Energy storage technology primarily refers to the storage of electrical energy. The stored energy can be used as an emergency energy source, or it can be used to store energy when the load on the grid is low and output energy when the grid is high, for peak and valley reduction and to mitigate grid fluctuations. Energy comes in many forms including radiant, chemical, gravitational potential, electrical potential, electrical, high temperature, latent heat and power. Energy storage involves converting difficult forms of energy into more convenient or economically storable forms.
The technological development of China’s energy storage industry began in the 1960s with the study of pumped storage power stations and the establishment of the first hybrid pumped storage power station, the Gangnan Hydropower Station; in the 1990s, the construction of pumped storage power stations came to a climax; in the early 21st century, China began to study other energy storage technologies, including compressed air energy storage and electrochemical energy storage, and accelerated after 2010. In the early 21st century, China began to research other energy storage technologies, including compressed air energy storage and electrochemical energy storage, and after 2010 accelerated the implementation of energy storage technologies such as compressed air and all-vanadium liquid flow batteries, accelerating the diversification of energy storage technologies.
According to the different storage media of different energy storage technologies, energy storage is mainly divided into mechanical energy storage, electrochemical energy storage, thermal energy storage, chemical energy storage, electromagnetic energy storage and so on. Using these energy storage technologies, electrical energy is stored in the form of mechanical, chemical and thermal energy, and fed back into the power network in due course.
Classification of energy storage technologies:
Mechanical energy storage
Mechanical energy storage is used in the form of pumped storage, compressed air storage and flywheel energy storage. The most mature form of large-scale energy storage is pumped storage, the basic principle of which is to use excess power in the low valley of the grid to pump water as a liquid energy medium from a low elevation reservoir to a high elevation reservoir, with the water in the high elevation reservoir flowing back to the lower reservoir to drive a turbine generator to generate electricity when the grid is at peak load.
Electrical energy storage
Electrical energy storage is used in the form of supercapacitor energy storage and superconducting energy storage. Superconducting energy storage is a device that uses the zero resistance of superconductors to store electrical energy. It can not only store electrical energy without loss in superconductor inductor coils, but also exchange active and reactive power quickly with external systems through power electronic converters, which can be used to improve the stability of power systems and improve the quality of power supply.
Electrochemical energy storage
Electrochemical energy storage mainly includes a variety of secondary batteries, including lead-acid batteries, lithium-ion batteries, sodium-sulphur batteries and liquid-flow batteries. Most of these batteries are technically mature and have become the focus of attention in recent years, with many practical applications.
Thermal energy storage
In a thermal energy storage system, thermal energy is stored in the medium of an insulated container and can be converted back to electrical energy when needed later, or it can be used directly without being converted back to electrical energy. There are many different technologies for thermal energy storage, which can be further divided into sensible thermal storage and latent thermal storage.
Chemical energy storage
Chemical energy storage mainly refers to the use of hydrogen or synthetic natural gas as a secondary energy carrier. Hydrogen is obtained by using the wind power to be discarded to produce hydrogen, by decomposing water into hydrogen and oxygen through electrolysis of water. Hydrogen can later be used directly as a carrier of energy, and then hydrogen is reacted with carbon dioxide to become synthetic natural gas (methane), using synthetic natural gas as another secondary energy carrier.
