This work provides an analysis of the future application of co-generation power plants operating for public district heating systems in Germany. It will be investigated if those co-generation plants will be able to provide residual power in an environment of high energy supply from renewables. For that reason, district heating systems must be further build, while heating demand is decreasing till 2050. Due to that tension between higher residual power demand and decreasing heat demand the questions occurs, if it is possible to generate enough heat sinks so that these plants are able to supply a high amount of residual power, thus energy. It is further stated, that if this goal should be achieved, flexibility must be added to these co-generation plants, meaning the application of heating storage and electrical heating devices. In the first part of this work all necessary technical and economical parameters of co-generation power plants and important influences of the future energy system based on the BMU- Leitstudie will be investigated. Two scenarios A and B will then be defined, where different district heating potentials are developed. Those scenarios will be compared to a reference scenario, where no further co-generation plants are built. These scenarios will then be simulated from 2020 to 2050 with a simulation software from Fraunhofer IWES, which is able to optimize the whole energy system in order to provide energy at its lowest costs. Results showed that it is possible to generate enough heat sinks so that an increase of co-generation power is possible. For both scenarios the measures of a higher electrical power potential as well as raising flexibility show to be economically. Furthermore the reduction of CO2- emissions and a high coverage of residual power, especially in 2050, were possible. The goal of 25 % of co-generation power based on the overall net current production was nearly met. Nonetheless the advantage of heat storage systems for raising co-generation heat and power did not meet the expectations. The storage systems were used preferably in 2020; 2050 the electrical heating devices supplied more heat into the district heating system instead. One reason is that the optimization tool is only able to look four days ahead and can therefore not optimize heat which must be stored for a longer period of time. For a better investigation of the heat storage impact on co- generation heat and power, the time frame should be longer; in the best case a time frame of a year. Also the electrical heating devices can be replaced by industrial heating pumps which could be a very efficient alternative to electrical heaters. Industrial heating pumps could also be used for substituting co-generation power and therefore supply district heating networks. To answer those questions more research work has to be done.