improve the safety and reliability of lithium-ion battery systems. For example, in the early warning system with temperature as the main characteristic parameter, the thermocouples or sensors used in the past to directly measure the surface temperature have certain errors. At present, experts and scholars have considered using infrared detection or built-in sensors to improve the accuracy of the measured temperature data. In the future, more accurate temperature measurement methods and high-temperature resistant and high-precision built-in temperature sensors can be used to monitor the battery temperature. The accuracy should be at least higher than the highest requirements of the existing accuracy standards. In addition, the battery monitoring system can be combined with the battery temperature prediction technology to obtain more accurate battery temperature data.
Fire Suppression Challenges: High Fire Risk and Difficult Extinguishment in Energy Storage Systems
Fire extinguishing end:
“Thermal runaway” is the root cause of safety hazards of lithium-ion batteries: The thermal runaway mechanism of lithium-ion batteries includes three stages. The first stage: the initial stage of thermal runaway of lithium batteries. Due to internal and external factors, the internal temperature of the battery rises rapidly to 90~100 ℃. At this time, the SEI passivation layer on the surface of the negative electrode decomposes and releases huge heat, causing the internal temperature of the battery to rise rapidly; when the temperature reaches 135 ℃ and 166 ℃ respectively, the PE and PP diaphragms begin to melt. As the temperature rises further, the diaphragm shrinks, and the positive and negative electrodes contact each other to cause a short circuit, thereby causing continuous heat release of the battery. The second stage: the battery bulging stage, at a temperature of about 250~350 ℃, lithium reacts with the organic solvent in the electrolyte to volatilize flammable hydrocarbon gas. The third stage: battery thermal runaway, explosion failure stage, in this stage, the positive electrode material in the charging state continues to undergo violent oxidation decomposition reaction with the electrolyte, generating high temperature and a large amount of toxic gas, causing the battery to burn violently or even explode.
Lithium-ion battery energy storage systems are predominantly represented by prefabricated container-type storage units. These systems are typically composed of dozens of battery cells connected in series and parallel to form battery modules. These modules are then connected in series to create battery strings, which are further integrated in parallel into a single energy storage battery cabinet.
Fires involving lithium-ion battery energy storage systems exhibit several distinct characteristics:
- Intense combustion and rapid thermal propagation
- High toxicity, dense smoke, and significant hazard potential
- High risk of re-ignition and considerable difficulty in extinguishment
As a result, safety concerns associated with lithium-ion-based energy storage systems have garnered increasing attention in recent years.
Fire Suppression Challenges: Lack of Targeted Extinguishing Agents
Lack of Targeted Fire Suppression Agents for Energy Storage Systems:
Given the high fire risk and difficulty of extinguishment associated with energy storage systems, current fire suppression agents often prove ineffective for lithium-ion battery fires. For instance, dry powder extinguishers have little to no effect on suppressing such fires. Agents like Halon 1301, CO₂, and FM-200 (heptafluoropropane) are only capable of extinguishing open flames but cannot fundamentally inhibit the onset of thermal runaway or prevent reignition. These agents lack both cooling and effective fire suppression capabilities, making them unsuitable for lithium battery fires.
Water sprinkler systems, while technically mature, cost-effective, and environmentally friendly, do offer effective cooling and fire suppression. However, water as an extinguishing medium comes with significant drawbacks: it requires large volumes, prolonged firefighting durations, and poses a high risk of causing short circuits and irreversible damage to the batteries, rendering the energy storage station inoperable after the fire.
Water-based fire extinguishing agents are relatively effective in cooling and extinguishing fires: In general, solid fire extinguishing agents are almost ineffective in fighting fires in lithium-ion battery energy storage systems; gas fire extinguishing agents have poor fire extinguishing efficiency and limited cooling effects; water-based fire extinguishing agents are not only environmentally friendly and low-cost, but also have significant cooling and fire extinguishing effects. Therefore, fire extinguishing protection is carried out for fire hazards of lithium batteries, especially large-scale energy storage lithium battery systems, and new high-efficiency, anti-reignition fire extinguishing agents and fire extinguishing agent release systems and devices are designed and developed, which is conducive to the large-scale commercial application of lithium-ion battery energy storage systems.
Compared to EV Power Batteries, Energy Storage System Fires Pose Greater Hazards
Considering the differences between the scale and performance requirements of power storage batteries and electric vehicle power batteries, we mainly analyze from the following aspects:
Battery system scale: Both lithium-ion energy storage systems and electric vehicles 48v 60v 72v 96v lithium-ion batteries as basic units, and their components can be divided into four levels: battery cells, modules, battery packs, and systems. However, the number of battery cells in energy storage systems far exceeds that of electric vehicle battery systems, and the overall energy of energy storage devices is 1 to 2 orders of magnitude higher than that of electric vehicle battery systems, making the extent and impact of fire accidents more serious.
Mechanism of fire accidents: Both energy storage system and electric vehicle battery fires are caused by battery abuse, which leads to thermal runaway of a single battery, thus causing large-scale fire accidents. However, the fire spread characteristics of the two are not exactly the same. In electric vehicle fires, the temperature of a thermal runaway battery cell rises, causing fires in adjacent battery cells or modules; while energy storage systems are usually composed of more than a dozen or even dozens of modules, and thermal runaway of a single battery usually causes fires to spread between modules.
Fire prevention and control measures: Fire prevention and control of lifepo4 battery energy storage systems usually requires consideration of module safety design, battery management system, fire warning system and fire fighting system. However, due to the volume limitation of battery compartment, fire prevention and control of electric vehicle battery systems usually only involves the first two levels. For energy storage systems, since thermal runaway of lithium-ion batteries erupts in a chain and fire spreads rapidly, the timeliness of the warning system and the effectiveness of the fire fighting system are very critical.
Safety evaluation standards: For the safety evaluation of electric vehicle power batteries, please refer to UL2580-2013 “Electric Vehicle Battery Safety Specification Standard” and GB/T 31485-2015 “Safety Requirements and Test Methods for Power Batteries for Electric Vehicles” and other standards and specifications. At present, there is no quantitative evaluation standard for energy storage battery safety. In practical applications, most of the relevant test standards for lithium-ion batteries for electric vehicles are cited. How to quantify the safety evaluation system of energy storage systems needs in-depth research.
Taking into account the actual increase in demand for the early warning and fire-fighting ends of energy storage systems and the differences and comparisons with electric vehicle power batteries, we believe that with the booming development of the energy storage industry, the demand for energy storage firefighting may increase significantly, ushering in a good opportunity for the development of the industry.
Policy-Backed Boom in Energy Storage Fire Safety: A Long-Term Growth Track
The policy emphasizes the safety of energy storage fire protection, which is beneficial to the development of the industry: the “Electrochemical Energy Storage Power Station Safety Regulations (Draft for Comments)” issued in September 2021 requires energy storage fire protection to be integrated into the video surveillance system and set up systematic solutions, which are more refined and technological, and stipulates the safety requirements for energy storage power station equipment safety technical requirements, operation, maintenance, overhaul, testing, etc. The “14th Five-Year Plan for National Fire Protection Work” issued in February 2022 proposed to strengthen fire protection design and source management around new energy storage facilities. Various policies put forward detailed requirements for the construction and management of energy storage power stations; guide the construction of supporting energy storage fire protection facilities to improve the safety of energy storage power station operations; put forward the 2025 target installed capacity and cost reduction and efficiency improvement goals, and policies guide the development of the energy storage market.
With the implementation of a number of policies and standards related to energy storage fire safety, it can be foreseen that the scale of energy storage installed capacity will increase rapidly. The importance of energy storage fire protection will continue to be highlighted under the new standards. The proportion of energy storage fire protection investment is expected to further increase, and the energy storage fire protection industry may usher in a long snow slope.
Diverse Downstream Applications of Energy Storage Fire Safety Poised for Rapid Expansion
Downstream application scenarios are diversified, and energy storage fire protection products are expected to increase in volume during the 14th Five-Year Plan period: the upstream raw materials of the energy storage fire protection product industry chain mainly include structural parts, electronic components, chassis and fire extinguishing agents; in addition to energy storage power stations, downstream application scenarios of energy storage fire protection products also include new energy vehicles, electric bicycles and household energy storage. As the scale of energy storage in the downstream industry expands, fire safety standards will become more stringent, and the demand for energy storage fire protection products will have broad prospects.
We expect that by 2025, the domestic energy storage fire protection market space is expected to reach 6.514 billion yuan, with a CAGR of 113% from 2021 to 2025; the future energy storage fire protection track is long and steep, and is expected to achieve rapid growth. The main assumptions are as follows:
China’s new installed capacity of electrochemical energy storage: According to the Energy Storage Industry Research White Paper 2023, China’s new installed capacity of electrochemical energy storage in 2024 is 1559.6MW. We assume that the cumulative installed capacity of electrochemical energy storage will grow at a compound annual growth rate of 64% from 2021 to 2025; Based on the energy storage ratio of major provinces in China as calculated by GGII, we assume that the storage time is 2 hours;
Ratio of fire protection investment: According to the announcement of Qingniao Fire Company, the current proportion of fire protection expenditure in China is about 2%, which is higher abroad; We expect that with the release of the “Electrochemical Energy Storage Power Station Safety Regulations”, the proportion of fire protection investment is expected to continue to increase, assuming that the proportion of fire protection investment will reach 7% in 2025;
Average price of energy storage bids: According to the data of Jibang New Energy Network, the overall average bid price of typical energy storage projects in 2024 reached 1.476RMB/Wh, and the National Energy Administration and others emphasized that energy storage power stations should optimize costs while developing. We assume that the cost of energy storage projects will decrease by 5% each year.
