Principles of large-scale energy storage mainly include the following main technologies:
Pumped storage: Pumped storage is a form of large-scale power energy storage that achieves energy storage through the kinetic energy of water in upstream and downstream reservoirs. During the low load period, the water in the downstream reservoir is transferred to the upstream reservoir for storage; during the peak load period, the water energy of the upstream reservoir is used to generate electricity. This technology has the characteristics of large power generation capacity, long continuous discharge time (up to several days) and high efficiency, and is suitable for power system peak regulation and backup power supply occasions.
Compressed air energy storage: Compressed air energy storage achieves energy conversion by compressing air. During the low power consumption period or non-peak period, electric energy is used to compress air and store it; when needed, the compressed air is heated to expand it and drive the steam turbine generator to generate electricity. This technology has the advantages of safety and long life, and is suitable for distributed energy storage and load balancing, but the site selection is difficult.
Flywheel energy storage: Flywheel energy storage uses the principle of flywheel rotation power generation to convert electrical energy into mechanical energy storage of the flywheel, and releases mechanical energy to drive the generator to generate electricity when needed. This technology is mature and has a long service life, but it has low energy density and high cost. It is suitable for UPS power supply and primary frequency modulation of power system.
Superconducting magnetic energy storage: Superconducting magnetic energy storage uses zero-resistance superconducting magnetic materials to make coils to convert electrical energy into magnetic energy storage. This technology has the advantages of high conversion efficiency, high equipment integration, and strong controllability, and is suitable for large-capacity energy exchange and power compensation.
Gravity energy storage: Gravity energy storage uses gravity blocks to lift for "charging" and puts down gravity blocks to generate power when needed. This technology has low cost, long life and no self-discharge problem, but the technology is not yet fully mature.
Lithium battery energy storage: Lithium battery energy storage uses the migration of lithium ions between positive and negative electrodes to store and release electrical energy. This technology is highly mature and suitable for large-scale grid energy storage, but the cost is relatively high.
These large-scale energy storage technologies have their own advantages and disadvantages and are suitable for different application scenarios. For example, pumped storage is suitable for long-term large-capacity energy storage, while flywheel storage is suitable for short-term high power demand. With the continuous advancement of technology and the expansion of application scenarios, large-scale energy storage technology will play an increasingly important role in energy management and power system stability.