The growing share of renewable energy generation eventually could lead to increased fluctuations in power supply and to negative residual loads. Therefore flexible power plants as well as significant long-term energy storage capacity are required. In this paper, an Integrated Gasification Combined Cycle (IGCC) power plant is combined with an electrolysis plant and substitute natural gas (SNG) synthesis. In this way a highly load-flexible IGCC plant is developed for excess power integration (EPI) from renewable energy sources or inflexible conventional power plants. The proposed IGCC-EPI concept is modeled in Aspen Plus. The decentralized power plant has a capacity of 125 MWth and runs on hard coal. An extensive parameter study has demonstrated the superior operation range from +67 MW to -253 MW of net power output/input Synergies between the IGCC-EPI power plant, the methanation process and the electrolysis indicate a maximum overall efficiency of 40.1% from coal and excess energy to SNG and back to electricity. (C) 2012 Elsevier Ltd. All rights reserved.