Microsoft bets on Indian startup Alt Carbon for rock weathering credits

The Bengaluru-based startup, founded in 2023, will deliver the credits by 2029 through its Darjeeling Revival Project. The process involves spreading crushed basalt from the Rajmahal Traps across farmland in West Bengal, where the rock reacts with rainwater and atmospheric carbon dioxide to form stable bicarbonates. Microsoft holds an option to increase its purchase volume if the startup hits specific delivery milestones.

This partnership follows a rigorous scientific review and due diligence process that lasted over a year. Alt Carbon co-founder Sparsh Agarwal noted that Microsoft demanded monitoring and data-sharing protocols that exceeded standard registry requirements. The credits will be issued via the Isometric registry, which maintains specific methodologies for rock weathering. This move solidifies India’s growing influence in the sector, with Global South developers now accounting for 26% of total carbon-removal credit issuances, a significant jump from 2% in 2022.

Alt Carbon currently works with over 35,000 farmers across 80,000 acres and operates internal laboratories in Bengaluru and Darjeeling to verify carbon quantification. The company plans to expand its footprint fivefold over the next few years to meet surging demand. Alongside this latest agreement, Microsoft continues to build its portfolio of Indian climate projects, including a previous deal with the biochar-focused startup Varaha. Alt Carbon also counts procurement coalitions like Frontier and NextGen among its clients, signaling broad market confidence in its verified output.