Microsoft buys carbon credits from Alt Carbon

Microsoft signs carbon removal deal with Indian startup Alt Carbon

12 reported

Microsoft has signed a three-year agreement to purchase nearly 37,000 metric tons of carbon removal credits from Indian startup Alt Carbon, marking the tech giant’s first enhanced rock weathering deal in Asia. 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, with an option for Microsoft to purchase additional volumes if milestones are met. The deal follows reports that Microsoft had paused parts of its carbon-removal procurement program, which the company rejected, stating it remained committed to its climate goals. Discussions between the two companies began in early 2025 and concluded after more than a year of scientific review, due diligence, and contract negotiations, according to Alt Carbon co-founder Sparsh Agarwal. Alt Carbon, founded in 2023 and based in Bengaluru, uses enhanced rock weathering by spreading crushed basalt on farmland to accelerate natural carbon storage. The startup has issued nearly 10,000 carbon-removal credits through this method to date, making it the world’s largest issuer of such credits, Agarwal stated. The agreement is not Microsoft’s first carbon-removal investment in India; in January, it signed a deal with another Indian startup, Varaha, for more than 100,000 tonnes of credits generated through biochar.

What’s reported

Microsoft signed a three-year agreement to buy nearly 37,000 metric tons of carbon removal credits from Alt Carbon.

Alt Carbon will deliver 36,920 metric tons of carbon dioxide removal credits by 2029 from its Darjeeling Revival Project.

Microsoft has an option to purchase additional volumes if Alt Carbon meets delivery and verification milestones.

The deal follows reports that Microsoft had paused parts of its carbon-removal procurement program; Microsoft rejected those claims.

Discussions began in early 2025 and concluded after more than a year of scientific review, due diligence, and contract negotiations.

Alt Carbon uses enhanced rock weathering, spreading crushed basalt from the Rajmahal Traps on farmland in West Bengal.

Alt Carbon has issued nearly 10,000 carbon-removal credits through enhanced rock weathering to date.

The startup expects to issue another 15,000 credits by the end of the year.

Alt Carbon works with more than 35,000 farmers across about 80,000 acres.

Credits under the Microsoft agreement will be issued through Isometric, a carbon-removal registry.

In January, Microsoft signed an agreement with Indian startup Varaha to purchase more than 100,000 tonnes of carbon dioxide removal credits through biochar.

Alt Carbon raised $12 million in a seed funding round led by tech investor Lachy Groom.