Techno-economic evaluation of the evaporative gas turbine cycle with different CO2 capture options

The techno-economic evaluation of the evaporative gas turbine (EvGT) cycle with two different CO₂ capture options has been carried out. Three studied systems include a reference system: the EvGT system without CO₂ capture (System I), the EvGT system with chemical absorption capture (System II), and the EvGT system with oxyfuel combustion capture (System III). The cycle simulation results show that the system with chemical absorption has a higher electrical efficiency (41.6% of NG LHV) and a lower efficiency penalty caused by CO₂ capture (10.5% of NG LHV) compared with the system with oxyfuel combustion capture. Based on a gas turbine of 13.78 MW, the estimated costs of electricity are 46.1 $/MW h for System I, while 70.1 $/MW h and 74.1 $/MW h for Systems II and III, respectively. It shows that the cost of electricity increment of chemical absorption is 8.7% points lower than that of the option of oxyfuel combustion. In addition, the cost of CO₂ avoidance of System II which is 71.8 $/tonne CO₂ is also lower than that of System III, which is 73.2 $/tonne CO₂. The impacts of plant size have been analyzed as well. Results show that cost of CO₂ avoidance of System III may be less than that of System II when a plant size is larger than 60 MW.