Enhanced weathering harnesses the power of nature to remove carbon dioxide from the atmosphere. Rather than reinvent the wheel, enhanced weathering accelerates the planet’s natural mineralization cycle by crushing rocks and transporting them to the right environment, allowing them to weather at an accelerated pace.
This scalable climate solution safely and permanently removes CO2 and offers significant potential for combating climate change. In this post, we’ll offer a snapshot of how enhanced weathering works and answer a few common questions.
Let’s dig in!
What is enhanced weathering?
Enhanced weathering is a scalable carbon dioxide removal (CDR) pathway rooted in geochemistry that’s been going on for millions of years.
In nature, rock weathering is a process that has existed for millions of years, helping to balance our planet’s carbon cycles: As rocks are exposed to rain and acidity, they slowly erode, and magnesium present in them binds with atmospheric carbon. This new carbon compound gets transported through waterways and ultimately to the ocean where carbon is locked up and safely stored for hundreds of thousands of years.
It’s an impressive cycle that has served—and continues to serve—our planet well. Today, however, Earth’s mineralization cycle is unable to keep up with the billions of tons of excess carbon that we are adding to the atmosphere each year.
That’s where enhanced weathering comes in.
The practice of enhanced weathering doesn’t reinvent the natural mineralization cycle. It speeds it up by crushing and applying the right kind of rock to the right environment, so it can weather and lock up carbon more quickly. It’s a down-to-earth way to remove a lot of carbon from the atmosphere, all by letting nature do the heavy lifting.
How do rocks store carbon?
Let’s take a look at the geochemistry behind enhanced weathering.
When silicate rock, like olivine, is added to the soil, it interacts with carbonic acid (water and carbon dioxide that combine naturally in soil water) and dissolves.
In the soil water, this reaction produces positively charged magnesium ions (Mg2+). Nature doesn’t like a charge buildup. To maintain neutrality, these magnesium ions (Mg2+) pair up with two bicarbonate ions (HCO3) to reach balance. So long as these magnesium ions are free, they keep the carbon trapped in solution.
Now paired, the magnesium and bicarbonate filter through the soil into waterways, and eventually reach their final destination in the ocean to be stored for thousands of years.
What type of rock is best for enhanced weathering?
Lots of different silicate minerals can work for enhanced weathering, including olivine, basalt, and wollastonite. We’ll need a variety of companies working with myriad materials to best meet the need for robust CDR action across the globe.
When comparing different minerals for enhanced weathering, factors like weathering rates, accessibility, and costs can vary widely between different rocks. Ultimately, two key considerations are the mineral’s effectiveness in weathering and the ability of the supplier to scale its use. Within the scalability question, important considerations include availability and accessibility to a consistent, plentiful source of rock, and whether landowners are willing to apply that particular mineral to their land.
For example, at Eion we choose to use olivine because it boasts the highest carbon removal efficiency among silicate minerals, so it’s an excellent choice for enhanced weathering. Olivine works as a 1:1 replacement for agricultural lime (ag lime) that farmers commonly apply to their fields, so it enables us to scale within the existing structures of agriculture rather than inventing new supply chains. Additionally, it’s plentiful—trillions of tons have been located within the Earth’s crust—and we have an excellent, environmentally-conscious source for it through our partnership with Sibelco, the world’s largest olivine producer.
Where can you deploy enhanced weathering?
Weathering rates vary widely depending on the environment it’s happening in, so choosing the right location for application is important.
For enhanced weathering to work well, you essentially need:
- A mineral with sufficient alkalizing potential, like olivine
- That is ground extremely finely to enable weathering
- Applied in warm, wet, and acidic places
Enhanced weathering works less well if:
- The material is too coarse; it won’t dissolve at the expected rate
- It’s applied in places that are too cold or too dry
- Too much material is applied and alkalizes the soil, shutting off the acidity needed to dissolve the rock
At Eion, field trials and soil sampling have helped us understand that enhanced weathering with olivine works best when the material is applied on acidic soils in warm, wet climates, so we focus on U.S. farmland that meets these conditions in the mid-South and Midwest.
How do you measure carbon removal in enhanced weathering?
As with all carbon removal technologies, it’s crucial to accurately determine how much carbon dioxide is removed during the process of enhanced weathering. After all, if we’re banking on this process to help us combat climate change, we better be sure it’s working.
Two common approaches to measurement, reporting, and verification (MRV)in enhanced weathering include using modeling to predict weathering rates and directly measuring soils before and after application. Eion champions direct soil measurement over hypothetical modeling because it’s necessary to build trust in a nascent market. It also takes more real-world variables into account—a critical advantage when working in a natural, open system. Direct measurement enables us to prove carbon removal has happened, rather than estimating using models.
Eion’s patented approach directly measures carbon dioxide removed by using before-and-after direct soil samples. These samples look at immobile trace elements to show that the applied minerals removed CO2 from the atmosphere and transported it away to be permanently sequestered.
Is enhanced weathering safe?
When we’re talking about tweaking anything in agriculture, it’s critical to ensure it’s safe. After all, we rely on the soil to feed us.
Applying minerals (like olivine or ag lime) to the soil to balance pH levels is a practice that dates back over a century. Olivine has been a legally approved and labeled agricultural input since the 1940s in the United States, Brazil, New Zealand, and Australia. About 2 million tons of serpentine (a cousin of olivine) have been applied on cropland in New Zealand without adverse consequences.
According to trusted data and risk exposure models from the Environmental Protection Agency (EPA) as well as a wealth of academic experts and published research studies, there is no evidence of ecosystem risk from applying silicate rocks, including olivine, at scale.
It’s important for enhanced weathering suppliers to follow EPA guidance and rigorously test to make sure trace elements like nickel and chromium—which are naturally present in agricultural soils and in rocks—stay at healthy levels. By actively measuring the soil, the olivine material we use, and downstream water runoff, Eion ensures these levels stay within our conservative safety thresholds.
How does enhanced weathering improve agriculture?
Farmers commonly use a soil amendment called agricultural lime (ag lime) to balance the pH levels in soils. Akin to Vitamin C for the soil, ag lime raises soil pH to make all of the little bugs in charge of processing nutrients happy, which means happier plants and healthier crops. Ag lime is usually applied every 2-3 years when farmers go out to prepare soils, either before planting or after harvesting.
While ag lime works well, it’s been getting more expensive over the years, which has left farmers looking for alternatives. Working with an enhanced weathering supplier like Eion gives farmers more operational freedom and choice by providing ready access to silicates like olivine—which can do the job of balancing soil pH just as well. In addition, enhanced weathering can help revitalize agricultural communities by creating stable job opportunities.
How does enhanced weathering compare to other carbon removal pathways?
One way to think about various CDR pathways is by using the open and closed systems framework.
Closed system pathways like direct air capture (DAC) and biochar score high on verifiability and permanence because they are man-made processes specifically designed to remove carbon dioxide. The trade-off? Closed systems require significant effort and investment to build and scale.
Open system pathways, such as soil, forests, oceans, and weathering, use intentional interventions to enhance Earth’s natural ability to remove massive amounts of carbon. Nature does the heavy lifting using processes refined over millennia. The trade-off? Open systems can be challenging to measure accurately.
Enhanced weathering stands out because it bridges the best of both: we’ve figured out how to optimize and accurately measure the natural processes at work. By leveraging a natural cycle, enhanced weathering ensures the permanence of CO2 removal without extensive maintenance. It can scale more quickly and cost-effectively than other CDR solutions offering similar permanence because we don’t need to build brand new machinery, infrastructure, or supply chains.
How can enhanced weathering combat climate change?
As the demand for high-quality, durable, and permanent carbon dioxide removal (CDR) solutions continues to grow, enhanced weathering has emerged as one of the most promising natural, scalable CDR pathways. It’s estimated that enhanced rock weathering has the potential to remove about two gigatons of carbon dioxide annually, a third of humanity’s goals.
While enhanced weathering has a foundation of well-understood science, there is a pressing need to commercialize and scale it. An advantage of enhanced weathering is that suppliers like Eion can leverage existing industries and supply chains—like mining and agriculture—to rapidly scale. There is enormous potential for enhanced weathering to grow in the U.S. because of the monumental scale of the American agricultural system. There’s no need to create enormous amounts of physical infrastructure from scratch as these systems and supply chains already exist.
Enhanced weathering represents a powerful intersection of nature and technology, providing a viable, scalable solution for addressing the climate crisis. By accelerating natural processes that have balanced the earth’s carbon cycle for millennia, enhanced weathering offers a pragmatic approach to removing CO2 from the atmosphere. The path forward involves continued innovation, rigorous testing, and strategic partnerships to ensure we can harness this technology to its full potential.
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Looking to learn more about enhanced weathering? Dig in deeper:
- A Buyer’s Guide to Assessing Enhanced Rock Weathering Suppliers
- A Deep Dive Into Enhanced Rock Weathering With OpenAir Collective
- Reach out to our team with your enhanced weathering questions at hello@eion.team