A collection of Generating Units (registered as a CCGT Module) comprising one or more Gas Turbine Units (or other gas based engine units) and one or more Steam Units where, in normal operation, the waste heat from the Gas Turbines is passed to the water/steam System of the associated Steam Unit or Steam Units and where the component Units within the CCGT Module are directly connected by steam or hot gas lines which enable those Units to contribute to the efficiency of the combined cycle operation of the CCGT Module.