Start-up costs of thermal power plants in markets with increasing shares of variable renewable generation

The emerging literature on power markets with high shares of variable renewable energy sources suggests that the costs of more frequent start-ups of thermal power plants may become an increasing concern. Here we investigate how this develops in Germany, where the share of variable renewables is expected to grow from 14% in 2013 to 34% in 2030. We show that the overall number of start-ups grows by 81%, while respective costs increase by 119% in this period. Related to variable renewables' production, start-up costs increase by a mere €0.70 per additional megawatt hour. While the expansion of variable renewables alone would increase start-up costs, more flexible biomass power plants and additional power storage have counteracting effects. Yet changes in reserve provision and fuel prices increase start-up costs again. The relevance of start-up costs may grow further under continued renewable expansion, but could be mitigated by increasing system flexibility.