Alt Carbon Raises $12 Million to Scale Carbon Removal from Indian Farmlands
From family tea estate roots, Alt Carbon pioneers enhanced rock weathering to trap carbon and boost soil health.
Representational Photo
BENGALURU, May 23, 2025 — Alt Carbon, a climate tech startup rooted in a family tea estate, has raised $12 million in a seed funding round to expand its carbon dioxide removal operations in India. The round was led by Lachy Groom, co-founder of robotics AI firm Physical Intelligence, marking a major step in scaling the company’s enhanced rock weathering technology.
The startup was founded by siblings Shrey and Sparsh Agarwal, who in 2020 returned to their family’s struggling Salem Hill tea estate in Darjeeling with the initial goal of saving the business. Instead, their visit inspired a pivot to carbon markets and climate innovation. They officially launched Alt Carbon in late 2023.
Alt Carbon spreads waste basalt rock dust, a byproduct of mining, on farmland where it chemically traps carbon dioxide for thousands of years while improving soil quality and crop yields. Sparsh Agarwal said, “Within carbon markets, our realization was that a lot of the projects in India, which are more avoidance-based, are of very low quality, and they produce junk credits.”
The company has grown from a pilot on 500 acres of tea estate land to plans for 500,000 hectares across tea, rice, and bamboo farms in North Bengal. By 2030, Alt Carbon aims to remove 5 million tons of carbon dioxide from the region.
Alt Carbon’s proprietary soil treatment, Hari Maati, combines basalt dust with organic materials to encourage farmer adoption. The company estimates carbon credits at $270 per metric ton, significantly lower than direct air capture costs, which Sparsh said run about $800 a ton.
To measure carbon removal, Alt Carbon uses a three-tier system involving soil and water sampling combined with machine learning and proprietary reactive transport models. The company’s approach follows standards set by registries such as Isometric and Puro.earth and has received endorsements from organizations including SBTi, ICVCM, and CORSIA.
Alt Carbon employs 25 staff, including 8 to 10 PhDs, working from labs in Darjeeling and Bengaluru. The seed funding will support lab expansion, remote sensing, and sensor deployment to improve data quality and reduce costs.
The company has already secured a $500,000 pre-purchase from Frontier and a $1 billion advanced market commitment from major tech and consulting firms including Stripe, Alphabet, Meta, Shopify, and McKinsey. It recently partnered with NextGen, a buyer coalition led by South Pole and Mitsubishi Corporation, to further scale its operations. A recent offtake agreement with Japan’s MOL Group commits to purchasing 10,000 tons of carbon removal credits.
Alt Carbon plans to deliver its first credits within a month through Isometric, Sparsh said.
Many projects in India’s carbon markets produce junk credits. We focus on quality and long-term impact.
