Municipality of Aigle, Jean-Luc Duroux, municipal councillor, jean-luc.duroux@aigle.ch, 024 468 41 11

About the job

Thermorezo in Aigle: green light for the connection between Satom SA and the WWTP

The expansion of district heating in Aigle, called "Thermorezo", marks a turning point in the energy strategy and decarbonisation of the Chablais region. An important step in the deployment towards Aigle has been taken with the green light granted by the cantons of Vaud and Valais for the construction of the section linking the thermal waste recovery plant of Satom SA to the Aigle WWTP. Alongside the ongoing laying of district heating pipes in the town of Aigle, construction of the Thermorezo backbone will be able to start in early 2025.

After covering a large part of the heat demand in the municipalities of Monthey and Collombey-Muraz, Thermorezo continues its development towards Aigle via the North DH network, before heading towards the southern part of the Chablais. A decisive step was taken this autumn for the Aigle connection with the granting of permits by the cantons of Vaud and Valais. The development of Thermorezo is part of an ambitious project to produce heat generated by thermal waste recovery.

Encouraging progress

As a reminder, two parallel construction sites were launched for the deployment of the North DH network in the municipality of Aigle. On the one hand, the laying of pipes in the town has been underway since September 2023, in accordance with an agreement established between the municipality of Aigle and Satom SA. On the other hand, the construction of the backbone towards Aigle is underway.

Submitted to the cantons of Vaud and Valais in July 2023, the public inquiry for this six-kilometre section linking the Satom SA plant and the AERA WWTP (Intermunicipal Association for Wastewater Treatment of the Aigle Region) recently received final approval from the authorities. With building permits granted, Satom SA is able to specify the next steps in the work schedule. These will take place from 2025 on both banks of the Rhône:

Construction sites and synergies

The route requires underground passage of side channels, the Rhône, and the motorway. A complex phase will take place between spring 2025 and autumn 2026 with the excavation of a gallery under the river using a micro-tunnel boring machine. This operation alone is estimated at 4 million francs. Romande Energie will take advantage of this structure to run medium voltage power lines through it.

Satom SA specifies that it will not need more waste to recover in order to supply energy to its thermal heating network in the Chablais plain. Through its various installation renewal projects, significant improvements in thermal energy recovery and energy efficiency will be made. All recovered thermal energy will be injected into Thermorezo at the Chablais scale and the remaining available energy in the form of steam will be supplied via the Ecotube to the neighbouring chemical site.

The connection to the AERA WWTP is an important asset. It is carried out in coordination with the construction project of the new regional wastewater treatment plant. The energy contained in the basin waters will eventually be recovered at the end of the plant by heat pumps and injected into Thermorezo. This backup plant will help strengthen the network’s reliability with an additional supply of decarbonised energy.

Towards the end of fossil fuels

The deployment of the North DH network in Aigle, representing a total investment of 150 million francs, is a major technical challenge but also a promise for the future of the entire region. This project will reduce dependence on fossil fuels and actively contribute to environmental protection. Thermorezo will supply two-thirds of the city’s energy needs and reduce CO2 emissions by 70% (-16,000 tonnes per year). To date, about 50 contracts have already been signed. Ultimately, the DH network will permanently retire 800 chimneys fuelled by fossil energies in the town of Aigle.

The Municipality of Aigle and Satom SA welcome this concrete step in the implementation of the energy transition in the municipality and the region, with the active support of the cantons.

Planned schedule

End of 2024: Building permit granted for the Satom SA – AERA WWTP connection

Winter 2024 – 2025: Start of work on the backbone between Satom SA and the Aigle WWTP

Spring 2025 – autumn 2026: Crossing of the Rhône at Illarsaz

Winter 2026 – 2027: Supply of the first buildings in Aigle with heat rejected from the UVTD (Thermal Waste Recovery Plant)

Schematic map of the North DH network route of Thermorezo between Satom SA and Aigle (pdf to download)

Contacts

Satom SA, Tanja Dubas, communications manager, tanja.dubas@satomsa.ch, 024 473 88 19

Municipality of Aigle, Jean-Luc Duroux, municipal councillor, jean-luc.duroux@aigle.ch, 024 468 41 11