Chemical looping combustion is a novel concept for the inherent capture of CO2 gas. The recent interest of the CLC study is the direct fuelling of coal for the metal-oxy combustion that simplifies the working components of the power plants. In addition, the effect of the ash content of coal in the CLC process is needed to be elucidated for the commercial implementation of this technology. Based on these objectives, the present study is focused on the process simulation of combined cycle power plants using ASPEN plus software. The simulation work intends to perform the CLC process in two different ways, namely, direct and indirect coal fuelled CLC process (without a gasifier). The effect of the gasifying medium (steam and CO2) on the net thermal efficiency of power plants is evaluated. The simulation results show that the direct CLC process with CO2 as the gasifying medium using iron oxide as an oxygen carrier achieved a higher efficiency of 46.8% and 43% in the case of low and high ash coal, respectively. Further, the economic analysis shows a low levelized cost of electricity (LCOE) for the direct CLC process by about 6.2-8.2 $/MWh, compared to the indirect CLC process. (C) 2018 Elsevier Ltd. All rights reserved.