Two scientists at Los Alamos National Laboratory say people will still be driving gasoline-powered cars 50 years from now, churning out heat-trapping carbon dioxide into the atmosphere; and yet that carbon dioxide will not contribute to global warming.

The scientists, F Jeffrey Martin and William L Kubic Jr, are proposing a concept for removing carbon dioxide from the air and turning it back into gasoline.

The idea is simple: air would be blown over a liquid solution of potassium carbonate, which would absorb the carbon dioxide. The carbon dioxide would then be extracted and subjected to chemical reactions that would turn it into fuel: methanol, gasoline or jet fuel.

This process could transform carbon dioxide from an unwanted, climate-changing pollutant into a vast resource for renewable fuels. The closed cycle—equal amounts of carbon dioxide emitted and removed—would mean that cars, trucks and airplanes using the synthetic fuels would no longer be contributing to global warming.

Although they have not yet built a synthetic fuel factory, or even a small prototype, the scientists say it is all based on existing technology.

“Everything in the concept has been built, is operating or has a close cousin that is operating,” Dr Martin said.

There is, however, a major caveat that explains why no one has built a carbon-dioxide-to-gasoline factory: it requires a great deal of energy.

According to their analysis, their concept, which would cost about US$5 billion to build, could produce gasoline at an operating cost of US$1.40 a gallon and would turn economically viable when the price at the pump hits US$4.60 a gallon, taking into account construction costs and other expenses in getting the gas to the consumer. With some additional technological advances, the break-even price would drop to US$3.40 a gallon, they said.