After the successful completion of a well doublet in the subsurface of the Groß Schönebeck site, a research power plant will be built in 2011 to demonstrate geothermal power generation in the north German basin and to serve as an in situ laboratory for investigating a wide range of issues. By means of a systematic monitoring program for both the subsurface and surface plant infrastructure, the operation of the plant will be scientifically analyzed and optimized. Important results for the efficiency increase of geothermal power plants, which can also be transferred to other sites, will be gained.