IGCC plant with reduced GHGs: performance analysis, life cycle assessment and exergetic life cycle assessment

The performance evaluation of an IGCC (Integrated Gasification Combined Cycle) plant with upstream CO2 removal, operating with coal, has been carried out by the means of Aspen Plus calculation code. With respect to the basic scheme of a conventional Integrated Gasification Combined Cycle - which already includes H2S removal - a shift reaction section followed by CO2 chemical absorption has been added, before the syngas combustion, in order to obtain a clean and H2-rich synthesis gas. Chemical absorption with aqueous solutions of ethanolamines, for both the removal processes, has been selected, due to its being a well-known technology in the chemical and oil industry. A final efficiency loss in the range of 7-8 % was found in comparison with a standard IGCC, mainly due to the shift reaction and CO2 removal. On the other hand, the CO2 specific emissions result 130 kgCO2/MWh vs. 725 kgCO2/MWh for the reference IGCC. The IGCC with CO2 removal, compared with the reference IGCC by means of LCA (Life Cycle Assessment), showed a substantial decrease in the carbon dioxide total production, being the CO2 equivalent production in the life cycle, per produced energy unit, one order of magnitude lower with respect to the parent IGCC. Furthermore, the major contribution to CO2 production comes from the operation/maintenance phase; likely, in the case of ELCA (Exergetic Life Cycle Assessment), the major exergy destruction - in term of MJ of destroyed exergy per produced energy unit - comes from operation/maintenance, which is two orders of magnitude greater than the contributions of the other phases.