BIOGAS UPGRADING GUIDES
What happens to CO₂ after biogas upgrading?
Removing CO₂ raises the methane concentration of biogas. It does not by itself determine what happens to the separated carbon. That depends on the upgrading process, treatment downstream and an actual outlet for the CO₂ or the product made from it.
Separation and utilisation are different decisions
In an upgrading project, first establish the biomethane requirement and then follow the carbon beyond the gas outlet. Ask whether CO₂ leaves in a residual gas stream, is recovered as a separate product or is converted within the process. The composition of that stream matters, including any residual methane.
Do not treat captured CO₂ as automatically ready for sale. Its intended use determines the necessary quality, conditioning and delivery arrangements. A buyer and a specification are part of the project, not a consequence of separating CO₂.
What are the general routes?
A project may release CO₂ in a residual stream, subject to its applicable requirements, or recover it for a defined use. Recovery can require further purification and conditioning. Methanation is another route: CO₂ reacts with hydrogen to produce additional methane. It requires its own hydrogen supply and process integration.
Geological storage is a separate route requiring a storage chain, transport and monitoring. These are general industry options, not a list of capabilities supplied by CarboLoop. Neither utilisation nor capture alone proves permanent storage or a quantified climate benefit.
What does CarboLoop do specifically?
The published CarboLoop process combines biogas upgrading with chemical CO₂ capture and conversion to liquid potassium carbonate. Its public process description identifies biomethane and a potassium carbonate solution as the two commercial products. This is a conversion route, not an offer of liquefied CO₂, methanation or geological storage.
The operator can discuss managing carbonate use or sales directly, or an available partner model for reagent supply and carbonate off-take. Scope and availability are agreed for each project. A potential outlet is not an unconditional purchase commitment or a guarantee of product acceptance.
What does the public evidence establish?
The linked Bureau Veritas report 28333657-1001 concerns witnessed tests of a pilot in Olloniego, Asturias, on 11 September 2025; the conclusion is dated 30 September 2025. The published 18-page redacted PDF includes Spanish and English sections, inspection material, photographs and an analyser-certificate annex.
The conclusion addresses the tested pilot and its industrial applicability. It is not C-300 product certification or a guarantee for every feed gas. Use the report for its stated test scope; define project performance against the agreed raw-biogas composition and engineering basis.
Which questions should an operator resolve?
Ask what leaves the plant, in what form, who accepts it and under which specification. For carbonate, discuss handling and the intended product outlet. For the whole system, ask how methane recovery and residual streams are addressed in the agreed configuration. CarboLoop describes near-complete methane recovery; it does not promise guaranteed zero methane loss.
Assess emissions over the complete project boundary, including energy, materials, transport and the eventual product use. Carbon in a useful product is not automatically permanent carbon removal. A project-specific assessment is needed before making climate claims.
Project discussion checklist
| Topic | What to establish |
|---|---|
| Residual stream | Clarify composition, treatment and applicable release conditions |
| Recovered CO₂ | Define quality, conditioning, delivery and buyer |
| Methanation | Requires hydrogen and a dedicated conversion process |
| Geological storage | Requires transport, storage and monitoring arrangements |
| CarboLoop conversion | Liquid potassium carbonate; product outlet agreed per project |
Sources and evidence scope
General industry context: IEA Bioenergy. CarboLoop information: published product specification and pilot report. General industry routes are not promised CarboLoop capabilities.