120 / 2021-12-30 08:54:14

Evaluation of Carbon Dioxide Geological Sequestration Potential in Coal Mining Area

deep coal seam,residual coal,mined-out area,geological sequestration potential,source and sink matching,coal base

Resource Development and Utilization of Underground Space > 8. CO2 Geological Storage

Coal bases are the concentration areas of coal exploitation and use in China in which the carbon emission sources are concentrated, and carbon emission reduction is challenging. However, the carbon emission sources and geological sequestration sinks typically correlate well with coal bases, providing favorable conditions for clustering carbon capture, utilization, and storage (CCUS). CCUS is the only way for coal bases to achieve near-zero carbon emissions in the future. This study established the constitutive equations of CO₂ sequestration capacity for unexploited deep coal seams, residual coal in producing and abandoned mines, and mined-out areas based on their CO₂ sequestration form, geological background, and coal mining status. Then, the geological sequestration potential of one of the most important coal bases in east China was discussed according to the constitutive equations of CO₂ sequestration capacity by considering matching relationships between sequestration sources (coal-fired power plants) and sinks. The results showed that the coal base has excellent CO₂ geological sequestration potential. The total CO₂ sequestration capacity in coal seams is approximately 0.85 billion tons, including 0.76 billion tons in unexploited deep coal seams, 5.17 million tons in residual coal in producing and abandoned mines, and 82.45 million tons in mined-out areas. The source–sink matching relationships of CO₂ geological sequestration in the coal base provide favorable conditions for CCUS, and the average distance between the CO₂ sequestration sources and target sequestration sinks is only 10 km. The unexploited deep coal seams with buried depths of 1000–1500 m are primary reservoirs for CO₂ geological sequestration in the coal base. In the next 30 years, CO₂-enhanced coal bed methane recovery (ECBM) in unexploited deep coal seams and CO₂ sequestration in mined-out areas should become a special CCUS technology in the coal base due to their great CO₂ geological sequestration potential. CO₂-ECBM and CO₂ sequestration in mined-out areas are also significant for other coal bases in China.