Scientists Amplify Mineral's CO2-storing Ability

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Magnesite is a mineral used in jewelry that's also a reliable carbon absorber. Rob Lavinsky/ Commons

Scientist have recently warned that Earth could become a "hothouse" if we don't put the brakes on our planet's warming trend. While it's smart to keep planting more trees and protect established forests, there's another way to preserve Earth as we know it: figure out how to absorb excess carbon dioxide (CO2) in our atmosphere. One such alternative is magnesite, a mineral that naturally stores carbon, but the mineral's growth process is very slow, making it an unlikely assistant in our quest.

That is until now. Scientists believe they've figured out a way to speed up magnesite's growth, the first step toward making it a viable large-scale CO2 catcher.

Rock-solid storage

To figure out how to speed up the development of magnesite, researchers had to better understand how the mineral forms in the first place. With that knowledge, they were on their way to determining how best to nudge along the process.

"Our work shows two things," Ian Power, a professor at Trent University in Ontario and the project's leader, said in a statement. "Firstly, we have explained how and how fast magnesite forms naturally. This is a process which takes hundreds to thousands of years in nature at Earth's surface. The second thing we have done is to demonstrate a pathway which speeds this process up dramatically."

Presented at an international conference on geochemistry, the 2018 Goldschmidt conference in Boston, Powers and his team showed that by using polystyrene microspheres as a catalyst, they were able to form magnesite in just 72 days. The microspheres, they said, are unchanged by the process and thus can be reused to form more magnesite or for other purposes.

"Using microspheres means that we were able to speed up magnesite formation by orders of magnitude. This process takes place at room temperature, meaning that magnesite production is extremely energy efficient," Power said.

A hunk of mangesite rock
We'll need a bit more mangesite than this to help us store CO2, but it's a start. Aleksandr Pobedimskiy/Shutterstock

"For now, we recognize that this is an experimental process, and will need to be scaled up before we can be sure that magnesite can be used in carbon sequestration. This depends on several variables, including the price of carbon and the refinement of the sequestration technology, but we now know that the science makes it do-able."

A tonne of magnesite can remove about half a tonne of CO2 from the atmosphere. About 46 billion tons of CO2 were released into the atmosphere in 2017, making the need for carbon sequestration all the more important. (A British tonne is 2,240 pounds; a U.S. ton is 2,000 pounds.)

"It is really exciting that this group has worked out the mechanism of natural magnesite crystallization at low temperatures, as has been previously observed — but not explained — in weathering of ultramafic rocks," professor Peter Kelemen at Columbia University's Lamont Doherty Earth Observatory, said. Kelemen was not involved in the study.

"The potential for accelerating the process is also important, potentially offering a benign and relatively inexpensive route to carbon storage, and perhaps even direct CO2 removal from air."