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The First Open Ocean Carbon Removal Project in the U.S. Just Got a Green Light

And it involves dumping 9,000 tons of fancy sand off the North Carolina coast.

A beach and clouds.
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When visitors flock to the beach this summer in Duck, North Carolina, a small, 6-mile long town on the Outer Banks, they may catch a glimpse of a climate experiment happening among the waves.

About 1,500 feet offshore, a company called Vesta will be pouring 9,000 tons of sand into the sea and watching carefully to see what happens next. This finely crushed rock will not be of the typical Outer Banks variety. Instead, it will consist of a mineral called olivine, which should enhance the ocean’s ability to absorb carbon from the atmosphere — and lock it away for thousands of years.

That the experiment can go ahead at all marks a milestone for ocean-based carbon removal, a category of climate solutions that prod the ocean into sucking up more CO2. A big obstacle for the field has been the lack of a legal framework for permitting real-world trials — U.S. laws governing the ocean weren’t written with the prospect of intentionally altering its chemistry to address an existential environmental crisis in mind. But after an 18-month interagency review process, Vesta is now the first company with a federal permit from the U.S. Army Corps of Engineers to deploy a stand-alone carbon removal test in U.S. waters.

Though 9,000 tons may sound like a lot, this is still a relatively small-scale pilot designed to assess how effective the olivine is in driving carbon removal, as well as observe any other changes in the environment and develop methods for tracking the movement of the sand in the water. These kinds of field trials are essential to establishing which marine carbon removal methods have potential and which don’t.

“We want to measure everything very carefully at this stage and make sure that we are fully understanding the safety profile and the carbon removal data from this project,” Tom Green, Vesta’s CEO, told me. But the company has big aspirations. If things go well, he said, maybe olivine could be used for beach nourishment projects all over the country, where sand is deposited along the shore to address erosion. “Imagine the carbon removal possibilities if we did that with olivine sand,” he said. “We could quickly become the largest technique for permanent carbon removal that's out there.”

Scientists generally agree that stopping global warming this century will require both reducing emissions and taking carbon out of the atmosphere. The sheer size of the ocean and its natural ability to store vast amounts of carbon make it an enticing place to look for solutions.

Dumping thousands of tons of non-native sand into the ocean may not sound like the most convincing option — especially since the ocean is already “experiencing unprecedented destabilizing changes through massive warming, acidification, deoxygenation, and a host of resulting effects,” according to an open letter published last year and signed by hundreds of scientists. However, despite this — or perhaps because of it — the letter called for accelerating research to find out whether any of the proposed ocean-based carbon removal methods, including releasing large quantities of ground olivine, are viable.

Olivine is an abundant mineral with special properties. When it comes into contact with seawater, it drives a chemical reaction that converts CO2 gas into more stable forms of carbon that can’t readily return to the atmosphere. This in turn creates a deficit of CO2 in the surface waters, which triggers the ocean to take up more from the atmosphere in order to maintain equilibrium.

Reactions like this are happening constantly in the ocean already, but on very slow timescales. Vesta’s innovation is to speed up the process by crushing and deploying olivine strategically where the wind and waves can most efficiently weather it away.

Southampton, New YorkThe site of an earlier Vesta test project in the Hamptons.Courtesy of Vesta

Olivine could address the harms of CO2 pollution in more ways than one. The ocean already absorbs about 30% of the carbon released into the atmosphere each year, which has made the water more acidic and less hospitable to many of its inhabitants. But when olivine triggers these reactions, it can act as a sort of antacid. This approach to carbon removal is also known as enhancing the ocean’s alkalinity and olivine is just one of a number of different ways to do it. Another company called Planetary is experimenting with adding a different mineral, magnesium hydroxide, to the ocean. Ebb Carbon, on the other hand, is sucking up seawater and running it through a membrane to increase its alkalinity, before returning it to the tides.

Both already have field trials up and running, but instead of trying to conduct stand-alone experiments in the open ocean they’ve hitched onto existing ocean dumping permits. Ebb, for example, has set up at the Pacific Northwest National Laboratory’s facility in Sequim, Washington, where it is releasing treated seawater into wastewater that flows into the bay. Similarly, Planetary is conducting pilot projects at the wastewater outflows of a water treatment facility and power plant in Canada. Other ocean carbon removal companies, such as Los Angeles-based Captura, have opted to move abroad for their early projects and avoid the U.S. permitting puzzle altogether.

Vesta went to Duck because it is among the most studied stretches of coastline in the country. The town is home to an Army Corps coastal field research center known for its long-term data set on the surrounding waters. “Few locations on the globe provide a better archive of wave, water, bathymetry and other forces that shape nearshore conditions,” according to the Army Corps’ website. (“Bathymetry” is the topography of the seafloor.) That means Vesta will be able to get a more accurate picture of any changes the olivine is responsible for.

When Drew Havens, the town manager in Duck, first heard about Vesta’s plans, he was skeptical. “You're dumping something into the ocean, people automatically go to, well, is it going to harm humans? Is it going to be harmful to wildlife or other living organisms?” he told me.

Though some in the town are still nervous, Havens said he has become more comfortable with the idea as the project has been rigorously reviewed by environmental protection regulators at the federal and state level. Vesta’s scientists also engaged with the town council, did an open house for members of the public, and have generally invited questions and open dialogue.

Just because regulators have determined that the risks of this pilot project are low, however, doesn’t mean using olivine for carbon removal is risk-free. For one, the rock has to be mined — in this case, from a quarry in Norway, although it is also found in the U.S. — and transported to the project site. That’s likely to produce some environmental impacts, though the company estimates that the project will ultimately remove about 10 times more CO2 from the atmosphere than the emissions associated with running the experiment, including the mining and shipping of olivine.

But the biggest risk with mined olivine is that it contains nickel, said Jaime Palter, an associate professor of oceanography at the University of Rhode Island who has no affiliation with Vesta. Nickel can act as both a nutrient and a toxin for phytoplankton, she told me, so it's important to study whether putting olivine in the ocean will result in adverse effects.

Vesta has been closely examining that possibility. In fact, the project in Duck will be the company’s second U.S. field trial. In the summer of 2022, Vesta got permission from the town of Southampton in Long Island to spread olivine on the beach as part of a larger sand replenishment project that was already in the works. Vesta’s scientists worked with local academic partners at Cornell, SUNY Stony Brook, and Hamilton College to do extensive monitoring both before and after the sand was placed, collecting data on more than 20 indicators of the effects on the water, sediment, and ecology.

The company has since published two annual reports on the project. It is still awaiting analysis of many of the samples, but so far, the results have been promising, Green said. There has been no sign of trace metal accumulation in Eastern Oysters, a species known to accumulate pollutants from their environment, for instance. There was also no significant difference in water quality between control areas and the sites with olivine, and trace metal concentrations were below the relevant EPA water quality guidelines. The area’s benthic macrofauna — critters like clams and small crustaceans that live on or near the seafloor — were as abundant and various as before.

Notably, the tests also showed evidence of an increase in alkalinity in the waters of the olivine-treated area, which is the key reaction that leads to carbon removal. But Green said there’s more work to be done in terms of calculating where and when removal may have happened.

There’s also more work to be done to understand the effects of olivine in different environments, which brings us back to Duck. There, it will be deposited in 25-foot deep water instead of on the beach, helping Vesta to further refine its data and measurement methods. The plan is to continue testing and collecting data at the site for at least two years. The company declined to comment on the budget for the project. Vesta is funded primarily by venture capital investors but also raises money for research through an affiliated nonprofit.

Vesta may have been the first to get a federal permit to run a marine carbon removal test, but it definitely won’t be the last. Nikhil Neelakantan, a senior project manager at Ocean Visions, which is a nonprofit that advocates for ocean-based climate solutions, told me there are a number of other domestic projects in the pipeline, including more than a dozen government-funded research projects. The White House also recently set up a marine carbon removal fast track action committee with the mandate to create recommendations for policy, permitting, and regulatory standards for both research and implementation.

Neelakantan said there is work to do on clarifying the role of different agencies in regulating ocean carbon removal, and which laws apply to each method.

“This is an early first step, and it's exciting to see that it's finally going to come to fruition,” he said, of Vesta’s project in Duck. “I think there's momentum with this federal task force. It's going to be the first of many others that will happen soon.”

Emily Pontecorvo profile image

Emily Pontecorvo

Emily is a founding staff writer at Heatmap. Previously she was a staff writer at the nonprofit climate journalism outlet Grist, where she covered all aspects of decarbonization, from clean energy to electrified buildings to carbon dioxide removal. Read More

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