Trade-off in emissions of acid gas pollutants and of carbon dioxide in fossil fuel power plants with carbon capture

This paper investigates the impact of capture of carbon dioxide (CO2) from fossil fuel power plants on the emissions of nitrogen oxides (NOX) and sulphur oxides (SOX), which are acid gas pollutants. This was done by estimating the emissions of these chemical compounds from natural gas combined cycle and pulverized coal plants, equipped with post-combustion carbon capture technology for the removal of CO2 from their flue gases, and comparing them with the emissions of similar plants without CO2 capture. The capture of CO2 is not likely to increase the emissions of acid gas pollutants from individual power plants; on the contrary, some NOX and SOX will also be removed during the capture of CO2. The large-scale implementation of carbon capture is however likely to increase the emission levels of NOX from the power sector due to the reduced efficiency of power plants equipped with capture technologies. Furthermore, SOX emissions from coal plants should be decreased to avoid significant losses of the chemicals that are used to capture CO2. The increase in the quantity of NOX emissions will be however low, estimated at 5% for the natural gas power plant park and 24% for the coal plants, while the emissions of SOX from coal fired plants will be reduced by as much as 99% when at least 80% of the CO2 generated will be captured.