Physical energy storage refers to the storage of energy using physical methods such as pumping water, compressed air, and flywheels, which has the advantages of being environmentally friendly and green.
1. Pumped hydro storage: A form of energy storage that converts electrical energy into gravitational potential energy.
Pumped hydro storage is a form of energy storage in which water is pumped from the lower reservoir to the upper reservoir during periods of low electricity load, converting electrical energy into gravitational potential energy for storage. Its overall efficiency is between 70% and 85%, and it is used for peak shaving and valley filling, frequency regulation, phase regulation, and emergency backup in power systems.
Pumped hydro storage can release energy in a time that can range from a few hours to a few days, with an overall efficiency between 70% and 85%. It is mainly used for peak shaving and valley filling, frequency regulation, phase regulation, and emergency backup in power systems.
2. Compressed air energy storage: an energy storage method that drives steam turbines to generate electricity.
Compressed air energy storage refers to an energy storage method that uses electrical energy to compress air during periods of low grid load and releases the compressed air to drive a steam turbine to generate electricity during periods of high grid load. The main types include traditional compressed air energy storage systems, compressed air energy storage systems with thermal storage devices, and liquid-gas compressed air energy storage systems.
Compressed air energy storage systems come in various forms and can be classified according to their working medium, storage medium, and heat source: traditional compressed air energy storage systems (which require fossil fuel combustion), compressed air energy storage systems with heat storage devices, and liquid-gas compressed energy storage systems.
3. Flywheel energy storage: An energy storage method that converts electrical energy into kinetic energy and stores it.
Flywheel energy storage refers to an energy storage method that uses an electric motor to drive a flywheel to rotate at high speed, and then uses the flywheel to drive a generator to generate electricity when needed. Its technical characteristics include high power density and long lifespan.
The flywheel body is the core component of the flywheel energy storage system. Its function is to increase the rotor's limiting angular velocity, reduce the rotor's weight, and maximize the energy storage capacity of the flywheel energy storage system. It is mostly made of carbon fiber materials.
Physical energy storage has advantages such as large scale, long cycle life and low operating cost, but it requires special geographical conditions and sites, which limits its construction. In addition, the one-time investment cost is high, making it unsuitable for small-capacity off-grid power generation systems.
