Comparative life cycle assessment of potassium carbonate and monoethanolamine solvents for CO2 capture from post combustion flue gases

Abstract

Carbon capture and storage (CCS) has the potential to enable significant reductions in carbon dioxide (CO2) emissions from stationary sources such as coal-fired power stations. The most advanced carbon capture technology is CO2 absorption using amine-based solvents, such as monoethanolamine (MEA). However, there is concern that the increased use of amine-based solvents will lead to other potential negative environmental impacts, such as increased human toxicity. The use of benign inorganic solvents, such as potassium carbonate, which do not degrade in the presence of oxygen or other impurities such as sulphurous or nitrous oxides offer significant advantages over amine-based solvents in terms of environmental impact.A comparative life cycle assessment (LCA) between the use of MEA and the CO2CRC's potassium carbonate based UNO MK 3 technology for the capture of 1tonne of CO2 from a brown-coal fired power station has been completed. The results reveal that the UNO MK 3 process is significantly better than MEA on ecotoxicity and carcinogen emissions and substantially better on all other indicators. The benefits of the UNO MK 3 process compared with MEA are due to avoidance of emissions from MEA degradation along with the savings in energy use for CO2 removal.The significant environmental benefits of the UNO MK 3 process compared with MEA were not altered by an uncertainty analysis or sensitivity analysis of key inputs and assumptions.