Humans release more than 30 billion metric tons of carbon dioxide into the atmosphere each year, thanks largely to the burning of fossil fuels. This number has been rising steadily for more than 100 years. As the climate situation becomes increasingly dire, scientists, environmentalists, businesspeople and politicians have been seeking solutions. Many of these solutions involve lowering carbon emissions—using greener fuels, driving less. But a growing number of solutions are less about lowering emissions and more about capturing them. One power plant in Iceland has figured out how to turn carbon into stone. A California company claims to have technology to sequester carbon in cement. Other emerging methods involve trapping carbon underground or in water.

Now, a Canadian startup has its own idea: pull carbon dioxide from the air and turn it into useful commodities, such as fuel. The company, Carbon Engineering, was co-founded by Harvard physicist David Keith and is partially funded by Bill Gates.

Carbon Engineering recently launched a test factory in Squamish, British Columbia, to demonstrate the viability of so-called “air capture” technology. In the factory, air is pushed by large fans into a liquid solution high in carbon dioxide. This is then processed into purified carbon dioxide. Then clean air is released, and the liquid is recycled for another round of carbon dioxide purification. Unlike other carbon capture technologies, which capture carbon dioxide as it emerges from factories, air capture can remove carbon dioxide that’s already been emitted by cars, planes, agricultural equipment and other sources. Air capture, Carbon Engineering says, is like a more efficient version of what trees already do.

“If we can enable industrial-scale carbon dioxide capture from the air at a price that is at all viable or reasonable, than this technology provides yet another pathway to control those sources of emissions,” says Geoff Holmes, the business development manager of Carbon Engineering.

The new plant removes about a ton of carbon dioxide from the air each day. While this is not much—hardly enough to offset the carbon footprint of three dozen Canadians—the company says it is ready to scale up many thousands of times. But ironically, the demonstration factory currently releases the carbon it captures right back into the atmosphere. That’s because the other piece of the puzzle—figuring out what to do with all the captured carbon dioxide—has not been solved yet.

One of the most promising paths Carbon Engineering is pursing involves turning the carbon dioxide into fuel. This process involves splitting water into oxygen and hydrogen, and combining the hydrogen with the carbon dioxide to create hydrocarbon fuel. This technology exists, but has never been tried on a commercial scale.

“This is a concept that might one day be able to supply truly global-scale quantities of fuels that are compatible with our current infrastructure and are carbon neutral,” Holmes says.

Holmes estimates Carbon Engineering might be ready to bring fuel made from air-captured carbon dioxide to market in “several” years, at about $1 to $2 dollars per liter.

Holmes knows air capture is no panacea for climate change. At best, it would only remove a fraction of humanity’s carbon dioxide emissions from the air.

“We really think the world needs more tools, not less, to help reduce emissions,” he says. “Air capture can add to our set of options. We want to be a part of driving emissions to zero as fast as possible.”