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Graphic shows how "carbon capture" and "carbon removal" can be used to extract harmful carbon dioxide gas so it can be stored deep underground in basalt rock.
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ENVIRONMENT

The tech startup turning carbon dioxide into stone

By Ninian Carter

March 9, 2021 - A tech startup is tackling climate change by turning carbon dioxide into rocks – permanently storing the greenhouse gas deep underground.

Icelandic startup, Carbfix, is grappling with a crucial aspect of reversing climate change by turning carbon dioxide (CO₂) into rocks, trapping the greenhouse gas forever underground, instead of allowing it to escape into the atmosphere and contribute to global warming.

The Reykjavik-based company has built a fully working prototype at the Hellisheidi geothermal power plant in Iceland, where it uses “carbon capture” to trap gas directly from smoke stacks – although geothermal plants are classified as renewable energy, they do still produce a tiny amount of the CO₂ when compared to a natural gas facility.

The gas is then mixed with water and injected into basalt deep underground (a porous, mostly vesicular rock filled with cavities), where the carbonated water reacts with elements such as calcium, magnesium and iron to form carbonates that fill up the hollow pockets – providing a permanent and safe carbon sink in less than two years.

A secondary experiment is underway at the site using Climeworks “carbon removal” technology to extract CO₂ directly from the air, before being stored underground in the same way.

Carbfix says its carbon capture method is very cheap, working out at $25 a tonne, which compares favourably with the current price of about $48 a tonne on the EU’s Emissions Trading System. Carbon removal is currently considerably more expensive though, costing around $600 a tonne.

In the last few years, capturing and storing CO₂ has become an area of immense interest for high-profile investors such as Microsoft founder Bill Gates, and Tesla and SpaceX CEO Elon Musk.

According to Carbfix, the global storage potential of using its technology is greater than the emissions from burning all fossil fuels on Earth.

The company is now working with global institutions to try and make its system applicable to types of rock other than just basalt, and aims to have one billion tonnes of permanently stored CO₂ by 2030.

Sources
PUBLISHED: 09/03/2021; STORY: Graphic News
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