Environmental Performance of Hypothetical Canadian Pre-Combustion Carbon Dioxide Capture Processes Using Life-Cycle Techniques

Abstract

Abstract:The methodology of life-cycle assessment was applied in order to evaluate the environmental performance of a hypothetical Saskatchewan lignite-fueled Integrated Gasification Combined Cycle (IGCC) electricity generation, with and without pre-combustion carbon dioxide (CO 2 ) capture from a full life-cycle perspective. The emphasis here is placed on environmental performance associated with air contaminants of the comparison between IGCC systems (with and without CO 2 capture) and a competing lignite pulverized coal-fired electricity generating station in order to reveal which technology offers the most positive environmental effects. Moreover, ambient air pollutant modeling was also conducted by using American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) air dispersion modeling to determine the ground-level concentration of pollutants emitted from four different electricity generating stations. This study assumes that all stations are located close to Estevan. The results showed a significant reduction in greenhouse gas (GHG) emissions and acidification potential by applying both post-combustion and pre-combustion CO 2 capture processes. The GHG emissions were found to have reduced by 27%-86%, and IGCC systems were found to compare favorably to pulverized coal systems. However, in other environmental impact categories, there are multiple environmental trade-offs depending on the capture technology used. In the case of post-combustion capture, it was observed that the environmental impact category of eutrophication potential, summer smog, and ozone depletion increased due to the application of the CO 2 capture process and the surface mining coal operation. IGCC systems, on the other hand, showed the same tendency as the conventional coal-fired electricity generation systems, but to a lesser degree. This is because the IGCC system is a cleaner technology that produces lower pollutant emission levels than the electricity generating station; thus, the benefits of capture are reduced on a comparative basis. The results from air dispersion analysis showed that the maximum ground-level concentrations of pollutants from all electricity generating stations are in compliance with all air quality standards, except for Co, Pb and Ni. The IGCC with capture revealed the lowest nitrogen dioxide (NO 2 ) ground-level concentration compared to all other scenarios. Moreover, IGCC systems both with and without pre-combustion CO 2 capture revealed no ground-level concentration of trace elements. This is because the IGCC system operates with an acid gas cleaning process that removes most of the trace contaminants from the syngas.