Eion Carbon, a Princeton, N.J.-based startup founded in 2021, is attempting to reverse climate change by scattering crushed rocks on farmland, and has successfully removed its first tons of carbon dioxide from the atmosphere, according to a Bloomberg report.

Eion said its product, CarbonLock, uses the mineral olivine at an optimal particle size and dissolution rate to deliver soil benefits quicker than agricultural lime, all while predictably and reliably removing carbon dioxide.

Eion has been deploying its technique commercially for eight months on farms in Mississippi and Illinois. The company said those tests have allowed it to remove approximately 50 tons of CO2, thus validating its approach to carbon removal.

The backbone of Eion’s carbon removal technology, dubbed enhanced rock weathering (ERW), is the mineral olivine, which is quarried, ground up, and scattered across farmland. As the mineral dissolves, a series of chemical reactions occurs that captures CO2 as it moves through the soil. That CO2 eventually makes its way through waterways to the ocean, where it is permanently locked up.

Eion is focused on refining its monitoring, reporting, and verification techniques (MRV), according to Chief Technology Officer and Co-Founder Elliot Chang. MRV is essential to ensuring that companies promising to remove CO2 from the atmosphere are actually delivering.

“How do you measure something that was captured and then flushed away? That’s the open system challenge,” Chang said.

Chang developed a way to measure the soil after olivine application, looking for trace elements in the soil samples that indicate the mineral has dissolved. Based on those measurements, Eion can model how much CO2 has been captured. The company then calculates the total of CO2 removed after accounting for the emissions generated through the process of mining, grinding, transporting, and applying the olivine.

For ERW to gain widespread use as a form of carbon removal, the agriculture industry will need to get onboard. Eion and other ERW startups pitch it to farmers as a substitute for agricultural lime, which is used to stabilize soil acidity.Chang said Eion’s olivine is cheaper than traditional agricultural lime in part because the company is able to sell carbon credits, offsetting some of the cost. It said the olivine can be used as a 1-to-1 replacement. Currently, the startup has a handful of partnerships with farming co-ops in the southern and midwestern US.

It also has a contract with mining partner and investor Sibelco, which guarantees the startup access to a minimum of 500,000 tons of olivine per year. It takes approximately one ton of olivine to remove nearly one ton of CO2 per Eion’s methodology.

Sibelco’s Chief Strategy and Business Development Officer Ian Sedgman estimates that the total market for olivine is upwards of 50 million tons annually. That would require farms across North America, South America, and Europe to make the switch from agricultural lime. Olivine isn’t necessary on all farms, because it’s mainly used to address acidic soils, which not all regions have.

“If we put a very ambitious but achievable target on Eion, if they scale to between 5 and 10 million tons a year, that would already be the largest negative emissions company on the planet by a huge scale,” Sedgman said.

According to Eion, olivine has been a legally approved and labeled agricultural input since the 1940s in the US, Brazil, New Zealand, and Australia. In addition to being a substitute for lime, it is also a recognized means to improve the availability of phosphate in crop production.

Eion’s olivine comes from Sibelco’s hydro-powered operations in Aheim, Norway, where it is quarried and pulverized to Eion-optimized fineness for fast weathering on fields. The company said 80% of the global olivine production originates in Norway, though the green silicate is one of the earth’s most abundant minerals, found on the beaches of Hawaii and the Galapagos, as well as the shores of Europe’s deepest lakes, and forms many of the San Juan Islands in Washington State.