Solid gravity energy storage: A review

Large-scale energy storage technology is crucial to maintaining a high-proportion renewable energy power system stability and addressing the energy crisis and environmental problems. Solid gravity energy storage technology (SGES) is a promising mechanical energy storage technology suitable for large-scale applications. However, no systematic summary of this technology research and application progress has been seen. Therefore, the basic concept of SGES and conducted a bibliometric study between 2010 and 2021 is first introduced to show SGES technology's evolution and predict future trends. Various SGES technologies have been intensively investigated in equipment, principles, materials, progress, and mathematical models. Furthermore, the key equipment's impact on SGES is discussed, and a systematical classification of SGES's different technical routes is conducted. Based on the technical characteristics, the advantages and disadvantages of SGES's different technical routes are discussed through their comparison. The decision tree is made for different technical route selections to facilitate engineering applications. Moreover, this paper also proposed the evaluation method of large-scale energy storage technology and conducted a comparative analysis of solid gravity energy storage with other large-scale energy storage technologies. Compared with other large-scale energy storage technologies, SGES has many advantages: high cycle efficiency (80 %-90 %), large energy storage capacity (up to several GWh), good geographical adaptability, and economy. Finally, the SGES's possible application scenarios and market scale assessment are presented based on SWOT analysis.