Analysis of water synergy benefits of coal de-capacity in China

The closure/withdrawal of mines, as one of the important measures to implement the State Council’s “Opinions on supporting the coal industries to resolve excess production capacity and achieve destructive development”, and is of great significance to the optimization of the regional energy structure, reduction of carbon emissions and environmental protection. In order to assess the synergistic benefits of water resources generated in the process of coal de-capacity and reveal the spatial and temporal evolution characteristics of closure/withdrawal mines, the number and capacity of closure/withdrawal mines during 2016—2022 were investigated with coal de-capacity as the policy background. Based on the analysis of the spatial and temporal distribution characteristics of the closure/withdrawal mines, the water resources synergy benefits brought about by coal de-capacity was quantified by combining the water resources-related mine water, water consumption and wastewater discharges coefficients in the coal mining and washing stages. The results show that a total of 4027 mines were closure/withdrawal from coal-related provinces in China during 2016—2022, with a de-capacity of 875 million t. The number of mines closure/withdrawal is concentrated in the upper reaches of the Yangtze River, and the areas with high density of coal de-capacity are concentrated in the "Ji" bays of the Yellow River. Meanwhile, the total of wasted water resources reduced by coal de-capacity is about 3 billion t, higher than the volume of China’s fourth largest freshwater Honghu lake, generating socio-economic benefits of about 46.165 billion yuan. The areas with positive benefits of water synergy are mainly located in the water shortage areas such as Southwest China, North China and the Yellow River basin. This research quantifies the synergistic benefits of water resources for coal de-capacity and discusses the future direction of mine water resources utilization, with a view to providing scientific basis and data support for sustainable development and “double carbon” target for coal de-capacity.