Frontier buyers sign world’s first enhanced weathering offtake agreements with Lithos Carbon

• Frontier buyers will pay Lithos $57.1 million to remove 154,240 tons of CO₂ between 2024 and 2028.
• It is the largest purchase Frontier has facilitated and the largest enhanced weathering purchase to date.
• On-field enhanced weathering offers 10,000-year permanence, farmer co-benefits, immediate scalability, and could remove gigatons of CO₂ annually.

Frontier has facilitated its first set of enhanced weathering offtake agreements with Lithos Carbon, a San Francisco-based carbon removal company. Lithos accelerates the natural ability of rocks to absorb CO₂ by spreading superfine crushed basalt on farmlands and measuring the removal empirically. Frontier buyers will pay Lithos $57.1 million to permanently remove 154,240 tons of CO₂ between 2024 and 2028. More than half of these tons are expected to be delivered by the end of 2025, an order of magnitude more carbon removal than has been achieved so far across all pathways worldwide. Frontier buyers were Lithos’s first customers through a prepurchase in Spring 2022, and are now the first to sign an offtake agreement with the company.

Enhanced weathering describes a variety of approaches to accelerate the natural absorption and storage of carbon in rocks. When exposed to rain, wind, or seawater, alkaline rocks slowly break down, or “weather.” During this process, the worn-down rocks absorb carbon dioxide from the atmosphere and turn it into bicarbonate, which eventually makes its way into the ocean through groundwater for permanent storage. This process normally takes hundreds or thousands of years, but by grinding up alkaline rocks like basalt or olivine to increase their surface area, and spreading them on fields to increase their exposure to ambient CO₂, the effect can be achieved in just a few years. Enhanced weathering approaches could account for 2–4 gigatons of carbon removal per year by 2050, which would be 40% of the projected global carbon removal portfolio.

There is scientific consensus that enhanced weathering results in permanent CO₂ removal, but the implementation of the approach has been slowed by the difficulty of measuring its impact. While most projects have relied exclusively on modeling to estimate carbon dioxide removed, Lithos measures carbon removal using a novel technique invented at Yale University that combines soil samples with high-precision elemental measurements. Instead of measuring the amount of bicarbonate directly, which requires burying many collection devices, Lithos monitors the change in the soil’s geochemical profile as a proxy for how much CO₂ is removed. This technique accurately measures the amount of carbon removed, but with fewer hardware needs, enabling Lithos to sample at high frequency without ballooning costs.

The scale of this offtake will generate large amounts of field data across diverse soil types and climate conditions. Lithos is committed to sharing this data with scientists and academics to accelerate transparency, scientific collaboration, and the development of more accurate geochemical models. On top of improving our understanding of enhanced weathering as a pathway, this will reduce the need for frequent in-field measurement, which will further drive down cost.

Lithos's method of sourcing ground basalt, spreading it, and measuring permanent CO₂ removal.

In addition to this measurement work, Lithos’s approach is compelling because it builds on existing industrial and agricultural practices, which will enable the company to scale and reduce costs quickly. The finely ground basalt Lithos needs already exists in large quantities as a waste by-product from existing quarries that produce construction aggregates. Lithos transports this basalt to farmers, who use it in place of ag-lime to deacidify the soil. Lithos’s early farmer partners have already reported healthier soil pH and yield improvements by switching from ag-liming to ground basalt.

In under two years, Lithos has secured partnerships with multiple quarries and deployed its enhanced weathering approach on more than 80 farms across nine US states, with more than 160,000 acres on its waitlist and millions of acres of immediately deployable farmland in its network. Lithos estimates that these existing partnerships could result in ~2.1M tCO₂/year of removal in the immediate future. The price of carbon removal through Lithos, inclusive of measurement, has already fallen 26% since the 2022 prepurchase Frontier facilitated, and could fall to ~$100/t by 2030.

The speed at which Lithos can deploy is not constrained by technological breakthroughs, access to superfine waste basalt, or interest from farmers. The company’s principal bottleneck has been finding buyers willing to pay for larger deployments. This offtake agreement will accelerate Lithos’s timeline by 3–4 years, enabling the company to get revenue for deliveries as soon as next year.

Frontier has facilitated purchases on behalf of Frontier Founding Members Stripe, Alphabet, Shopify, and McKinsey Sustainability, as well as Autodesk, H&M Group, JPMorgan Chase, and Workday. Also, Aledade, Boom Supersonic, Canva, SKIMS, Wise, and Zendesk have purchased via Watershed’s partnership with Frontier.

Enhanced weathering is promising but still early in its development. To help inform prospective buyers, we’re sharing resources for enhanced weathering buyers based on what Frontier and partners have learned so far on how to assess a company’s approach to measurement and responsible ecosystem development.

Mary Yap, founder and CEO, Lithos: “This offtake accelerates our deployment by 3–4 years, allowing us to push the limits of our established supply chain and accelerate scientific understanding across diverse soils and climates. By publicly sharing this data, we hope to help enhanced weathering scale safely and responsibly. By learning faster, we unlock a step-function reduction in cost, and compounding benefits for agricultural communities. We’re thrilled to have Frontier’s support in scaling transparent and scientifically rigorous removal—this agreement will help pave the way for billion-ton carbon removal.”

Nan Ransohoff, Head of Frontier: “Lithos has a path to delivering meaningful amounts of carbon removal at reasonable prices within the next few years. They’re charting a path for what responsible scale-up looks like for a pathway that’s likely to be a sizable part of the global carbon removal portfolio.”