Swiss intermunicipal wastewater association EBBV (Basse-Broye/Vully) has issued a public procurement tender for a complete biogas upgrading facility at a sewage sludge digestion plant — with a mandatory option to capture, purify and liquefy the biogenic CO2 stream separated during upgrading.

The contract covers the full process chain: membrane-based upgrading of digester gas and injection of the resulting biomethane into the domestic Swiss gas distribution network. The CO2 clause is the notable part. It obliges the winning contractor to equip the facility for biogenic carbon dioxide recovery and liquefaction, not merely to vent the off-gas.

That requirement reflects a broader European shift. Developers of upgrading projects increasingly treat non-methane streams as a monetizable product — for industrial use or food-grade applications — rather than a byproduct to be released.

What does the tender change for suppliers?

The EBBV tender opens immediate commercial ground for process engineering firms working in:

• membrane separation;
• gas purification;
• CO2 liquefaction;
• thermal integration.

Because the CO2 option is written into the procurement as mandatory rather than optional, bidders must price liquefaction capability into their offers. That sets the facility apart from legacy upgrading plants, which were typically specified to do one thing: clean raw biogas to grid quality and discard the CO2 fraction.

The feedstock is sewage sludge biogas from municipal wastewater treatment — a stable, continuously available stream that utilities across Europe already manage at digestion stage. The EBBV project converts that stream into two marketable outputs: grid-injectable biomethane and liquefied biogenic CO2.

How large is the Swiss market behind it?

Switzerland's biomethane sector remains smaller than those of its neighbors, but it is expanding on a clear trajectory.

• Grid connectivity: the country is approaching 50 operational biomethane installations linked directly to the gas grid.
• Unmapped capacity: national biogas potential is estimated at 4 to 6 TWh per year, leaving significant headroom above current utilization.
• Asset conversion: existing biogas plants are transitioning away from electricity generation toward direct gas grid injection, which raises demand for upgrading and injection infrastructure of exactly the kind EBBV is procuring.

The arithmetic matters for equipment vendors. Fifty grid-connected plants against an estimated 4–6 TWh annual potential means the installed base has not saturated the resource. Each conversion from power generation to grid injection requires an upgrading train — and, if the EBBV model spreads, a CO2 recovery and liquefaction unit alongside it.

Why is CO2 liquefaction becoming standard?

The tender language points to an evolving standard across European upgrading projects. As biomethane plants scale, the CO2 separated during membrane upgrading represents a concentrated, biogenic carbon stream. Liquefaction makes it transportable and sellable into industrial and food-grade markets.

For municipal water utilities, the configuration also serves a policy function. EBBV's project reflects broader Swiss regional initiatives to decarbonize local utility networks by embedding carbon capture and utilization (CCU) directly into wastewater treatment infrastructure — placing the technology inside plants the municipalities already own and operate.

What happens next?

The decisive milestone is the tender award itself. EBBV's procurement will show which process engineering firms can deliver integrated biomethane-plus-CO2 systems at municipal scale, and at what price. A second signal to watch is whether subsequent Swiss wastewater association tenders copy the mandatory CO2 clause — which would turn biogenic carbon recovery from a differentiator into a default specification for the sector's remaining headroom toward 4–6 TWh per year.