Current situation and technical conception of gravity energy storage power generation

The mountain gravity energy storage (MGES) proposed by IIASA Institute [45-46] mainly uses the terrain of steep mountainous areas to store energy through the potential energy of sand and gravel, as shown in Figure 4. When electricity is abundant, an electric system similar to a ski lift is used to lift containers filled with sand and gravel to the top of the mountain for storage. During peak power consumption, the sand and stone are transported back to the ground by gravity from the top to generate electricity by releasing the potential energy of the sand and stone. The institute believes that the mountain gravity energy storage system is a longer duration and larger scale energy storage method than the lithium battery energy storage system. Mountain gravity energy storage seems simple and easy, but the efficiency of the cable car system applied is not easy to improve, the comprehensive benefit of the energy storage power generation system may not be ideal, and the relevant technical solutions need to be developed.

2. Discussion on gravity energy storage power generation technology

By analogy with pumped storage technology, the gravity energy storage power generation scheme conceived in this paper is shown in Figure 5. The fluid "water" is replaced by a solid "heavy object", the upper and lower "reservoir" is replaced by the upper and lower "warehouse", and the "pumped storage unit" is changed into "gravity energy storage unit". When the power grid is low and there is a surplus of power, the transmission system (crane, transmission equipment, etc.) lifts the weight of the lower bin to the upper bin of the higher position, and converts the surplus electric energy into the potential energy of the weight to be stored and used. When power consumption peaks and power supply is insufficient, heavy objects fall in turn, converting the potential energy of heavy objects into mechanical energy and electrical energy, that is, through "electrical energy → mechanical energy → mechanical energy → mechanical energy → electrical energy", electricity storage and recycling are realized.

2.1 Theoretical capacity of gravity power generation

The energy storage power station involved in power system regulation must have a certain installed capacity, and the application scenario is bound to be limited if the capacity is too small. In addition, energy storage, power generation and other efficiency is the core index of energy storage technology, low comprehensive efficiency will lose the value of commercial development. Therefore, in order to study and develop gravity energy storage power generation technology, it is first necessary to find out the theoretical power generation capacity and the possible level of energy conversion efficiency under certain technical and economic conditions. By analogy with the basic formula of hydropower output, this paper discusses the scale and efficiency of gravity power generation theoretically.