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Enhanced Rock Weathering (ERW) is emerging as a promising, low-cost method to combat climate change by removing carbon dioxide (CO₂) from the atmosphere. According to Trellis via GreenBiz, the technique has recently garnered significant backing, with Google, Microsoft, and other companies investing $300 million into ERW-focused startups.
How ERW Works
ERW accelerates natural geochemical processes to sequester carbon. The method involves crushing basalt, a common volcanic rock, into a fine powder and spreading it across farmland. When rainwater containing dissolved CO₂ interacts with basalt, it produces bicarbonate, a stable molecule that can remain in the soil or flow into groundwater, ultimately settling as ocean sediment. Additionally, the process enriches farmland with essential minerals, offering soil health benefits.
Scientists estimate that ERW could remove between 2 billion and 4 billion tonnes of CO₂ annually if scaled globally.
Major Investments in Carbon Removal
ERW has attracted increased investment from major players:
Terradot, a Brazilian startup, secured $58 million in funding and a $27 million contract from Frontier, a coalition of companies, including Stripe and Meta, that supports emerging carbon removal technologies.
Google, a Frontier founding member, purchased an additional 200,000 tonnes of removal credits.
Heirloom, another ERW company, raised $150 million in funding.
Competitors Lithos and Undo have reported sales to BCG and Microsoft, respectively.
Frontier’s recent purchases demonstrate confidence in ERW’s scalability. With costs projected to drop below $100 per tonne, ERW will significantly undercut direct air capture (DAC), which currently costs around $500 per tonne.
Benefits and Challenges of ERW
ERW’s appeal lies in its ability to use existing farmland, avoiding the need for costly industrial infrastructure. However, it also presents challenges:
Unlike DAC, where CO₂ capture is directly measurable, ERW occurs in open systems, making precise carbon accounting complex. CO₂ may leave fields in multiple ways, such as bicarbonate runoff or atmospheric release.
Estimates of ERW’s effectiveness vary widely, creating uncertainty around its true impact.
A review by CarbonPlan, cited by Trellis, underscored this uncertainty, noting that estimates of ERW’s effectiveness vary widely.
CarbonPlan research scientist Tyler Kukla said: “It’s clear that we are still in the early stages of learning about enhanced weathering. We encourage caution when interpreting carbon removal estimates in the literature.”
Companies like Terradot are addressing these uncertainties through rigorous data collection and analysis. Co-founder James Kanoff explained that the team uses treated and control plots to measure outcomes, including soil samples and water analysis post-rainfall. The approach, informed by work from Cascade Climate, aims to deliver accurate and verifiable carbon capture data.
Kanoff said: “The question is, can we take a natural process that occurs over millennia and accelerate it to remove carbon in years?
“If we can achieve that and provide reliable measurements, ERW could play a significant role in addressing climate change.”
Enhanced Rock Weathering offers a cost-effective alternative to traditional carbon capture technologies. It has the potential to scale globally and contribute meaningfully to climate goals. As investments pour in and methodologies evolve, ERW becomes a key contender for scalable, sustainable carbon removal solutions.