The environmental impact of post-combustion CO 2 capture with MEA, with aqueous ammonia, and with an aqueous ammonia-ethanol mixture for a coal-fired power plant

Abstract

In this paper the authors compare monoethanolamine (MEA) to aqueous ammonia (AA) and a solvent mixture of aqueous ammonia and ethanol (EAA) with respect to their post-combustion CO 2 capture performance and their environmental impact. Simulation of all processes was carried out with Aspen Plus ® and compared to experimental results for CO 2 scrubbing with ammonia. Of special interest was the formation of stable salts, which could be observed in the experimental CO 2 capture with both ammonia solvents. If CO 2 can be captured in the form of ammonium salts, energy requirements are greatly reduced, since no energy is required for solvent regeneration and CO 2 compression. The environmental impact of CO 2 capture was investigated for a 500 MW pulverised coal power plant employing Life Cycle Assessment (LCA) using the software SimaPro ®. For a comprehensive evaluation of this impact, influencing factors such as solvent production and solvent emissions were included. With kinetics taken into account, no salt formation could be observed in CO 2 removal with aqueous ammonia. The necessary reduction of ammonia emissions leads to further energy requirements, and solvent production as well as the remaining ammonia losses to the environment have a more significant environmental impact than CO 2 removal with MEA.