How a new type of sand on the Outer Banks could help fight climate change

DUCK, N.C. — On the Outer Banks, sand is a valuable resource. Millions of dollars every year go into making sure there’s enough sand in the dunes to keep infrastructure intact and slowdown shoreline erosion.

An experiment off the coast of Duck hopes to prove adding a new, naturally occurring mineral to that sand can not only help beach nourishment projects, but can also help fight climate change.

The public benefit corporation, Vesta, plans to put a mineral called olivine, ground up into sand, into the ocean to remove carbon dioxide from the atmosphere and store it safely underwater, reducing net greenhouse gas emissions and hopefully slowing down climate change.

How does it work?

Olivine experiments fall into a category of carbon capture and removal proposals called ocean alkalization or the process of increasing the pH value of the water to make it less acidic.

When there’s more carbon dioxide in the air, it also dissolves into seawater, making water more acidic. For billions of years, that CO2 in water has bound itself to naturally occurring magnesium creating a type of salt that sinks to the bottom of ocean.

Olivine is high in magnesium, so when ground into a sand, it dissolves faster in water where its magnesium can bind to carbon dioxide as a part of that natural process. Jaclyn Cetiner, the senior scientist for the Duck project, considers their experiment a faster version of what olivine and ocean water have been doing for as long as they’ve been on earth.

“We’re just extracting that mineral and making it dissolve faster,” she said. “So instead of it happening on thousands, or tens of thousands of years plus time scales it happens in tens of years or shorter.”

Should the pilot project prove successful, Drew Syverson, a research assistant professor at UNC Charlotte, said the minerals involved are so abundant, these types of projects can be scaled up enough to take gigatons of CO2 out of the atmosphere.

What is the project exactly?

In collaboration with the Army Corps of Engineers, Vesta plans to deploy 6,150 cubic yards of olivine 1,500 feet off the shore of Duck in Spring 2024. It’s Vesta’s second pilot project using olivine for carbon capture.

A similar experiment deployed in Southampton, New York put ground olivine into Shinnecock Bay. A year into the study, Cetiner said the results so far are promising.

“Even from some of the very first measurements that they started collecting they did see evidence of carbon removal,” she said.

The Duck project marks the first time Vesta is deploying olivine into open ocean, exposing the mineral to the full fury of the wind and waves off the coast of the Outer Banks.

Cetiner hopes that will allow Vesta to see if the ocean will make the sand dissolve more quickly and how far their sediment might travel.

Is there a downside?

At the scale of the Duck project, the Army Corps of Engineers believes any significant environmental impact is unlikely. That’s part of why the pilot project is so small to start with. Vesta will measure multiple different factors besides carbon capture to try to predict what larger projects could do to the environment before rolling them out.

There are critics of ocean alkalization projects in general, however.

While minerals like olivine make the ocean less acidic, there needs to be a balance. There’s concern overdoing it could negatively impact ocean chemistry. There’s also concern other elements of olivine could fertilize the oceans potentially leading to algae overgrowth.

Another issue is mining. Olivine is an abundant material on earth, there are even significant deposits in western North Carolina, but it does need to be extracted. While olivine mining has a much lower environmental impact than things like lithium or heavy metal mining, there’s no such thing as mining without an environmental impact.

The olivine for the Duck experiment comes from Norway which also means there’s a transportation cost involved and the carbon emissions involved will reduce the net capture of the olivine. Should the project scale, Vesta plans to target beaches within 190 miles of the source of their olivine to reduce emissions.

The sand also has a greenish hue. It’s not very noticeable when mixed with native sand, but for those who feel strongly about white sand beaches, that could be a downside. The sand on the Outer Banks has a slightly yellow-brown hue anyway, so olivine mixtures actually make the sand look lighter.

The final criticism levied against the project focuses on its philosophy. Emitting CO2 and other greenhouse gasses is driving climate change, and while carbon capture and removal projects could cut down on the CO2 in the atmosphere, Svyerson argues no one should rely on negative emission technologies as a free pass to maintain the status quo when it comes to emissions.

“We have about 200 years worth of CO2 that we’ve put into the atmosphere already, so to actually mitigate what we’ve done already we need the negative emissions technology,” he said. “We have to figure out a balance of emitting CO2 from fossil fuels and also having some type of negative emission technology to counterbalance that.”

What should we expect on the Outer Banks?

Vesta is finishing up its baseline measurements this fall and winter and will deploy the olivine sand in the spring. Scientists will study monitor its impact over the next two years.

Should the project pan out, Vesta hopes to scale up, eventually introducing olivine into existing beach nourishment projects. Duck currently replaces 500 thousand cubic yards of sand every year, and Cetiner hopes, if they add olivine to that sand, it could give shoreline restoration projects a second purpose as a carbon sink.

“We match the grain size with the native sand so it moves the same, it acts the same,” she said.

If Vesta does its job correctly, Cetiner said most visitors to the Outer Banks wouldn’t notice a difference.

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