4f. Capturing Carbon Dioxide
Capturing carbon dioxide during electrical generation from lignite is a challenging process. Depending on the type of combustion, power plants have two options for capturing the CO2. Both options require specialized equipment, which makes carbon dioxide capture expensive.
Pre-Combustion
Carbon dioxide can also be captured before combustion has completed. In plants using oxy-combustion and Integrated Gasification Combined Cycle, the carbon dioxide gas is at a higher pressure and not diluted by atmospheric air, making it easier to capture.
Post-Combustion
In order to capture carbon dioxide, the gas must first be separated from other gases in the chimney, such as nitrogen and water vapor. Capturing CO2 in the chimney can be difficult because the emissions mix with air from the atmosphere, lowering the concentration of CO2. The gas is also at normal temperature and pressure, which makes it more difficult to separate from other gases