With the expansion of renewable, but fluctuating power generation from wind and solar energy, the demand placed on the security and reliability of supply is increasing. To ensure grid stability in the future, controllable power production via biogas plants has great technical and economic potential. In order to demonstrate the operation of controllable electricity production, an existing industrial-scale biogas plant was modified to produce electricity in accordance to the demands of the electricity market. In the course of scientific monitoring, extensive instrumentation was installed at the demonstration plant, which allows detailed evaluation of the operation of the limited gas storage volume and the behavior of the combined heat and power units (CHPs) during flexible operation.