That giant sucking sound may just be a climate solution

When I finally find the courage to tell my young daughter about the climate crisis, I’m half expecting to hear this innocent rejoinder: “If we’ve spewed all that carbon pollution into the air, can’t we just suck it back out again?”

It’s not a silly question. “Direct air capture” (DAC), an industrial process that removes carbon dioxide from ambient air so it can be locked away underground (or recycled into products such as synthetic fuels), sounds like science fiction. However, the technology to vacuum the skies clean already exists, it just hasn’t been fully industrialised. It’s a climate insurance policy we shouldn’t ignore.

I’m not talking here about traditional carbon capture and storage, which is the process of removing CO2 from a power plant or factory smokestack. A DAC plant filters ambient air. Hence it can be built anywhere there’s a surplus of low-carbon energy to run it.

Integrating DAC with nuclear power is one option. Another is using geothermal power, which is what the largest DAC facility yet constructed does. Built by a Swiss company called Climeworks AG, the Iceland plant has dozens of fans that suck air into a collector where the CO2 binds to a filter. After applying heat, the gas is dissolved in water and pumped underground, where it gradually turns into stone.

While impressive, the Climeworks’ facility will capture just 4,000 tons of CO2 a year, an amount that HSBC analysts note is equivalent to the pollution caused by just a few hundred cars. And the cost to remove a ton of carbon is about 10 times the equivalent cost of polluting in Europe’s carbon market.

It’s a challenging task. Though CO2 concentrations are far too high, the gas makes up just 0.04% of the air we breathe. Hence a DAC plant has to process about 2-million cubic metres of air just to extract one ton of CO2. Depending on the process used, it can require a 300MW power system to remove a million metric tons of carbon.

Carbon Engineering, a Canadian rival, is developing a 1-million-tons-a-year plant in the US Permian Basin, in partnership with Occidental Petroleum, and another in northeast Scotland, in conjunction with British firm Storegga. Storegga has attracted investment from M&G, Macquarie Group, GIC (Singapore’s sovereign wealth fund) and Mitsui & Co.

We’ll need to remove billions of tons of carbon yearly to reach climate neutrality and DAC can help reverse the damage we’ve done to the climate already. It is a more permanent and less land-intensive solution than simply planting a lot of trees, though of course we should do that too.

Even these are still several orders of magnitude too small to make a real dent in global emissions: we release about 39-billion tons of CO2 yearly. However, by starting small, the industry thinks it will learn how to construct much larger plants at lower cost. There’s no physical reason we “won’t be able to take a ton of CO2 out of the air for around $100 (about R1,500) in the next 10 to 20 years,” Jan Wurzbacher, co-CEO of Climeworks, told a DAC conference in September. 

Subsidies and grants helped solar, wind power and electric vehicle manufacturers to innovate and scale up, and they can do the same for DAC. To attract more institutional investors, verifiable carbon removals need to be integrated into emissions trading systems so more corporate and institutional investors are willing to pay for them. 

There’s been some progress on all these fronts. The bipartisan US infrastructure bill includes $3.5bn (about R54bn) for four DAC hubs, while the US budget reconciliation package includes higher tax credits for carbon capture. The UK has committed £100m (about R2bn) for DAC research and it’s considering how to include greenhouse gas removals in its emissions-trading system. 

Microsoft founder Bill Gates and Tesla’s Elon Musk don’t agree on much, but both are writing large cheques to support carbon removal. United Airlines, Stripe and Shopify are among companies paying to sequester carbon this way, as is the band Coldplay for its next world tour.

S​​​ome environmentalists fear carbon removal will distract from the important task of eradicating fossil fuel use; they note there are many other cheaper methods to lower emissions. They are wary that several oil companies are investing in the technology and at least one wants to use captured CO2 to extract yet more oil.  

DAC isn’t a silver bullet. Think of it as a “safety valve” or “backstop” that complements the other important actions we must take, Julio Friedmann, a senior research scholar at Columbia University’s Center on Global Energy Policy says. 

Even if the energy transition is swift and successful, there will be some sectors, such as airlines, where emissions will be difficult to fully eradicate, in part because they can’t be captured at source. We’ll need to remove billions of tons of carbon yearly to reach climate neutrality and DAC can help reverse the damage we’ve done to the climate already. It is a more permanent and less land-intensive solution than simply planting a lot of trees, though of course we should do that too.

So when my daughter asks if we can suck carbon out of the air, I’ll answer: Yes, we can. With the caveat there’s still a lot of work to do, it will cost a lot and we don’t have much time.

Chris Bryant is a Bloomberg Opinion columnist covering industrial companies. He previously worked for the Financial Times.

— Bloomberg Opinion. More stories like this are available on bloomberg.com/opinion