Potential assessment of CO₂ source/sink and its matching research during CCS process of deep unworkable seam

It is of great significance for the engineering popularization of CO₂-ECBM technology to evaluate the potential of CCUS source and sink and study the matching of pipeline network of deep unworkable seam. In this study, the deep unworkable seam was taken as the research object. Firstly, the evaluation method of CO₂ storage potential in deep unworkable seam was discussed. Secondly, the CO₂ storage potential was analyzed. Then, the matching research of CO₂ source and sink was carried out, and the pipe network design was optimized. Finally, suggestions for the design of pipe network are put forward from the perspective of time and space scale. The results show that the average annual CO₂ emissions of coal-fired power plants vary greatly, and the total emissions are 58.76 million tons. The CO₂ storage potential in deep unworkable seam is huge with a total amount of 762 million tons, which can store CO₂ for 12.97 years. During the 10-year period, the deep unworkable seam can store 587.6 million tons of CO₂, and the cumulative length of pipeline is 251.61 km with requiring a cumulative capital of $ 4.26 × 10¹⁰. In the process of CO₂ source-sink matching, the cumulative saving mileage of carbon sink is 98.75 km, and the cumulative saving cost is $ 25.669 billion with accounting for 39.25% and 60.26% of the total mileage and cost, respectively. Based on the three-step approach, the whole line of CO₂ source and sink in Huainan coalfield can be completed by stages and regions, and all CO₂ transportation and storage can be realized. CO₂ pipelines include gas collection and distribution branch lines, intra-regional trunk lines, and interregional trunk lines. Based on the reasonable layout of CO₂ pipelines, a variety of CCS applications can be simultaneously carried out, intra-regional and inter-regional CO₂ transport network demonstrations can be built, and integrated business models of CO₂ transport and storage can be simultaneously built on land and sea. The research results can provide reference for the evaluation of CO₂ sequestration potential of China's coal bases, and lay a foundation for the deployment of CCUS clusters.