Rennes Métropole has signed a thirteen-year concession agreement with ENGIE Solutions to develop and operate an urban district heating network in the southern part of the city, powered exclusively by renewable and recovered energy sources. The project will extend the existing network to 78 kilometres, with 32 kilometres to be newly built. The total investment amounts to EUR156mn ($167mn), with a planned capacity equivalent to 47,000 connected households.
A dedicated project company
The project is structured under a single-operation semi-public company (SEMOP), governed jointly by ENGIE Solutions (46%), Rennes Métropole (34%), and Banque des Territoires (15%). For the first time in France, 5% of the company’s capital will be opened to citizen participation through the “Chaleur Renouvelable Citoyenne Rennes Sud” initiative, which brings together residents and subscribers. Two public information meetings have already been held, and participatory workshops are planned.
Five-year expansion plan
Work will begin in Rennes and Saint-Jacques-de-la-Lande with the installation of three kilometres of new pipelines and the modernisation of two kilometres in the Bréquigny district. The network will then be extended to Sud Gare, Francisco-Ferrer, Landry, Gaité Sud, and the South-East eco-pole up to Chantepie. Existing infrastructure in Blosne, Poterie, and Bréquigny will also be upgraded and expanded.
Biomass heating plants and hydrostorage
Two new biomass heating plants will be built by 2028: a 23-megawatt facility in Blosne, including a 3,000 m³ hydrostorage tank, and a 21-megawatt plant in Saint-Jacques-de-la-Lande. These will complement existing installations, ensuring supply during peak demand and maintaining independence from fossil fuel markets.
Digital modernisation and support
The network will include 547 connected substations, managed using digital tools to optimise energy performance. ENGIE Solutions will also offer energy assessments and a EUR500,000 ($536,000) solidarity fund over five years to support building adaptations for new connections.
Local sourcing and circular economy
Wood supply will be sourced locally, including hedgerow wood, end-of-life timber, and forestry chips. Agricultural partnerships will be developed to structure this supply chain. The project also plans to reuse 15 tonnes of materials from construction work, in collaboration with the Bâti Récup association, and to promote recycling of technical equipment among new customers.
Frank Lacroix, Deputy Chief Executive Officer of ENGIE in charge of Local Energy Infrastructures, stated that “this project marks a major step forward in the decarbonisation of Rennes Métropole.” According to projections, the initiative will prevent 670,000 tonnes of CO₂ emissions over the duration of the contract.
