Clarke Energy’s Perpignan biogas upgrading project illustrates the use of sewage-sludge biogas to supply a gas distribution network. This dated case study preserves a project milestone in the development of biomethane production in France.
Originally published on 19 January 2020. Updated on 20 October 2026 as a historical project archive. Project specifications, responsibilities and performance claims below describe the original supplier reporting; they are not confirmation of present-day operating conditions or contracts.
The Perpignan Project
According to Clarke Energy’s project case study, the company supplied a membrane upgrading installation at Perpignan’s wastewater treatment works in France. Its source gas came from sewage-sludge digestion, with upgraded biomethane entering the GRDF distribution network.
Archive photograph of the Perpignan biogas upgrading installation, retained from our original Clarke Energy case study.
Historical Project Details
| Item | Detail reported by Clarke Energy |
|---|---|
| Location | Perpignan, France. |
| Client | City of Perpignan. |
| Commissioning | September 2017. |
| Installer | Clarke Energy. |
| Separation technology | Membranes identified as Evonik. |
| Reported biomethane quality guarantee | 97% methane. |
| Gas destination | The GRDF distribution network. |
The original account assigned maintenance to Clarke Energy and operation to Veolia under a renewable five-year arrangement. That historical description should not be read as confirmation of the current contract.
What Did “First” Mean?
Clarke Energy described the installation as its first upgrading plant at a wastewater treatment works. Its 2018 inauguration report also described Perpignan as the first wastewater treatment works in Occitania and the Mediterranean Arc to produce renewable gas for network injection.
This should not be expanded into a claim that Perpignan was France’s first biomethane plant.
Archive photograph: general view of the Perpignan installation, retained from the original case study. Click to enlarge.
How Sewage-Sludge Biogas Becomes Biomethane
The project provides a useful example of the distinction between producing biogas and upgrading it.
Anaerobic digestion produces a methane-containing gas from suitable biodegradable material. Raw biogas also contains carbon dioxide, water vapour and trace constituents.
An upgrading installation combines the gas preparation and separation processes needed to produce methane-rich gas. Membrane systems separate gas components through differences in their permeation behaviour.
Gas cleaning and upgrading are related but different duties. Removing hydrogen sulphide and moisture alone does not remove the bulk carbon dioxide or establish that the gas meets a network’s entry requirements.
For current technical explanations, see our guides to biogas upgrading technologies and upgrading biogas to biomethane.
Reading the Original Performance Figures
The source case study remains linked above for readers who want its complete published specifications. Those figures should be treated as historical supplier information rather than independently verified operating data.
In particular, the methane recovery rate, methane concentration and percentage removal of a contaminant are different measurements. An undefined “purification rate” should not be assumed to mean all three.
The earlier version of this page also repeated an energy figure under an “output power” heading. Kilowatt-hours measure energy, while kilowatts measure power. Without a clear reporting period and measurement basis, an energy total cannot establish a plant’s power rating.
Likewise, inlet and outlet gas-flow figures should only be used together in a methane balance when their reference conditions, compositions and operating basis are compatible.
Why Keep This Project Archive?
Individual project records help show how anaerobic digestion developed beyond electricity generation into renewable gas supply.
They also document the roles of equipment suppliers, installers, operators and network companies. A dated archive can preserve that context without presenting an older installation as a new announcement.
For anyone evaluating a project today, this historical account is a starting point for understanding an application. Current supplier capabilities, references, guarantees and service arrangements should be obtained directly for the proposed installation.
Sources and Related Reading
- Clarke Energy: Perpignan wastewater biogas upgrading case study.
- Clarke Energy: Perpignan biomethane unit inauguration report.
- Clarke Energy: biogas upgrading.
- GRDF.
- Uses and applications of biogas.
[Published on 19 January 2020. Updated on 20 October 2026.]
