In a remarkable transformation from a struggling family tea estate to a pioneering force in climate technology, Alt Carbon has successfully secured $12 million in a seed funding round. This significant investment, spearheaded by Physical Intelligence, an AI robotics company co-founded by Lachi Groom, is set to propel Alt Carbon’s innovative carbon dioxide removal efforts across India. The climate-tech startup employs enhanced rock weathering on farmlands to sequester carbon for millennia, a method gaining considerable traction in the environmental investment landscape.
The genesis of Alt Carbon traces back to May 2020, amidst the initial throes of the COVID-19 pandemic. Brothers Shrey and Sparsh Agarwal embarked on a poignant 16-hour journey from Kolkata to Darjeeling, a region synonymous with tea cultivation in the picturesque Himalayan foothills. Their mission was to bid farewell to Salem Hill, their family’s tea property, which teetered on the brink of bankruptcy. This seemingly somber farewell, however, unexpectedly germinated the idea for Alt Carbon, officially launched in late 2023.
Initially, the brothers explored carbon markets as a potential lifeline for their ailing family business and a means to support other tea growers in the region by providing an additional income stream. It was during this exploration that they stumbled upon the concept of enhanced rock weathering. This revelation proved to be a turning point, shifting their perspective from merely mitigating climate change risks to actively pursuing climate action.
Sparsh Agarwal, in an exclusive interview, highlighted a crucial realization within the carbon markets: “Many projects in India, which are more avoidance-based, are of very low quality, and they produce junk credits.” This insight underscored the need for high-integrity, verifiable carbon removal solutions, which Alt Carbon now aims to provide.
Alt Carbon commenced its pilot program last year on approximately 500 acres of their family tea estate. Recognizing the broader potential of their approach, they subsequently expanded their scope to include rice and bamboo fields in North Bengal. The ambitious startup aims to scale its operations to encompass an impressive 500,000 hectares of land. By 2030, Alt Carbon projects to remove 5 million tonnes of carbon from the region, as Sparsh disclosed to TechCrunch.
Harnessing Nature’s Carbon Sink: The Science Behind Alt Carbon
Alt Carbon utilizes basalt rock dust, a waste product from mining and construction industries, primarily sourced from the volcanic Rajmahal traps in Eastern India. This finely crushed rock is spread across agricultural fields, where it interacts naturally with rainwater. This interaction facilitates a chemical process that effectively removes atmospheric carbon dioxide ().
Beyond carbon sequestration, the application of rock dust enriches the soil with vital micronutrients, enhancing its fertility and health, and consequently boosting crop yields. When -laden rainwater comes into contact with the basalt dust, stable bicarbonate ions are formed. These ions are then stored in the soil and gradually transported by rivers to the sea, where they precipitate as calcium carbonate (), locking away carbon for over 10,000 years. This process mimics natural geological cycles, accelerating them to address contemporary carbon imbalances.
Logistics and Innovation: Driving Efficiency and Impact
To transport the specialized rock dust from its sources to the farm fields, Alt Carbon leverages existing rail and diesel truck networks. They cleverly utilize “one-level rent” arrangements, integrating into the established goods transport system of the tea industry. This approach minimizes new logistical infrastructure and associated emissions. Furthermore, the startup avoids emissions from dedicated rock processing by relying on waste basalt from existing mining and crushing operations, further enhancing their carbon footprint.
A key innovation from Alt Carbon is their proprietary blend of basalt with other organic ingredients, which they have named “Hari Mati” (green soil in Hindi). This unique formulation is provided to farmers for application on their land, potentially optimizing the carbon removal process and soil benefits.
Cost-Effectiveness and Verification: A New Benchmark in Carbon Removal
Alt Carbon estimates the cost of its carbon credits at $270 per metric ton, a figure significantly more competitive than direct air capture credits, which are currently estimated at around $800 per ton. The startup is optimistic about further reducing this cost within the next 36 to 48 months, making high-quality carbon removal more accessible.
To ensure the integrity and accuracy of their carbon removal claims, Alt Carbon employs a robust three-layered measurement protocol, as explained by Shrey to TechCrunch. This begins with direct measurements to track the progress of rock weathering, followed by detailed measurements of water within the soil, groundwater sampling, and river monitoring. The third layer incorporates reactive transport models, which meticulously track the movement of ions from soil to water bodies. The startup also utilizes machine learning-powered modeling to refine its carbon removal estimations.
Alt Carbon asserts that its models align closely with the prescribed functionalities of leading carbon removal registries, including Isometric and Puro. The company has also secured approvals from influential intergovernmental organizations such as SBTI, ICVCM, and Corsia, underscoring the credibility of their approach.
Expanding Horizons: Research, Partnerships, and Future Growth
Alt Carbon is committed to continuous research and development. They operate their own laboratories in Darjeeling and Bangalore, employing a team of 8 to 10 PhDs among their 25 employees. Their future plans include scaling these laboratories and establishing a hardware studio for enhanced, high-quality data collection through expanded soil sample analysis and even remote sensing. The startup also intends to deploy ground-based sensors to gain deeper insights more cost-effectively and rapidly. These advancements will be funded by the recently secured seed round, led by Lachi Groom.
Last year, Alt Carbon made headlines by securing a $1 billion advanced market commitment from Frontier, with pre-purchases from prominent entities like Stripe, Alphabet, Meta, Shopify, and McKinsey. More recently, they forged a strategic partnership with NexGen, a buyer coalition launched by South Pole and Mitsubishi Corporation, aimed at accelerating increased rock weathering initiatives. This group also includes other major players such as BCG Group, Swiss Re, LGT, and UBS. Just last month, the startup signed an off-take agreement with Japan’s shipping company, MOL Group, for the purchase of 10,000 tonnes of carbon removal credits.
Alt Carbon is poised to distribute its inaugural carbon credits through the Alt Carbon Isometric platform in less than a month, marking a pivotal moment in their journey to revolutionize climate action.
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