Anaerobic digestion has recently gained interest in contributing to territorial strategy regarding the deployment of the circular economy and energy transition. Most projects bring together multiple actors from a wide variety of backgrounds. The article analyzes the evolution of synergies and cooperative behaviors between local stakeholders over the period 2010-2020 in an anaerobic digestion cluster in France. The study draws on social network analysis and proximity theory, which have recently been used for analyzing regional innovation systems, local clusters, territorial governance, and rural development. We reveal that local stakeholders develop dense relational networks that vary and evolve throughout the project. Different groups exist and behave in a semi-autonomous manner. All the actors are located in close geographical proximity. Still, their links in terms of organized proximities are related to various types of relations, resulting from cognitive resemblances or common origins. This explains the persistence and resilience of local relationships and how they maintain a collaborative dynamic over time.