Costs of electricity of three systems are shown in Fig. 4. Compared with System I, the increments of COE caused by CO2 Fuel cost represents the largest fraction of COE in all systems, especially in the system without CO2 capture (System I). Total investment costs are the second largest component of COE. The sum of fuel cost and investment costs represents about 90% of the total in all systems. For the systems with CO2 capture (System II and System III), the main cost differences are TIC and VOM. Comparatively, COE of System II is 5.4% lower than that of System III because of the higher electrical efficiency of System II. Fig. 5 shows the breakdown of the cost of CO2 avoidance. Similar to the results about COE, System II has a lower COA than System III. The major components of COA for both systems come from the total investment costs and fuel cost. They are corresponding to the large investment cost of capture plants and the large electrical efficiency penalty caused by CO2 capture.
Table 1 Summary of system simulation resu