Torn between transitions: energy transition, post-socialist transition, and transition of Large Technical Systems.: In the furnace of district heating system reconfigurations in Magdeburg (Germany)

International audienceOver the last twenty years, most of the cities of the Eastern part of Germany have seen an accumulation of transitions in their urban and energy systems. First, they have experienced the various effects of the post-socialist transition (Bontje, 2004). This turn is characterised by the transformation of the urban fabric through increasing numbers of vacant houses and brownfields, processes of intense depopulation and deindustrialisation (Bernt, 2009). This has tremendous repercussions on district heating systems, as consumption levels drastically dropped by up to two thirds within twenty years. This transformation consequently requires an important transformation of the whole sociotechnical system. Second, as in other contexts, these Large Technical Systems that have been at the core of the urban fabric (Summerton, 1992) have been questioned and challenged by the development of new decentralised systems (Coutard and Rutherford, 2010), supported by a discourse focusing on more local energy provision systems. Last, these cities are supposed to be at the vanguard of the national programme of energy transition (Energiewende) that has been launched since 2011 in Germany and promotes the use of decentralised or greener energy systems. These manifold transitions have forced the district heating operators to adapt their networks to this new context. Our paper wants to report on the strategies that have been developed by operators through the analysis of a multi-utility (Stadtwerk) where we carried out a six month internship in a middle-sized city of Germany, Magdeburg, particularly focusing on the transformation of the central district heating networks. This should show a silent and somewhat successful transition through the valuing of waste and the development of cogeneration systems that outreaches the traditional scheme of national energy transition. Yet, some new pitfalls raised by these transformations partly question its economic and environmental sustainability due to the lack of sufficient volumes of available waste and its increasing marketization