Gravity energy storage is a kind of mechanical energy storage. Its energy storage medium is mainly divided into water and solid matter. The charging and discharging process of the energy storage system is realized by lifting the energy storage medium based on the height drop. Because of the strong fluidity of water, the water medium gravity energy storage system can rely on well sealed pipelines, shafts and other structures. Its site selection flexibility and energy storage capacity are limited by the terrain and water source. It is easier to build a large-scale energy storage system near the natural water source. Solid weight type gravity energy storage mainly relies on mountains, underground shafts, artificial structures and other structures. Heavy objects generally choose materials with high density, such as metal, cement, sand and gravel, so as to achieve high energy density.
Water medium energy storage system mainly uses electric generator and water pump turbine to convert potential energy and electric energy. Generally, it is controlled by water valve, electric generator current and other parameters to realize the charge and discharge process. The solid weight energy storage system mainly uses the crane, cable car, rail train, winch, crane and other structures to control the lifting and falling of the weight. The power conversion system mainly includes the electric generator and mechanical transmission system, which is controlled by the current and other parameters of the electric generator to realize the charge and discharge process.
British Energy Magazine, volume 190, 2020, "the drop of pumped storage power station is limited to 1200 meters, while the drop of mountain gravity energy storage can exceed 5000 meters". "The annual cost of energy storage in the system is between $50 and $100 per megawatt hour. The greater the drop between the lower and upper storage stations and the steeper the mountain, the lower the cost of energy storage." "Mountain gravity energy storage is combined with hydropower. If there is a river on the mountain where the mountain gravity energy storage power plant is built, the container can be filled with water instead of sand or gravel. This creates a mixed mountain gravity energy storage hydropower station, and the feasibility of the project is greatly improved. The advantage of mountain gravity energy storage system is that it can add water at any height of the system, use water at different heights in the mountain, and build a reservoir to improve mountain gravity Energy storage potential of energy storage system. "
