This Is Interesting

This is interesting

To Combat Climate Change, Researchers Want to Pull Carbon Dioxide From the Ocean and Turn It Into Rock

Running seawater through an ocean carbon capture plant could chemically convert carbon dioxide to limestone on a grand scale

Excerpt from this story from Smithsonian:

Anew method for combatting climate change feels like a bit of modern-day alchemy: scientists have figured out how to take carbon dioxide out of the ocean and turn it into harmless rock.

For every tonne of carbon dioxide we pump into the air, roughly a quarter of it gets absorbed by the ocean like a giant, watery sponge. All of this excess carbon dioxide is acidifying the water and threatening organisms, such as those with calcium carbonate shells, that are sensitive to the change.

To avert this fate, carbon emissions need to drop—fast. But many scientists also believe that active carbon capture—deliberately pulling carbon dioxide out of the environment—will be a necessary step to help curb, and potentially even reverse, the rise in emissions responsible for countless environmental impacts. However, capturing enough carbon to make a difference is a massive task, one that has so far proved challenging and expensive.

“You’re talking about removing some 10 to 20 gigatonnes of [carbon dioxide] per year, starting from 2050, probably for the next century,” says Gaurav Sant, a civil and environmental engineering professor and director of the Institute for Carbon Management at the University of California, Los Angeles.

To date, most efforts to capture carbon have focused on direct air capture—trying to pull the gas out of the atmosphere. But to make carbon capture more efficient, Sant’s research team is turning to the ocean for help.

Oceans and other large bodies of water can hold more than 150 times more carbon dioxide than the air. Sant and his colleagues’ idea is that if you can remove carbon from the ocean, the water will absorb more from the atmosphere to maintain a state of equilibrium. Now, they’re proposing an innovative way of getting carbon out of the ocean—by turning it into rock.

Seawater contains a lot of calcium and magnesium. When the calcium or magnesium ions combine with carbon dioxide, they form calcite or magnesite. The chemical reaction is similar to how many marine organisms build their shells. But by introducing a third ingredient, electricity, Sant and his team can make that reaction happen quickly, efficiently and, perhaps eventually, on a large scale. Putting this all together, the scientists have proposed a new technology that will run seawater through an electrically charged mesh, using electrolysis to trigger the chemical reactions needed to form carbonate rocks.

So far, the team has built a 1.5-by-1.5-meter prototype that they can flood with simulated seawater. They are collecting data on the amount of carbon dioxide that can be removed over various periods of time, analyzing the process efficiency and the amount of energy required. Aside from simply demonstrating the concept, they are using the model to determine what operational variables might impact the process.