The world's largest fans designed to suck carbon from the air are up and running in Iceland

• Climeworks' direct-air-capture plant can remove up to 36,000 metric tons of carbon from the air a year. 
• Carbon removal is becoming a key climate technology because the world isn't cutting emissions fast enough.
• The tech is still in its early stages and expensive, ranging from $600 to $1,000 per ton of carbon.

The startup Climeworks this week switched on the largest direct-air-capture plant, which pulls carbon dioxide from the sky and locks it away underground.

Climeworks said the plant, called Mammoth, has about 10 times the capacity of its first facility and could capture up to 36,000 metric tons of carbon emissions a year once it's completed.

That amount is a small fraction of the more than 40 billion metric tons estimated to have been emitted globally in 2023, but the opening of Mammoth in Iceland marks a milestone for a nascent technology that scientists say will be key to slowing the climate crisis.

Countries that signed the 2015 Paris Agreement said they would keep global temperatures from rising 1.5 degrees Celsius above preindustrial levels. A UN science panel has warned that the risk of catastrophic climate effects — including deadly heat waves, drought, famine, and infectious diseases — increases with each degree of warming.

Since then, planet-warming emissions have continued to rise. The Global Carbon Project estimated that these emissions reached record levels in 2023, mainly driven by burning fossil fuels like oil, gas, and coal for energy and transportation. European climate scientists on Wednesday said April was the hottest month on record, continuing an 11-month streak.

Countries and companies aren't slashing emissions fast enough, so technology like direct air capture is becoming more important.

But it's an expensive and uncertain pathway. Analysts estimate that for direct air capture to be widely adopted, the price of removing and storing 1 ton of carbon dioxide would have to fall to $100 by 2050. Today it ranges from $600 to $1,000. Climateworks' Mammoth plant also cost hundreds of millions of dollars to build, though the company didn't disclose the exact amount.

The company, which has big-name customers including Microsoft, Shopify, Swiss Re, Stripe, and JPMorgan Chase, said cost reduction was a priority. It added that while the Mammoth project wouldn't achieve that, it would help it innovate further and make the technology more efficient as it scales.

Climeworks aims to become large enough to remove 1 million metric tons of carbon a year by 2030 and 1 billion metric tons by 2050 — or a megaton and gigaton.

Climeworks' operations in Iceland are powered by renewable geothermal energy. In a press call, Jan Wurzbacher, a cofounder and co-CEO of Climeworks, described the process: Fans draw air through filters to separate out the carbon dioxide, which is then compressed with water and pushed underground into basalt rock formations. Within two years the mixture turns into rock and is stored away for millions of years. In early 2023, an independent third party verified that the process and its results were sound.

"There is more needed to scale up this industry," Wurzbacher said. "It's about offtake. It's about markets, standards, and regulations. And it's about public and private funding. A lot is needed in that area, and we need to move forward quickly to reach our targets."

Wurzbacher said Climeworks had projects in the early stages of development in the US, Canada, Norway, Oman, and Kenya.

The US Department of Energy last year announced $1.2 billion in funding for direct-air-capture demonstration plants. Climeworks is involved in a project in Louisiana, while Occidental Petroleum was selected for a plant in West Texas. The two plants could remove more than 2 million metric tons of carbon dioxide from the air each year.