In the new energy storage, lithium-ion batteries, especially lifepo4 battery occupy an absolute dominant position, accounting for 97%.
In addition, projects with compressed air energy storage, flow batteries, sodium ion batteries, flywheels and other technical routes have made breakthroughs in scale, and application modes have gradually increased.
1. Different technical routes
New energy storage mainly refers to energy storage projects that mainly use output electricity as the main form and provide services in addition to pumped storage. Due to the short construction period, flexible site selection and strong adjustment ability, it is more compatible with the development and consumption of new energy, and the advantages are gradually highlighted.
From the point of view of technical development, new energy storage is currently advancing in a variety of technologies. From the current node, six new energy storage routes, namely compressed air energy storage, flow battery energy storage, sodium ion battery energy storage, molten salt energy storage, gravity energy storage, and flywheel energy storage, are the most worthy of attention.
2. Compressed air energy storage
Compressed air energy storage is a form of mechanical energy storage. In the trough of the power grid, excess electrical energy is used to drive the compressor to produce high-pressure air. High pressure air is stored in the air storage chamber, and electrical energy is converted into air pressure potential energy.
The initial investment cost of compressed air systems mainly includes system equipment, land costs and infrastructure. The system equipment includes compressor unit, expander unit, heat storage system, electrical and control equipment, gas storage chamber, etc. Among them, the system equipment is the main part of the initial investment cost.
The industrial chain is divided into three parts: upstream equipment, midstream project engineering construction, and downstream power grid system investment and operation. At present, the development of compressed air energy storage is generally in the stage of demonstration verification and commercial promotion transition.
At present, 100 MW of compressed air demonstration projects have been completed in China. The downstream can be connected to the grid system, which plays the role of peak shaving and valley filling, renewable energy consumption, etc.
3. Flow battery energy storage
All-vanadium redox flow battery is a redox battery with vanadium as the active material and a circulating flow liquid, which realizes the storage and release of electrical energy through the valence change of vanadium ions in the electrolyte. At present, it can achieve more than 15,000 times of charging and discharging, and the service life is more than 20 years. This extremely long battery life, easy to adjust capacity size, and high security.
However, the energy density is low and the material cost is high. At present, the initial investment of all-vanadium redox flow batteries is about 3000-4000 RMB/KWh, and the cost is about twice that of lithium batteries. However, because the electrolyte does not degrade and the recycling rate is high, the residual value of all-vanadium redox flow batteries is high.
With the right business model, the problem of high initial investment in all-vanadium redox flow batteries can be solved. From the perspective of the industrial chain, electrolyte and stack are the core components of vanadium redox flow batteries. The main raw material of electrolyte accounts for about 41% of the total cost, so the price change of vanadium upstream has a large impact on the cost of the battery.
Stacks account for about 37% of the total cost, and most stacks are currently supplied in-house by vanadium battery manufacturers. Graphite felt electrode is the preferred material for all-vanadium flow electrodes, and the relevant electrode materials are prepared by optimizing the carbon fiber production process.
4. Sodium ion battery energy storage
Energy storage is a more suitable scenario for sodium ion batteries, and the core reason is that large-scale energy storage systems do not have high requirements for energy density and higher requirements for safety and economy. Among them, large-scale energy storage mainly includes wind power plants, solar power plants and home energy storage.
Compared to lithium-ion batteries, cathode materials, anode materials and current collectors for sodium-ion batteries have cost advantages. Therefore, sodium ion battery systems have stronger bidding advantages on the power grid side and power supply side, and can effectively improve the penetration rate of distributed power sources and improve the stability and economy of distribution network operation.
At present, the top 10 sodium-ion battery companies in the world have attracted a lot of attention. One type is the leading lithium battery companies led by CATL, which have the advantages of rapid large-scale start-up and stable upstream and downstream customer structure, which is conducive to its rapid seizure of the sodium electricity market.
CATL released the first generation of sodium-ion batteries in 2021 and is expected to industrialize in 2023. The other category is leading-edge companies focusing on the research and development of sodium ion batteries. Its research and development base is strong, involving batteries, cathodes and anode, electrolyte, separator and other fields, mass production in the forefront of the world, with the potential to open up the market first.
5. Molten salt energy storage
Thermal energy storage mainly refers to molten salt energy storage, which is a high-capacity, long-term (six to eight hours) energy storage technology path. At present, it is mainly used in the field of solar thermal power generation and flexible transformation of thermal power units. Due to the large scale, molten salt energy storage on the grid side can store abandoned wind and solar power and valley power, carry out new energy consumption, and improve the flexibility of power plants.
The user side can be directly involved in clean heating and industrial steam supply. As a heat transfer medium, molten salt can realize the conversion of solar energy to thermal energy, and as an energy storage medium, it can realize the two-way conversion of heat energy and electric energy, which can well adapt to and solve the above two contradictions.
After the cultivation of solar thermal power generation distribution and storage market, the development of molten salt heat storage industry chain is relatively mature. The upstream of molten salt heat storage is mainly concentrated equipment, heat absorbing materials, heat storage materials, etc.
The downstream power generation and heating side can either cooperate with the power company to generate electricity, or directly cooperate with the heat company to provide heat. Molten salt energy storage industry chain: With favorable policies and the vigorous development of new energy storage, molten salt energy storage, as an emerging subdivision of energy storage, is expected to usher in development space.
6. Flywheel energy storage
Flywheel energy storage is the use of the flywheel's high-speed rotation to store electrical energy in the form of mechanical energy. Compared with other energy storage methods, flywheel energy storage has the performance advantages of large energy storage density, deep energy discharge density and fast response, and has technical advantages such as safety, reliability, low maintenance and no pollution.
However, flywheel energy storage also has great limitations, low relative energy density, large static loss, and is only in the early stages of commercialization. At present, China's flywheel energy storage has not been fully promoted. There are currently mainly in the extensive experimental stage, small prototypes have been successfully developed and applied to practical examples, and the trend of developing mainframes is developing.
Flywheel energy storage technology is mainly concentrated in flywheel frequency regulation power stations, UPS and other fields, and has been used on a certain scale. With the maturity of technology and the reduction of prices, flywheel energy storage is expected to become a new revolution in the field. Under the background of dual carbon, the rapid growth of renewable power generation will be the fastest growing new energy sector in the next few years.