Can Rock Dust Soak Up Carbon Emissions? A Giant Experiment Is Set to Find Out

Mary Yap has spent the final 12 months and a half attempting to get farmers to fall in love with basalt. The volcanic rock is chock stuffed with vitamins, captured as its crystal construction varieties from cooling magma, and might make soil much less acidic. In that approach it’s like limestone, which farmers usually use to enhance their soil. It’s a bit extra finicky to use, and definitely much less acquainted. But basalt additionally comes with an essential aspect profit: It can naturally seize carbon from the environment.

Yap’s pitch is a part of a decades-long effort to scale up that pure weathering course of and show that it will probably lock carbon away for lengthy sufficient to make a distinct to the local weather. “The bottleneck is getting farmers to want to do this,” Yap says.

On Thursday, Yap’s younger startup, Lithos Carbon, received a $57.1 million increase for its quest to show basalt mud right into a viable local weather answer. It got here from Frontier, a profit company backed by a consortium of firms aiming to finance promising approaches to carbon dioxide elimination, or CDR. Lithos says it is going to use the funds to absorb 154,000 tons of CO₂ by 2028, by sprinkling basalt mud on 1000’s of acres of US farmland. The common US automobile emits about 4 tons of CO₂ every year.

The carbon elimination buy is the most important but by Frontier, which was fashioned final 12 months with practically $1 billion from its tech-dominated members. Many of these firms, which embrace Meta, Alphabet, and funds processor Stripe, which owns Frontier, have made local weather pledges that require not solely lowering the emissions from their operations and provide chains but additionally “negative emissions”—sucking up carbon from the environment to cancel out different emissions.

That accounting trick has been simpler to show out on paper than in apply. Many firms would have as soon as turned to purchasing carbon offsets from actions like defending forests that might in any other case be felled. But some have been attempting to maneuver away from these scandal-plagued and infrequently short-lived approaches and into extra sturdy methods for carbon elimination.

The present choices for firms searching for adverse emissions are restricted. Frontier’s purchases are primarily down funds on concepts which can be nonetheless of their infancy—usually too arduous to confirm or too costly, or each, to draw a major buyer base. “What we’re trying to evaluate the field on is whether it’s on the trajectory to get to climate-relevant scale,” says Nan Ransohoff, who leads Frontier and likewise local weather work at Stripe. The group begins with small “pre-purchases” meant to assist promising startups, after which strikes on to “offtake” agreements for bigger quantities of carbon that its members can rely towards their emissions objectives.

The Lithos buy is a kind of bigger offers. It costs carbon removals at $370 per ton, a couple of quarter of which can pay for subject monitoring and modeling to confirm carbon is being sequestered away from the environment for the long run. Ransohoff says that Frontier believes Lithos is on a path to attending to its purpose of seeing enterprise take away CO₂ for lower than $100 per ton, and at a price of not less than a half a billion tons per 12 months.

‘Most Promising’ Approach

Lithos, based in 2022, is growing a know-how known as enhanced rock weathering. It includes spreading a superb mud of basalt throughout fields earlier than planting. As the rock additional weathers from rainfall, it reacts with CO₂ within the air. That varieties bicarbonate, which locks away the carbon by combining it with hydrogen and oxygen atoms. Ultimately, the compound is washed into the ocean, the place the carbon ought to keep put.

The technique has the advantage of piggy-backing on issues that people already do, Yap says. That’s in distinction with methods like direct air seize, which includes constructing industrial vegetation that suck out carbon from the environment. It’s straightforward to measure carbon eliminated that approach—it’s all captured there onsite—however critics say will probably be tough to scale up as a result of eradicating sufficient carbon to make a distinction would require 1000’s of dedicate, resource-intensive services.