First ‘Negative Emissions’ Plant Opens in Iceland, Turning Atmospheric CO2 Into Stone

It sounds like science fiction: A device that sucks greenhouse gasses out of our warming atmosphere and turns it to stone. But as Akshat Rathi reports for Gizmodo, a new experimental facility in Iceland is doing just that—albeit it on a very small scale.

The plant is the latest in carbon capture and storage efforts, which have been attempted for decades. At its core, each variation of this technology does exactly what its name describes, capturing carbon dioxide from the air (or from plant emissions) and storing it.

There are several big hurdles to this goal. For one, long-term storage is a challenge. Many scientists thought that by injecting the CO2 into the Earth, it would eventually turn to stone; but it takes hundreds of thousands of years for this to happen. Another issue is that many of these plants struggle to pull carbon dioxide from the ambient air. CO2 molecules are actually relatively scant compared to the total number of molecules in air, which makes the process like searching for a needle in a haystack.

But the startup Climeworks, based in Switzerland, believes it has a solution. Last year, the team turned on a carbon capture plant that draws emissions from the atmosphere using sensitive filters and funnels the captured CO2 into greenhouses to boost plant growth.

But the company was hoping to lock away the emissions in a more permanent form, so they teamed up with researchers from the Icelandic project CarbFix. Last year, researchers with CarbFix published a study that documented how carbon dioxide injected into the ground turned into carbonate minerals in less than two years.

This seemingly miraculous feat happens because of the local geology and some tricky geochemistry. Most carbon dioxide is injected into sedimentary rock, which doesn't react with the gas. But in Iceland, volcanic rocks known as basalt are found all across the island, and carbon dioxide reacts relatively quickly with this type of rock to create carbonate rocks. This means carbon capture facilities won't have to carefully manage giant underground gas reservoirs for centuries, avoiding accidental releases, reports Amelia Urry for Grist.

Climeworks paired its sensitive filter technology with the "carbon neutral" Reykjavik Energy geothermal power plant in Hellisheidi, Iceland. This plant was already running the CarbFix technology, turning carbon dioxide to stone. Now in operation, the plant can draw carbon from the air, not just the small amount of CO2 emissions the geothermal plant releases. The company claims the operation is the first "negative emissions" plant in the world, meaning that it takes in more carbon than it uses.​​​ ​

For now, however, the plant is functioning less like a vacuum and more lika a straw, notes Scott Johnson of Ars Technica. Still at its pilot stage, the device is only capturing around 50 tons of carbon dioxide per year, which is roughly equivalent to the emissions from one U.S. household. And Climeworks technology remains extremely expensive. As Rathi writes, according to a 2011 report from the American Physical Society, capturing CO2 from air costs between $600 and $1,000 per metric ton of CO2.

Carbon capture has long been a controversial technology. Many worry that it has questionable promise on a large scale and distracts researchers and the public from the pressing need to limit carbon emissions.​ And if they fail, the impacts will be most felt in low-emission communities who are both "geographically and financially vunerable" to the rapidly changing climate, leading climate scientists Kevin Anderson and Glen Peters argued in an editorial in journal Science last year.

"Negative-emission technologies are not an insurance policy, but rather an unjust and high-stakes gamble," they wrote.

But Climeworks is powering ahead, hoping to start scaling up their process and bring down the costs. "Our plan is to offer carbon removal to individuals, [corporations] and organizations as a means to reverse their non-avoidable carbon emissions,” Climeworks head Christoph Gebald says in a statement.

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Ben Panko is a staff writer for Smithsonian.com