Versorgungsicherheit in Deutschland und Mitteleuropa während Extremwetter-Ereignissen (VERMEER) - Der Beitrag des transnationalen Stromhandels bei hohen Anteilen erneuerbarer Energien

Abstract

The VERMEER project evaluates the consequences of extreme weather events for the securi-ty of supply of electricity in Germany, considering the flexibility potential of cross-border electricity trading with regard to weather-dependent transmission grid transfer capacities. For this purpose, several specialized models for defining extreme weather situations, calcu-lating renewable energy generation timeseries, simulating cross-border trading and grid transfer capacities have been further developed and coupled. "Dunkelflauten" or dark dol-drums, periods of low combined wind and solar power generation, are projected to increase in the coming century by approximately 11% to 19% according to two climate projection calculations. An in-depth analysis of historical weather patterns (applied to wind and solar generation fleet of the target year of this study - 2035) reveals this for a system as defined in the TYNDP Distributed Energy scenario. During the winter of 1996/1997, the residual load, an indicator of potential under-supply situations like cold dark doldrums, reached notably high levels over a three-month period - but also for shorter periods such as days or weeks. Analyses of the German and neighboring electricity markets show that within the assump-tions based on this scenario extreme weather events such as the examined cold dark dol-drums lead to shortages in the German market zone that cannot be compensated by conven-tional generation or cross-border trading. Trading flows to neighboring market zones are significantly altered during such events compared to a base case scenario. The simultaneous occurrence of extreme weather across Europe limits the effectiveness of increased trans-mission capacities in ensuring security of supply, necessitating additional reserve capacities. Regarding power grids, the analyzed extreme situation reduces the occurrence of grid bot-tlenecks, as they strongly correlate with wind power generation and constitute a weak wind event. However, with increased transmission capacity, the overall amount for redispatch rises; renewable energy curtailment is less affected than conventional power plants. In addi-tion to the market-oriented assessment of security of supply, network simulations indicate that a slight amount of load shedding is necessary in all scenarios to ensure a bottleneck-free operation. The necessary load shedding does not exhibit a significant increase between the base scenario and the extreme situation, nor can it be substantially reduced by increas-ing transmission capacities. In summary, and contrary to expectations, the expansion of the electricity network does not offer significant additional relief during extreme weather events.