Microsoft has signed a three-year agreement to buy nearly 37,000 tons of carbon removal credits from Indian startup Alt Carbon, marking the tech giant’s first enhanced-rock weathering deal in Asia, according to a report by TechCrunch.
The Deal
Under the agreement, Alt Carbon will deliver 36,920 metric tons of carbon dioxide removal credits by 2029 from its Darjeeling Revival Project in eastern India. Microsoft also retains an option to purchase additional volumes if Alt Carbon meets delivery and verification milestones, TechCrunch reported. The agreement follows reports that Microsoft — the world’s largest buyer of carbon-removal credits — had paused parts of its procurement program, but the company rejected those claims, reaffirming its commitment to climate goals while refining its sustainability strategy.
Enhanced Rock Weathering Technology
Alt Carbon, a Bengaluru-based startup founded in 2023, specializes in enhanced rock weathering, a technique that involves spreading crushed basalt and other silicate rocks on farmland to accelerate natural chemical reactions that store carbon dioxide. The startup sources basalt from the Rajmahal Traps in eastern India and deploys it across farmland in West Bengal, where the rock reacts with rainwater and atmospheric CO₂ to form stable bicarbonates.
Discussions with Microsoft began in early 2025 and culminated more than a year later after extensive scientific review, due diligence, and contract negotiations, Alt Carbon co-founder and President Sparsh Agarwal told TechCrunch. Microsoft required additional monitoring, reporting, and verification (MRV) measures beyond registry requirements, including expanded data-sharing and carbon quantification protocols.
Verification and Market Context
| Metric | Value |
|---|---|
| Credits issued to date (Alt Carbon) | ~10,000 credits |
| Expected additional issuance by end of year | 15,000 credits |
| Farmers engaged | 35,000+ across ~80,000 acres |
| Global South share of credit issuances (current) | ~26% |
| Global South share of credit issuances (2022) | ~2% |
Alt Carbon has issued nearly 10,000 carbon-removal credits through enhanced rock weathering to date, making it the world’s largest issuer of such credits, according to Agarwal. The startup expects to issue another 15,000 credits by the end of the year. Credits under the Microsoft agreement will be issued through Isometric, a carbon-removal registry that developed an enhanced rock-weathering methodology.
“The problem that exists right now is that there are a lot of suppliers, but there are very few verified deliveries out there. When companies are able to deliver, everyone wants to ensure that they get a part of the supply.” — Sparsh Agarwal, co-founder and President, Alt Carbon
Alt Carbon operates two carbon-removal projects in North Bengal, including one dedicated to Japanese shipping giant Mitsui OSK Lines and a larger program from which Microsoft’s credits will be sourced. The startup has expanded beyond tea estates into rice-growing areas.
India’s Growing Role in Carbon Removal
The deal reflects the growing role of emerging-market suppliers in carbon removal. Developers from the Global South now account for about 26% of carbon-removal credit issuances, up from roughly 2% in 2022, Agarwal noted. He added that international buyers were often skeptical of Indian carbon projects when Alt Carbon launched, but growing issuance volumes and stricter verification standards have helped improve confidence in the market.
Microsoft’s agreement with Alt Carbon is
Sources:
