Developed over 20 years of research at the University of British Columbia, Canada, carbon sequestration company Arca works on industrial-scale carbon mineralisation in mine tailings, offering permanent carbon dioxide (CO₂) removal, which it considers to have massive commercial potential as a carbon credit offering.
The company offers three technologies. First is its monitoring, reporting and verification solution, which enables users to see carbon flux – the drawdown of CO₂ into mine tailings – in real time.
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Secondly, Arca offers what it terms “smart churning”. This involves amphibious, autonomously capable rovers churning ultramafic rock, exposing unmineralised tailings to the surface, where they undergo carbon mineralisation, a natural geochemical process in which magnesium carbonate crystals form a crust on the surface.
The final technology – which the company considers its “breakthrough technology” – is mineral activation. Using microwaves, the mineral lattice structure of the mine waste is broken, liberating more of the reactive elements. Around 99% of the Earth’s carbon is stored in rock, and carbon mineralisation has shaped the climate for millions of millennia – Arca’s technology offers a fast-track solution.
The Vancouver-based company won the Excellence in Mine Decarbonisation Innovation award in May 2025, and in June received $315,000 from the Mining Innovation Commercialisation Accelerator, funded by the Canadian Government.
Yet, its commercialisation potential is in its early stages. Here, Arca head of external affairs, Sean Lowrie, tells Mining Technology that the carbon credit potential of legacy mine waste is worth $1.3trn. He suggests that this sum could quadruple with the inclusion of all historical legacy alkaline waste streams and envisages a future of carbon-negative metal with an additional trillion-dollar revenue stream.
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Eve Thomas (ET): How would Arca’s technology work commercially as a carbon credit programme?
Sean Lowrie (SL): When we accelerate the natural rate of carbon mineralisation, we are able to measure unambiguously, using International Organisation for Standardisation (ISO) validated methodologies, the amount of CO₂ that has been pulled out of the air and sequestered permanently in the surface of the rock. One tonne (t) of CO₂ removed is one carbon credit, which we can sell on the voluntary carbon markets and soon the compliance market (markets that are government regulated). The voluntary markets now are comprised of multinational corporations that have made net-zero commitments and want to kick-start the CO₂ removal industry. They are buying advanced purchases and using offtakes to buy removals from companies like Arca.
We would work with the mining industry in several different models: we might pay for access on the tailings, then sell the credits; we might partner and share the credits; or we might license our technology to the mining company. There are a number of ways that we can structure the relationship with the mining company, but the main business model is removing CO₂, generating and selling the credits to either governments or corporations.
ET: How much money do mining companies stand to make by adopting Arca’s idea?
SL: This is quite a significant revenue opportunity for mining. We have mapped billion of tonnes (bt) of the right type of legacy mafic and ultramafic mine rock waste. It is lying on the surface of the Earth right now and represents a projected storage potential of 6.5bt, which at $200/t would be a one-time, $1.3trn opportunity for the mining industry.
If you look at all historical legacy alkaline waste streams, it is a lot more – four-times that. Moreover, the mining industry produces 3bt of waste in these commodities per year, so there is an ongoing revenue opportunity here. This incorporation of CO₂ removal in the mining process is financially attractive, as our white paper said; it also addresses the social licence to operate. The communities and indigenous groups that we have spoken to also like the idea that mine operations can contribute to the response to the climate crisis.
ET: Carbon credit programmes have become shrouded in claims about ‘greenwashing’. What makes Arca different, and what would you say to critics who accuse carbon credits of being a ‘quick fix’?
SL: The CO₂ removal industry is comprised of different technology pathways and different feedstocks. Some use something called direct air capture: it uses these high-tech vacuum cleaners that suck air through filters that separates the CO₂, which is then pumped underground. Others work with trees, so as trees grow, they capture CO₂ and the forests become carbon sinks. Others work with soils, where they crush and spread reactive rock, like basalt, over farmers’ fields and that creates a chemical reaction that pulls CO₂ out of the air, and it gets into the groundwater and goes to the ocean.
Our pathway is called industrial mineralisation. We work with industrial infrastructure and alkaline waste streams to accelerate the process of carbon mineralisation. Carbon mineralisation is an exciting way of removing CO₂, because it is permanent. We are creating these new baby rocks; these magnesium carbonate crystals are inert and durable on geological timescales, so the removals are 10,000 years in duration – the sort of timescales the Earth moves on, and the highest quality of removals. Our message to the mining industry is that it is possible to measure this with complete certainty – the removals are highly durable using methodologies that have been validated to ISO. The mining industry can enter the project with the confidence that their actions won’t be questioned.
ET: There has been a cross-industry push for decarbonisation of supply chains as businesses look to reduce scope 3 emissions, but it can be a slow process. Have you seen a trend away from big-ticket decarbonisation projects and towards technologies like Arca’s, which offer faster, more tangible returns?
SL: Our removals would ideally be the last step in the chain. The use of mine waste to remove CO₂ doesn’t replace the need to reduce emissions through easier means. It is more efficient and cheaper to reduce emissions through electrification and renewable energy sources than through CO₂ removal with mine waste.
However, there will be hard-to-abate emissions, like the use of explosives, that producing CO₂ removals with mine waste would abate. Ideally, a mining operation would decarbonise as much as it can through electrification of its haul fleets, green energy sources, etc. Then, for the very last bit, they would use CO₂ removals in mine waste to bring them into carbon neutrality, or even carbon negativity. It is possible that, if the right type of mine and technology mix is there, that carbon negative commodities could be produced. Imagine selling nickel that was carbon negative, so that when you buy a car with nickel in the battery, that nickel is actually removing CO₂ from the atmosphere.
ET: Who are the customers for commercial carbon sequestration and what is the demand?
SL: A range of companies including Microsoft, Stripe, JP Morgan, Swiss Re and Airbus are buying credits now. Microsoft is the biggest buyer. It has made a leading commitment to be carbon neutral by 2030. It is even talking about removing all of its historical emissions since the beginning of the company. However, there are other companies that are also buying carbon removal. There are 10,000 companies that have signed up to the science-based targets initiative, of which only a few have begun to purchase carbon removals on that voluntary market. There is a lot of future demand that is out there that will come into the market.
ET: What are the next steps for Arca to make this carbon credit programme mainstream?
SL: Arca is the first and only company to complete a demonstration project in an active mine site. At the BHP mine Mount Keith in Western Australia, we ran an 18-month demonstration project that proved that we could integrate CO₂ removal seamlessly into the operations of an active mine.
The next step for us is to develop projects. We are developing them now in Canada and Australia to take what we have learned from that demonstration and apply it at a bigger scale. The pilot project in Australia only demonstrated the first two technologies from our technology portfolio: the monitoring technology and smart churning that uses robots. The third technology, mineral activation, is still in the lab and has another year or so of research before it is ready to deploy. What we have built in our lab is a prototype flow through a mineral reactor. Mining is about a flow of rock, so our technology would need to fit into the mining circuit or be deployed on the tailings post-circuit, but both of those require the ability to activate a large amount of feedstock.
So, what we have developed and built in our lab is a prototype flow through the activator, which will be used to build the first deployable prototype in a year or so.
