The frequent energy storage fire accidents around the world have not only caused significant casualties and property losses, but also triggered a deep reflection on the safety management and supervision of energy storage power stations.
The Electric Power Research Institute of the United States has established a relevant database through the study of multiple energy storage power station fire incidents publicly disclosed from 2018 to 2023. After classifying and comparing fire accidents with the Pacific Northwest National Laboratory (PNNL) of the US Department of Energy and Twaice of Germany, it was found that in addition to the risks of the battery cells and control systems themselves, the integration and operation of energy storage power stations are also important factors leading to accidents.
The scale of installed capacity has increased significantly, technology has been diversified, capital has poured in intensively, and industrial clusters have emerged. However, behind the frenzy of growth, there are also concerns about overcapacity caused by building but not using. The "price war" is full of smoke, and corporate profitability and product quality are facing double tests.
The essence of energy storage is "adjustment" rather than "storage". In the future, as a supporting industry for the new power system, energy storage will be involved in power system transactions and return to commercial applications to achieve high-quality development and give full play to the long-term value of energy storage.
At present, this market shift is gradually happening.
Driven by multiple factors, the long-term value of energy storage is gradually returning
In the past year, under the influence of multiple factors such as policy support, corporate efforts, and market favor, China has become the largest wind, solar, and storage market in the world. According to the 《Energy Storage Industry Research White Paper 2024》, China's new energy storage will have an additional installed capacity of 21.5GW in 2023, a record high.
In contrast, under the superposition of multiple factors such as raw material price cuts, vicious competition, and technological homogeneity, the market price of energy storage systems has been declining. Liu Manping, a senior economist at the Price Monitoring Center of the National Development and Reform Commission, said: "At present, the capacity of the energy storage industry is expanding rapidly, and the problem of structural overcapacity is prominent; some projects are "built but not used", and the actual utilization rate of new energy storage is not high; the operating model and market mechanism are not yet perfect, which has become a bottleneck restricting the development of the industry."
"Involution" or "idle"? How can the energy storage industry break through? The industry value logic oriented to the market and commercial application needs to be rebuilt urgently.
Energy storage itself is an important supporting component of the new power system. At present, the power systems in my country and even in developed countries in Europe and the United States are undergoing a transformation, namely "clean and low-carbon, safe and controllable, flexible and efficient, intelligent and friendly, open and interactive". The development direction of energy storage is closely related to multiple factors such as policy, market and technology.
From the policy point of view, as early as 2015, the Opinions of the CPC Central Committee and the State Council on Further Deepening the Reform of the Electricity System (hereinafter referred to as "Electricity Reform Document No. 9") proposed the goals of orderly promoting electricity price reform, rationalizing the electricity price formation mechanism, promoting the reform of the electricity trading system, and improving the market-oriented trading mechanism, which kicked off the opening of the electricity market. After the "dual carbon" goal was proposed, the National Development and Reform Commission clearly proposed the 1+N policy system, which further established a new power system with new energy as the main body from the top level around energy storage demonstration application, standardized management, electricity price reform, and diversified and intelligent applications. By 2023, the National Development and Reform Commission and the National Energy Administration issued the Basic Rules of the Electricity Spot Market (Trial) to implement specific incentive plans at the power system level. It is expected that by 2025, the power market will be gradually liberalized to form an open and interactive power system. The rise of the energy storage industry is fundamentally an important supporting factor in building an open and market-oriented power system.
From the market point of view, the operation time of domestic energy storage systems is long, and the system utilization rate is also constantly improving. The 2023 Electrochemical Energy Storage Power Station Safety Information Statistics show that in the first quarter of 2024, the average daily operating time of domestic energy storage power stations has increased from 3.12 hours to 4.16 hours, and the average utilization index has increased from 27% to 41%. With the issuance of the "Notice on Promoting the Grid Connection and Dispatching of New Energy Storage" by the National Energy Administration, the functional positioning of new energy storage has been further clarified, and the promotion of the dispatching and utilization of new energy storage has been accelerated. Energy storage projects are no longer just an appendage to meet the "strong allocation" policy of new energy, but an asset that can bring real long-term sustainable benefits to owners.
From a technical point of view, the reliability of energy storage power stations depends largely on the performance of energy storage batteries. The battery system is closely related to the battery management and integration capabilities. Taking battery consistency management as an example, during the use of energy storage cells, due to production differences, aging, temperature changes or different load conditions, the voltage and capacity between cells will be different, and this difference will increase with the increase in the number of charge and discharge cycles, thereby making the system economic benefits worse. Therefore, more and more battery balancing technologies are being applied to commercial and mature markets. According to a research report by Wood Mackenzie, an internationally renowned consulting firm, due to the more open overseas markets and power markets, energy storage owners are more concerned about the economic efficiency of the entire life cycle of the project. The advantages of active balancing technology in reducing the life cycle cost of energy storage systems have been widely recognized, and the proportion of applications in overseas energy storage projects has reached 74%.
Industry insiders said that driven by multiple factors, the energy storage industry is moving towards a stage of high-quality development. In the early 24th year, policies were intensively introduced around power market transactions, which will accelerate the new changes in the development of my country's power marketization and will also become an important driving force for the value transformation of the energy storage industry.
From "passive" to "active" Battery management technology upgrade
From price to value, in order to achieve the long-term goal of energy storage, industry manufacturers have conducted research and development and exploration from multiple dimensions, including:
Energy storage battery optimization: Select positive electrode, negative electrode, and diaphragm materials with better thermal stability; Select a lamination process with thinner thickness and larger surface area; Shorten the length of the pole ear to reduce resistance and other optimizations.
Advanced temperature control technology: From the traditional air cooling solution to the liquid cooling solution with higher heat transfer coefficient and better cooling effect, in order to cope with the growing market demand for thermal management systems.
Digital technology operation and maintenance: Monitor the operation status of power stations through digital technologies such as BMS, EMS, and AI, make a visual analysis of the battery life cycle operation status, identify early signs of failure, and provide safety warning design.
Fire protection technology guarantee: The mainstream products in the industry have realized a three-layer fire protection system at the cell level, pack level, and system level to achieve a more detailed and accurate fire protection effect.
Efficient battery management: That is, the battery management system (BMS) uses advanced algorithms to monitor the voltage of each cell during discharge and evaluate the battery's state of charge (SOC), state of health (SOH), and state of power (SOP). Since the life of the battery pack also depends on the cell with the shortest life, when the lowest single cell voltage reaches the discharge cut-off voltage, the entire battery pack will stop discharging. Balancing the state parameters of the energy storage cells has become the only way to maximize the battery cycle life and improve the cycle efficiency of the energy storage system, especially in high-power and large-capacity application scenarios such as large storage and industrial and commercial storage.
Based on the demand for optimizing and improving the consistency of battery packs, energy storage BMS balancing technology came into being. Among them, there are two main ways of battery balancing in the battery management system: passive balancing and active balancing.
Passive balancing balances the battery by releasing electricity through resistance heat during the discharge of the battery pack. This method does not require complex controllers and circuits, but the balancing speed is slow and wastes electricity. Heat is also generated during the process, increasing the risk of thermal runaway.
Active balancing realizes the direct transfer of electricity between cells through DC-DC converters, which can control the voltage difference between cells in the battery pack within a certain range, significantly reducing the cycle efficiency loss caused by imbalance. This technology usually requires the use of a dedicated balancing controller and extremely demanding circuit design, and ultimately achieves full-link balancing from PACK level to cluster level, then to system level, and even site level. Compared with traditional passive balancing technology, active balancing not only avoids energy waste, but also improves the overall performance of the energy storage system by redistributing energy, reducing operating costs and improving system safety.
At present, due to factors such as cost price, according to EESA's 2023 annual data statistics, domestic energy storage projects are almost all passive balancing projects (98.4%). In overseas markets, about 70% of projects use "active balancing". Taking the Texas TX10 project served by Kelu Electronics as an example, according to Modo Energy statistics, the revenue of 9 sites are all among the top 30 Texas power station revenues. John Smith, an analyst from Wood Mackenzie, pointed out: "In the context of intensified market competition, advanced battery management technology can not only improve system safety and reliability, but also significantly reduce operating costs, thereby improving the economic benefits of the project." In the future, as the degree of domestic electricity marketization increases, the economic advantages of active balancing technology in the long-term operation of power stations will gradually emerge. With the acceleration of the commercial application of domestic energy storage, active balancing technology will be used more and more.
Source：https://mp.weixin.qq.com/s/c9FptBX5qO9u4IyVOVxPJA