Lab-Made Mineral Could Help Combat Climate Change – But There's A Huge Catch

Early days: the mineral (not pictured) forms naturally and locks in carbon dioxide as it is. klikkipetra/Shutterstock

Robin Andrews 16 Aug 2018, 15:45

You’ve probably never heard of magnesite, and why would you have? It’s a rather innocuous carbonate mineral, one in which magnesium is bound to carbon and three atoms of oxygen. According to a team led by Trent University, however, it could provide us with a way to combat climate change.

Its ability to store carbon dioxide is well-known, and through various geological processes, the formation of magnesite allows this to occur naturally. What if, though, we could manufacture it in greater quantities in a laboratory, trap carbon dioxide within it, and bury it deep underground?

Indeed, that lofty goal is precisely what the researchers have taken a step towards. Presenting their proof-of-concept work at the Goldschmidt conference in Boston this week, their abstract explains that experiments in the lab were designed to better explain how the mineral forms fairly speedily at Earth's surface under a range of conditions.  

We now have a better understanding of nature’s ways, but those experiments clearly have profound implications. Independent carbon capture experts seem to agree.

Forbes’ Trevor Nace notes that the basics of magnesite production require first getting hydrogen carbonate by dissolving carbon dioxide into water. Then, you’d get magnesium to displace that hydrogen and voila, you have your magnesite.

Magnesite crystals, from Brazil. iRocks.com/Wikimedia Commons; CC BY-SA.3.0

This new work demonstrates that magnesite is able to form around very tiny spheres of polystyrene. This process is similar: the spheres are carboxylated, meaning they have an organic compound of carbon, oxygen, and hydrogen attached.

This allows for an efficient capture of magnesium, and permits a decent chunk of the mineral to form in just 72 days. Normally it takes centuries or even millennia to form magnesite minerals.

Prof. Ian Power, an environmental geochemist at Trent, led the work. He explained to IFLScience that magnesium ions are fairly small and dense with charge, which means they latch onto water molecules incredibly tightly. Removing the magnesium to form magnesite is therefore normally very difficult, but those microspheres act as effective thieves.

Previous work investigating this precise mechanism found that magnesite required fairly high temperatures to precipitate, which unfortunately requires additional energy input to achieve. This new process apparently takes place at room temperature.

There's plenty of potential here, sure. If you think that we're about to suddenly solve anthropogenic climate change, though, you've got another thing coming.

It's worth stressing that one unit of magnesite removes half a unit of carbon dioxide. That means you’d need to manufacture billions of tons of it per year in order to trap and ideally bury a lot of CO2 to make a significant difference.

“We’re still working to better understand the fundamental science, and do not currently have plans to ‘scale up’,” Power said.

Scaling up would push this experimental process under the umbrella of carbon capture and storage (CCS). As it happens, this entire field of research is still taking baby steps, let alone magnesite production.

It’s pretty clear that in order to achieve the goals of the Paris Agreement we’ll need to not just stop carbon dioxide escaping into the air, but we’ll have to build CCS machines that’ll actively draw down carbon dioxide already present up there. Proof-of-concept carbon scrubbers that’ll do just that exist, but plenty of uncertainties remain.

Who will fund the production and proliferation of these machines? Evidence is mounting that it’s an increasingly affordable tech, and that gases can be trapped long-term underground, but can the tech be scaled up effectively? Will we need to use biomass to help absorb more CO2?

These technologies, including this latest addition to our repertoire, aren’t silver bullets against climate change, no matter how effective they may ultimately prove to be. This existential crisis still requires a fundamental reorganization of the way our economies work, and a rapid switch from fossil fuels to low-carbon sources of energy.

“My sense is that there will need to be numerous solutions for addressing greenhouse gas emissions,” Power added. Magnesite could help, but “green energy, greater efficiency, reduction of waste,” as well as “carbon management and sequestration technologies” is the way forward here.

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