Energy storage technologies offer a viable solution to provide better flexibility against load fluctuations and reduce the carbon footprint of coal-fired power plants by minimizing exergy losses, thereby achieving better energy efficiency.
At present, large-scale energy storage technology is not yet mature. Improving the flexibility of coal-fired power plants to suppress the instability of renewable energy generation is a feasible path. Thermal energy storage is a feasible technology to improve the flexibility of coal-fired power plants.
The underground space resources of abandoned coal mines in China are quite abundant, and the research and development of underground space energy storage technology in coal mines have many benefits.
However, the key issues, such as the uneven heat transfer of the system and the corrosion and scaling of the heat transfer medium, need to continue to be addressed. (3) The potential for compressed air energy storage in coal mines' underground spaces is enormous, and it can be used with less costly excavation.
The use of coal mining space for electrochemical energy storage has not yet been commercialized [ 95 ], and four key problems still need to be broken through, namely, site safety evaluation of underground space for coal development, construction of electrochemical energy storage geological bodies.
Various energy storage technologies and risks in coal mine are analyzed. A significant percentage of renewable energy is connected to the grid but of the time-space imbalance of renewable energy, that raises the need for energy storage technologies.