Life cycle assessment of natural gas combined cycle integrated with CO₂ post combustion capture using chemical solvent

In light of global warming consequences and the need to take drastic steps to reduce its impact by capturing the CO₂ from stationary sources, environmental performance assessment of CO₂ capture processes is vital for deploying existing or innovative capture technologies. Life cycle assessment (LCA) methodology was used in this study to evaluate the impacts associated with CO₂ capture from a natural gas combined cycle power plant, by using a scientific approach of process design and sizing of important unit operations. The environmental assessment was conducted for 90% and 80% CO₂ capture efficiencies, using conventional monoethanolamine (MEA) and advanced solvent (KS-1), at various CO₂ compression configurations. The results show a major reduction in greenhouse gas emission (GHG) for both capture efficiencies. For the 90% CO₂ capture efficiency with conventional MEA, a reduction of 76% in GHG emission was achieved for the entire compression configuration. The 80% CO₂ capture efficiency with conventional MEA, on the other hand, showed a 65% reduction in GHG emission. Using the KS-1 solvent resulted in a 78% reduction in GHG emission due to reduction in energy required for CO₂ regeneration.However, the assessment shows that CO₂ capture operations has led to an increase in other environmental impacts such as human toxicity potential, abiotic depletion, marine eutrophication potential, fresh water aquatic ecotoxicity, marine aquatic ecotoxicity, acidification, terrestrial ecotoxicity and photochemical oxidant formation potential. These impacts are mainly due to the additional energy required for the CO₂ capture, infrastructures and chemical solvent used. The advantage of using the novel solvent (KS-1) is clear at 90% CO₂ capture compared to the conventional MEA solvent.