CO2 capture in natural gas combined cycle with SEWGS. Part A: Thermodynamic performances

An innovative process for CO₂ capture named SEWGS (sorption enhanced water gas shift) was investigated from technical and economic point of view when applied to natural gas power plants. This activity was carried out under the FP7 project CAESAR financed by the EU community. The SEWGS working conditions were optimized in terms of carbon capture ratio and purity of the CO₂ separated as well as number of vessels adopted. Moreover, two different types of sorbent, Sorbent Alfa and Sorbent Beta, were considered in order to evaluate the impact of sorbent cyclic capacity on system performances. Results show that SEWGS with Sorbent Alfa can avoid 91% of CO₂ emissions reducing the efficiency penalty of amine scrubbing technologies from 8.4% to 7.2%with a CO₂ avoided of 91%. No significant impact of CO₂ purity on system performances was determined.The adoption of Sorbent Beta, which has an improved capacity of 60% than Sorbent Alfa, can further reduce specific primary energy consumption for CO₂ avoided together with vessel number.The best overall performance in terms of specific primary energy consumption for CO₂ avoided has a net electrical efficiency of 51.93% and CO₂ avoided of 86%. Part B presents the economic assessment of the investigated cases together with three reference cases selected for electricity production with and without CO₂ capture in order to benchmark the innovative solution.