The world’s largest carbon-capture plant just switched on

That makes the new plant nine times bigger than the previous record-holder, the Climeworks “Orca” plant, which opened in Iceland in 2021 — though still tiny given the millions of tons of carbon experts say the world will need to pull out of the air to limit warming to 2 degrees Celsius this century.

But Mammoth shows the industry is starting to grow beyond pilot plants and lab demonstrations. “It’s a drop in the bucket, but it’s a much bigger drop in the bucket than any we’ve seen so far,” said Klaus Lackner, who heads the Center for Negative Carbon Emissions at Arizona State University.

How Mammoth works

The Climeworks Mammoth plant is basically a giant air filter. Fans pull air through a series of filters designed to catch stray CO2 molecules, which make up a tiny share of air’s mass — just 0.04 percent. Then, another company called Carbfix mixes the CO2 with water and pumps it deep underground, where it reacts with basalt rock and turns into stone.

The entire process runs on Iceland’s plentiful geothermal energy, so powering the machines doesn’t produce more carbon emissions. Outside scientists confirmed that the Climeworks Orca project and an earlier pilot plant really do remove carbon while producing very few emissions in a 2021 analysis published in Nature.

Climeworks then sells offsets based on that captured carbon. It doesn’t publicly say how much it charges its big corporate customers, including Microsoft, Shopify and Stripe, for the service — but it offers regular people carbon removal subscriptions at a price of $1,500 per metric ton of carbon removed. More than 20,000 people have signed up, according to the company’s website.

“The only people purchasing Climeworks removals at this point are very wealthy individuals or very wealthy companies that are … paying a lot of money to bring down the costs of what they see as a potential future industry,” said Rudy Kahsar, manager of carbon dioxide removal at the clean energy think tank RMI.

“$100 is tolerable,” he said. “The world can manage and afford it. At $1,000, they cannot.”

Bigger than Mammoth

The record-breaking Mammoth plant may soon be dwarfed by much larger facilities set to open this decade. Next year, a subsidiary of the oil company Occidental Petroleum plans to open a plant in Texas capable of removing 500,000 metric tons of carbon per year — equivalent to emissions from 119,000 cars. Climeworks is designing another plant in Louisiana it says will capture 1 million tons of carbon annually by 2030. That’s 238,000 cars.

Experts say these early plants will play an important role in proving whether these machines work — and just how expensive and energy-hungry they will be.

“We need to show that these facilities can be done at a commercial scale so we can see that they work, that they’re [socially] accepted, that you can get financing for it,” said Kahsar. Mammoth “paves the way for other facilities to come behind it.”

Capturing carbon from the atmosphere remains controversial. Critics say the technology is an unrealistic distraction or an excuse to keep using fossil fuels. But a 2022 U.N. report concluded the world is so far behind on cutting greenhouse gas emissions that capturing at least some carbon is now “unavoidable” if humanity hopes to meet its climate goals.

“It’s not an excuse to do nothing,” said Eric Gimon, a senior fellow at the energy and climate policy think tank Energy Innovation. “We still need to be firing on all cylinders for everything else we need to do to decarbonize.”

Although solar panels, wind turbines, electric vehicles and other established green technologies can cut most of the world’s greenhouse emissions, U.N. climate scientists predict there will be some stubborn emissions remaining by 2050 in sectors like air travel, shipping and steelmaking.

To meet key climate targets, the world may need to directly capture as much as 600 million tons of CO2 per year, according to the International Energy Agency, or as little as 20 million tons of CO2 per year, according to a 2022 report from the U.N.’s Intergovernmental Panel on Climate Change. That report notes there hasn’t been much research on the potential impact of direct air capture, which makes it hard to predict how big a role the technology will play in fighting climate change.

But the report predicts some amount of carbon capture will be necessary to offset whatever emissions remain.

“If we get stuck, and there’s a last few percent [of emissions] that’s really hard to do … we’ve got a way to take care of it,” Gimon said.