Promoting The Development Of New Energy Storage Helps Build A New Power System

With the promotion of carbon neutrality, new energy sources such as wind and solar energy have developed rapidly. Photovoltaic power generation and wind power generation have strong volatility, randomness, and are constrained by the location of resources, resulting in the imbalance of power supply and demand in time and space scales, and bringing unprecedented challenges to the power system. The new energy storage represented by electrochemical energy storage has the characteristics of fast response speed, flexible project location and short construction cycle, and can achieve active support, inertia management, fast frequency response and black start, and can be used as an important flexible regulation resource to help build a new power system.

China's energy storage industry presents a diversified development trend

According to the industry standard DL/T 2528-2022 "Basic Terms for Power storage" issued by the National Energy Administration, energy storage power stations are divided into electrochemical energy storage power stations and physical energy storage power stations according to different technical principles. As a traditional physical energy storage technology, pumped storage has been applied in the power system, and the new energy storage refers to the power storage technology other than pumped storage.

China is building an electric energy storage system based on pumped storage and supplemented by new energy storage. In the new energy storage, lithium-ion battery energy storage occupies a dominant position, and other energy storage such as sodium-ion batteries, flow batteries, compressed air, and flywheels have also made breakthroughs in the application scale, and the application mode has gradually increased.

In recent years, China's electric energy storage installed capacity has grown rapidly, and the energy storage industry has shown a diversified development trend. According to the statistics of the National Energy Administration, by the end of 2023, the cumulative installed capacity of new energy storage projects has reached 31.39 million kilowatts / 66.87 million kilowatt-hours, with an average storage time of 2.1 hours, and the new installed capacity in 2023 is about 22.6 million kilowatts / 48.7 million kilowatt-hours, an increase of more than 260% from the end of 2022. In terms of technology route, lithium-ion battery energy storage is still dominant, accounting for more than 97%, and its integration scale is developing to the gigawatt level. Compressed air energy storage and flow battery energy storage accounted for 0.5% and 0.4% respectively, and were in the demonstration stage of hundred-megawatt engineering application. The remaining types of energy storage, such as flywheels, gravity, and sodium-ion batteries, account for a relatively small scale and are still in the small-capacity pilot demonstration stage.

New energy storage helps ensure safety, supply and consumption

In recent years, the "double high" feature of the power system has become prominent, and the power grid is facing challenges in terms of safe and stable operation, power balance, and new energy generation consumption.

The access of high proportion of new energy leads to the reduction of the moment of inertia of the power system, the reduction of the adjustment ability and the anti-disturbance ability. At the same time, the active distribution network results in the decrease of the cut load. The characteristics of "large installed capacity and small electricity", "extremely hot no wind, late peak no light" of new energy power generation are significant, which increases the difficulty of ensuring power supply during the summer and winter, and increases the uncertainty of the balance of intra-day power supply and demand. New energy power generation has become an important participant in power supply assurance, and the accuracy of new energy power generation output prediction is required to be higher. Areas rich in scenery resources and areas with large power demand are in reverse distribution, and it is difficult to absorb and send new energy power.

In order to ensure safety, supply and consumption, the power system needs to enhance the corresponding flexible adjustment ability for the daily cycle (daily) fluctuation and intra-day (hourly) fluctuation of new energy generation. The new energy storage can provide bidirectional flexible adjustment ability and dual support of power and energy on a wide time scale from milliseconds to several days, and will become an indispensable adjustment means for new power systems. In terms of security, in areas with a high proportion of new energy generation and large capacity DC access, the new energy storage power station can provide inertia support and primary frequency modulation for the power system, reducing the risk of frequency instability of the receiving end of the grid. In terms of supply protection, in local power grids with large peak-valley difference, large-scale new energy storage power stations can meet the demand for power supply during peak hours, reduce the load peak-valley difference, delay the investment in transmission network construction and distribution network transformation and upgrading, and improve the utilization rate of power grid equipment. In terms of promoting consumption, in areas with a high proportion of new energy generation centralized access to the grid, large-scale new energy storage power stations as peak load resources can help improve the consumption level of new energy power; In areas with a high proportion of distributed power supply access to the low-voltage distribution network, the distributed new energy storage power station can suppress the power fluctuations caused by distributed power supply access, reduce the risk of voltage exceedance, and improve the acceptance capacity of the distribution network for new energy generation.

In the future, long-term energy storage technology needs to be developed

The "Guidelines on Accelerating the Development of New Energy Storage" issued by the National Development and Reform Commission and the National Energy Administration proposed that by 2025, new energy storage will be transformed from the initial commercialization to large-scale development; By 2030, we will realize the comprehensive market-oriented development of new energy storage. Taking into account the power supply guarantee and new energy generation consumption needs, under the premise of fully considering the technology and economy of the power system, it is estimated that by 2025 and 2030, the new energy storage configuration needs of the operating area of the State Grid Company Limited will be 32 million kilowatts / 76.8 million kilowatt-hours and 100 million kilowatts / 260 million kilowatt-hours, respectively.

In terms of flexibility adjustment in short and medium time scales (minute level, hour level) and long time scales (cross-day, cross-season), the economy of new energy storage technologies such as lithium-ion batteries, compressed air, flow batteries, sodium-ion batteries and flywheels is still weaker than that of pumped storage technology. Before 2030, the new energy storage is mainly used to transfer the daily peak load, but it is difficult to become an important support for ensuring the power supply of the power system. After 2030, it is necessary to develop low-cost and large-scale long-period energy storage technology to solve the problem of insufficient long-period regulation capacity of the power system.

At present, lithium-ion battery energy storage technology has initially achieved large-scale application, and will become the fastest developing and most widely applied energy storage technology in the process of achieving the target of carbon peak. In recent years, the level of key technologies such as ontology research and development, large-scale integration, and safety protection in the lithium-ion battery energy storage industry has continued to improve, and has passed the large-scale application function verification. The technical standard system and application management system for power system application are improving day by day. It is expected that by 2030, the unit capacity cost of lithium-ion battery energy storage power stations will be lower than that of pumped storage power stations, about 500 to 700 yuan/KWH, and the cost of KWH is close to 0.1 yuan.

Other new energy storage technologies such as flow batteries, sodium-ion batteries, compressed air, and flywheels have comparative advantages in some indicators and are candidates for diversified application scenarios of energy storage. However, there is still a large gap between the relevant technologies in terms of comprehensive technical performance and practical application needs, the application economy needs to be improved, the practical application effect still needs to be further tracked, evaluated and verified, and the construction of technical standard system and application management system for power system applications needs to be accelerated.

Different types of energy storage output performance is very different, and the output characteristics need to be adapted to the application scenario to better play the corresponding advantages. At present, new energy storage such as lithium-ion batteries, compressed air, flow batteries, sodium-ion batteries and flywheels are intra-day flexibility regulation resources. In view of the existing technical reserves, the energy storage technology that has been applied on a large scale is difficult to achieve breakthroughs in the comprehensive performance of low cost, high safety, long cycle (more than 100 hours), and large-scale, and the long-cycle energy storage technology direction recognized by the academic community mainly includes large-scale heat storage, water storage and hydrogen energy storage.

(Author: China Electric Power Research Institute Co., LTD.）

Article source: China Energy storage network