India-based climate tech startup Alt Carbon and Microsoft announced a new multi-year carbon removal deal, with Microsoft agreeing to purchase 36,920 tons of carbon dioxide removal (CDR) credits, generated from Alt Carbon’s Darjeeling-focused enhanced rock weathering (ERW) project.
The agreement marks Microsoft’s first ERW-based carbon credit purchase deal in Asia, and also provides Microsoft with the opportunity to purchase additional volumes from Alt Carbon, subject to successful delivery and verification milestones.
Founded in 2023 by brothers Shrey and Sparsh Agarwal, Alt Carbon has set a goal to remove 5 million metric tons of CO2 by 2030, with a focus on Carbon Dioxide Removal (CDR) in South Asia, through technology pathways like ERW. The company’s ERW method sources basalt rock dust from mines, and spreads it across agricultural fields, where it reacts naturally with rainwater through a chemical reaction that converts it into stable bicarbonate ions that are stored in the soil, and over time travel through rivers to the ocean, residing as calcium carbonate for over 10,000 years.
The carbon credits under the new agreement will be generated from Alt Carbon’s Darjeeling Revival Project (DRP), which aims to revive Darjeeling’s heritage tea estates and neighboring agricultural networks like rice paddies, by making it a hub for removing CO2 at scale. In addition to removing carbon, Alt Carbon cited agricultural benefits from the project including boosting soil health, balancing pH, and improving crop yields for farmers.
Shrey Agarwal, CEO and Co-founder of Alt Carbon, said:
“Our deal with Microsoft is built upon years of work building high-integrity carbon removal infrastructure in India. From laboratory capabilities to field operations and farmer networks, we have focused on advancing the science of rock weathering globally… Climate Change remains one of the most significant civilizational challenges we face & India can be a global leader in tech based carbon removal”
The agreement marks the second carbon removal purchase to be announced by Microsoft since reports emerged in April indicating that the tech giant has informed carbon credit suppliers that it is pausing its carbon removal purchases. In a subsequent statement by the company, Chief Sustainability Officer Melanie Nakagawa said that the “carbon removal program has not ended,” but acknowledged that while program will continue to form part of its strategy to achieve its climate goals, it “may adjust the pace or volume of our carbon removal procurement.” Microsoft has been by far the largest buyer of carbon removal credits globally, representing approximately 90% of the market in 2025, according to carbon dioxide removals (CDRs) platform CDR.fyi.
Phil Goodman, Program Director, Carbon Removal at Microsoft, said:
“Our contract with Alt Carbon for high-quality carbon removal uses field deployments to collect primary and secondary quantification methods for carbon quantification, while using a high standard to safeguard against environmental impacts. We are encouraged by Alt’s efforts to build durable carbon removal capacity in India given their past success in delivering carbon credits.”
