In an effort to combat the devastating impact of pollution on the climate, tech giants like Google have been investing in innovative strategies to reduce greenhouse gas emissions. One such approach is enhanced rock weathering (ERW), a relatively low-tech tactic that aims to slow down climate change by trapping carbon dioxide using rocks.
The Terradot Partnership
Recently, Google and several other big companies, including H&M Group and Salesforce, collectively agreed to pay Terradot $27 million to remove 90,000 tons of carbon dioxide from the atmosphere. This deal was brokered by Frontier, a carbon removal initiative led by Stripe, Google, Shopify, and McKinsey Sustainability.
Separately, Google announced its own deal with Terradot to purchase an additional 200,000 tons of carbon removal, although the company declined to disclose how much this deal is worth. If the cost is similar to the Frontier agreement (roughly $300 per ton of CO2 captured), it could add up to $60 million.
The Significance of Enhanced Rock Weathering
Enhanced rock weathering attempts to speed up a natural process that might otherwise take thousands of years. Rainfall naturally "weathers" or breaks down rock, releasing calcium and magnesium, which triggers a chemical reaction that traps CO2 in water as bicarbonate. Groundwater carrying this bicarbonate eventually makes its way to the ocean, where it is stored, keeping it out of the atmosphere.
Accelerating this process involves crushing up rocks and spreading them over a large area, increasing the surface area of exposed rock that reacts with CO2. Terradot has a 2029 deadline to make good on the 90,000-ton Frontier deal, and it’s supposed to capture an additional 200,000 tons for Google by the early 2030s.
The Terradot Model
Terradot takes basalt from quarries in southern Brazil to nearby farms. Farmers can use the finely-ground basalt to manage the pH of soil, and carbon removal is a bonus. The startup has struck up a partnership with Brazil’s agricultural research agency (EMBRAPA), allowing it to use this strategy on over one million hectares of land.
Another perk in Brazil is its hot, humid climate, which helps speed up the weathering process. However, the tricky part will be trying to count how much CO2 Terradot actually manages to trap.
The Challenges Ahead
Google admits that measuring with precision how much CO2 this process removes from the atmosphere is difficult. But it believes that deploying ERW widely in the real world will help develop more rigorous measurement tools.
Terradot plans to take soil samples to assess how much CO2 is captured based on how the rock degrades over time. However, figuring out how much calcium, magnesium, and bicarbonate makes it to the ocean to permanently sequester CO2 is harder.
Fertilizer in the soil can potentially limit how much carbon is captured through ERW. "How much they sequester is still the outstanding question," says Dr. Jagoutz, a geologist at Harvard University.
The Importance of Emissions Reduction
While Google’s carbon removal plan is an effort to counteract its legacy of pollution, it’s essential to note that switching to clean energy is the only effective way to stop climate change. Carbon removal, at best, can help mitigate some of a company’s emissions while it makes this transition.
Even though Google says it signed the biggest ERW deal to date, 200,000 tons of carbon removal is still a small fraction of the 14.3 million metric tons of carbon dioxide pollution the company was responsible for last year.
"It’s very clear that this is not a substitute for emissions reductions at all," says Kanoff, co-founder and CEO of Terradot. "We need both of these tools."
Conclusion
The battle against climate change requires innovative strategies to reduce greenhouse gas emissions. Enhanced rock weathering is one such approach that has shown promise in trapping carbon dioxide using rocks.
While there are challenges ahead, including measuring the effectiveness of this process, Google’s partnership with Terradot highlights the importance of exploring new ways to mitigate pollution while transitioning to clean energy.
As Dr. Jagoutz so aptly puts it: "Why not try?"
