From a struggling family tea estate to a pioneering climate venture, Alt Carbon has secured $12 million in a seed round to enhance its carbon dioxide removal efforts in South Asia. The climate tech startup, which sequesters carbon for millennia through enhanced rock weathering on agricultural lands, received investments led by Lachy Groom, co-founder of the robotics AI company Physical Intelligence.
The venture began in May 2020 when siblings Shrey and Sparsh Agarwal traveled from Kolkata to Darjeeling, intending to bid farewell to their family’s financially troubled tea estate, Salem Hill. This visit, however, inspired the creation of Alt Carbon, officially launched in late 2023.
Initially exploring carbon markets to rejuvenate their family business and assist other tea estates, they discovered that enhanced rock weathering could transform Darjeeling from a climate-vulnerable area to a leader in climate action.
Sparsh stated that many Indian carbon market projects were of low quality, producing substandard credits.
Last year, Alt Carbon initiated a pilot on approximately 500 acres around their family estate, later expanding in North Bengal to rice and bamboo farms, aiming to cover 500,000 hectares. By 2030, they plan to remove 5 million tons of carbon from the region.
Alt Carbon utilizes waste basalt rock dust from the Rajmahal Traps to enhance soil fertility and sequester carbon. The dust reacts with rainwater, forming stable bicarbonate ions, which are stored in the soil and eventually settle as calcium carbonate in the ocean, sequestering carbon for over 10,000 years.
The company uses existing rail and truck systems for transportation and benefits from waste basalt from current mining activities. They also developed a proprietary blend called Hari Maati to incentivize farmers to use it.
Alt Carbon estimates its carbon credits at $270 per metric ton, significantly cheaper than direct air capture credits, and anticipates cost reductions within 36 to 48 months.
The startup employs a three-tier measurement system to track weathering and carbon removal, utilizing machine learning models aligned with methodologies from carbon removal registries like Isometric and Puro.earth, and approved by organizations such as SBTi, ICVCM, and CORSIA.
With labs in Darjeeling and Bengaluru, Alt Carbon is expanding its team and infrastructure for enhanced soil analysis and data collection, supported by the seed funding.
Previously, the company secured a $500,000 pre-purchase by Frontier and a $1 billion commitment led by major companies. It has also entered a strategic partnership with NextGen and signed an offtake agreement with Japan’s MOL Group for carbon removal credits.
Alt Carbon aims to deliver its first carbon credits in less than a month through Isometric.
