Summary of Post-Combustion CO 2 Capture Technologies for Existing Coal-Fired Power Plants

Due to mounting concern over climate change due to anthropogenic greenhouse gases, carbon dioxide emission legislation is being discussed and is expected to be passed in the near future. Utilities are relying on science to develop and improve CO2 capture technologies that will allow them to reduce their emissions as well as continue to provide customers with affordable electricity. Cleaner coal fired power plants are being planned and built, but the nation’s current operating power plants must be retrofit to have the greatest impact on emissions in the near future. Although few are proven on a commercial scale, there are several post-combustion capture technologies that have shown great promise. The most well-known capture technology is absorption by aqueous amines or ammonia. The solvents react with the CO2, separating it from other flue gas constituents. The solution can be regenerated through heating. The carbon dioxide is released during this regeneration step and can be processed for sequestration. The major challenges to absorption technologies are the corrosive nature of the solutions, degradation from other pollutants and the energy required for regeneration. One ammonia-based technology is projected to be commercial by 2011. Solid sorbents are also a promising CO2 capture technology, which may offer greater ease of handling. However, solid sorbents for CO2 are still being developed that will meet the required CO2 capacity, regeneration ability, selectivity and immunity to flue gas constituents. Another capture technology is membrane separation, which offers design simplicity. Membranes are currently being developed to improve their CO2 selectivity. Solid sorbents and membranes are currently in laboratory and bench-scale development. In the end, it will require a range of solutions to achieve meaningful greenhouse gas reductions. This paper/presentation will provide the up to date status and results of several CO2 capture technologies.