This article outlines the objectives of Project OPTIGAZ and in general terms describes the methodological approach being used and developed for modeling and optimizing the synthesis (configuration), component design and operation of energy systems. In particular, this approach will be used for looking at new combined cycle and retrofit options and the gas pipelines which supply the fuel that they use. A final goal of this project is to propose long term technology options which might parallel developments in the supply of natural gas in Switzerland.