In the previous article, we learned about the background of the development of China's energy storage industry. In today's sharing, China exportsemi net will present to you the technical status of the energy storage market. What are the energy storage methods? and the development of new energy storage technologies.
What are the energy storage methods ?
According to the different forms of energy storage, generalized energy storage technology is mainly divided into three categories: thermal energy storage, electrical energy storage, and hydrogen (ammonia) energy storage. Among them, electrical energy storage includes electrochemical energy storage, mechanical energy storage, and electromagnetic energy storage. . At present, in energy storage projects in power systems, pumped hydro storage is still the main method, but a variety of new energy storage methods represented by electrochemical energy storage are developing rapidly (Figure 1).
Figure 1: Energy storage technology classification
Traditional energy storage: Pumped hydro energy storage is currently the mainstream, but its future development space may be limited.
Pumped hydro energy storage uses water as an energy storage medium to realize the storage and release of electrical energy through the conversion of electrical energy into potential energy of water. Generally speaking, a pumped storage power station consists of an upper reservoir, a lower reservoir with a certain height difference, a water diversion system connecting the two reservoirs, and an underground powerhouse (reversible turbine unit). When the power load is at a low point, or new energy sources such as wind power and solar energy continue to work, the power station uses the reversible turbine unit located in the underground factory to use the excess electric energy of the power system to pump water to the upper reservoir and store it in the form of potential energy. During peak power load periods, or when wind, solar and other new energy sources stop working, water from the upper reservoir is released to the lower reservoir to generate electricity, converting water energy into electrical energy and transmitting it to the grid.
From the structural point of view, the pumped storage power station is based on the ordinary hydropower station and adds pipelines and corresponding water pump systems to realize water transportation from the lower reservoir to the upper reservoir. It is like a large-scale clean energy "battery" that can be used without excessive While reducing fuel consumption, it effectively improves the security, economy and reliability of the power grid. At the same time, pumped storage has the advantages of mature technology, large energy storage capacity, high system efficiency, long operating life, and high safety performance. It is currently a mainstream energy storage technology with a high degree of commercialization and a wide range of applications1,2 . From the perspective of the international market, pumped hydro energy storage occupies an absolute leading position. As of the end of 2020, the installed scale of pumped hydro energy storage accounted for 94% of the total scale of power energy storage projects 3 . Among them, China has basically formed a whole industry chain development system and professional development model for pumped hydro energy storage. According to IRENA statistics, as of the end of December 2021, my country's cumulative installed capacity of pumped hydro energy storage has reached 36.4GW, a year-on-year increase of 15.6%, and the scale of built and under construction ranks first in the world. The United States and Japan rank second and third respectively, with a cumulative installed capacity of approximately 21.9GW. Countries such as Germany, India, and South Korea also have many practices in the field of pumped hydro energy storage, with a cumulative installed capacity of more than 4.7GW (Figure 2).
Figure 2: Cumulative installed capacity of pumped hydro energy storage in major countries around the world in 2021, GW
From the perspective of the industry structure, China's pumped storage power stations that have been put into operation are dominated by State Grid Xinyuan, a subsidiary of the State Grid Corporation of China, and Shuangdong Company, a subsidiary of China Southern Power Grid4 . As of the end of 2021, State Grid Xinyuan's pumped storage capacity in operation and under construction was 23.51 million KW and 45.78 million KW respectively, occupying an absolute leading position in the pumped storage development, construction and operation market5 . During the Winter Olympics, State Grid Xinyuan Hebei Fengning Pumped Storage Power Station was put into operation to generate electricity. Its installed capacity, energy storage capacity, underground factory and cavern group size all ranked first in the world, making it the first Beijing Winter Olympics venue to achieve 100% green electricity. The strong guarantee of supply will also provide green momentum for the coordinated development of Beijing, Tianjin and Hebei in the future6,7 .
Driven by the "double carbon" goal, changes in the energy structure and the promotion of low-carbon clean new energy have made the importance of pumped hydro storage increasingly apparent. In September 2021, the National Energy Administration released the "Medium and Long-term Development Plan for Pumped Hydropower Storage (2021-2035)". Pumped hydropower storage was listed as the "three most" 8 energy storage methods, affirming the role of pumped hydropower storage in the field of energy storage. After a series of national supporting policies were introduced one after another, the enthusiasm for industrial investment was ignited, and it became a hot stage for the development of the industry. At present, technologies such as variable speed pumped storage, large-capacity ultra-high head pumped storage, joint operation control of pumped storage and new energy, seawater pumped storage, and pumped storage based on abandoned mines have become research hot spots. In April 2022, the National Development and Reform Commission and the National Energy Administration jointly issued a notice deploying to accelerate the development and construction of pumped hydro energy storage projects during the "14th Five-Year Plan" period and effectively promote the large-scale development of pumped hydro energy storage.
However, the construction of pumped storage power stations is limited by terrain factors. For example, the upper and lower reservoirs need to meet a height difference of about 40-600m, and the reservoirs need to have a certain capacity9 . The construction period is long, usually about 7 years. In the future, with the development of electrochemical As the cost of new energy storage such as energy storage decreases, the development space of pumped hydro energy storage in the power system may be limited.
New energy storage: Electrochemical energy storage has become a new driving force in the industry. In the future, lithium iron phosphate batteries, flow batteries, etc. are expected to further open up market space.
New energy storage mainly includes electrochemical energy storage, hot (cold) energy storage, compressed air energy storage, flywheel energy storage and hydrogen (ammonia) energy storage. The inherent characteristics of different new energy storage technologies are different, and each has its own advantages and disadvantages. Applicable scenarios (Table 1). Among them, electrochemical energy storage has a wide power range, high energy density, and is more mature than other new energy storage technologies, so it is applicable to a wider range of scenarios. In addition, compared with pumped hydro energy storage, electrochemical energy storage is more convenient to install and is not subject to location restrictions, and is facing broad development prospects.
Table 1 : Comparison of major new energy storage technologies10
Judging from the scale of new energy storage installations globally and in China in 2021 (Figure 3), electrochemical energy storage is expected to become a new driving force for the development of the energy storage industry. According to data from the Zhongguancun Energy Storage Industry Technology Alliance (CNESA), 18.3GW of newly installed energy storage capacity will be added globally in 2021, with electrochemical energy storage adding 10.2GW, accounting for 56%. China's data also reflects the important position of electrochemical energy storage in the energy storage market. In 2021, China's newly installed energy storage capacity will be 10.5GW, and electrochemical energy storage will add 2.3GW, accounting for 13%.
Figure 3 : Scale and composition of new energy storage installed capacity in the global and Chinese markets in 2021, GW
The installed scale of electrochemical energy storage is dominated by lithium-ion batteries. According to data from the China Electricity Council (referred to as China Electricity Council), as of the end of 2022, the proportion of lithium-ion batteries in the cumulative electrochemical energy storage projects put into operation in China is 89.5%, of which lithium iron phosphate batteries account for 88.7% (Figure 4).
Figure 4 : Cumulative proportion of electrochemical energy storage battery types in China as of the end of 2022
Compared with other types of electrochemical energy storage technologies, lithium-ion batteries have the advantages of fast response, large capacity, low pollution, and long life. They can be widely used in wind power, photovoltaic and other new energy generation-side distribution and user-side energy storage. They are One of the fastest growing electrochemical energy storage technologies in recent years (Table 2). Lithium-ion batteries account for a high proportion, but they also have safety risks such as thermal runaway and flammability during large-scale application. According to incomplete statistics reported by the National Energy Information Platform, there have been more than 70 fire and explosion accidents in energy storage power stations around the world in the past 10 years. Most of the batteries involved in the accidents were ternary lithium-ion batteries (mainly referring to cathode materials containing nickel, cobalt, manganese/aluminum). battery type with metal elements) 11. In June 2022, the National Energy Administration issued the "Twenty-Five Key Requirements for Preventing Electric Power Production Accidents (2022 Edition) (Draft for Comments)", proposing that medium and large electrochemical energy storage power stations must not It is not advisable to use ternary lithium batteries and sodium-sulfur batteries instead of echelon-utilized power batteries. This means that in the future, safer lithium iron phosphate batteries and flow batteries are expected to further open up the market space.
Table 2 : Comparison of major electrochemical energy storage technologies
New energy storage technologies are applicable to different scenarios, focusing on three major cost reduction ideas to promote large-scale application
From the perspective of technological maturity, China is currently one of the most active countries in basic research on energy storage technology in the world, including lithium-ion batteries, lead batteries, flow batteries, supercapacitors, compressed air energy storage, hot (cold) energy storage, etc. The technology has reached or is close to the world’s advanced level, but there is still a certain distance between flywheel energy storage and the world’s advanced level (Table 3).
Table 3 : China’s major energy storage technology research and development progress in 2021
In the process of promoting the large-scale application of technology, it is necessary to screen out mainstream technologies that can meet the needs of high security, large scale, long life, low cost, and high efficiency of the power grid based on different application scenarios (Table 4). From the perspective of scenario applicability, in addition to the market prospects of electrochemical energy storage technology that deserve attention, the commercialization potential of compressed air energy storage, flywheel energy storage, hydrogen (ammonia) energy storage, etc. cannot be underestimated. For example, compressed air energy storage is regarded as the best alternative to pumped hydro energy storage. Both are mechanical energy storage and have the advantages of large capacity and long life. Compressed air energy storage has looser site selection conditions and has an impact on the ecological environment. Smaller, it is suitable for large-capacity and long-term energy storage scenarios such as power grid peak shaving and valley filling, centralized renewable energy grid integration, etc. Flywheel energy storage has large instantaneous power, millisecond-level response speed and minute-level discharge time, and is more suitable for high-frequency short-term scenarios such as power grid frequency regulation and power quality improvement. In addition, hydrogen (ammonia) energy storage has attracted more and more attention recently. The principle is to use the intervariability of "electricity-hydrogen-electricity" to achieve energy storage and release. It has the advantages of clean and low carbon, long storage time, and long transportation distance. It is widely used in large areas. The advantages are obvious in large-scale long-distance energy storage and transportation scenarios.
Table 4 : Applicable technology types for various energy storage application scenarios
It is not difficult to see that various new energy storage technologies are both substitutable and complementary in application, which is an important prerequisite for promoting the diversified development of new energy storage. However, it should also be noted that the mainstream energy storage form in China at this stage is still pumped hydro storage. The reason is that the cost of electricity per hour of new energy storage such as electrochemistry is relatively high (Figure 5), which is also a key bottleneck currently restricting the large-scale application of new energy storage. one.
Figure 5: Comparison of electricity costs per unit of electricity, yuan/kWh Figure 12
Taking chemical energy storage as an example, the energy storage system consists of a battery pack, a battery management system (BMS), an energy management system (EMS), a energy storage converter (PCS), and other electrical equipment. The cost of the battery pack accounts for nearly 60% 13 , which is the key to reducing the cost of energy storage systems. According to the goals set out in the "14th Five-Year Plan for New Energy Storage Development Implementation Plan", by 2025, the cost of electrochemical energy storage systems will be reduced by more than 30%. In this regard, there are three main technical cost reduction ideas proposed by the industry : First, focus on improving the cycle life of battery packs; second, reasonably reduce supply chain costs, such as realizing low-cost material substitution; third, optimize technologies such as energy storage cooling and integration methods to improve Overall efficiency of energy storage system14 .
1 Chen Haisheng, Li Hong et al. Research progress of energy storage technology in China in 2021 [J]. Energy Storage Science and Technology, 2022, 11(03): 1052-1076. DOI: 10.19799/j.cnki.2095-4239.2022.0105.
2 Wu Weinan. Pumped hydro energy storage cooling and heating [J]. Energy, 2022(07):10-16.
7 Beijing Winter Olympics accelerates energy transformation [EB/OL]. February 11, 2022
8 The “three bests” refer to the most mature technology, the best economics, and the most favorable conditions for large-scale development.
9 Hu Yulong, Ma Jinbiao. Prospects of my country's pumped storage industry [J]. Hydropower Station Electromechanical Technology, 2021, 44(12): 54-56. DOI: 10.13599/j.cnki.11-5130.2021.12.022.
10 The performance parameters are not absolutely accurate, but they allow readers to compare and analyze various technical characteristics from the order of magnitude level of the performance parameters. With the development of energy storage, the scale of electrochemical energy storage power stations has jumped from MW to GW level. For example, the scale of the "Huining Times Jiangmen (Taishan) Nuclear Storage Complementary Electrochemical Energy Storage Power Station" project to be started in October 2022 is 1.3GW. /2.6GWh.
12 The evaluation index is the currently internationally used levelized cost of electricity (LCOS) of energy storage based on full life cycle modeling of energy storage. For the detailed calculation process, please refer to "Yingda Securities-Energy Storage Industry In-Depth Report: Development of Six Types of Energy Storage" and its economic evaluation》
14Technological innovation drives cost reduction in the energy storage industry, International Energy Storage Network, May 19, 2022
Report source: KPMG analysis
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