Researchers Discover Novel Method to Convert CO2 into Ethanol

Scientists with the Oak Ridge National Laboratory have come up with a relatively efficient way to convert CO2 into ethanol, but its viability or importance as a scaled-up technology is still uncertain.

Published Oct 19, 2016

On 28 September 2016, researchers at the federally funded Oak Ridge National Laboratory published a paper describing a novel way to convert CO2 into ethanol using carbon, copper, electricity, and nanoscale engineering. The story grew in internet popularity after Oak Ridge issued a press release on 12 October 2016 that began:

In a new twist to waste-to-fuel technology, scientists at the Department of Energy’s Oak Ridge National Laboratory have developed an electrochemical process that uses tiny spikes of carbon and copper to turn carbon dioxide, a greenhouse gas, into ethanol.

In broad terms, scientists found a way to turn atmospheric CO2 into ethanol (the alcohol we drink, but also an industrial product with myriad uses, including as a fuel source or fuel additive) in a way that does not use expensive or rare chemicals and can be performed under conditions that do not need a lot of energy to maintain.

SEM image of the catalyst, which is made of copper nanoparticles (seen as spheres) embedded in carbon nanospikes. Credit: Oak Ridge National Laboratory
SEM image of the catalyst, which is made of copper nanoparticles (seen as spheres) embedded in carbon nanospikes. Credit: Oak Ridge National Laboratory.

But the findings have led some readers on the Internet to hail this as the solution to two of Earth’s most pressing problems: climate change and energy production. An example of this argument can be found in a Business Insider article:

The discovery is a major breakthrough, considering the process turns carbon dioxide — one of the leading air pollutants contributing to climate change — into fuel, which in turn generates more CO2 that could be turned back into more fuel. (Burning a gallon of diesel fuel produces about 22 pounds of CO2.) If the technology becomes cost-efficient and widely available, it could provide a new carbon-neutral alternative to fossil fuel production.

The notion that the process would be carbon neutral is not necessarily accurate, however, as electricity (which could come from carbon or an alternative energy source) is required to convert the CO2 into ethanol, meaning that the process represents a net loss of energy. As the authors concede in the study itself, the technology as currently developed is likely not economically viable because of its high overpotential (which is the difference between the mathematically determined theoretical electrode voltages and the actual electrode voltages needed to drive the reaction at the desired rate in practice):

The overpotential (which might be lowered with the proper electrolyte, and by separating the hydrogen production to another catalyst) probably precludes economic viability for this catalyst ...

It should also be noted that the scientific mechanism behind the technology, as stated in the study, “has not yet been elucidated” and therefore has a long way to go before it could be scaled up.

While the technology stops short of creating a never-ending supply of carbon-neutral fuel, it does largely reduce the amount of energy it would take to convert CO2 into ethanol, and its development, given some refinements or future breakthroughs, could result in some exciting applications. One such application would be balancing energy supply from an intermittent energy source like solar energy, as described in an official press release from the Oak Ridge National Laboratory:

“A process like this would allow you to consume extra electricity when it’s available to make and store as ethanol,” [lead author Adam] Rondinone said. “This could help to balance a grid supplied by intermittent renewable sources.”

Alex Kasprak is an investigative journalist and science writer reporting on scientific misinformation, online fraud, and financial crime.