In short, energy storage mainly refers to the storage of electrical energy. As mentioned above, in the vast majority of cases, electricity is generated and used immediately, mainly because it is not easy to store electricity directly. When storing electrical energy, it is necessary to convert it into other forms of energy for storage, and then convert other forms of energy into electrical energy when needed. This leads to problems such as complexity, high cost, and low efficiency in energy storage technology.
The purpose of energy storage is to use the stored electrical energy as a flexible regulated energy source, storing energy when the grid load is low and outputting energy when the grid load is high, for grid peak shaving and valley filling.
At present, electricity can only be stored under special circumstances, and the global installed capacity of energy storage power sources is about 90GW (GW is gigawatts, 1 gigawatt=1000 megawatts), accounting for about 3% of the total global installed capacity.
Equipping the power system with energy storage systems or devices is like equipping a mobile phone with a power bank. Store the electricity in advance for future use. Therefore, energy storage systems or devices are like a super ‘power bank’.
The recently put into operation Hebei Fengning Pumped Storage Power Station by State Grid is currently the world’s largest pumped storage power station in terms of installed capacity, energy storage capacity, and underground plant scale.