To achieve the goal of carbon peak and carbon neutrality, we must build a clean, low-carbon, efficient and secure energy system, vigorously promote the replacement of fossil energy with green and new energy, deepen the reform of the power system, and strive to build a new power system with new energy as the main body. To alleviate the intermittent power of the new energy features, support renewable energy given new energy access, and distributed to meet the needs of power system load frequency control under the new situation, energy storage technology and the integrated application of renewable energy power generation is to realize the future high proportion the necessary way for large-scale application of renewable energy, so you need to develop and build up energy storage system.
Advanced energy storage technology is the key supporting technology to achieve high proportion of new energy power system
At present, China has the world's largest energy system (production and consumption), in which the proportion of non-fossil energy in primary energy is only about 15%. To achieve the goal of carbon dioxide reduction, the development and utilization of renewable energy represented by solar and wind energy has become a top priority. With the acceleration of the energy revolution, new energy is experiencing explosive growth. It is expected that by 2030 and 2060, new energy will account for more than 25% and 60% of China's electricity generation respectively. Wind power generation and photovoltaic power generation are the mainstream new energy generation technologies at present. Due to their vulnerability to external natural conditions, both wind power generation and photovoltaic power generation show significant intermittent fluctuation of power, which brings great interference to the power system. With the continuous increase of the permeability of intermittent new energy such as wind power in the power system, the new power system is bound to face serious power fluctuation problem. Developing advanced energy storage technology is of great significance for promoting the consumption of renewable energy and improving the flexibility of power system.
On the one hand, in order to suppress the power fluctuation of new energy and support large-scale new energy grid connection and distributed new energy open access, it is necessary to develop multi-angle, multi-level and multi-scale energy storage technology while transforming traditional thermal power and improving its flexibility. In order to break through the bottleneck of traditional flexible regulation ability of new power system, a perfect energy storage system suitable for multiple scenarios is constructed. From the power side, energy storage and renewable energy generation are combined to form a combined system. Through the energy storage and release of the energy storage system into the network, intermittent renewable power energy becomes stable, safe and efficient clean energy. At the same time, wind, light and other new energy is difficult to adjust the power of the grid load disturbance, and their power amplitude changes greatly in the daily cycle. Flexible two-way adjustment ability of energy storage power station can combine with grid current frequency modulation depth of the load control, power grid power balance and power generation cost, give attention to two or morethings to provide for the operation of the peak shaving, FM, backup and black start, demand response support and other services, is to improve the traditional power system the important means of flexibility, economy and safety, It has become an important part and key supporting technology of smart grid and "Internet Plus" smart energy.
On the other hand, the application of a large number of advanced energy storage technologies will significantly improve the consumption level of renewable energy such as wind and light, support distributed power and micro-grid, which is the key technology to promote the replacement of the main energy source from fossil energy to renewable energy. It can promote the open sharing and flexible trading of energy production and consumption, and realize multi-energy synergy. It is the core foundation for constructing energy Internet, promoting the reform of electric power system and promoting the development of new forms of energy business. Therefore, advanced energy storage technology is of great significance to the construction of intelligent and digital new power system with deep integration of source network, load and storage.
Vigorously develop pumped storage, electrochemical energy storage and compressed air and other diversified energy storage technologies
Energy storage technology can be realized in various ways, including pumped storage, chemical battery, compressed air storage, flywheel, supercapacitor, superconducting magnetic system, hydrogen energy, cold storage, heat storage and so on. In recent years, hundreds of megawatt and above energy storage demonstration projects have been built worldwide. By the end of 2020, the cumulative installed capacity of global energy storage projects has reached 191.1 GW, and that of China's energy storage projects is 35.6 GW. Among many energy storage technologies, pumped storage, electrochemical storage, compressed air, flywheel and other energy storage technologies have been focused on due to their superior performance in energy storage scale, safety and economy.
1. Pumped storage will continue to be the main energy storage technology in the foreseeable future
Pumped storage is a mature and widely used energy storage technology, which has the characteristics of large scale, long life and low operating cost. By the end of 2020, the cumulative installed capacity of pumped storage in the global energy storage market reached 172.5GW, accounting for 90.3%. The cumulative installed capacity of pumped energy storage in China has reached 31.79 GW, accounting for 89.3% of China's energy storage projects. The main development direction of pumped storage technology is energy efficiency improvement of key components, system control optimization and intelligent linkage with the plant network. Many experts and scholars put forward the concept of underground pumped storage, which can reduce the environmental impact to a low level and is a potential future energy storage system. The key achievement of "Demonstration Platform of Variable Speed Pumped Storage Unit in wave Disturbance Environment", the national key RESEARCH and development program "Seawater Pumped Storage Power Station Prospective Technology Research Project" hosted by China Southern Power Grid, passed the expert review meeting in May 2021. It is believed that with the development of more and more new pumped storage technologies, there will be more demonstration projects to provide basic data and accumulate experience for future commercial promotion.
2. Electrochemical energy storage technology will develop rapidly
With the vigorous development of electric vehicle industry, the battery industry, its core component, has also been paid attention to and studied, thus driving the great development of battery energy storage power station. The scale of energy storage power stations using batteries is expanding, and the proportion of the electricity storage market is second only to pumped storage. At present, in the field of energy storage, especially electricity storage, pumped storage is the main energy storage, supplemented by battery storage. By the end of 2020, the installed scale of global electrochemical energy storage reached 14.2 gw, accounting for 7.5%. In terms of technology distribution, the cumulative installed scale of lithium ion battery in the global electrochemical energy storage is relatively large, reaching 13.1 gw, and the cumulative scale of both electrochemical energy storage and lithium ion battery has broken through 10 GW for the first time. The cumulative installed capacity of electrochemical energy storage in China is 3.28 gw, accounting for 9.2%. The newly installed power scale reaches 1.56 GW, and the annual increase exceeds 1 GW for the first time, ranking the first in the world, and the growth rate is much higher than that of pumped energy storage. At present, battery technology is still in the stage of rapid improvement. Besides pumped storage, lithium ion battery is a high application of energy storage technology, but there are also challenges such as high safety risks, high cost and complex control technology. The application of new electrochemical energy storage technologies, such as sodium ion batteries, will expand. During the "14th Five-year Plan", electrochemical energy storage will be focused on achieving essential safety, low cost and long life.
3. Compressed air energy storage is a potential means of energy storage
Compressed air energy storage uses air as medium and has the characteristics of large scale, long life and low operation and maintenance cost. The improved adiabatic and steam injection enthalpy compressed air energy storage technology has the advantages of expansibility, environmental protection and high energy storage efficiency, and can avoid the use of fossil fuels, with more significant economic advantages. Under ideal conditions, the energy storage efficiency of compressed air can reach more than 70%, and the construction cost is 3000 ~ 4000 YUAN/kw, which can even be competitive with pumped storage, but also has full location flexibility. At present, there are two compressed air energy storage power stations in commercial operation, namely Huntorf power Station in Germany and McIntosh Power Station in the United States. Because of the good application prospect, the governments of all countries strongly support the research of compressed air energy storage technology. In 2019, the world's first 10 megawatt advanced compressed air energy storage demonstration system passed the acceptance of the Ministry of Science and Technology in China. In addition, the first international 100 MW advanced compressed air energy storage project has been officially started in Zhangjiakou, and the national key RESEARCH and development program "10 MW advanced compressed air energy Storage Technology RESEARCH and Development and Demonstration" will be accepted in 2021. Compressed air energy storage technology in China will be transformed from theory and demonstration to small-scale commercial application. With the further explosion of distributed new energy generation, small and medium-sized compressed air energy storage projects will be developed in a wider range in the future.
In April 2021, the National Energy Administration issued the Guidance on Accelerating the Development of New Energy Storage (Draft), proposing: "Insist on diversified energy storage technology, and promote relatively mature new energy storage technology such as lithium ion battery costs continue to drop and the commercial scale application, compressed air, liquid flow battery long time energy storage technology into commercial development initial period, to speed up the flywheel energy storage, such as sodium ion battery technology to carry out large scale experiment and demonstration, demand oriented, Explore and carry out research and demonstration applications of hydrogen storage and other innovative energy storage technologies." Once again, it is clear that different energy storage technologies will meet the requirements of different duration and frequency of energy storage in typical application scenarios, and the goal of diversified development of energy storage technologies is proposed.
Build a diversified energy storage system to meet the needs of power system regulation
To new energy as the main body of the novel in the power system of power imbalance is diverse and different time scales and significant gradation, its causes, including new energy power generation randomness, load disturbance and a variety of factors such as fault, and show the seconds, minutes, hours or even quarter etc. Various levels of time scale. The energy storage system in the new power system needs to balance the power fluctuation of the new power system in time and coordinate with the grid regulation strategy to realize the safe and economical operation of the new power system. To achieve this goal, the energy storage system is required to have three functions.
1) Large capacity: The power support capacity of the energy storage system must be able to cover the large fluctuation of new energy generation power in the system, so it must have a large capacity;
2) Quick response: Energy storage systems generally support post-heuristic power and must have quick response capability;
3) Multi-level power support capability: the sources and characteristics of power imbalance in the new power system are very diverse, and the energy storage system should have strong multi-level support capability for all types of power imbalance.
The energy storage system with a single technical structure and control strategy is difficult to meet the above requirements, so it is necessary to build an intelligent diversified energy storage system, which is embodied in three aspects.
1) Technical diversity: Any power station with energy storage technology has its advantages and disadvantages. In order to meet diverse power support requirements, the energy storage system should include a variety of different types of energy storage power stations, and the capacity ratio of various energy storage power stations is consistent with the characteristics of the new power system.
2) Functional hierarchy: In order to realize the safe and economic operation of the new power system, the energy storage system needs multi-level power support capability. It is necessary to formulate targeted control strategies and plan different roles for energy storage power stations with various characteristics so that they can play specific roles in the system and realize the overall hierarchical matrix regulation of the energy storage system.
3) Intelligent digitalization: all energy storage stations in the power system are controlled by the grid center, forming a networked matrix energy storage system to achieve optimal configuration of energy storage stations and optimal control of power support. The traditional operation mode of energy storage power station is changed with digital technology, and the planning management and scientific decision-making of energy storage power station are driven by data, which is deeply integrated with the construction of digital power grid.
At present, pumped storage power station of China Southern Power Grid occupies an absolute dominant position, and battery storage and compressed air storage technologies are in the ascendant. Future energy storage system construction will rely on the construction of digital new power system, realize the coordination and cooperation between energy storage and power system through the integrated planning and optimization of source, network, load and storage, support large-scale new energy consumption and complex large power grid control, and support the transformation of energy structure. Efforts should be made to build a smart grid with "flexible and adjustable resources", "flexible and controllable" power flow and "resilient and recoverable faults", so as to contribute to the goal of carbon peak and carbon neutrality.
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