Microsoft Partners With Alt Carbon, Highlighting India’s Expanding Carbon Removal Industry

Microsoft has entered into a three-year agreement to purchase nearly 37,000 metric tons of carbon removal credits from Indian climate-tech startup Microsoft Signs Carbon Removal Deal With Alt Carbon, Highlighting India’s Expanding Role in Climate Tech
, marking the company’s first enhanced rock weathering partnership in Asia.

As part of the arrangement, Alt Carbon will supply 36,920 metric tons of carbon dioxide removal credits by 2029 through its Darjeeling Revival Project in eastern India. The agreement also gives Microsoft the option to acquire additional volumes in the future, provided the startup achieves specified delivery and verification targets.

The announcement comes after reports suggested that Microsoft, currently the largest buyer of carbon-removal credits globally, had slowed certain aspects of its carbon-removal purchasing. The technology company pushed back against those claims, stating that it remains committed to its long-term climate objectives while continuing to refine aspects of its sustainability strategy.

For Alt Carbon, the agreement represents a significant milestone. Founded in Bengaluru in 2023, the startup focuses on carbon removal technologies, including enhanced rock weathering. The process involves spreading crushed basalt and similar silicate rocks across agricultural land to accelerate naturally occurring chemical reactions that capture and store atmospheric carbon dioxide.

The company sources basalt from the Rajmahal Traps region in eastern India and applies the material across farmland in West Bengal. There, the rock interacts with rainwater and atmospheric carbon dioxide, eventually producing stable bicarbonates that help lock away carbon.

According to Alt Carbon co-founder and president Sparsh Agarwal, conversations with Microsoft began in early 2025. They concluded more than a year later, following extensive scientific assessments, due diligence reviews, and contract discussions.

Agarwal noted that Microsoft requested additional monitoring, reporting, and verification measures beyond standard registry requirements. These included expanded data-sharing processes and more detailed carbon quantification protocols designed to strengthen confidence in the resulting credits.

The agreement arrives as demand for proven carbon-removal projects continues to grow in a market where verified supply remains limited. However, hundreds of startups have emerged with technologies aimed at removing carbon dioxide from the atmosphere; only a relatively small number have successfully delivered verified credits at commercial scale.

“The problem that exists right now is that there are a lot of suppliers, but there are very few verified deliveries out there,” Agarwal said. “When companies can deliver, everyone wants to ensure that they get a part of the supply.”

To date, Alt Carbon has issued close to 10,000 carbon-removal credits through enhanced rock weathering, which Agarwal said represents the largest issuance of such credits globally. The company expects to generate an additional 15,000 credits before the end of the year.

The startup currently operates two carbon-removal initiatives in North Bengal. One project is dedicated to the Japanese shipping company Mitsui OSK Lines, while the larger initiativisis initiative is the credits supplied under the Microsoft agreement.

Agarwal said the company has expanded beyond tea-growing regions into rice-producing areas and now collaborates with more than 35,000 farmers across roughly 80,000 acres of agricultural land.

The carbon-removal credits associated with the Microsoft deal will be issued through Isometric, a carbon-removal registry that developed a dedicated methodology for enhanced rock weathering projects.

The agreement also underscores the increasing contribution of emerging-market developers within the carbon-removal sector. According to Agarwal, suppliers from the Global South now account for approximately 26% of carbon-removal credit issuances, compared with about 2% in 2022.

He added that when Alt Carbon launched more than two years ago, international buyers were often cautious about Indian carbon projects. However, increasing issuance volumes and stronger verification standards have helped improve trust and credibility across the market.

The Alt Carbon partnership is not Microsoft’s first carbon-removal commitment in India. Earlier this year, in January, the company signed a separate agreement with Indian startup Varaha to purchase more than 100,000 tonnes of carbon dioxide removal credits generated through biochar projects over three years.

Microsoft now joins a growing list of organisations purchasing Alt Carbon credits. That list includes procurement initiatives such as Frontier, whose members include Google, Stripe, and Shopify, as well as NextGen, which is supported by companies including UBS, Swiss Re, and Boston Consulting Group, according to registry records.

Looking ahead, Agarwal said Alt Carbon intends to expand its deployment footprint by roughly five times over the next four to five years, increasing from around 80,000 acres today as demand for high-quality, verified carbon-removal credits continues to rise.

Alt Carbon, which secured $12 million in seed funding last year in a round led by technology investor Lachy Groom, has also developed its own monitoring, reporting, and verification infrastructure. This includes laboratory facilities in Bengaluru and Darjeeling that are used to analyse soil and water samples and measure carbon-removal outcomes.

According to Agarwal, strengthening verification systems while reducing measurement costs will play a crucial role in scaling enhanced rock weathering projects across India and other markets in the years ahead.