As a new challenge for territories, energy management at a local scale aims to respond, in part, to the imperatives of energy transition. Yet, this scale of management is not a recent development: city electrification was the starting point of energy municipalization. The city of Metz established a local power supply company (an ELD) at the beginning of the 20th century, under German rule (Stadtwerke). The UEM (Usine d’Électricité de Metz), attached to the city’s services, produced electricity as early as 1901 and gave new means of funding to the municipality. Its proximity management strengthens the local economy. The nationalization of energy in 1946 led to a change in scale of energy management in the area of Metz and marginalized these companies on the national scene. This article shows the links between energy management at a local scale and a thriving local economy. These links are studied from the perspective of the economic strategies of the UEM from its creation to the present day. I also demonstrate the resistance from the UEM in the face of centralised energy management at a national scale, and its strategies of adaptation to the opening of the European energy market.