Flywheel energy storage is a type of physical energy storage that uses an electric motor to drive a flywheel to rotate at high speed in a vacuum. When needed, the flywheel's inertia drives a generator to produce electricity. It has advantages such as fast response speed, good power characteristics, and long service life.
Composition of flywheel energy storage
The flywheel energy storage system mainly consists of three parts: the rotor system, the support system, and the motor energy storage converter.
The rotor system is the basic structure of the flywheel energy storage system. Depending on the materials used, it can be divided into composite materials and steel flywheels.
When the flywheel rotates at a low speed (approximately 10,000 revolutions per minute), a steel flywheel is generally used, which can effectively improve the safety and stability of rotor operation. Currently, steel flywheels are the main type of flywheel used in my country's power grid energy storage products.
When the rotational speed is high (100,000 revolutions per minute), using lightweight but high-performance composite materials results in a cost that is far higher than that of steel flywheels.
Support systems can be mainly divided into three types: mechanical bearings, permanent magnet bearings, and electromagnetic bearings. They support rotor rotation, reduce frictional resistance, and ensure the entire device operates with minimal losses. Currently, mechanical bearing technology in my country is maturing and is the most widely used method.
The flywheel energy storage system has a built-in motor that can adjust between charging and discharging states. To achieve grid frequency regulation, a motor-driven energy storage converter is required. During charging, electrical energy is converted into mechanical energy, and during discharging, mechanical energy is converted back into electrical energy. The frequency is also converted to the grid frequency, allowing the AC power to be promptly input into the grid system, thus achieving the frequency regulation function.
In addition, vacuum and cooling are also important components of flywheel energy storage systems. Generally, the higher the electrical power of a flywheel energy storage system, the greater the cooling requirement. Insufficient cooling can lead to overheating of the flywheel, causing damage to the machine. Therefore, heat sinks are usually installed on the flywheel housing to increase the heat dissipation area and ensure the effective operation of the system.
Application scenarios
Due to its advantages such as fast response, high power, small footprint, and long lifespan, flywheel energy storage is generally used in many scenarios such as uninterruptible power supplies (UPS), rail transportation, automotive batteries, power grid frequency regulation, and power grid peak shaving.
Uninterruptible power supply: When the power grid experiences fluctuations, momentary interruptions, or intermittent interruptions, flywheel energy storage can provide emergency power instantly. At the same time, flywheel energy storage can continuously and rapidly charge and discharge deeply, which is irreplaceable by electrochemical energy storage.
Rail Transit: In August 2021, my country’s first megawatt-level flywheel energy storage device was put into use in Hebei as a railway traction substation. When the train brakes as it enters the station, it generates a huge amount of electricity to charge the flywheel energy storage system; when the train accelerates out of the station, the flywheel releases kinetic energy to the train.
Automotive batteries: In the early days, there were buses that were completely driven by flywheels. In addition, flywheel energy storage was also used in many Porsche race cars and achieved good results in the competition. However, due to its low battery capacity and low cost performance, it is not suitable for cars with long range. But its performance indicators and safety are suitable for cars. If its energy density can be improved in the future, it will have great development potential.
Grid peak shaving and frequency regulation: Due to the large fluctuations in energy sources such as wind power and photovoltaics, and the imbalance between power generation and consumption in the power grid, it is necessary to add peak shaving and frequency regulation power stations to the power grid. At present, my country's energy storage is mainly pumped storage, followed by electrochemical energy storage. Flywheel energy storage has advantages such as small size, high power, and no pollution, and has a very promising application prospect in the power grid. Currently, many institutions abroad have connected flywheel energy storage to wind power generation systems.
Currently, flywheel energy storage faces numerous challenges that limit its development. These include its high cost, requiring the development of economical and durable rotors; its short energy release time, with energy being depleted within tens of hours; and the excessive stress generated by the constant high-speed-low-speed transitions of the flywheel, potentially leading to tearing and safety issues.
Related listed companies
Stocks related to flywheel energy storage include Huayang Technology, Sinomach Heavy Equipment, Guangda Special Materials, Xiangtan Electric, Jiangsu Transportation Research Institute, Shaanxi Construction Engineering Group, and Power Investment Energy. The following is a summary of these companies' Q3 performance and the current status of flywheel energy storage development, compiled by Vico.com:
Huayang Energy (600348.SH): Currently, it has a production capacity of 200 sets of flywheel energy storage per year, with an annual production of about 50-60 sets. The downstream market is mainly high-power applications of 200KW-600KW. Two 600KW flywheel energy storage products have been delivered to Shenzhen Metro.
Sinomach Heavy Equipment (601399.SH): The company's flywheel energy storage product technology is maturing and is gradually upgrading to high-power, high-energy storage. Currently, 13 projects have been delivered, and 4 projects are under construction.
Guangda Special Materials (688186.SH): Currently conducting research and development on key components of high-power vacuum magnetic levitation flywheel energy storage rotors, aiming to achieve rotor energy storage capacity exceeding 200KWh, energy storage density exceeding 20Wh/kg, and safe service life exceeding 20 years.
Xiangdian Co., Ltd. (600416.SH): In May of this year, the first 1-megawatt flywheel energy storage device in my country, jointly developed by Qingdao Metro and Xiangdian Co., Ltd. and other units, was successfully installed, commissioned and connected to the grid at Wannianquan Road Station of Qingdao Metro Line 3.
Suzhou Transportation Research Institute (300284.SZ): The second-generation flywheel energy storage battery has completed its iterative design and is currently in trial production. It is expected that the prototype test will be completed by the end of this year. The flywheel battery weighs about 90 kg per kilowatt-hour, and the flywheel battery with a capacity of about 40 kWh weighs about 4-5 tons.
Shaanxi Construction Engineering Group (600248.SH): In September of this year, the world's first carbon dioxide + flywheel energy storage demonstration project in Deyang, Sichuan, undertaken by Shaanxi Construction Engineering Group, entered the final and commissioning stage. It covers an area of 18,000 square meters and has an energy storage capacity of 10MW/20MWh, which can store 20,000 kWh of electricity in 2 hours.
Power Investment Energy (002128.SZ): The company's Holingol Circular Economy Multi-Energy Complementary Technology Research and Application Innovation Demonstration Project includes a 3 MW hybrid energy storage research sub-project, which consists of three different technical routes, including 1 MW flywheel energy storage, 1 MW liquid-cooled lithium battery energy storage and 1 MW iron-chromium redox flow battery energy storage.
