When we burn fuels like petroleum during combustion to power our cars, we produce carbon dioxide as a waste product that is released into the atmosphere. But what if we could reverse the process, and turn that carbon dioxide back into the fuel we need?
That’s what one team is proposing. Published in PNAS, researchers from the University of Texas at Arlington claim to have shown that concentrated light, heat, and high pressures can convert carbon dioxide and water into usable liquid hydrocarbon fuels, such as petroleum, diesel, and kerosene.
Using these fuels would of course return the carbon dioxide to the atmosphere – but the team says its method could lead to a “carbon-neutral fuel cycle,” where we don’t add any more into the atmosphere. It’s a bit of a leap, sure. But it’s an interesting idea nonetheless.
“We are the first to use both light and heat to synthesize liquid hydrocarbons in a single stage reactor from carbon dioxide and water,” said Brian Dennis, co-principal investigator of the project, in a statement.
To demonstrate that their proposal works, the team used a reactor operating at 180 to 200°C (350 to 390°F), and a pressure of 1 to 6 atmospheres (1 atmosphere is the atmospheric pressure at sea level), with a catalyst composed of a mixture of cobalt and titanium dioxide. This converted carbon dioxide and water into liquid hydrocarbons and oxygen at various yields, although there were a lot of waste by-products. The team noted that in their best run, they could produce 13 percent useful hydrocarbons, such as octane (used in petroleum).
The team behind the research, from left to right: Mohammad Fakrul Islam, Frederick MacDonnell, Wilaiwan Chanmanee, and Brian Dennis. Credit: UTA
But the big idea is to use sunlight, rather than a reactor, to provide the heat and energy needed for the reaction to take place. The team suggests this could be achieved using parabolic mirrors, leading to a solar-powered reverse combustion system.
Clearly there is still a way to go with this method. But if it can be improved, it could allow access to “drop-in replacements for existing liquid hydrocarbon fuels,” said the researchers. “[This] would revolutionize how solar fuel replacements for gasoline, jet, and diesel solar fuels could be produced and could lead to a carbon-neutral fuel cycle,” they added in their paper.
One way the team hopes to improve its method is to use a better catalyst; at the moment, its titanium dioxide-based catalyst, in the form of a white powder, cannot absorb the entire visible light spectrum, and thus is not best suited to make use of sunlight.
In an age of more and more renewable technologies, though, it might be somewhat difficult to convince people that producing new fossil fuels to burn is a good idea. And unless the entire world agreed to the switch in fuel production, the net effect would likely still be an increase in global carbon dioxide levels.
But who knows. Maybe there’s something here.