Major DHC investment in Lons-le-Saunier • 60.000 homes to be heated by waste and geothermal heat • Lyon develops wastewater-based DHC network • Read more about the developments in sustainable heating and cooling in this month's news update from France
The city of Lons-le-Saunier has formalised a new phase in the development of its district heating network through an agreement between the municipality and ENGIE Solutions. The project aims to modernise the existing infrastructure, improve reliability, and continue the decarbonisation of the local energy system. With a current network length of 12 kilometres, 85 substations, and an annual output of 36 GWh, the system already supplies heat to the equivalent of 4,400 housing units using 85 percent renewable and recovered energy, primarily from a waste incineration plant and biomass sources.
Due to growing demand from public institutions, residential buildings, and commercial properties, the network has reached its capacity limits. To address this, the city and ENGIE Solutions are launching a major upgrade. The plan includes converting the network from high to low temperature, resizing certain pipeline sections to improve energy efficiency, and constructing a new hot water link between the incineration plant and the existing Marjorie heating plant. An additional 8 kilometres of network will be built, enabling the recovery of 3 MW of surplus heat from the incineration facility.
These enhancements will allow 57 new buildings, including approximately 700 housing units, to be connected without reducing the share of renewable and recovered energy in the system. The project is also expected to reduce natural gas consumption by 14 percent and will contribute to national carbon reduction targets under the French Low-Carbon Strategy. The Lons-le-Saunier hospital will be among the new users, benefiting from a stable and compliant heating solution aligned with regulatory requirements for energy efficiency in public and tertiary buildings.
The total investment for the project is estimated at 21 million EUR. Construction is scheduled to begin in May 2025 and will continue over a three-year period. The additional energy from the incineration plant is expected to be integrated into the network by early 2027. This expansion reinforces the city’s commitment to energy transition by ensuring long-term access to competitively priced, low-carbon heat for its residents and institutions.
Read more in article from Engie Solutions
The Grand Paris Sud agglomeration has adopted a new master plan for its district heating networks, setting a target to supply 40 percent of its housing and public buildings—equivalent to 60,000 units—with heat from geothermal and recovered energy sources by 2035. This marks a significant increase from the current 42,000 housing equivalents already connected to the network. The initiative is part of the region’s broader Territorial Climate Air Energy Plan, which aims to multiply renewable and recovered energy production fivefold between 2013 and 2030.
The strategy focuses on expanding existing geothermal infrastructure and integrating waste heat from data centres. A major contributor to this progress is the geothermal network developed by the Société d’Exploitation des Énergies Renouvelables (SEER), initially established in Grigny and Viry-Châtillon and later extended to Ris-Orangis and Sainte-Geneviève-des-Bois. Further extensions are planned to reach Morsang-sur-Orge, Saint-Michel-sur-Orge, and Savigny-sur-Orge. Once completed, this network will serve 50,000 homes and 110 public facilities. The cost of this expansion is estimated at 61 million EUR.
In parallel, a new district heating network is being developed in Corbeil-Essonnes, the second-largest city in Essonne. This system will supply heat to 7,000 homes using waste heat from a large data centre located in Lisses. The heat, initially at around 40 degrees Celsius, will be upgraded to 70 degrees using heat pump systems. The creation of this network represents an investment of approximately 57 million EUR.
The agglomeration has identified several high-potential zones for further development, particularly on the right bank of the Seine. These areas are being targeted for future network extensions and new installations. The use of alternative energy sources for heating already prevents the emission of 80,000 tonnes of carbon dioxide annually. The expansion of these networks is expected to provide residents with a more stable and cost-effective energy supply, less exposed to the volatility of fossil fuel markets.
The Grand Paris Sud community, which includes 23 municipalities and a population of 360,000, is positioning itself as a leader in sustainable urban heating. The integration of geothermal energy and waste heat from data centres is seen as a key lever for achieving energy sovereignty and meeting long-term climate objectives.
Read more in article from Les Echos
In the southern suburbs of Lyon, the metropolitan authority and Engie Solutions are constructing an innovative tempered water loop in the La Saulaie district of Oullins-Pierre-Bénite. Scheduled to be operational by the end of 2026, the system will use energy recovered from treated wastewater to provide both heating and cooling to new buildings in the area.
The project is based on the principle of cloacothermy, which involves extracting thermal energy from wastewater. The installation will draw water from the Pierre-Bénite wastewater treatment plant, filter it, and stabilise it at a temperature of around 15 degrees Celsius. This water will then circulate through a 2.5-kilometre underground loop. Each connected building will be equipped with heat pumps to raise the temperature for heating in winter, or with chillers to lower it for cooling in summer.
The installation includes six thermal exchangers and is considered a first of its kind in Europe at this scale. The system is designed to serve approximately 2,000 residents and 3,500 employees who will occupy the new buildings in the district. The project is backed by a total investment of 20 million EUR, including 7.7 million EUR in funding from ADEME, the French Agency for Ecological Transition.
This development is part of a broader strategy by the Lyon metropolitan area to expand its district energy infrastructure. Between 2020 and 2024, around 120,000 housing equivalents were connected to one of the seven urban heating networks operating across the territory. The new system in La Saulaie is expected to offer both environmental and economic benefits, including improved comfort and reduced energy costs for users.
Read more in article from Les Echos
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