Study on off-season cyclic energy storage in underground space of abandoned mine

With the proposal of the goal of “carbon peaking and carbon neutralization” in China, the proportion of coal in the primary energy consumption structure will gradually decrease, and the number of closed mines will increase year by year.Directly closing or abandoning mines not only causes a huge waste of resources, but also very likely induces a series of safety, environmental and other problems.It is necessary to put forward the development and utilization patterns of surplus resources in line with the current situation of abandoned mines in China.Based on this, the current situation of development and utilization of abandoned mines worldwide is expounded systematically, focusing on the utilization mode of underground energy storage of abandoned mines, and the off-season cycle energy storage process system of abandoned mines is put forward.The system fully considers the underground space resources, geothermal resources, water resources and aboveground renewable resources of abandoned mines, and provides electric energy for surrounding users by arranging photovoltaic and wind power generation equipment at the subsidence area.Taking the constant temperature rock and soil mass in the underground roadway group and goaf as the energy storage space, using the mine water as energy storage medium, the system provides heat/cooling for surrounding users through photovoltaic heat collection and geothermal energy resources, and stores heat energy underground in the season without heating/cooling, realizes off-season cyclic energy storage.Three key technologies of underground off-seasonal cyclic energy storage in abandoned mines are discussed with a view to be solved, namely a multi-scale spatial heat storage evaluation method, an overall optimization design method of off-seasonal cyclic energy storage in abandoned mines, and a multi-source coupling operation mode of off-seasonal cyclic energy storage.Taking the abandoned mine of Wangping Village in the west of Beijing as an example, the energy saving and emission reduction benefits of the system are studied, the results show that compared with traditional fossil fuels, the application of an off-seasonal cycle energy storage system for heating and cooling can reduce carbon dioxide emissions by approximately 2 781.1 t/a.If solar energy and wind energy collector power generation systems are added, the effect of energy saving and emission reduction will be more obvious.Great attention should be paid to the development and utilization of abandoned mine resources, and the scientific research on the development and utilization of abandoned mine resources should be strengthened.Relevant departments and mining enterprises should actively and steadily promote the green and low-carbon development and utilization of abandoned mines, increase the proportion of renewable clean energy utilization, control the total amount and intensity of carbon emissions, so as to provide assistance for the realization of the national goal of “carbon peak and carbon neutrality”.