Scaling energy system optimizations: Techno-economic assessment of energy autonomy in 11000 German municipalities

Increasing energy autonomy is one of the main reasons for municipalities to invest in renewable energy technologies. In this study, the potential of weather-robust autonomous energy systems is evaluated for 11003 German municipalities in over one million parallelized techno-economic optimizations utilizing high-performance computing clusters. For this purpose, a holistic municipal-level energy system model (ETHOS.FineRegions) was developed that minimizes annualized system costs in 2045. The completely energy autonomous supply can be established in around 90% % of German municipalities corresponding to 50% % of the country's population. Especially highly populated municipalities often do not have the capacity to meet their own energy demands due to low wind and open-field PV potentials. Large rooftop PV capacities account for 40% % of installed capacity in the autonomous municipalities. Seasonal storage needs are met by large underground thermal storage tanks and batteries provide intraday storage. Furthermore, huge capacity increases are often required for the final 20% % of energy demand to be met in order to achieve a degree of autonomy of 100%. %. The large storage and rooftop PV capacities lead to high specific system costs in the autonomous municipalities with between 144 <euro>/MWh and 174 <euro>/MWh on average, depending on legislation and opposition towards onshore wind installations. By paying a premium of up to 50% compared to the grid- dependent system, 3945 municipalities with 17.2 million inhabitants could become completely autonomous by 2045. For regions that could achieve an autonomous energy supply at moderate costs, however, lost revenues through energy exports could be a decisive argument against autonomy efforts.