Recent Advances in Carbon Dioxide Sequestration in Deep Unmineable Coal Seams Using CO2-ECBM Technology: Experimental Studies, Simulation, and Field Applications

CO2-enhanced coalbed methane (CO2-ECBM) technology helps to store CO2 while producing a clean source of energy (CH4) through the sorption process. This technique can sequester much CO2 at low temperatures and pressures while recovering CH4, which will help offset the associated costs, such as capturing injection gases, drilling and completion infrastructure, compression, and injection expenses. This review paper critically analyzes the CO2 sequestration potentiality in deep unmineable coal seams. The results revealed that, despite several researchers' insights from proposed concepts, experimental data, modeling and simulations, and pilot tests, there are no reported full field CO2-ECBM technology applications for CO2 sequestration and CH4 recovery because implementing the projects is uneconomical. Also, CO2 sequestration and CH4 recovery effectiveness on coal seams depend on wettability changes of the CO2–H2O–coal system. The identified research gaps and challenges in this paper are going to help various researchers and shareholders in conducting extra investigations toward full field application of CO2 sequestration while simultaneously producing a clean source of energy (CH4) in deep unmineable coal seams to meet the Paris climate summit agreement to achieve net zero emissions by 2050 and a maximum global temperature rise of 1.5 °C.