Why is carbon dioxide difficult to remove from coal plant flue gas?

Removing carbon dioxide (CO₂) from coal plant flue gas is challenging primarily due to the low concentration of CO₂ in the gas stream, which typically ranges only up to about 14 percent. Because the CO₂ is diluted by other gases, extracting it requires significant investments in specialized pollution-control equipment and chemical solvents, making the process expensive.1

Techniques such as post-combustion capture involve using solvents to selectively separate CO₂ from the flue gas, followed by heating the mixture in recovery columns to isolate the gas for compression. These processes are energy-intensive and require substantial infrastructure, such as scrubbers and piping, to be retrofitted onto existing power plants. While alternative methods like pre-combustion capture or oxyfuel combustion can offer higher CO₂ concentrations or easier separation, they often involve even higher capital costs for new gasification infrastructure or specialized equipment to handle high combustion temperatures and oxygen separation. Ultimately, the economic burden of these technical requirements remains a major barrier to the widespread implementation of carbon capture at coal-fired facilities.12