The surprising technology that's being touted as a climate solution: rocks.

In an effort to mitigate the impact of their pollution on the climate, Google and other major companies have invested in a plan to capture carbon dioxide using rocks. Recently, they announced multimillion-dollar deals with a startup called Terradot, which has been backed by Sheryl Sandberg.

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A Gaggle of Companies Pledge $27 Million for Carbon Removal

Google, H&M Group, and Salesforce are among the companies that have collectively agreed to pay Terradot $27 million to remove 90,000 tons of carbon dioxide from the atmosphere. The deals were brokered by Frontier, a carbon removal initiative led by Stripe, Google, Shopify, and McKinsey Sustainability.

Google Announces Additional Deal for Carbon Removal

Separately, Google announced its own deal to purchase an additional 200,000 tons of carbon removal from Terradot. However, 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.

Enhanced Rock Weathering: A Low-Tech Tactic for Carbon Removal

The strategy used by Terradot to try to slow climate change is known as enhanced rock weathering (ERW). This process involves crushing up rocks and spreading them out over a large area, increasing the surface area of exposed rock that reacts with CO2. ERW accelerates the natural process of rock weathering, which can take thousands of years.

A Big Deal: Terradot’s Partnership with Google

Google has described its deal with Terradot as the biggest purchase yet of carbon removal through ERW. Oliver Jagoutz, a professor of geology at MIT, praises the initiative, saying it’s "a big deal" and should be taken out of the academic world into the industrial sphere.

Terradot: A Startup with Big Ambitions

Terradot was founded by James Kanoff, Sasankh Munukutla, and Scott Fendorf, who is now the company’s chief scientist and technical advisor. The startup grew out of a research project at Stanford, where the founders were undergraduate students. Terradot has a partnership with Brazil’s agricultural research agency (EMBRAPA), allowing it to use its strategy on over one million hectares of land.

The Challenges Ahead

While Terradot has made significant progress in developing its technology, there are still challenges ahead. Measuring the amount of CO2 captured by ERW is difficult, and the company will need to take soil samples to assess how much carbon is removed based on how the rock degrades over time.

The Uncertainty of Carbon Sequestration

Jagoutz notes that the uncertainty of how much calcium, magnesium, and bicarbonate makes it to the ocean to permanently sequester CO2 is still an outstanding question. However, he believes that trying out ERW in the real world is essential, even if there are uncertainties.

Carbon Removal: Not a Substitute for Emissions Reduction

While carbon removal is an important tool in mitigating climate change, it’s not a substitute for reducing emissions. Google has emphasized that its investment in Terradot is just one part of its strategy to address its legacy of pollution and transition to clean energy.

The Future of Carbon Removal: A Collective Effort

As companies like Google continue to invest in carbon removal technologies, it’s clear that this effort will be a collective one. By working together, we can accelerate the development of these technologies and make a meaningful impact on climate change.