Decarbonizing GHG intensive sectors such as energy comes with major challenges. In the Trinational Metropolitan Region Oberrhein (TMO) these are linked particularly to securing a stable and reliable energy supply in the context of increasing generation from renewable energy sources (RES) while scaling down nuclear and fossil fuel based capacities. Implementing a 100% regional RES-based energy system requires holistic approaches, both top-down and bottom-up, considering aspects ranging from enhanced flexibility in system operations to meeting local demand via citizen energy. The main goal of this project is to examine the synergies arising from complementary generation, demand and storage capacities as well as from cross-border energy initiatives in the TMO, with a view to developing policy recommendations assisting with the energy transition. The technical, economic, regulatory, political and sociocultural framework conditions of a RES-based regional energy system in the TMO are being analyzed in the following work packages.