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Clean energy journalism for a cooler tomorrow

World’s largest direct air capture plant starts sucking CO2 from the sky

Climeworks just began operating its Mammoth plant in Iceland. The 36,000-ton facility is a significant step up for the costly, energy-intensive tech.
By Maria Gallucci

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The Mammoth direct air capture plant in Hellisheiði, Iceland, is capable of capturing up to 36,000 metric tons of CO2 per year. (Climeworks)

Climeworks has officially switched on the world’s largest direct air capture” plant, which sits on a lava plateau in southern Iceland.

On Wednesday, the Swiss company said it started operations at its Mammoth facility, marking an important milestone in the world’s emerging efforts to remove planet-warming carbon dioxide from the atmosphere and permanently lock it away.

The plant’s opening also helps lay the groundwork for a significantly larger direct-air-capture facility that Climeworks plans to build in the United States using federal funding, experts say.

At the Mammoth site, not far from Iceland’s capital city, Reykjavík, a dozen collector containers” are stacked high in rows that resemble giant window blinds from the front. Fans pull air into the collectors, then run it over a solid filter material to separate out the carbon dioxide. Climeworks’ partner, Carbfix, takes the resulting concentrated CO2 and reacts it with basaltic rock to trap the greenhouse gas below ground.

When fully completed later this year, Mammoth will have 72 total collectors capable of removing up to 36,000 metric tons of CO2 from the sky annually. That’s exactly nine times the capacity of Climeworks’ Orca plant, also in Iceland, which opened in 2021 and until now was the largest direct-air-capture (DAC) facility in the world. While that’s a step up for DAC, it’s still a tiny drop in the bucket of overall emissions.

Both facilities get their heat and electricity from the nearby Hellisheidi geothermal power plant, which harnesses energy from the bubbling hot springs and boiling mud pots that blanket the volcanic country. This always-on clean energy helps minimize the CO2 emissions the company generates in the pursuit of capturing and storing carbon.

At Mammoth, giant industrial fans suck up air then run it over a solid sorbent filter material. (Climeworks)

It’s a very big deal,” Erin Burns, executive director of the nonprofit Carbon180, said about the Mammoth plant’s unveiling. Just a few years ago, I think a lot of people wouldn’t have believed that this could’ve happened, and that it could’ve happened as quickly as it did.”

Jan Wurzbacher, co-founder and co-CEO of Climeworks, said the Mammoth opening is another proof point in Climeworks’ scale-up journey.”

Going forward, the company aims to build DAC plants that can remove 1 million metric tons of CO2 per year — nearly 30 times the capacity of Mammoth — potentially starting with Project Cypress in southwest Louisiana. Climeworks and its partners Heirloom and Batelle recently received an initial $50 million award from the U.S. Department of Energy to begin developing and permitting the project, which is eligible for up to $600 million in matched federal investment.

Scaling up in Iceland to export tech stateside

Climeworks, founded in 2009, is among the longest-standing players in the heady world of carbon dioxide removal.

Today, more than a thousand companies and research teams globally are pursuing novel ways to reverse carbon emissions, including injecting carbon-rich wastewater underground, burying bricks of dried-up biomass, and spreading crushed-up rocks over cropland.

Critics of carbon-removal solutions say they risk diverting scarce funding away from the far more urgent task of deploying clean energy and dramatically reducing emissions. At their worst, they worry, these projects could provide a smokescreen for oil and gas companies to keep extracting fossil fuels. Still, climate scientists say that at least some form of carbon removal will be needed in order to achieve net-zero emissions by 2050.

Direct air capture has been in development for decades, and 27 test, pilot, and commercial projects have been commissioned around the world. That includes Climeworks’ first DAC project in Hinwil, Switzerland, which captured up to 900 metric tons of CO2 per year but has since been phased out.

Yet DAC continues to be the most expensive carbon-removal solution. Because CO2 is so diluted in the atmosphere, DAC plants must use copious amounts of energy and novel materials to both absorb CO2 and then release it so that it can be permanently sequestered or used to make synthetic fuels or industrial products.

In 2023, Climeworks sold credits to JPMorgan Chase worth around $800 per ton of CO2 removal, as part of a $20 million, nine-year agreement with the global banking giant. That per-ton figure is about eight times more expensive than what the industry generally considers to be the benchmark for achieving economic viability.

Wurzbacher said it was too early to give a precise number for the per-ton cost of operating Mammoth at full capacity. On a ballpark level, we’re closer to the $1,000 per ton mark than we are to the $100 per ton mark,” he said on a Wednesday call with reporters. But future facilities using the company’s next generation of DAC technology are expected to approach $300 to $350 per ton of captured CO2 by 2030, he added.

The first 12 of Mammoth's 72 collector containers are now installed and operating. (Climeworks)

That’s because as Climeworks and other companies continue to expand and improve their technologies, the cost of developing and building new projects is expected to decline in step.

Douglas Chan, chief operations officer for Climeworks, said that’s been the case in Iceland. Between Orca and Mammoth, the company saw a 10 to 20 percent reduction in capital expenditures per ton of CO2 captured. It also slashed its operations and maintenance costs in half. (Even with the improvements, the plant cost on the order of low-triple-digit millions” to build, he said.)

To really drive down the cost of direct air capture, we really need to understand how they operate in the real world,” said Giana Amador, the executive director of Carbon Removal Alliance, an advocacy group. We’re at an inflection point, where we’re starting to see larger-scale projects [like Mammoth] that can give us some important information about what their potential to scale is.”

The Mammoth facility in Iceland is a great opportunity for Climeworks to test technology that they’ll then export to the U.S.,” she added, referring to Project Cypress in Louisiana.

Last August, the Biden administration named Project Cypress as one of the early winners in its $3.5 billion DAC hub” program, which was created in 2021 by the Bipartisan Infrastructure Law. Climeworks and its partners will design and operate a carbon-sucking machine capable of removing over 1 million metric tons of CO2 per year. The company Gulf Coast Sequestration will take the captured CO2 and permanently store it in a Class VI deep saline aquifer. The project is likely still a few years away from starting construction.

For carbon-removal proponents, the 36,000-ton Mammoth plant and even the much larger Project Cypress are still only the beginning. The world will eventually need to build DAC plants big enough to capture 1 billion metric tons of CO2 per year to have any meaningful impact on limiting global temperature rise, they say.

To reach that scale, the U.S. will need to adopt stronger federal policies that boost government support and accelerate private-sector investment in these new, risky, technologies, said Burns of Carbon180. The business models of today’s startups largely rely on voluntary commitments from private companies, like Climeworks’ deal with JPMorgan Chase and others.

The carbon-removal sector as a whole needs to keep our eye on the fact that voluntary compliance markets, while extremely helpful, are going to be totally insufficient to get us to gigaton scale, which is what we need to meet our climate goals,” she said.

Maria Gallucci is a senior reporter at Canary Media. She covers emerging clean energy technologies and efforts to electrify transportation and decarbonize heavy industry.