Microsoft Teams Up with Alt Carbon: A Major Step for India’s Growing Role in Carbon Removal

Microsoft has taken a significant step towards its sustainability goals by entering into a three-year agreement to purchase nearly 37,000 metric tons of carbon removal credits from Indian startup Alt Carbon. This deal is not just a milestone for Microsoft; it’s also a major validation for India's burgeoning role in the carbon removal market.

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. The deal is part of Microsoft’s broader efforts to combat climate change and align with its commitment to being carbon negative by 2050.

Alt Carbon, a Bengaluru-based startup founded in 2023, specializes in enhanced rock weathering—a technique that involves spreading crushed basalt on farmland to accelerate natural chemical reactions that store atmospheric CO2. The company sources its basalt from the Rajmahal Traps in eastern India and deploys it across farmland in West Bengal.

The collaboration began in early 2025, with extensive scientific reviews, due diligence, and contract negotiations lasting over a year. Microsoft required additional monitoring, reporting, and verification (MRV) measures beyond registry requirements, including expanded data-sharing and carbon quantification protocols. This level of scrutiny underscores the importance Microsoft places on verified and credible carbon removal projects.

Alt Carbon’s CEO Sparsh Agarwal highlighted that this deal is a significant boon for his company. To date, Alt Carbon has issued nearly 10,000 carbon-removal credits through enhanced rock weathering, making it the world's largest issuer of such credits. The startup expects to issue another 15,000 credits by year-end and aims to expand its operations fivefold over the next four to five years.

The deal with Microsoft is part of a broader trend where international buyers are increasingly seeking proven carbon-removal projects in a market that remains scarce in verified supply. Agarwal noted, 'The problem right now is that there are a lot of suppliers, but very few verified deliveries. When companies can deliver, everyone wants to ensure they get a part of the supply.'

Microsoft has been active in India's carbon removal market; earlier this year, it signed an agreement with another Indian startup, Varaha, for more than 100,000 tonnes of carbon dioxide removal credits generated through biochar over three years. Other buyers include procurement coalitions like Frontier and NextGen.

Alt Carbon plans to expand its deployment footprint significantly in the coming years as demand for verified carbon-removal credits grows. The company has built its own MRV infrastructure, including laboratories in Bengaluru and Darjeeling, to analyze soil and water samples and quantify carbon removal. Improving verification capabilities and lowering measurement costs will be crucial for scaling enhanced rock weathering projects both in India and globally.