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Exterra hones process to turn asbestos mines into carbon sinks

Firm hopes to raise $15 million for Series A round

The Thetford Mines site in Quebec, where Exterra plans to build its Hub One carbon storage facility. (Courtesy Exterra Carbon Solutions)

For Olivier Dufresne, co-founder and CEO of Montreal-based Exterra Carbon Solutions, the goal is not just to develop a method to capture carbon, but to reshape the perception surrounding the mining industry.

Dufresne was born in a mining town in northern Quebec, and the industry has been a constant throughout much of his life.

“I always received negative views on the mining industry from outsiders and wanted to change the face of that industry,” he told Sustainable Biz Canada in an interview.

He carried that aspiration into his professional life as a mining engineer for Osisko Gold Royalties Ltd. for four years. He then changed careers, moving into investment banking at BMO Capital Markets in Montreal, where most of his work involved technology and cleantech companies.

His background led him to co-found Exterra in 2021 based on his mining experience where he saw “sustainability often comes at extra cost, which ends up not happening,” the rise of carbon markets, and his knowledge of fundraising.

Already having signed a partnership with a rising carbon capture company, Exterra plans to raise more funding for a site in Quebec to help store large amounts of carbon dioxide and produce carbon-neutral critical minerals.

Exterra’s carbon storage process

Exterra's process accelerates the natural weathering of rocks to transform mineral waste into large-scale carbon sinks.

Piles of mining waste rich in magnesium or calcium are crushed and bathed in acid to dissolve their magnesium content in a solution. Once the magnesium is dissolved, the solid components like silica are separated out. The silica can be sold to the cement or construction industries.

Carbon dioxide is injected into the magnesium- or calcium-rich solution to produce magnesium or calcium carbonate, which is inert and can store carbon for thousands of years.

Dufresne said Exterra looks to provide industrial carbon emitters or direct carbon capture firms a turnkey and verifiable solution for carbon storage.

The permanence and quality of the carbon credits generated from mineralizing carbon dioxide is “extremely important,” Dufresne continued. Buyers will be able to audit their carbon credits by checking the carbon-injected rocks.

“That adds a very big differentiator from other ways of removing carbon and storing it, where you can’t access (it); you need to base your assumption on models that it has mineralized, whereas we are producing those rocks on surface and it adds that extra layer of transparency and quality.”

To bring its ambition to life, Exterra first needs to develop a project to prove it can mineralize carbon dioxide at scale using mine waste.

Building a site

Exterra plans to develop Hub One at an inactive asbestos mine in Quebec to treat the mining waste and sequester millions of tonnes of carbon dioxide. The capacity for Hub One is projected to be 500,000 tonnes of carbon dioxide per year, with the potential to raise that figure to four million tonnes annually.

In addition to storing carbon dioxide, the Exterra process would destroy the asbestos fibres, eliminating their health risks, and extract nickel, which can be concentrated for use in electric vehicle batteries.

Exterra has secured material in Thetford Mines and is in the process of securing material in Val-des-Sources. Hub One could be located at either location, with a second hub at the remaining site.

If all goes as planned getting the required permits, Dufresne expects construction of Hub One to happen in 2027.

The projected capex for Hub One is $400 million. Dufresne believes that money can be raised mostly through off-take agreements on carbon dioxide mineralization and nickel concentrate.

Its carbon storage will be offered to the likes of Montreal-based carbon removal company Deep Sky and regional industrial emitters as part of a previously announced pilot project. If Exterra’s technology is proven, Dufresne said Exterra will look to license the company's technology to operating mines.

It will also explore beyond asbestos waste and into other types of minerals.

A pilot alongside Deep Sky for a carbon removal facility in southern Quebec is starting in a few weeks in Val-des-Sources, with the ability to store 1,000 tonnes of carbon dioxide per year.

Fundraising plans

Exterra has launched its Series A funding round and is aiming to raise $15 million. The Series A will allow Exterra to complete preliminary feasibility studies and support operations of its pilot and demonstration facilities.

A Series B financing to follow would support a full feasibility study and detailed engineering.

Exterra has raised $4.1 million to date: $3 million in equity from its pre-seed and seed rounds, and the remainder from the Quebec government.

The main focus for Exterra now is getting Hub One off the ground, according to Dufresne. Strategic partners, such as large emitters who want to capture carbon dioxide, are being sought.

Once Hub One is off the ground, Exterra will seek to get Hub Two moving. Dufresne also anticipates expanding globally to the United States, South America and Europe.

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