“If these costs are real, it is an important result,” said Ken Caldeira, a senior scientist at the Carnegie Institution for Science. “This opens up the possibility that we could stabilize the climate for affordable amounts of money without changing the entire energy system or changing everyone’s behavior.”

The team published their results Thursday morning in Joule, a new American scientific journal printed by the same publisher behind the biology journal Cell.

“What we’ve done is build a [direct-air capture] process that is—as much as possible—built on existing processes and technologies that are widespread in the world,” said David Keith, a professor of applied physics at Harvard and the lead author of the new study. “That’s why we think we have a reasonable possibility of scaling up.”

Keith is also a founder and executive chairman of Carbon Engineering, a Bill Gates–funded company that has studied how to directly remove carbon dioxide from the atmosphere.

Carbon Engineering says the technique unveiled today has already been implemented at its small, pilot plant in Squamish, British Columbia. It is currently seeking funding to build an industrial-scale version of the plant, which Keith says it can complete by 2021.

Their technique, while chemically complicated, does not rely on unprecedented science. In effect, Keith and his colleagues have grafted a cooling tower onto a paper mill. It has three major steps.

First, outside air is sucked into the factory’s “contactors” and exposed to an alkaline liquid. These contactors resemble industrial cooling towers: They have large fans to inhale air from the outside world, and they’re lined with corrugated plastic structures that allow as much air as possible to come into contact with the liquid. In a cooling tower, the air is meant to cool the liquid; but in this design, the air is meant to come into contact with the strong base. “CO 2 is a weak acid, so it wants to be in the base,” said Keith.

Second, the now-watery liquid (containing carbon dioxide) is brought into the factory, where it undergoes a series of chemical reactions to separate the base from the acid. The liquid is frozen into solid pellets, slowly heated, and converted into a slurry. Again, these techniques have been borrowed from elsewhere in chemical industry: “Taking CO 2 out of a carbonate solution is what almost every paper mill in the world does,” Keith told me.

Finally, the carbon dioxide is combined with hydrogen and converted into liquid fuels, including gasoline, diesel, and jet fuel. This is in some ways the most conventional aspect of the process: Oil companies convert hydrocarbon gases into liquid fuels every day, using a set of chemical reactions called the Fischer-Tropsch process. But it’s key to Carbon Engineering’s business: It means the company can produce carbon-neutral hydrocarbons.