A machine that farms the sky

In British Columbia, there’s a little valley where the Squamish River snakes down past the cliffs of the Malamute, a popular hiking spot. The hills in all directions are, like much of BC, thickly forested with firs. And nestled in that valley is a newfangled industrial plant that aims to replicate what those millions of trees do: suck carbon dioxide out of the air.

The plant was built by Carbon Engineering, a pioneer in the technology known as direct air capture (DAC). In a long, squat building, a huge ceiling fan draws air inside, where it reacts with a liquid chemical that grabs hold of CO₂ molecules. This “sorbent” flows into a nearby machine that transforms the gas, which is then stored in pressurized tanks. The goal is to help rid the atmosphere of its most ubiquitous climate change culprit. The Squamish plant will process up to 1,000 metric tons of CO2 annually. That’s a minuscule drop in the bucket of the planet’s annual emissions, an estimated 33 billion metric tons last year, but this plant is only a pilot facility.

If the process can be scaled up massively, what might happen to all the captured CO₂? There are several possibilities, CEO Steve Oldham explains. You could, for example, sell some of it to companies like soda makers or concrete manufacturers. You could also convert it into liquid fuel to burn in cars, trucks, planes, and power plants. That would release still more CO₂, but in Oldham’s vision, which involves a vast network of his company’s machines, you would simply run that pollution right back through the process. You could do it over and over, he says, allowing a society to burn fossil fuels in perpetuity without adding to global warming. Call it catch-and-release. Oldham thinks we should all hop on board with this mode of carbon recycling: “We can’t wait. We have to get on with decarbonizing now.”

Of course, governments around the world could go much further than catch-and-release. They could flat-out try to reverse climate change by using direct air capture to grab surplus atmospheric carbon and bury it deep in the Earth—rewinding the Industrial Revolution. Ridding the atmosphere of the billions of tons of so-called legacy carbon we’ve emitted over the past 150 years wouldn’t come cheap. At current prices, nations would have to shell out, collectively, about $5 trillion a year for the rest of the century. But a dire report in August from the UN Intergovernmental Panel on Climate Change (IPCC) warned that our climate situation could decline so rapidly that we are left with little choice. Policymakers may well decide that removing all that legacy carbon is worth the cost, Oldham argues. “I personally like the analogy of water treatment,” he says. “When water was a problem with cholera and typhoid, governments worldwide built a water treatment infrastructure. It’s part of what they provide to their citizens. Today we have an air problem, so we need an air-treatment infrastructure.”

Solving climate change with CO₂-sucking machines? It sounds, at first, like something from a Neal Stephenson sci-fi novel—or a particularly delirious Silicon Valley TED Talk. And for years, indeed, DAC resided in mad-scientist territory. Only a handful of startups worldwide were fiddling with prototypes, and few serious investors were paying attention.

That all changed in 2018, with the release of an earlier IPCC report. The panel warned that if we wanted to keep the planet from warming by more than 1.5 degrees Celsius—the goal of the Paris agreement on mitigating climate change—we’d need to slash atmospheric CO₂ dramatically. Planting forests would help. Shifting to renewables would be crucial, too. But given humanity’s plodding embrace of wind and solar, the IPCC figured we’d have to start pulling carbon directly out of the atmosphere by 2100. A lot of carbon. Ten billion metric tons per year, equal to nearly a third of our current CO₂ output.

Direct air capture, along with other capture and sequestration schemes—from planting trees to figuring out how to make marine organisms lock up surplus carbon—was suddenly hot, perhaps