CO₂ capture in natural gas combined cycle with SEWGS. Part B: Economic assessment

This two part-paper investigates the adoption of an innovative CO₂ capture concept named SEWGS (sorption enhanced water gas shift) in natural gas combined cycle. In Part A, SEWGS working conditions were optimized in terms of carbon capture ratio as well as CO₂ purity and two different sorbent performances were analyzed. Part B presents the economic assessment of investigated SEWGS cases together with three reference cases selected for electricity production: without carbon capture, with post-combustion carbon capture by MEA and with pre-combustion carbon capture by MDEA. Results shows that with reference sorbent performances the calculated cost of CO₂ avoided is about 58€/t_CO2, which is lower than reference MDEA (64€/t_CO2) but higher than MEA (48.5€/t_CO2). The adoption of a sorbent with improved performances brings down the cost of CO₂ avoided down to 49€/t_CO2, which is comparable to post combustion technology. This is a consequence of reforming sections costs which penalizes pre-combustion technologies: specific investment costs for SEWGS cases are 15% higher than MEA. Finally, as far as SEWGS working conditions are concerned, the optimal CO₂ capture rate depends on the sorbent cyclic capacity ranging from 90% to 95%, while the selected CO₂ purity is 99%. This activity was carried out under the FP7 project CAESAR financed by the EU community.