The World’s Largest Greenhouse Gas Capture Facility Just Went Online in Iceland

The world’s largest carbon dioxide capture facility has begun operations in Hellisheiði, Iceland, a pivotal milestone in the development of what is known as direct air capture (DAC), technologies that are aimed at scrubbing the atmosphere of excess carbon dioxide. Although a drastic reduction in the amount of human-based CO2 emissions is paramount in the fight against global warming, this otherwise chemically-stable greenhouse gas can persist in the atmosphere for centuries, making the active removal of CO2 from the air vital to the stabilization of the planet’s climate.

The facility, called “Mammoth” by Climeworks AG, the Swiss-based direct air capture company that runs it, employs numerous modular “collector containers” that draw in air and pass it through specialized filters that absorb the carbon dioxide in it; once completely saturated by CO2, the filters are heated to 100°C (212°F), releasing the CO2 for collection by Climeworks’ carbon storage partner, Reykjavik-based Carbfix.

From there, the captured gas is dissolved in water to make carbonic acid; this solution is then pumped deep into Iceland’s basalt rock formations. There, the mixture reacts with the calcium, iron and magnesium in the rocks to form solid carbonate compounds that can’t leak back to the surface and into the atmosphere.

Currently, Mammoth has 12 of its planned 72 DAC modules up and running; the company expects to have the facility running at its full 36,000-ton capacity by the end of the year.

Aside from simply chemically locking it away in rocks, carbon dioxide has other uses: in 2017 Coca-Cola HBC Switzerland started using Climeworks’ captured CO2 to carbonate mineral water for sale as a soft drink; and CO2 can also be used to produce useable fuel: recently, researchers with Northwestern University developed a process using simple sugar that converts CO2 into carbon monoxide, valuable as a precursor in the production of synthetic fuels that could replace gasoline.

Although Mammoth’s 36,000-ton collection capacity eclipses that of the company’s previous facility, Orca, by ten times, the rate of capture needs to be scaled up by several orders of magnitude to make a meaningful impact in countering human-based carbon emissions; as an example, Climeworks client Microsoft emitted nearly 13 million metric tons of CO2 in 2022 alone, and that one company represents a mere 0.035 percent of the 37.2 billion tons emitted globally in the same year.

Two large-scale projects in the U.S. have already received a combined $3.5 billion in funding from the Department of Energy: California-based startup Heirloom, making use of a limestone-based capture method; and Louisiana-based Project Cyprus, a DoE project that makes use of Climeworks’ technology. Both projects are expected to capture a minimum of one million tons of CO2 annually.

Needless to say, Carbfix, Climeworks and Heirloom aren’t the only companies working to develop DAC technologies: the Xprize Foundation has announced the 20 finalists in their Xprize Carbon Removal competition—a roster that includes Heirloom—that “represent leading [carbon dioxide removal] solutions with the potential to make meaningful contributions to a diverse, global, sustainable, gigatonne-scale CDR effort.”