Can rocks absorb enough CO2 to combat climate change? These companies think so

Stripe, Alphabet, Shopify and a slew of other companies plan to spend a total of more than $57 million to fight climate change by spreading crushed stone over farmland.

The goal is to tap into rocks’ natural ability to absorb carbon dioxide, which may sound low-tech, but speeding up the process and finding a way to reliably measure how much CO2 is captured is quite significant. proved difficult. It’s a planet-warming carbon dioxide capture tactic known as “enhanced weathering” that researchers have been studying for decades but has lagged behind other emerging technologies in 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 the deal.

It’s a tactic to capture planet-warming carbon dioxide called “enhanced weathering” that researchers have been studying for decades but has lagged behind other emerging technologies in its move to commercialization.

Their offtake agreements are with agtech startup Lithos Carbon, which says it has developed a way to empirically measure how much carbon is captured through enhanced weathering, rather than having to rely on models.

Essentially, the companies rely on alkaline rocks that absorb CO2 from the air as they break down or “weather.” In nature this happens when rain, wind or waves work on the rocks. Without help, this process of capturing CO2 could take thousands of years.

People can intervene by grinding rocks such as basalt into gravel or dust to speed up the process. Doing this and then spreading the crushed rock over a strip of land increases the surface area and exposes it to more carbon dioxide from the environment to absorb.

Lithos gives crushed basalt to farmers to spread over their fields for free; they could use it to manage the pH balance of the soil. The basalt then reacts with rainwater to capture carbon dioxide in the air as bicarbonate. Ultimately, the bicarbonate moves through groundwater to the sea, where Lithos expects it to be stored for at least 10,000 years or more.

Then comes the really hard part: Lithos needs to be able to tell companies how much carbon dioxide has been captured and stored safely. The company says it does this by taking soil samples and monitoring the chemical composition of the soil to assess how much CO2 has been removed. It is a process that emerged from research at Yale University.

Getting this part right is crucial, not only to ensure that companies get what they pay for, but also to demonstrate that they are actually fighting climate change

Getting this part right is crucial, not only to ensure that companies get what they pay for, but also to demonstrate that they are actually fighting climate change. When it comes to Lithos’ method of measuring how much carbon dioxide is captured, “this is quite a challenge,” says Oliver Jagoutz, a professor of geology at MIT. “And while I consider this a newer approach, I am very critical of whether this is a game changer.”

“[Lithos’ measurement] method is a step-by-step improvement, but there are still major unresolved questions,” says Jagoutz The edge.

Data shared by the company in a pre-print study essentially shows that “is an absolute maximum estimate of what could be, and the reality is unfortunately much more complicated,” he added. There is a risk of overestimating how much carbon dioxide is sequestered if you do not fully take into account how fertilizers in the soil influence the process.

There are other possible side effects that you can try to avoid through improved weathering. Flooding a given area with too much bicarbonate is one problem, as that can have its own effects on ecosystems. The environmental footprint of mining, crushing and transporting rock must also be taken into account. Lithos uses waste material from quarries to minimize these types of impacts. On farms it is also important to ensure that dust does not get into the air and affect air quality.

But if all these challenges can be overcome, Jagoutz is optimistic about the future of enhanced weathering as a strategy to combat climate change. “I think it’s great that people are trying new methods and putting into practice the different ideas that are going around,” he says.

In fairness, environmentalists have also raised concerns about companies paying to remove carbon dioxide from the atmosphere instead of focusing all their efforts on preventing fossil fuel emissions by switching to clean energy.

To that end, Lithos CEO Mary Yap says she sees the strategy more as a “mop” than a panacea for climate change. “You can’t clean up a flood… definitely stop the flood or we’re all doomed… But you do need a mop because the tap may not be completely turned off yet,” she says. You also need the “mop” to deal with the damage that has already been done, she says, in this case from the greenhouse gas emissions that have built up in the atmosphere since the industrial revolution.

This $57.1 million off-take agreement for enhanced weatherization is the first of its kind, according to Frontier. That should cover the cost of storing more than 154,000 tons of CO2 by 2028, equivalent to taking about 34,000 cars off the road for a year. Calculated at around $370 per tonne of CO2 removed, it is still expensive, but significantly cheaper than new industrial plants being built to filter the greenhouse gas from the air at around $600 per tonne.

“Improved weathering has the potential to reach very large scales in a relatively short time at relatively low cost,” said Nan Ransohoff, head of Frontier.

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