Energy storage via storing flood in abandoned mines and low temperature heat energy utilization from mine water

The utilization of underground space in abandoned mines is a key direction supported by the coal industry. By combining underground space utilization, flood storage, and heat supply in winter, this paper proposes a comprehensive utilization model of flood storage and heat extraction in the abandoned mine, based on three technologies: ground flood diversion, underground flood storage and heat pump. This paper addresses the concept, key technologies and scientific issues of the model. The distribution of abandoned mines in China and its relationship with precipitation distribution were analyzed. The potential for flood and energy storage in abandoned mine was also studied. Results showed that 13 provinces, including Anhui, Henan, and Shandong province, can utilize approximately 60 million cubic meters of underground space and store nearly 6 volumes of West Lake water, making it suitable for engineering demonstration of flood storage and heat extraction in abandoned mines. Among them, five abandoned mines in Huainan mining area can utilize approximately 300 000 cubic meters of underground space, with energy storage capacity of up to 94 500 GJ that can meet the heating demand of 210 000 square meters. Taking Qishan Mine as an example, a scheme was designed based on ground flood diversion and storage, underground water storage, and mine water extraction and utilization. According to preliminary calculations, the heating power of Qishan Mine can reach 6 835 kW which can provide heating for 136 700 square meters of buildings, reduce carbon dioxide emissions by about 5 330 tons, and save 3.507 5 million yuan. This demonstrates the feasibility of flood and energy storage in abandoned underground space. Research showed that the comprehensive utilization model of flood storage, energy storage, and heat extraction in abandoned mines can not only effectively utilize the underground space of abandoned mines but also alleviate local flood disasters during the flood season. It can develop low-grade clean energy in mine water and has certain significance in improving the added value of underground space utilization in abandoned mines and promoting the utilization of underground space in abandoned mines.