Alt Carbon’s $12M Seed Round to Scale Enhanced Rock Weathering in India

On May 22, 2025, India-based climate tech startup Alt Carbon raised $12 million in a seed funding round, the largest for a climate tech company in India, to scale its Enhanced Rock Weathering (ERW) solution for carbon dioxide removal (CDR) across the Global South. Founded in 2023 by brothers Shrey and Sparsh Agarwal, Alt Carbon aims to remove 5 million metric tons of CO2 by 2030, starting with its Darjeeling Revival Project (DRP). By spreading basalt rock dust on agricultural fields, the startup locks away carbon for over 10,000 years while boosting soil health and crop yields. With partnerships like Mitsubishi Corporation and a 10,000-tonne offtake deal with MOL Group, can Alt Carbon turn India into a CDR hub, or will scaling challenges slow its ambitious vision?

The Technology and Mission

Alt Carbon’s ERW process involves sourcing basalt rock dust, a mining byproduct, and applying it to farmlands. Rainwater reacts with the dust, converting atmospheric CO2 into bicarbonate ions that are stored in soil and eventually form calcium carbonate in oceans, sequestering carbon for millennia. The process also enriches soil, reducing fertilizer needs and increasing yields by 10-20%, per field trials. The DRP, launched on the Agarwals’ family tea estate in Darjeeling, spans 500 acres and plans to expand to 500,000 hectares across tea, rice, and bamboo farms by 2030.

Founded after the Agarwals faced bankruptcy at their Salem Hill tea estate in 2020, Alt Carbon emerged from a pivot to carbon markets.

“We saw ERW as a way to revive Darjeeling and fight climate change,” said Sparsh Agarwal.

The startup’s goal is to make India a CDR leader, addressing the global need to remove 10 billion tons of CO2 annually by 2050, per IPCC estimates, and India’s $1 trillion climate finance gap by 2030.

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Funding and Strategic Moves

The $12 million round, led by Lachy Groom of Physical Intelligence, included Shastra VC and angels like Jason Zhao (PIP Labs) and Tanmay Bhat. The capital will fund:

• R&D: Expanding labs in Darjeeling and Bengaluru, employing 8-10 PhDs to refine ERW models.

• Hardware: Developing precision applicators for rock dust, improving efficiency.

• Scaling: Growing operations to 500,000 hectares, targeting 5 million tons of CO2 removal by 2030.

Key partnerships bolster credibility. A $500,000 pre-purchase from Frontier (backed by Stripe, Alphabet, Meta) and a $1 billion advance market commitment from Stripe, Alphabet, Meta, Shopify, and McKinsey signal demand. Recent deals include a Mitsubishi Corporation framework to scale ERW in Asia and a 10,000-tonne offtake with Japan’s MOL Group, the first ERW deal between Indian and Japanese firms. A NextGen coalition (South Pole, BCG, UBS) further supports credit purchases.

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Impact and Opportunities

Alt Carbon’s ERW offers multiple benefits:

• Carbon Removal: Each hectare removes 2-10 tons of CO2 annually, with Darjeeling’s humid climate accelerating weathering. The 5-million-ton target by 2030 equals 0.5% of India’s 2023 emissions (2.8 Gt).

• Agriculture: Basalt dust raises soil pH, improving fertility. Pilot farms saw 15% yield increases, vital for Darjeeling’s tea estates, where 70% face climate-driven losses.

• Economic: Carbon credits, priced at $100-$200 per ton, generate income for farmers. The DRP could inject $500 million into North Bengal by 2030, per company estimates.

• Cultural: Restoring Darjeeling’s tea legacy preserves a $1 billion export industry.

The startup’s three-layer measurement system—tracking weathering, water sampling, and proprietary reactive transport models—ensures accuracy, adhering to Isometric and Puro.earth standards. Machine learning optimizes carbon accounting, validated by SBTi, ICVCM, and CORSIA.

Challenges and Risks

Scaling ERW faces hurdles:

• Infrastructure: Spreading dust across 500,000 hectares requires 10-20 million tons of basalt annually, straining logistics. India’s 14% logistics cost (vs. 8% globally) adds $50-$100 million in costs.

• Verification: Measuring carbon sequestration is complex. While Alt Carbon’s models are robust, scaling to gigaton levels risks discrepancies, as seen in early biochar projects.

• Funding: India’s climate tech struggles post-Series A, with only 3% of startups securing Series B, per IIMA Ventures. Alt Carbon’s $12 million is a start, but $100-$200 million may be needed for 2030 goals.

• Policy: India’s carbon market is nascent, with the Carbon Credit Trading Scheme (CCTS) still developing. Policy shifts under Modi’s net-zero-by-2070 pledge could help, but regulatory delays persist.

What’s Next?

Alt Carbon plans to deliver its first Isometric-verified credits in June 2025, expand to 10,000 hectares by 2026, and reach 500,000 by 2030. New hires—Yashovardhan Bhagat (COO), Adithya Venkatesan (Climate Studio lead), and Dr. Sourav Ganguly (science head)—strengthen operations. The DRP aims to revive 50% of Darjeeling’s tea estates, restoring 10,000 livelihoods.

Globally, ERW gains traction. Mati Carbon, an XPRIZE winner, removed 1,000 tons in India, while InPlanet’s €1.2 million Brazilian project shows tropical potential. Meta’s 650 MW solar PPAs and the EU’s CO2 storage mandates signal a CDR boom, but India’s $1 trillion finance gap looms large.

“ERW is a permanent, scalable solution,” said Shrey Agarwal. “We’re building the backbone for a climate revolution.”

Success hinges on logistics, policy support, and sustained investment. Will Alt Carbon make India a CDR powerhouse, or will scaling stall its bold revival?

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