A large number of research undertakings and system modelling works study different coal fired Integrated Gasification Combined Cycle (IGCC) configurations, mostly with the conflicting purposes and aims, to increase system efficiencies, to reduce costs and to diminish environmental impacts. The increased penetration levels of intermittent renewable energy systems experienced in many parts of the world, however, makes the establishment of flexible power generation systems to be a more challenging task. The integration of a diurnal syngas storage system as a means to increase system flexibility is investigated in this work with reference to different syngas qualities. All the systems are based on a reference coal-fired IGCC power plant. The system modification is limited to the gas processing units including a CO2 removal option allowing for different syngas compositions. Apart from the reference syngas, four further options are proposed here: hydrogen rich syngas with and without a carbon capture, a scenario with a partial carbon capture and finally a Synthetic Natural Gas (SNG) production case. The techno-economic analysis is implemented in connection with a short-term geological syngas/hydrogen rich gas storage reservoir. The results show that a hydrogen rich gas generation without a carbon capture will be techno-economically less attractive and requires a relatively large reservoir volume. A methanation process towards a SNG production adds significantly to the overall cost and reduces the cold gas efficiency. The storage volume requirement is however considerably reduced. Finally, a short comparison will be drawn to a potential case configuration with a compressed air energy storage system. (C) 2011 Elsevier Ltd. All rights reserved.