Climate-Responsive Spreading of Crushed Rock over Farmland: How Does Frontier Spend Thousands of Dollars to Combat Climate Change?
Stripe, Alphabet, Shopify, and a slew of other companies plan to spend more than $57 million cumulatively to fight climate change by spreading crushed rock over farmland.
It is a tactic for trapping carbon dioxide called “enhanced weathering” that has been studied for years, but it has been far behind other technologies in moving to commercialization.
The current options for companies seeking negative emissions are limited. Frontier’s purchases are essentially down payments on ideas that are still in their infancy—generally too hard to verify or too expensive, or both, to attract a significant customer base. “We’re looking at whether the field is moving in the correct direction to make it climate-relevant scale,” says a woman who leads Frontier and also works on climate work. The group starts with small “pre-purchases” meant to help promising startups, and then moves on to “offtake” agreements for larger amounts of carbon that its members can count toward their emissions goals.
Lithos, founded in 2022, is developing a technology called enhanced rock weathering. It involves spreading a fine dust of basalt across fields before planting. As the rock further weathers from rainfall, it reacts with CO2 in the air. That combines hydrogen and oxygen atoms into bicarbonate, which locks away carbon. The compound ends up in the ocean, where it should stay.
Sand or gravel can be used to speed up the process. Doing so and then splaying the crushed rock out across a swath of land increases surface area and exposes it to more ambient carbon dioxide to absorb.
Farmers can use basalt for free if they want to manage the pH of the soil. The carbon dioxide is trapped in the air with the help of the basalt. Eventually, the bicarbonate moves through groundwater out to the sea where Lithos expects it to be stored for at least 10,000 years or longer.
It is crucial that the part is correct to assure that companies are receiving their money and that they are fighting climate change.
The data that the company shared in a pre-print study shows an absolute max estimate of what can be, and the reality is much more complicated. Namely, there’s a risk of overestimating how much carbon dioxide has been sequestered when not fully accounting for how fertilizers in the soil affect the process.
Boosting Climate Change by Adding Enhanced Weathering to Forests and Farmlands: A Case Study of the Frontier Fund for Co-economic CO2 Removal
Enhancement of weathering can cause other side effects to be avoided. Flooding any particular area with too much bicarbonate is one issue, since that could have its own effects on ecosystems. It is important that the environmental footprint of mining,crushing, and transporting rock is taken into account. Waste material from quarries can be used to reduce those types of impacts. At farms, it’ll also be important to make sure the dust doesn’t get airborne and affect air quality.
But if all those challenges can be overcome, Jagoutz is optimistic about the future of enhanced weathering as a strategy for fighting climate change. He thinks it’s great that people try new methods and go to the field to investigate the different ideas out there.
To be sure, environmental advocates have also voiced concern about companies paying to take carbon dioxide out of the atmosphere rather than focusing all their efforts on preventing fossil fuel emissions by transitioning to clean energy.
On Thursday, Yap and the company he founded, Lithos carbon, received a $57.1 million boost for their quest to turn basalt dust into a viable climate solution. Frontier is an benefit corporation backed by a group of companies that want to finance promising approaches to carbon dioxide removal. The money will be used to sprinkle basalt dust on thousands of acres of farmland in the U.S. in order to soak up 154,000 tons of CO2 by 2028. The average US car emits about 4 tons of CO2 each year.
This $57.1 million offtake agreement for enhanced weathering is the first of its kind, according to Frontier. That’s supposed to cover the costs of sequestering more than 154,000 tons of CO2 by 2028, equivalent to taking about 34,000 cars off the road for a year. It is a lot more expensive than industrial plants being built to remove greenhouse gas from the air at a rate of $600 a ton.
That accounting trick has been easier to prove out on paper than in practice. Many companies would have once turned to buying carbon offsets from activities like protecting forests that would otherwise be felled. But some have been trying to move away from those scandal-plagued and often short-lived approaches and into more durable techniques for carbon removal.
One of the larger deals is the Lithos purchase. It prices carbon removals at $370 per ton, about a quarter of which will pay for field monitoring and modeling to verify carbon is being sequestered away from the atmosphere for the long term. Ransohoff says that Frontier believes Lithos is on a path to getting to its goal of seeing business remove CO2 for less than $100 per ton, and at a rate of at least a half a billion tons per year.
The strategy has the benefit of piggy-backing on things that humans already do, Yap says. That’s in contrast with techniques like direct air capture, which involves building industrial plants that suck out carbon from the atmosphere. It is easy to measure carbon removed that way but critics say it will be hard to scale up since it will take thousands of dedicated facilities to make a difference.