The integration of renewables into the electricity system is technical and economic challenge for utilities, especially operators of conventional power plants. Due to feed-in priority and remuneration, as well as low marginal costs, renewable energies are increasingly displacing conventional power plants from the electricity market. Furthermore, the forecast errors of wind energy and photovoltaic plants result in a need for power that can be used at short notice. This requires, among other things, a flexible use of conventional generation and storage facilities in order to balance electricity demand and supply at all times. In view of the expansion targets for renewable energies in Germany and Europe, it is to be expected that the requirements for flexible operation of conventional power plants will continue to rise in the future. On the other hand, there is a limited operational flexibility of fossil-fueled power plants, which is due on the one hand to the power plant technology and on the other hand to economic conditions and the regulatory framework.
Within the scope of this work, the future requirements for flexible operation of fossil-fueled power plants in Germany will be examined, considering various developments in the energy industry up to the year 2030. In addition, it will be clarified to what extent the existing conventional generation system already meets these requirements and to what extent flexibilization will improve the integration of renewables into the electricity system.
The simulation results for the German electricity system for the years 2020 and 2030 indicate that the future requirements for flexible operation of fossil-fueled power plants will be strongly influenced by several other developments in addition to the progressive integration of renewable energies. In particular, the German phase-out of nuclear energy by 2022 and the progressive integration of the European energy markets are reducing the requirements for flexible use of fossil-fueled power plants. Assuming an ambitious climate and energy policy, the requirements for a flexible use of fossil-fueled power plants will increase by 2030; in particular, these will be operated much more frequently at partial and minimum load. Today’s fossil-fueled power plants fleet already shows a high operational flexibility and can, in the medium term, enable the integration of renewable energies as well as the balancing of uncertainties of wind energy and photovoltaic. The flexibilization of fossil-fueled power plants can reduce the variable system costs and CO2 emissions as well as improve the integration of renewable energies to a small extent. In this context, the economic and ecological benefits of flexibility measures must be critically assessed.