Carbon removal agreement between Microsoft and UNDO to use wollastonite

By Michelle Dorey Forestell, Local Journalism Initiative Reporter, Kingstonist.com

Microsoft and UNDO have announced a new carbon removal agreement to capture 28,900 tonnes of carbon by 2036, supported by innovative debt financing from Canadian climate fund Inlandsis.

On Wednesday, Oct. 21, 2025, UNDO, a U.K.-based carbon removal company, and Microsoft announced a new agreement to remove 28,900 tonnes of carbon dioxide (CO2) by 2036. The project, supported by innovative debt financing from the Canadian climate fund Inlandsis, will utilize wollastonite sourced from the Canadian Wollastonite mine near Seeley’s Bay, Ontario, in a process known as enhanced rock weathering (ERW). By spreading finely crushed silicate rock on farmland, UNDO accelerates a natural chemical reaction that captures CO2 from the atmosphere and stores it in a stable form in soil and groundwater for centuries. 

The agreement builds on Microsoft and UNDO’s ongoing collaboration, highlighting both the scalability of ERW as a climate solution and the role of financial innovation in unlocking large-scale carbon removal projects.

“Innovative financing is the catalyst for unlocking gigatonne-scale carbon removal,” said Jim Mann, Founder and CEO at UNDO. “The support of Inlandsis shows how financial backers can help transform carbon removal into a genuine asset class – one that is scalable, tradable, and investable. By combining financial innovation, strategic partnerships and bleeding-edge science, UNDO is accelerating deployment and delivering both climate and agricultural benefits in Ontario and beyond.”

“Inlandsis is very pleased to provide capital to this strategic and innovative deal, helping to strengthen the growing relationship between Microsoft and UNDO while advancing the critical fight against climate change,” noted David Moffat, Managing Director at Inlandsis. “This collaboration marks several milestones for us – our first investment in an ERW project and the first Canadian investment for our second fund – and highlights our commitment to advancing carbon finance across Canada and beyond.”

Unlike traditional grant or equity funding, the new financing structure gives UNDO up-front capital to scale ERW projects immediately, using the long-term purchase agreement with Microsoft as security for repayment. By turning future carbon credit revenue into a bankable, investable asset, this innovative model removes the risk from large-scale ERW deployment, accelerates carbon removal projects in Ontario and beyond, and shows how financial innovation can unlock gigatonne-scale climate solutions while supporting sustainable agriculture.

Phillip Goodman, Director, Carbon Removal Portfolio at Microsoft, commented: “Enhanced rock weathering is a promising pathway to gigatonne-scale carbon removal. UNDO’s commitment to scientific rigour gives us confidence in both the durability of these credits and their role in helping Microsoft achieve its goal of being carbon negative by 2030.”

With the backing of leading brands such as Barclays, British Airways, and McLaren, UNDO is well positioned to spread millions of tonnes of mineral-rich silicate rock annually—an important step towards the billion-tonne scale needed to meet the urgent climate challenge.

Wollastonite, a calcium-silicate mineral unique in Canada to this small Eastern Ontario deposit, has become a sought-after ingredient in the emerging carbon removal industry. For UNDO, the Kingston region offers both the geological and agricultural bases to scale up quickly.

UNDO’s Canadian team removed 1,209 tonnes of CO2 in verified carbon storage during the recent XPRIZE Carbon Removal competition — a performance that earned the company US $5 million and international recognition. That success, partly achieved using wollastonite from the Kingston area, lends scientific weight to its Ontario operations.

Microsoft’s bet on mineral weathering

For Microsoft, this collaboration fits a broader corporate strategy of investing in measurable, science-based carbon removal. The company’s sustainability reports show that a growing share of its carbon credits now comes from “durable” methods — those storing carbon for hundreds or thousands of years.

Enhanced rock weathering fits that definition. Once CO2 binds with crushed rock, it forms stable carbonates that cannot be released into the atmosphere. Third-party verification ensures that each tonne removed is traceable and permanent.

The company will finance the spreading of tens of thousands of tonnes of wollastonite across Ontario farmland, capturing and storing CO2 equivalent to the annual emissions of several thousand cars.

From mine to field — a local supply chain

The St. Lawrence Wollastonite Deposit has been active for over a decade, but its environmental story is a quiet standout. As Kingstonist reported last year, the mine site features restored wetlands and protected wildlife areas, a rare distinction for an industrial operation. That ecological track record helped position Canadian Wollastonite as a credible partner in carbon removal.

From the mine, UNDO trucks the crushed rock to farms across Eastern Ontario, from Napanee to Brockville. Farmers receive the mineral free of charge, part of UNDO’s model that exchanges rock application and field data for carbon credit revenue. The benefits aren’t just environmental. According to local trials, wollastonite improves soil pH, strengthens crops against pests, and replenishes calcium and silicon — making the collaboration as much about soil health as climate repair.

A Kingston-based innovation hub

Kingston’s role in this story extends beyond rural fields. In May 2025, Queen’s University reopened Nixon Field after replacing the turf with a system embedding locally mined wollastonite beneath the playing surface. The goal: to turn the field itself into a small-scale carbon sink.

That project marked one of the first instances of enhanced rock weathering being used by a municipality or institution in Canada. It demonstrated how Kingston’s mix of research, materials, and community partnerships could make it a testbed for climate innovation.

Additionally, UNDO is the first tenant of the newly launched 30,000-square-foot clean-tech innovation lab, RXN Hub, located at 945 Princess Street. Backed by a $3 million city investment to support startups in green chemistry, clean energy, and sustainable manufacturing, the lab underscores Kingston’s growing role as a hub for clean tech innovation and carbon-reduction research.

From rural Ontario to a global model

UNDO’s collaboration with Canadian Wollastonite began modestly in 2023, but its results have positioned the region as a global showcase. Kingston-area farmers, already familiar with limestone spreading, have become early adopters of ERW — a process that appears similar on the surface but has a more profound climate impact.

Meanwhile, researchers from Queen’s University and the University of Guelph are studying how soil chemistry changes after wollastonite application, giving the project academic grounding and long-term monitoring data.

UNDO’s $5 million XPRIZE win, its Microsoft partnership, and its Kingston supply chain all underscore a broader trend: carbon removal is shifting from theory to infrastructure. And in this case, the infrastructure consists of the farms and fields of eastern Ontario.

As the climate industry races to scale up, what’s happening around Kingston could serve as a microcosm of how rural economies and global technology can intersect in the era of carbon removal.