Energy Storage Principles and Technology

Principles and Technology of Energy Storage are related as follows:

1.

The energy storage device composed of energy storage components and the grid access device composed of power electronic devices become the two major parts of the energy storage system. The energy storage device is important to realize energy storage, release or fast power exchange. Grid access device to achieve the energy storage device and the grid between the two-way transfer and conversion of energy to achieve power peaking, energy optimization, improve power supply reliability and power system stability and other functions.

The capacity range of the energy storage system is relatively wide, from tens of kilowatts to hundreds of megawatts; discharge time span, from milliseconds to hourly; wide range of applications throughout the power generation, transmission, distribution, power system; large-scale power energy storage technology research and application has just begun, it is a completely new subject, but also a hot area of research at home and abroad.

2, commonly used energy storage methods.

At present, energy storage technology important physical energy storage (such as pumped storage, compressed air energy storage, flywheel energy storage, etc.), chemical energy storage (such as various types of batteries, renewable fuel power batteries, liquid current batteries, supercapacitors, etc.) and electromagnetic energy storage (such as superconducting electromagnetic energy storage, etc.).

Physical energy storage in the most mature, the most common application is pumped storage, important for power system peak, fill the valley, frequency control, phase control, emergency standby, etc.. The release time of pumped storage can be from a few hours to a few days, and its energy conversion efficiency is 70% to 85%. The construction period of pumped storage power station is long and limited by the terrain, and the transmission loss is larger when the power station is far away from the power consumption area. Compressed air energy storage was realized as early as 1978, but due to the constraints of terrain and geological conditions, there is no large-scale promotion.

Flywheel energy storage utilizes an electric motor to drive the flywheel to rotate at high speed to convert electrical energy into mechanical energy to store, and the flywheel drives the generator to generate electricity when needed. Flywheel energy storage is characterized by long life, pollution-free, low maintenance, but lower energy density, can be used as a supplement to the battery system.

Chemical energy storage categories are more, the level of technological development and application prospects are also different:

1, battery storage is currently the most mature and reliable energy storage technology, according to the different chemicals used, can be divided into lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, sodium-sulfur batteries, etc.. Lead-acid batteries have mature technology, can be made into a large-capacity storage system, low unit energy cost and system cost, safe, reliable and good reuse, etc., and is currently the most practical energy storage system, has been widely used in small-scale wind power, photovoltaic power generation systems, as well as small and medium-sized distributed power generation systems.

But because lead is a source of heavy metal pollution, lead-acid batteries are not the future development trend. Advanced batteries such as lithium-ion, sodium sulfur, nickel-metal hydride batteries and other high-cost, large-capacity energy storage technology is still immature, the performance of the product is not yet able to meet the requirements of energy storage, and its economy can not be commercialized operation.

2, large-scale renewable fuel power cell investment, high price, cycle conversion efficiency is low, is not yet suitable for commercial energy storage system.

3, liquid current energy storage battery with high energy conversion efficiency, operation, maintenance costs and other advantages, is highly efficient, large-scale grid-connected energy storage, regulation of one of the technologies. Liquid current energy storage technology in the United States, Germany, Japan and the United Kingdom and other developed countries have demonstrative applications, China is still in the research and development stage.

4, supercapacitor is a new type of energy storage device emerged in the 1980s, due to the use of special materials to make electrodes and electrolyte, the storage capacity of this capacitor is ordinary capacitors 20 to 1000 times, while maintaining the traditional capacitor to release the energy of the advantages of the speed of the capacitor, it has been continuously applied to alpine meteorological stations, border posts and other power supply occasions.