China, as a major pumped storage country, has entered a peak period of development

China, as a major pumped storage country, has entered a peak period of development



Pumped storage is a large-scale energy storage method that involves energy storage through the conversion of electrical energy to water potential energy. Pumped storage is the process of converting electrical energy into the potential energy of upstream reservoir water during low electricity consumption periods, and converting the potential energy of water into electrical energy through a hydroelectric generator during peak electricity consumption periods. The total amount of energy stored is proportional to the drop and volume of the reservoir.



Pumped storage power stations have a history of 140 years since their inception in 1882. China began the construction of pumped storage power stations in the 1960s and 1970s. During the 12th and 13th Five Year Plans, in order to adapt to the rapid development of new energy and ultra-high voltage power grids, the development of pumped storage energy has reached a new peak. As of the end of 2020, the installed capacity of pumped storage in operation worldwide was 172.5 million kilowatts, of which China's installed capacity of pumped storage reached 31.49 million kilowatts, accounting for over 18%, ranking first in the world.




Pumped storage: mature technology but limited construction, demand and electricity pricing mechanisms are the main factors restricting development



Pumped storage is currently the largest (GW level) energy storage technology, with the most mature technology, the longest service life (about 50a), and the best economic efficiency (cost per kilowatt hour of electricity is 0.21-0.25 yuan/kWh). This low absorption and high generation energy storage mode is mainly applied in situations such as peak shaving and valley filling, frequency modulation and phase modulation, emergency backup, and black start of the power grid. It can achieve "water light complementarity", effectively regulate the dynamic balance of the power system, and improve the comprehensive operating efficiency of the power grid system by 70% to 85%.



Based on its mature technology, multiple cycles, long service life, and low losses, the cost advantage of pumped storage power stations is relatively large. However, the total amount of pumped storage energy resources is limited, the selection of station sites is limited by geographical conditions, the construction period is long, and the investment cost is increasing year by year. The demand and electricity price mechanism are the main factors restricting the development of pumped storage.




Flywheel energy storage: in the development stage, and future applications require breakthroughs



Among the current energy storage technologies suitable for large-scale commercial operation, flywheel energy storage has comprehensive advantages such as high power density, fast charging and discharging response speed, long service life, large discharge depth, no environmental pollution, low operating cost, and low safety risk, making it very suitable for fast and high-power charging and discharging applications.



From the current development of flywheel energy storage technology, most of the flywheel energy storage applications in the Chinese market are pilot products, with few mature operating products, low operating power, extremely short backup time, and some technical performance needs to be further improved. There is an urgent need for innovation and breakthroughs in system capacity, conversion rate, service life, security, and other aspects. At the same time, the commercialization of flywheel energy storage still faces problems such as high costs, lack of price incentive policies, immature technical routes, and a lack of technical specifications and access standards.




Compressed air energy storage: The promotion of new technologies has significantly improved efficiency and established conditions for large-scale commercialization



The compressed air energy storage system is a system that uses high-pressure air pressure energy as the form of energy storage and generates electricity through the expansion of high-pressure air when needed. The efficiency improvement space of traditional compressed air energy storage systems is very limited. Domestic and foreign scholars have developed various new types of compressed air energy storage technologies by using methods such as optimizing thermal cycles on the basis of traditional compressed air energy storage. The promotion of new technologies has significantly improved efficiency, and the efficiency and cost have been comparable to pumped storage, forming the conditions for large-scale commercialization.