People who care about new energy sources such as wind power and photovoltaic will know that the bottleneck of new energy is actually largely energy storage. The energy of wind and light is abundant, but it is very unstable, for example, when the wind is not blowing, there is no wind power, and when the sun is not out, there is no photovoltaic. Connecting such unstable electricity to the grid is a huge difficulty. In September 2021, many parts of the country experienced power cuts, partly because some places with large numbers of wind turbines happened to be without wind for several days in a row, dragging the power grid to the brink of collapse. Therefore, the biggest problem of new energy is not that it cannot generate electricity, but that it cannot be saved. If there is an efficient and safe energy storage technology, these unstable energy ** can be stored, and then used smoothly, which can greatly improve the utilization rate of new energy.
So, what is the level of China's energy storage technology in the world? Recently, I saw a very detailed review article "Research Progress of Energy Storage Technology in China in 2021", written by Dr. Chen Haisheng, a researcher at the Institute of Engineering Thermophysics of the Chinese Academy of Sciences and director of the Energy Storage Committee of the China Energy Research Society, and others. Through a review and analysis of basic research, key technologies and integrated demonstration, they summarized the main progress of China's energy storage technology in 2021, including pumped hydro storage, compressed air energy storage, flywheel energy storage, lead-acid batteries, lithium-ion batteries, flow batteries, sodium-ion batteries, supercapacitors, new energy storage technologies, integrated technologies and fire safety technologies. Here are a few excerpts.
In terms of basic research, the number of "energy storage" as the subject word in the Web of Science database can be counted. In 2021, a total of 26,510 such articles were published around the world. Among them, China published 11,949 articles, accounting for 45%, ranking first, far ahead of the second place United States with 3,336 articles and the third place India with 2,420 articles, more than the sum from second to seventh! In this sense, China has become the most active country in the world in basic research on energy storage technology.
Looking at the sub-technologies, in all individual technologies such as pumped storage, compressed air, heat storage, flywheels, lead-acid batteries, lithium-ion batteries, sodium-ion batteries, flow batteries, supercapacitors, liquid metals, metal-ion batteries and aqueous batteries, China ranked first in the world in terms of the number of ** published in 2021.
You can also see the change of ** number over time. From 2010 to 2021, the number of publications in the field of energy storage has increased significantly in all major countries, such as the United States from 1,223 to 3,336 and China from 684 to 11,949. In 2010, China's ** number was only half that of the United States, but in 2013 it surpassed the United States, and then it was **-style growth, far behind other countries. After 2017, the number of ** articles in the United States per year has basically stabilized at about 3,500 articles, while China is still growing significantly, which is completely consistent with the situation that China's ** and enterprises have increased their support for energy storage technology research and development during the "12th Five-Year Plan" and "13th Five-Year Plan" period.
Table 1 summarizes China's key technological progress and integrated demonstration progress in various energy storage technologies in 2021, such as the "world's largest pumped storage power station with installed capacity" in pumped storage, and the "grid-connected power station in Feicheng International, Shandong Province, the first 10 MW salt cavern advanced compressed air energy storage commercial demonstration power station" in compressed air energy storage.
These technical routes can be divided into three categories.
The first category is basically mature technology, which mainly includes pumped hydro storage, lead-acid batteries and heat and cold storage. The focus of their development is to further improve the performance of the existing technology.
The second category is integrated demonstration technology, which mainly includes lithium-ion batteries, flow batteries, compressed air energy storage and flywheel energy storage. The focus of their R&D is to break through specific key technologies from integrated demonstration to industrial application. Among these four technologies, the research and development of lithium-ion battery technology is the most active, and the number of demonstration projects is also the most, and it is also the technology closest to mature technology and complete industrial chain.
The third category is the technology based on the research and development of key technologies, mainly including sodium-ion batteries, supercapacitors, liquid metals, metal-ion batteries and aqueous battery technologies. The focus of their research and development is to break through the key technologies of materials, monomers, and modules, and realize the transformation from laboratory technology to integrated demonstration. Among these five technologies, sodium-ion batteries have made a number of technological progress, and a demonstration of 1 MW·h was also achieved in 2021, which is the emerging energy storage technology that has attracted the most attention. The research of supercapacitors is also very active, and the demonstration application of large-scale energy storage has been realized in 2021, which is also worth paying attention to.
Figure 5 shows that the various energy storage technologies can be divided into four echelons in terms of installed capacity. The first echelon is pumped storage, with a single unit scale of more than 100 MW, accounting for 79% of the new installed energy storage capacity in the country in 2021. The second echelon is lithium-ion batteries, compressed air energy storage, flow batteries, lead-acid batteries, and heat and cold storage, with a single unit scale of up to 10 100 MW. Among them, the new installed capacity of lithium-ion batteries has reached 18%, and it is possible to form a separate echelon in the future. The third echelon is sodium-ion batteries, flywheel energy storage and supercapacitors, and the current scale of a single unit can reach MW level. Among them, the development of sodium ion has attracted the most attention, and after a period of development, it is possible to enter the second echelon in the future. The fourth echelon is new energy storage technologies such as liquid metal, metal-ion batteries and aqueous batteries, which require further research and development to achieve integrated demonstration and industrial application as soon as possible.
Figure 6 is one of the most interesting graphs I have seen, drawing a comparison between the international level and the domestic level on each technical route. At a glance, it can be seen that in most technical routes, the international and domestic levels are very close, and only the flywheel energy storage, supercapacitors and pumped storage have a large gap. On the other hand, the domestic level is higher than that of the international in some fields, including compressed air energy storage, flow batteries and sodium-ion batteries.
Finally, a few excerpts from the outlook. The basic summary is that China has become the most active country in the world in basic research on energy storage technology, and has also become one of the main core countries in the world for energy storage technology research and development and demonstration.
In terms of pumped storage, China has achieved leapfrog development in the construction, design, manufacturing, installation and commissioning of ultra-high head and ultra-large capacity pumped storage power stations. In terms of fixed-speed pumped storage technology, it has realized the transformation from following and running to leading, and has reached the world's leading level; In terms of variable speed pumped storage technology, China is still in the stage of exploration and research, although some achievements have been made, there is still a big gap with foreign technology.
In terms of compressed air energy storage, China has made a number of milestones in the 10 100 MW compressed air energy storage system. In particular, the Zhangjiakou International First 100 MW Advanced Compressed Air Energy Storage National Demonstration Project of the Institute of Engineering Thermophysics of the Chinese Academy of Sciences was connected to the grid and debugged, indicating that China has reached the international leading level in the field of compressed air energy storage.
In terms of lithium-ion batteries, China has made important breakthroughs in key technologies such as cathode and anode materials, fast charging technology, and solid-state battery technology.
In terms of sodium-ion batteries, as the closest battery technology to lithium-ion batteries, China has made important progress in the basic research, technical level and integrated demonstration of sodium-ion batteries, and has been in a leading position in the world.
In terms of supercapacitors, China has carried out full-chain technical research in key materials, monomer technology, group control, system integration and application, and service performance, and has achieved demonstration in the field of large-scale energy storage.
Looking ahead to 2022, China's pumped storage, lithium-ion batteries, compressed air, flow batteries, sodium-ion batteries and other technologies will develop rapidly, and large-scale integrated demonstration projects of 100 megawatts will become the norm. Driven by the dual-carbon strategy, China's energy storage technology is expected to continue to "accelerate".