Flexibility of thermal power generation for RES supply in Germany until 2020

Directive COM (2008) 19 gives individual targets in emission reduction and renewable energy share to the member states of the European Union [1]. Germany has to reduce its green house gas emissions by 14% until the year 2020 related to the reference year 2005 and the share of renewable in the final energy demand should reach 18%. In the sector of electrical energy – which is the main topic of this paper – the portion of renewable electricity has to be increased from 12.4% in 2005 to 40% until 2020 [2]. Because of the short period of time, this forms a big challenge in development of adequate renewable generation and storage capacities, extension of the transmission and distribution grid and flexible operation of the energy system with a high portion of fluctuating generation especially from wind and photovoltaic (PV). To maintain the high standard of security of supply, a Task Force of VDE investigated over a period of two years the needs for balancing of the German energy system under the aspect of high penetration of RES. For the analysis of the consequences for the residual power generation a sophisticated simulation model of regions of the German energy system has been elaborated, comprising the development of RES, demand, storage and line capacities until 2020. Under the assumption that the peak load of 80 GW will not change due to measures for more efficiency, the installed power of RES will probably show the following development: wind approximately 60 GW, photovoltaic (PV) 60 GW, running hydro 5 GW (constant) and biomass 7 GW. In total the installed power of RES will achieve 130 GW. Considering the coincidence of RES generation it will touch the peak load and to a small extend overshoot. As no overshoot of the peak load will occur over a longer period of time, flexible power generation with the ability of total maximal gradients of 15 GW/h will be able to balance the German energy system. As the power stations will in future have only a capacity factor below 20% it will be difficult to find an economic operation scheme within the existing electricity market model.