Earth’s climate is full of terrifying feedback loops: Decreased rainfall raises the risk of wildfires, which release yet more carbon dioxide. A warming Arctic could trigger the release of long-frozen methane, which would heat the planet even faster than carbon. A lesser-known climate feedback loop, though, is likely mere feet from where you’re sitting: the air conditioner. Use of the energy-intensive appliance causes emissions that contribute to higher global temperatures, which means we’re all using AC more, producing more emissions and more warming.

But what if we could weaponize air conditioning units to help pull carbon dioxide out of the atmosphere instead? According to a new paper in Nature Communications, it’s feasible. Using technology currently in development, AC units in skyscrapers and even your home could get turned into machines that not only capture CO 2 , but transform the stuff into a fuel for powering vehicles that are difficult to electrify, like cargo ships. The concept, called crowd oil, is still theoretical and faces many challenges. But in these desperate times, crowd oil might have a place in the fight to curb climate change.

The problem with air conditioners isn’t just that they suck up lots of energy but that they also emit heat. “When you run an air conditioning system, you don't get anything for nothing,” says materials chemist Geoffrey Ozin of the University of Toronto, coauthor on the new paper. “If you cool something, you heat something, and that heat goes into the cities.” Their use exacerbates the heat island effect of cities—lots of concrete soaks up lots of heat, which a city releases well after the sun sets.

To retrofit an air conditioner to capture CO 2 and turn it into fuel, you’d need a rather extensive overhaul of the components. Meaning, you wouldn’t just be able to ship a universal device for folks to bolt onto their units. First of all, you’d need to incorporate a filter that would absorb CO 2 and water from the air. You’d also need to include an electrolyzer to strip the oxygen molecule from H 2 O to get H 2 , which you’d then combine with CO 2 to get hydrocarbon fuels. “Everyone can have their own oil well, basically,” Ozin says.

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The researchers’ analysis found that the Frankfurt Fair Tower in Germany (chosen by lead author Roland Dittmeyer of the Karlsruhe Institute of Technology, by the way, because of its landmark status in the city’s skyline), with a total volume of about 200,000 cubic meters, could capture 1.5 metric tons of CO 2 per hour and produce up to 4,000 metric tons of fuel a year. By comparison, the first commercial “direct air capture” plant, built by Climeworks in Switzerland, captures 900 metric tons of CO 2 per year, about 10 times less, Dittmeyer says. An apartment building with five or six units could capture 0.5 kg of CO 2 an hour with this proposed system.

Theoretically, anywhere you have an air conditioner, you have a way to make synthetic fuel. “The important point is that you can convert the CO 2 into a liquid product onsite, and there are pilot-scale plants that can do that,” says Dittmeyer, who is working on one with colleagues that is able to produce 10 liters a day. They hope to multiply that output by a factor of 20 in the next two years.

For this process to be carbon neutral, though, all those souped-up air conditioners would need to be powered with renewables, because burning the synthetic fuel would also produce emissions. To address that problem, Dittmeyer proposes turning whole buildings into solar panels—placing them not just on rooftops but potentially coating facades and windows with ultrathin, largely transparent panels. “It's like a tree—the skyscraper or house you live in produces a chemical reaction,” Dittmeyer says. “It's like the glucose that a tree is producing.” That kind of building transformation won’t happen overnight, of course, a reminder that installing carbon scrubbers is only ever one piece of the solution.