As the world continues to grapple with the challenges of climate change, innovative solutions are being explored to mitigate its impacts. One such approach is enhanced rock weathering (ERW), a technology that uses crushed rocks to absorb carbon dioxide from the atmosphere. Recently, Google and other major companies have partnered with Terradot, a startup backed by Sheryl Sandberg, to deploy ERW on a large scale.
The Partnership: A Multimillion-Dollar Deal
In a significant move, Google and several other prominent companies, including H&M Group and Salesforce, have collectively agreed to pay $27 million to Terradot 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 an additional deal with Terradot to purchase 200,000 tons of carbon removal through ERW. While the exact cost of this deal is not disclosed, it is estimated to be in the range of $60 million, assuming a similar price per ton as the Frontier agreement.
A New Approach to Carbon Removal
ERW is a relatively low-tech method for removing carbon dioxide from the atmosphere. It involves crushing rocks and spreading them out over a large area, increasing the surface area exposed to CO2. This process accelerates the natural weathering of rocks, which releases calcium and magnesium ions that combine with CO2 in water to form bicarbonate.
The Science Behind ERW
Enhanced rock weathering is based on the natural process of rock weathering, which occurs over thousands of years. Rainfall breaks down rocks, releasing minerals such as calcium and magnesium, which react with CO2 in water to form bicarbonate. This reaction traps CO2 in the water, preventing it from entering the atmosphere.
By accelerating this process, ERW aims to capture more CO2 in a shorter period. Terradot’s approach involves using basalt rocks from quarries in southern Brazil and applying them to nearby farms as a soil amendment. The finely ground basalt increases the surface area of exposed rock, enhancing the weathering reaction.
Challenges and Limitations
While ERW shows promise, there are several challenges associated with this technology. One of the main concerns is measuring the amount of CO2 removed from the atmosphere. Terradot plans to take soil samples to assess the degradation of the rocks over time, but it is unclear how much calcium, magnesium, and bicarbonate will make it to the ocean to permanently sequester CO2.
Fertilizers in the soil can potentially limit the amount of carbon captured through ERW, making it difficult to predict the effectiveness of this technology. Jagoutz, a geologist who has studied ERW, notes that "how much they sequester is still the outstanding question."
The Role of Carbon Removal in Climate Change Mitigation
While ERW shows promise as a carbon removal strategy, it is essential to note that this approach should not be seen as a substitute for emissions reductions. In fact, Google’s own data suggests that 200,000 tons of CO2 removed through ERW is only a small fraction of the company’s annual carbon footprint.
Kanoff, CEO of Terradot, emphasizes the importance of both emissions reductions and carbon removal strategies in addressing climate change: "Any of the partners we’re even thinking about working with, they have some of the most aggressive emission reduction strategies of any companies really in the world. And those are the groups that we really want to partner with to advance carbon removal."
Conclusion
The partnership between Google and Terradot marks a significant step forward in the development of ERW as a carbon removal strategy. While there are challenges associated with this technology, it has the potential to make a meaningful contribution to climate change mitigation efforts.
As the world continues to grapple with the impacts of climate change, innovative solutions like ERW will be essential in addressing the scale and complexity of this global challenge.