Microsoft has entered a long-term agreement with Arca to remove nearly 300,000 tonnes of carbon dioxide from the atmosphere over the next decade. The deal supports Microsoft’s broader goal of becoming carbon negative by 2030 through verified, durable carbon removal technologies.
BNN Bloomberg spoke with Paul Needham, CEO of Arca, about how the company’s mineralization process uses mining waste and microwave energy to permanently store carbon dioxide, and how this partnership could accelerate industrial-scale climate repair.
Key Takeaways
- Microsoft’s 10-year deal with Arca will remove nearly 300,000 tonnes of atmospheric carbon dioxide.
- Arca’s process uses mine tailings and microwave energy to speed up natural carbon mineralization.
- The approach offers a low-cost, permanent way to store carbon within existing industrial sites.
- Microsoft’s investment reflects its goal to be carbon negative by 2030 and erase all historic emissions by 2050.
- The agreement validates mineralization as a scalable, durable carbon removal pathway.
Read the full transcript below:
ANDREW: We hear a lot about cutting carbon emissions. We also hear a lot about carbon capture, which happens at the source of emissions — say, a big smokestack — where some of the carbon dioxide is captured. There’s also an emerging industry for removing carbon dioxide directly from the air. Advocates say we have to go there if we’re going to reach anything close to a net-zero global economy.
So let’s talk to one of the players in that carbon removal space. Microsoft has entered into an agreement with a carbon removal company called Arca to remove nearly 300,000 tonnes of carbon dioxide over the next 10 years. We’re joined now by Paul Needham, CEO of Arca. Thanks very much for joining us, Paul. You have an appalling pun on your website — “rocking CEO,” too — and one of the things you’re involved in is working on rocks that absorb carbon dioxide. It’s a natural process, but you speed it up. We’re showing a board there — you already have a pilot with BHP at a mine in Western Australia — but just explain how your technology works, please.
PAUL: Thanks very much for having me, Andrew. Most people are surprised to learn that certain kinds of rocks can actually capture CO₂ from the air. It’s a natural geochemical process called carbon mineralization. What happens is that carbon dioxide molecules bind with, for example, magnesium that leaches out of rocks or minerals. The magnesium and the carbon dioxide form new minerals, so these rocks effectively capture CO₂ and turn it into more rock.
ANDREW: What do you do to the rock to speed up the process? How do you add value here?
PAUL: The hard part is getting enough of this rock to have a big enough impact. What our team discovered is that certain types of mining waste — mine tailings — contain the right minerals with the potential to capture and permanently store CO₂. So we partner with producers of critical metals like nickel and work with the mine tailings. We activate the minerals left behind in that mine waste so they start capturing CO₂.
One of the methods we use is microwave energy. Our process uses high-intensity bursts of microwave energy to break molecular bonds in these minerals, which releases magnesium. When CO₂ is introduced, the magnesium binds with it and stores it away permanently.
ANDREW: I’ve been doing a bit of research. Scientific American just ran an article about carbon removal. A lot of people around the world are working on it. One approach involves pulverizing suitable rocks and spreading them on agricultural fields.
PAUL: Yes, that’s called enhanced rock weathering. In that case, you move the material to other places. In our case, we’re working within the industrial footprint of the mine — we’re not moving materials out onto cropland or forest land. Staying within the mine’s footprint has several advantages. It’s a much lower-cost approach, and we can also partner directly with mining companies and leverage their on-site infrastructure.
ANDREW: Tell us about your deal with Microsoft. Microsoft doesn’t produce mine tailings, so how will this work?
PAUL: Great question. On the demand side of our business, we partner with buyers — companies with net-zero targets that are ready to take responsibility for their emissions. They pay us to remove CO₂ from the atmosphere.
Microsoft, very famously, has promised its customers, investors and the world that it will be net negative by 2030, and by 2050 it will remove from the atmosphere all of the CO₂ it has ever emitted since the company was founded in 1975. These are very bold and ambitious climate targets. To achieve them, Microsoft needs companies like ours to help remove CO₂ from the atmosphere — and to ensure those removals are independently verified.
ANDREW: I was just looking at research from Wood Mackenzie indicating that the massive growth in electricity demand — not all of it driven by AI — will jeopardize progress toward net zero.
PAUL: It certainly increases the challenge, but it also increases the opportunity for companies in the carbon dioxide removal industry. Rule number one is not to emit — we must reduce emissions — but there are unavoidable and historical emissions, and there’s already too much CO₂ in the atmosphere. That’s why there’s a growing need for carbon dioxide removal.
ANDREW: Can you give us an idea of how much money you’ve raised so far?
PAUL: The amount we’ve raised is still confidential, but we will be raising more based on this. We’ve been negotiating this deal for many months. It’s the result of 20 years of academic research led by Professor Greg Dipple, our co-founder and head of science, and his team at the University of British Columbia. This company has been 20 years in the making — and many months in the making for this particular contract.
ANDREW: We’re tight for time, but your technology has potential in the steel industry as well.
PAUL: Yes, there are several industrial waste streams where this technology can be applied, with the potential to repurpose waste for climate repair.
ANDREW: Climate repair — that’s a new one for me, Paul. Thanks very much. Fascinating story. Paul Needham, CEO of Arca.
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This BNN Bloomberg summary and transcript of the Oct. 29, 2025 interview with Paul Needham are published with the assistance of AI. Original research, interview questions and added context was created by BNN Bloomberg journalists. An editor also reviewed this material before it was published to ensure its accuracy and adherence with BNN Bloomberg editorial policies and standards.
