In Europe, socio-technical energy systems in urban areas undergo fundamental changes. First, liberalization changed the pre-existing, stabilized governance structure; second, decarbonization goals and the increasing share of renewables in energy production changed the technological structure and led to decentralization; third, digitalization, recently opens up entirely new technical and managerial opportunities to design decentralized, renewable and diversified urban energy systems. While these fundamental transition processes are providing phaszinating social and technical innovations and new opportunities, the energy system still is a critical infrastructure which needs to remain functional and resilient to provide crucial public services - while undergoing change.
For the social and technical resilience of urban energy systems in federalist states, the so called urban utility companies play a crucial role. These public firms, which are owned by the city, provide the urban system with all public services (energy, water, mobility, waste management) and manage all the critical infrastructures (grids, production sites).
In our contribution, we first present a theoretical concept, to operationalize and analyze resilience of socio-technical systems in transitions. The concept builds on two core attributes of resilience: diversity and connectivity, for which we propose an indicator set encompassing three fundamental diversity properties—variety, balance and disparity—and three basic connectivity properties —average path length, degree centrality and modularity. Subsequently, we apply this concept to the case of urban energy systems and question, which role the urban utility companies play for its social and technical resilience. Thereby, we build not only on our theoretical considerations but also on empirical evidence from large cities in Switzerland and Germany (Geneva, Zürich, Basel, Munich, Cologne and Hannover). In so doing we provide rich insights on urban energy system resilience and self-governance in urban infrastructure management, which can be applied to planning practices and policy making.