From the tea-free family of struggling families to innovative climate ventures, Alt Carbon has raised $12 million in seed rounds as it plans to expand carbon removal operations in South Asian countries. By intensifying rock weathering on farmland, Climate Tech’s startup, which has been shutting down carbon for millennia, has attracted investments led by Lachy Groom, co-founder of Robotics AI Company Physical Intelligence.
The trip began in May 2020 with a bittersweet return home. Brothers Sri and Sparsh Agarwal drove 16 hours from eastern Kolkata and were hoping to say goodbye to Salem Hill, a family tea ruins, from Darjeeling, known for tea farming in the lush hills of the Himalayas. Instead, that farewell visit planted Alt carbon seeds, which were officially launched in late 2023.
Initially, they explored the carbon market as a way to support other tea plants in the region by reviving family businesses and generating supplemental income. However, during their exploration, they discovered enhanced rock weathering as an approach that could turn Darjeeling’s legacy from the risks of climate change impacts into a frontier of climate action.
“In the carbon market, our perception was that many of India’s projects are more evasive and very low quality, generating junk credits,” Sparsh said in an exclusive interview.
Last year, Alt Carbon began piloting around Agarwals family tea grounds on approximately 500 acres. They later expanded in North Bengal, expanding the rice and bamboo scope from the tea farm. The startup aims to expand to 500,000 hectares of land.
By 2030, the startup is aiming to remove 5 million tonnes of carbon from the region, Sparsh told TechCrunch.
Alt Carbon unfolds the weathering of the fortified rock using waste basalt rock dust from mines and quarries in the volcanic region of Rajmahal in eastern India. Rock dust, a waste material in the construction industry, spreads across farm fields, where it reacts naturally with rainwater to remove carbon dioxide and adds micronutrients to the soil, improving its fertility and health, and increasing crop yields. When rainwater containing carbon dioxide interacts with basalt dust, it forms stable bicarbonate ions. These are stored in the soil and eventually flow through the river into the ocean, where they precipitate as calcium carbonate, closing carbon for over 10,000 years.
To transport special dust from the source location to the farm, the startup relies on rails and diesel trucks, which are part of the tea industry’s freight transport system, so they pay one-way freight. The startup also avoids emissions from dedicated rock processing by relying on waste basalt from existing mining and grinding operations.
Instead of using only basalt dust, the startup has developed its own combination of basalt and other organic components. This is called Harimati (Hindi green soil) and persuades farmers to spread across the farmland.
Alt Carbon estimates its carbon credits are $270 per metric tonne. This states that Sparsh is significantly cheaper than direct air capture credits. However, he expects the startup to cut costs within 36-48 months.
The startup relies on the measurements in the three layers to understand how weathered the rocks are and how much carbon the carbon is being removed, Schlie told TechCrunch. It starts with measurements to track weathering progression, then moves to measuring water in the soil, groundwater sampling, and river monitoring. The third layer uses a unique reactive transport model that helps track ions transported from the soil into the water. Startups use machine learning-driven modeling to obtain carbon removal numbers.
According to Alt Carbon, the model is closely adhered to the methodology set up by a carbon removal registry containing isometric and Puro.Earth. They have also received approval from intergovernmental organizations, including SBTI, ICVCM and Corsia.
The startup has labs in Darjeeling and Bengaluru, employing 8-10 doctoral degrees, with 25 employees earning 25 doctoral degrees. The purpose is to scale these labs, perform more soil sample analysis, and set up hardware studios for better, high quality data collection on the ground using remote sensing. Also, startups are planning to deploy sensors on the ground to gain more insights at a lower cost and faster time. All this is done through that species round led by the groom.
Last year, the startup secured $500,000 advance purchases by Frontier and a $1 billion sophisticated market commitment led by Stripe, Alphabet, Meta, Shopify and McKinsey. We also recently signed a strategic partnership with NextGen, a buyer coalition launched by Southport and Mitsubishi companies, expanding our enhanced rock weathering. This group included the BCG group, Swiss Re, LGT, and UBS. Last month, the startup signed an off-take agreement with Japanese shipping company Mol Group to purchase 10,000 tonnes of carbon removal credits.
Sparsh said Alt Carbon will deliver its first carbon credits within a month.