Three types of coal based integrated gasification combined cycle (IGCC) systems with CO2 capture using physical absorption, chemical looping combustion (CLC), and calcium looping process (CLP) for power generation are modeled using Aspen Plus. The effects of key variables on the thermodynamic performance, such as the energy efficiency and the exergy efficiency; are investigated separately. The process variables examined are mainly in the gasification unit, they are steam to coal mass ratio (S/C) in the range of 0-20% and oxygen to coal mass ratio (O/C) in the range of 70-105%. The performances of the above three capture technologies are compared with respect to their energy and exergy efficiencies. An IGCC plant without carbon capture is also considered as a benchmark to quantify the efficiencies. The results show that the CLC technology has an energy efficiency of 39.78%, which is 2.06% and 3.57% higher than the CLP and physical absorption-based technologies, respectively. Additionally, the CLC technology has an exergy efficiency of 35.67%, in contrast to 33.86% for CLP and 32.74% for physical absorption technology. Furthermore, the economic evaluations are performed for estimation of capital cost, net present value (NPV), internal rate of return (IRR) and other economic values. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.