We Can Vacuum Carbon From the Sky. Will It Make a Difference?

Climeworks AG is on a mission to go big.

The Swiss direct air capture (DAC) company reached a milestone earlier this year, providing a certified carbon removal service to corporate clients — Microsoft, Spotify and Stripe — for the first time. The removal took place at its Orca plant, currently the largest DAC facility in the world, located roughly half an hour outside of Reykjavik. The carbon dioxide was then injected several hundred meters underground into nearby basaltic rock formations by partner Carbfix, where it will be permanently turned to stone. Next door, its big brother Mammoth is under construction. Mammoth will be nine times the size of Orca, eventually capturing 36,000 metric tons of carbon dioxide per year.

But Climeworks is already thinking about its next move. It’s considering putting in an application for the US’s DAC Hubs program, part of the Inflation Reduction Act. The program specifies that projects must be able to capture at least 50,000 tons per year to start, with the demonstrated potential to reach 1 million tons in the long term.

These are big numbers, but as Carlos Härtel, Climeworks’ chief technology officer, is the first to point out, they amount to a drop in the ocean compared to the scale of the problem. In 2022, the world pumped more than 40 billion tons of CO2 into the atmosphere.

Like other carbon removal technologies, DAC is no silver bullet, but it will be an important technology for cleaning up legacy emissions once we’ve managed to halt the flow of greenhouse gasses into the atmosphere. At the moment, there’s still a gap between what we’ll need and the capacity that’s currently in the pipeline. So as technologies attract more investment, scalability is on the carbon removal industry’s mind.

When it comes to DAC, a report from ratings agency BeZero Carbon cites the technology’s high energy needs as a “very significant” barrier to scaling. Härtel’s best guess for the long-term energy needs of DAC is no lower than two kilowatt hours per kilogram of CO2 — the equivalent of running two hairdryers for an hour to capture 1kg of carbon dioxide. Scaling that up to a gigaton gives you an energy requirement of somewhere around 5% of global renewable energy generation by 2050.

Ultimately, the power requirements will be significant, and DAC is only ever going to be able to draw down a modest amount of CO2 per year. That’s not to say scaling up the technology isn’t worth it, but when allocating efforts to decarbonizing, reducing emissions is much more important than removing them right now.

Besides, there will be other challenges to solve before energy needs become a significant problem.

Take the reliability of the technology itself. It works, but it will need to work better to meet future needs. That means figuring things out like how to bring the cost down, and other more fundamental things like how weather and climate affects the machinery. For example, high heat or humidity will reduce efficiency, meaning the plant captures less CO2 from the air. The Hellisheidi plateau in Iceland, where Climework’s facilities are located, is exposed and stormy, submitting machinery to harsh conditions — ice, snow, wind. In a warmer, drier environment, machines might have to deal with sandstorms instead. These things will only be improved by deployment in the field. The plants being built today are big learning opportunities.

Another issue for DAC is the market and financing. While there’s likely enough momentum and volume in the voluntary carbon market to fund the next decade or so, will there be enough people willing to fund a gigaton or more of annual carbon removals? Härtel says it needs government action including regulation. The current offset market — in which companies buy credits for avoided emissions rather than removed emissions — is rife with low-quality or even bogus credits. Solving that in the removals market will require strong universal measurement, reporting and verification (MRV) standards, among other things.

The final challenge is building a good supply chain to push the cost of the technology down. Right now, each DAC container system — the big boxes that remove and collect the CO2 from the air — is handcrafted. That makes sense for small, specialized batches (Orca has just eight collector containers, Mammoth will have 72), but it’s expensive. The industry will need a semi-automated manufacturing process to actually build the machinery if it wants to see DAC following the cost curves of wind and solar.

But supply chains are hesitant when the market opportunity is unclear and when people don’t know which technology to bet on. Härtel explains: “In five years, if we still have, for example, eight companies with eight different approaches all trying to get attention and gain traction, the supply chain will just stay put and do nothing.”

There’s currently a range of different processes within direct air capture. Costs will start coming down when the sector rallies around a method, in the same way that companies rallied around silicon for solar photovoltaic cells and lithium-ion for batteries.

A lot of pieces need to fall into place before DAC plants start asking for a lot more energy. In the meantime, there’s work to do. While policymakers can’t drop the ball on DAC, it’ll ultimately be worthless if we can’t slash emissions. As Härtel told me, “I can help you long term, I can’t help you today.”

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Lara Williams is a Bloomberg Opinion columnist covering climate change.

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