Capturing and storing CO₂Schematic diagram of the three capturing methods

Researchers are currently pursuing three processes for capturing CO₂ in combustion processes. Following combustion (post combustion), CO₂ can be captured using chemical flue gas scrubbing. The process can be retrofitted in existing power plants. With the oxyfuel process, nitrogen is removed entirely from the air prior to the combustion. The combustion with highly concentrated oxygen means that the CO₂ is also highly concentrated at the end. When recycling waste gases, the temperatures should not be so high that they damage materials. The air separation using cooling technology is energy and cost-intensive. The air separation also marks the beginning of the pre-combustion process. Here, the coal is converted before combustion into a synthesis gas that predominantly consists of hydrogen and carbon monoxide (CO). Additional water vapour then converts the CO to CO₂ and additional hydrogen is created. The synthesis gas is used in a combined gas and steam turbine power plant process.