A 2,500 m² test facility at Holcim's cement plant in Martres-Tolosane, France, is now operating at 5–30 tonnes of CO2 captured per day — roughly one-hundredth of the throughput a full-scale capture unit would handle on the same site. The plant, called CaptureLab, is the cement industry's first dedicated carbon capture test platform, and it exists to close a specific gap: proving capture technologies on real cement kiln flue gas before the sector commits billions to industrial-scale CCUS installations.

Holcim says eight of its full-scale CCUS projects in Europe have secured grants from the EU Innovation Fund. The company has pledged to reach net zero by 2050 and to bring near-zero cement and concrete to market from 2030, where the necessary transport and storage infrastructure exists. CaptureLab is the de-risking instrument behind that 2030 commitment.

Why cement flue gas is different

Cement plant flue gas runs roughly 60% nitrogen, 20% CO2, 12% water vapor and 8% oxygen, with about 0.1% trace elements — sulfur and nitrogen oxides measured in parts per million. Those ppm-level contaminants are the hard part. Pipeline operators and storage site owners demand extremely pure CO2, and when CO2 from multiple sources is mixed into a single transport stream, trace elements must be monitored to protect infrastructure integrity.

"Our objective is to ensure the removal of trace elements down to the specifications required for safe transport and permanent storage," says Matthieu Aragones, CaptureLab project manager at Holcim. "We're aiming to transform industrial flue gas into a stream that is at least 99.7% pure CO2. At this level, we ensure the captured carbon meets the highest quality standards for the global value chain."

De-risking high-CAPEX commitments

"Although carbon capture has existed for over 50 years, the reality is that it's a new technology for the cement industry," Aragones says. "Given the high CAPEX and OPEX of CCUS projects, there is no room for error, and we must be ready to operate from day one. CaptureLab allows us to 'derisk' these major investments by proving the technology works at a pilot scale before we commit to full-scale operations."

Developed by Holcim R&D teams in Switzerland and France, the platform lets engineers simulate real plant conditions. They can vary raw meal composition or the fuel mix and measure directly how routine operational changes affect capture efficiency — variables that bench-scale research cannot reproduce.

The plug-and-play model

The infrastructure splits into two parts. Holcim owns and operates the fixed side: the flue gas pre-treatment system connected to the plant's stack, plus utilities and analytical equipment. Partners occupy the pilot side — technology providers and startups plug their proprietary capture units directly into Holcim's feed system.

"This plug-and-play approach allows Holcim to easily install new pilots, and to test both mature and breakthrough technologies over time on the same installation, with the option to also adjust the flue gas composition," Aragones explains. "By providing the necessary pretreatment and utilities, we enable partners to focus exclusively on the performance of their capture technology, accelerating the time it takes to move from the pilot stage to a commercial plant."

The first pilot is already running, in partnership with Air Liquide.

Separating built capacity from pipeline

The distinction matters here. CaptureLab is built and operating — a pilot-scale facility with a 5–30 tonne-per-day envelope. The full-scale projects it feeds are not: they are announced installations across Holcim's global network, eight of them in Europe backed by Innovation Fund grants, intended to deploy technologies only after validation at Martres-Tolosane. Technologies proven at the test platform would then scale "with confidence, and in a way that makes business sense," according to the company.

Ram Muthu, Holcim's head of group operational excellence, frames the facility as an open-innovation asset: validated technologies will be deployed at Holcim's own sites, advancing what the company calls its decarbonization roadmap and the production of near-zero cement.

What to watch

The metrics that decide whether CaptureLab matters are narrow and measurable: the 99.7% CO2 purity specification for pipeline-grade and storage-grade output, sustained performance of the Air Liquide pilot under variable kiln conditions, and conversion of pilot results into final investment decisions at Holcim's eight Innovation Fund-backed European projects. The binding deadline is 2030 — the date Holcim has set for scaling near-zero cement and concrete commercially, contingent on CO2 transport and storage infrastructure being in place. Each pilot cycle at Martres-Tolosane between now and then either advances a technology toward a full-scale order or screens it out before capital is committed.