Both of the new power plants in Irsching are combined cycle power plants that use natural gas as the fuel source for operating at a very high level of efficiency. The special characteristic of the combined cycle power plant is the high utilization of fuel when producing energy. As opposed to conventional steam power plants, the hot flue gases first drive the rotors of the gas turbine which are connected to a generator. Thereafter, the flue gas is channelled into a heat-recovery steam boiler to produce steam. The steam that is created here is fed to a steam turbine to generate electricity. During this procedure a very high level of efficiency is attained which is currently measured at 58 percent. Irsching 5 will attain a level of efficiency of over 58 percent and Irsching 4 will attain the highest level of efficiency in the world at 60 percent. This tremendous feat of engineering is made possible by the new gas turbine generation SGT58000H which was developed by Siemens Power Generation.