Microsoft signs three‑year carbon‑removal deal with Indian startup

Microsoft has entered a three‑year agreement to purchase nearly 37,000 metric tons of carbon‑removal credits from Indian startup Alt Carbon, the first enhanced rock‑weathering deal the tech giant has secured in Asia [1].

Key takeaways

• Microsoft will receive 36,920 t of CO₂‑removal credits from Alt Carbon’s Darjeeling Revival Project by 2029 [1].
• The agreement includes an option for additional purchases if Alt Carbon meets delivery and verification milestones [1].
• Alt Carbon’s enhanced rock‑weathering technique spreads crushed basalt on farmland to accelerate natural carbon sequestration [1].
• The startup already issued about 10,000 credits and expects another 15,000 by year‑end, working with over 35,000 farmers on roughly 80,000 acres [1].
• Credits will be registered through Isometric, which has developed a methodology for enhanced rock weathering [1].

Microsoft’s first enhanced rock‑weathering contract in Asia

The deal was finalized after discussions that began in early 2025 and involved extensive scientific review, due‑diligence, and contract negotiations, according to Alt Carbon co‑founder Sparsh Agarwal [1]. Microsoft required additional monitoring, reporting and verification (MRV) measures beyond standard registry requirements, including expanded data‑sharing and carbon‑quantification protocols. Alt Carbon will deliver the credits from its Darjeeling Revival Project in eastern India, where basalt sourced from the Rajmahal Traps is spread across farmland in West Bengal. The rock reacts with rainwater and atmospheric CO₂ to form stable bicarbonates, a process known as enhanced rock weathering [1].

Alt Carbon, founded in 2023 and based in Bengaluru, operates two carbon‑removal projects in North Bengal. One serves Japanese shipping giant Mitsui OSK Lines, while the larger project will supply Microsoft’s credits. The company has built its own MRV infrastructure, including laboratories in Bengaluru and Darjeeling, to analyze soil and water samples and quantify carbon removal [1]. Alt Carbon’s recent seed round raised $12 million, underscoring investor interest in scaling the technology [1].

Why it matters

The agreement highlights the growing role of emerging‑market suppliers in the global carbon‑removal market; developers from the Global South now account for about 26 % of credit issuances, up from roughly 2 % in 2022 [1]. By securing verified credits from a startup that meets stricter MRV standards, Microsoft signals confidence in Indian carbon‑removal projects, which have historically faced skepticism from international buyers [1]. The partnership also follows Microsoft’s earlier Indian deal with Varaha, a biochar‑based carbon‑removal startup, indicating a broader strategy to diversify its climate‑action portfolio across multiple removal technologies [1]. As demand for verified credits rises, Alt Carbon plans to expand its deployment footprint roughly fivefold over the next four to five years, potentially accelerating the adoption of enhanced rock weathering in India and beyond [1].