Measuring how much carbon dioxide is sequestered: A challenge facing the cost of cut-back carbon removal with improved weathering techniques

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.

The aim is to use rocks’ natural ability to absorb carbon dioxide, which might sound low-tech, but speeding up the process and finding a way to reliably measure how much CO2 is sequestered has proven pretty hard. Enhanced weathering, a tactic for trapping carbon dioxide that has been studied for decades but has yet to move to commercialization, is one of the technologies that has yet to move to commercialization.

The deal was announced today by Frontier, a carbon removal initiative led by Stripe, Alphabet, Shopify, and McKinsey Sustainability. Autodesk, H&M Group, JPMorgan Chase, Workday, Zendesk, Canva, and Boom Supersonic are also among the more than a dozen companies that signed onto the deal.

It’s crucial to get this part right, not only to assure that companies are getting what they pay for but also to show that they’re actually combating climate change. When it comes to Lithos’ method for measuring how much carbon dioxide is sequestered, “this is very challenging,” says Oliver Jagoutz, professor of geology at MIT. I am very critical whether that is a game-changer, as I see this as a newer approach.

People can intervene by grinding rocks like basalt into gravel or dust to speed up the process. Doing so and splaying the crushed rock out across a swath of land exposes it to more carbon dioxide, which leads to an increase in surface area.

Farmers who get crushed basalt will spread it across their fields for free, and it can be used to maintain the pH balance of the soil. The basalt reacts with water to trap carbon dioxide in the air. Once through the ground, it moves through the sea where it will be stored for a long time.

It is important to make sure that companies are getting what they pay for, and also to make sure that they are actually fighting climate change.

The data shared by the company shows an absolute maximum estimate of what can be, and it’s difficult to know what’s true. There is a risk of overestimating how much carbon dioxide has been sequestered when not fully accounting for howfertilizers affect the process.

Boosting a Basalt Dust Startup to Ensure Enhanced Weathering and Carbon Reduction in the US: A Case Study of Frontier

Try to avoid the other side effects with enhanced weathering. Flooding any particular area with too much bicarbonate is one issue, since that could have its own effects on ecosystems. It is important to consider the environmental footprint of mining, crushing and transporting rock. Lithos uses waste material from quarries to minimize those kinds of impacts. At farms, it’ll also be important to make sure the dust doesn’t get airborne and affect air quality.

“Enhanced weathering has the potential to get to very large scale at relatively low costs in a pretty short amount of time,” says Nan Ransohoff, head of Frontier.

Environmental advocates have voiced concern that companies pay to take carbon dioxide out of the atmosphere instead of focusing on preventing fossil fuel emissions.

On Thursday, Yap’s young startup, Lithos Carbon, got a $57.1 million boost for its quest to turn basalt dust into a viable climate solution. Frontier is a benefit corporation backed by a group of companies that are looking to finance promising approaches to carbon dioxide removal. Lithos says it will use the funds to soak up 154,000 tons of CO2 by 2028, by sprinkling basalt dust on thousands of acres of US farmland. The average US car emits about 4 tons of CO2 each year.

Frontier said that the offtake agreement for enhanced weathering is the first of its kind. 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. New industrial plants that can remove CO2 for $600 a ton are cheaper than the 370 per ton that it takes to remove CO2 from the air.

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.

The Lithos purchase is one of those larger deals. It charges $370 per Ton for carbon removal and a quarter of that will go towards field monitoring and modeling to verify that carbon is being sequestered away from the atmosphere. Frontier believes that if business removes CO2 for less than $100 per ton, and at a rate of over a billion tons a year, it will be able to get to its goal.

Yap says the strategy will help people do things that they already do. Direct air capture involves building industrial plants that will suck out carbon from the atmosphere. It’s easy to measure carbon removed that way—it’s all captured there onsite—but critics say it will be difficult to scale up because removing enough carbon to make a difference will require thousands of dedicate, resource-intensive facilities.