Mary Yap has spent the past year and a half trying to get farmers to fall in love with basalt. The volcanic rock is packed with nutrients, captured because the crystal structure is formed from cooling magma, and can make the soil less acidic. In that respect, it is similar to limestone, which farmers often use to improve their soil. It is a little more difficult to apply, and certainly less known. But basalt also has an important additional advantage: it can naturally capture carbon from the atmosphere.
Yap’s pitch is part of a decades-long effort to scale up that natural weathering process and prove it can trap carbon long enough to change the climate. “The sticking point is that farmers want to do this,” says Yap.
On Thursday, Yap’s fledgling startup Lithos Carbon received a $57.1 million boost for its quest to turn basalt dust into a viable climate solution. It came from Frontier, a benefit company backed by a consortium of companies looking to finance promising approaches to carbon dioxide removal, or CDR. Lithos says it will use the money to capture 154,000 tons of CO2 by 2028, by spreading basalt dust on thousands of acres of American farmland. The average American car emits approximately 4 tons of CO2 every year.
The carbon removal purchase is the largest yet from Frontier, which was founded last year with nearly $1 billion from its tech-dominated members. Many of these companies, including Meta, Alphabet and payment processor Stripe, which owns Frontier, have made climate pledges that require not only reducing emissions from their operations and supply chains, but also “negative emissions” – sucking carbon from the atmosphere. to neutralize other emissions.
That accounting trick was easier to prove on paper than in practice. Many companies would once have been committed to buying carbon offsets for activities such as protecting forests that would otherwise be cut down. But some have tried to move away from these scandal-plagued and often short-lived approaches and toward more sustainable carbon removal techniques.
The current options for companies seeking negative emissions are limited. Frontier’s purchases are essentially down payments for ideas that are still in their infancy – generally too difficult to verify or too expensive, or both, to attract a significant customer base. “What we’re trying to assess the field on is whether it’s on track to reach climate-relevant scale,” says Nan Ransohoff, who leads Frontier and also climate work at Stripe. The group starts with small “upfront purchases” intended to help promising startups, then moves to “off-take” agreements for larger amounts of carbon that members can count toward their emissions targets.
The purchase of Lithos is one of those bigger deals. It will cost carbon removal at $370 per ton, of which about a quarter will pay for field monitoring and modeling to verify that carbon is sequestered from the atmosphere for the long term. Ransohoff says Frontier believes Lithos is moving toward its carbon removal goal2 to customers at a cost of less than $100 per ton, and at a rate of at least half a billion tons per year.
‘Most promising’ approach
Founded in 2022, Lithos is developing a technology called enhanced rock weathering. This involves spreading a fine basalt dust over the fields before planting. As the rock continues to weather due to rainfall, it reacts with CO2 in the air. That forms bicarbonate, which traps the carbon by combining it with hydrogen and oxygen atoms. Ultimately, the compound is washed into the ocean, where the carbon should remain.
The strategy has the advantage of piggybacking on things people are already doing, Yap says. That contrasts with techniques such as direct air capture, which involves building industrial plants that suck carbon from the atmosphere. It’s easy to measure the carbon removed that way — it’s all captured on site — but critics say it will be difficult to scale because removing enough carbon to make a difference would require thousands of dedicated, resource-intensive facilities required.