Within this study energetic and exergetic theoretical analyses of a novel IGCC power plant concept with CO2 capture are carried out. The core process of the concept examined is based on the high pressure steam gasification of high moisture low grade coals where CO2 is captured reacting exothermically with CaO-based sorbents and high hydrogen-content carbon-free fuel gas is produced without using additional shift reactors and CO2 separation stages. The carbonated sorbents are continuously fed to an oxygen blown calcination reactor where pure CO2 is released and active CaO is reproduced. This concept can be realised in a dual fluidised bed reactor system where coal gasification and CaCO3 calcination are taking place simultaneously. In this paper possible plant configurations are presented and detailed simulation of 400 MWe IGCC power plant based on a state of the art gas turbine cycle with a three pressure stage heat recovery steam generator is performed. The calculated results demonstrate the capability of the power plant to deliver almost decarbonised electricity while achieving net plant efficiencies at about 38.4 % of coal lower heating value (LHV). Based on the energy analysis and the data generated from the simulation an exergy analysis was performed in order to quantify and localize the thermodynamic irreversibility in each process component as well as to asses the overall thermodynamic imperfection of the proposed process.