Municipal utilities (so-called Stadtwerke) play a crucial role in terms of the decentral Energiewende in Germany. The national way to accomplish the energy transition with a massive expansion of renewables requires local actors to participate actively. Thus, we developed a decarbonization strategy to supply a 12.000+ municipality CO2-neutral till 2035. This considered that the influence of the municipal utility is limited to its own electricity and natural gas grid as well as municipal buildings and vehicles.

Our study focused on the optimal expansion of sustainable energy generation coupled with short- and long-term storage options and transformation of consumption (mobility, power-to-heat, power-to-gas) of the existing local distribution grids. We aimed for a high autarky respecting long-term economic efficiency and high self-consumption of renewables. Natural gas should be replaced by alternatives as far as economically possible.

Energy consumption was determined and separated into domestic, commercial, and industrial and together with hourly generation profiles from existing renewables used to remodel the known annual consumption. Likewise, the hourly generation profiles from existing renewables were considered. The resulting degree of self-sufficiency (e.g., physical autarky) and annual share of renewable energy (accounting self-consumption) was calculated.

From this status quo, we developed future scenarios to answer the following questions:

·         What impact will the transformation to power-to-heat and electromobility have on the electricity demand up to 2035?

·         How do the parameters self-consumption and self-sufficiency behave for the respective expansion of the technologies PV systems, wind turbines and battery storages?

·         What is the techno-economic optimal combination of PV systems, wind energy systems and battery storage and what is the potential for hydrogen?

·         In what way does the injection of biogas and hydrogen affect the electricity and natural gas grids?

Based on the load and generation profiles, we have adjusted the type and scope of the technologies used. Thereby, the local conditions were again considered to only implement feasible concepts. A techno-economic analysis was carried out to plan an optimal transformation.