Neustark introduces its carbon removal technology to France with…

Name: neustark
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The Swiss climate tech pioneer is bringing its carbon removal technology to France, building the first French storage plant at partner’s Lafarge’s site in Gennevilliers near Paris.
Neustark's technology captures biogenic CO₂ at nearby biogas production facilities and stores it in recycled concrete aggregate (RCA) – turning the world’s largest waste stream, demolition concrete, into a durable carbon sink.
The Gennevilliers site will be able to store and remove more than 1,000 tonnes of CO₂ per year. Lafarge will use the carbonated RCA as circular construction material.

The Swiss carbon removal developer neustark, announces the introduction of its technology to France as part of a strategic partnership with Lafarge, part of the Holcim Group. By turning the world’s largest waste stream – demolition concrete – into a carbon sink, neustark generates crucial negative emissions by turning demolition concrete into a carbon sink. In mid-2025, neustark's first storage site in France will be deployed at the Lafarge recycling site in Gennevilliers near Paris, permanently storing and removing more than 1,000 tons of biogenic CO₂ annually.

Lafarge has installed a new production line for sorting and crushing granulates that will then be carbonated via neustark's technology. Once enriched with CO₂, the carbonated recycled concrete aggregate (cRCA) will either be used to produce fresh recycled concrete (by ready-mix concrete plants or prefabrication companies) or for road construction (frost protection and base layers). The carbonated RCA retains all of its properties compared to standard RCA, as lab tests and recent third-party studies have shown.

Locking CO₂ into demolition waste

Neustark captures the carbon dioxide at nearby biogas plants. During the biogas upgrading process, highly pure CO₂ is separated from biomethane. Neustark captures this biogenic CO₂ (which would have otherwise be emitted into the atmosphere), and transports it to nearby storage sites. There, the technology injects it into the recycled concrete aggregates and triggers an accelerated mineralization process, which permanently binds the CO₂ to the pores and the surface of the aggregates. Since the carbon dioxide captured and stored is of biogenic nature, neustark creates negative emissions that are highly durable (>1000 years).

By launching this solution in the French market, neustark offers businesses in the construction industry a unique opportunity to drive carbon capture, storage and removal forward in France as well as ensure more circularity in the built environment.
  
"Removing unavoidable emissions from our atmosphere is – next to massively reducing our emissions – one of the greatest challenges of our time," explains Valentin Gutknecht, founder and co-CEO of neustark.

"In France, more than 20 million tonnes of demolition concrete are produced annually. Storing CO₂ locally in mineral waste – or: onshore surface mineralization – is an innovative and still little-known technology. We can store around 10 kg of CO₂ per tonne of RCA, which translates into a potential of several hundred thousand tonnes of CO₂ that could be durably stored and removed per year in France alone."

"This unique technology generates crucial negative emissions onshore, i.e. without having to transport and store the captured CO2 in the underground in the Nordics. By turning demolition waste into a carbon sink, neustark provides local, tangible and immediate climate action, also addressing the IPCC's call for ambitious action in the heavy-emitting construction industry."

Demolition concrete is our carbon ‘sink’. You have the demolition concrete – we have the technology to add on. Learn more about how you can team up with us and turn the decarbonization of construction into an opportunity for your business.

A first-of-its-kind in France

Neustark has already deployed its carbon capture and removal solution technology at 29 sites across Europe. This partnership with Lafarge represents a major step forward in a key market for neustark, building on its strategic collaboration with the Holcim Group.

“The launch of this pioneering technology in France and the storage of CO₂ directly in recycled materials represents another step in our commitment to advancing the sustainable transformation of the construction industry. We are proud to offer this innovative solution to our customers in the Paris region, enabling them to incorporate carbonated RCA into their production," exclaims Xavier Bullot, Chief Executive Officer of Lafarge Aggregates.  

Valentin Gutknecht concludes, "We are committed to a sustainable future by helping limit global warming to 1.5 degrees. Neustark's technology complements companies' efforts to reduce emissions by removing hard-to-abate emissions from the atmosphere. The introduction of our technology in France marks an important milestone in our growth. Our partnership with Lafarge is a powerful step to expand our presence and scale our climate impact."

FAQs

Carbon dioxide mineralization is a process in which CO₂ reacts with alkaline metal to form solid carbonate minerals.

Demolished concrete aggregate contains hydrated cement phases. These hydrated cement phases are in contact with water, e.g. pore water – and thus in a solid-liquid equilibrium. Part of the hydrated cement is dissolved in the water and therefore present as ions. As CO₂ is also dissolved in this water, new mineral that exhibit lower solubility than the hydrated cement phases precipitate. And voilà, calcium carbonate (CACO₃) is formed.

Thus, the CO₂ and the hydrated cement undergo a chemical transformation to form rock. This so-called carbonation reaction of 1 kg CO₂ releases heat such that the temperature of 1,000 kg of concrete increases by about 2.5°C.

CACO₃ is considered to be amongst the most permanent ways to sequester carbon. Only temperatures above 600°C or very strong acids could trigger the release of CO₂. This ensures that the CO₂ remains stored in the concrete, even if it is demolished again after being reused.
Currently we can store around 10 kg of CO₂ per ton of demolition concrete on an industrial and economical basis – and we’re continuously working on optimizing this figure. Depending on the material characteristics, we can store up to 25 kg of CO₂ per ton.

In terms of speed, our latest plant stores around 1000 kg of CO₂ per hour in concrete granulate. As a comparison: fast-growing pine trees absorb about 20kg of CO₂ per year . So one neustark plant can do in one hour what 50 trees need a whole year for.

Or, in other words, within 24 hours, one neustark plant can store the same amount of CO₂ in demolished concrete granulate as the CO₂ that is on average emitted by two single-family homes heating with oil in Switzerland in a year’s time.

For more information, please see Johannes Tiefenthaler et al’s Technological Demonstration and Life Cycle Assessment of a Negative Emission Value Chain in the Swiss Concrete Sector.