My watch list
my.chemeurope.com  
Login  

New route to carbon-neutral fuels from carbon dioxide discovered

18-Sep-2019

Cube3D

Artistic representation of a nickel-based electrode as a broken down fuel pump and of a cerium-based electrode as a new, productive pump.

If the idea of flying on battery-powered commercial jets makes you nervous, you can relax a little. Researchers have discovered a practical starting point for converting carbon dioxide into sustainable liquid fuels, including fuels for heavier modes of transportation that may prove very difficult to electrify, like airplanes, ships and freight trains.

Carbon-neutral re-use of CO2 has emerged as an alternative to burying the greenhouse gas underground. In a new study published in Nature Energy, researchers from Stanford University and the Technical University of Denmark (DTU) show how electricity and an Earth-abundant catalyst can convert CO2 into energy-rich carbon monoxide (CO) better than conventional methods. The catalyst - cerium oxide - is much more resistant to breaking down. Stripping oxygen from CO2 to make CO gas is the first step in turning CO2 into nearly any liquid fuel and other products, like synthetic gas and plastics. The addition of hydrogen to CO can produce fuels like synthetic diesel and the equivalent of jet fuel. The team envisions using renewable power to make the CO and for subsequent conversions, which would result in carbon-neutral products.

"We showed we can use electricity to reduce CO2 into CO with 100 percent selectivity and without producing the undesired byproduct of solid carbon," said William Chueh, an associate professor of materials science and engineering at Stanford, one of three senior authors of the paper.

Chueh, aware of DTU's research in this area, invited Christopher Graves, associate professor in DTU's Energy Conversion & Storage Department, and Theis Skafte, a DTU doctoral candidate at the time, to come to Stanford and work on the technology together.

"We had been working on high-temperature CO2 electrolysis for years, but the collaboration with Stanford was the key to this breakthrough," said Skafte, lead author of the study, who is now a postdoctoral researcher at DTU. "We achieved something we couldn't have separately - both fundamental understanding and practical demonstration of a more robust material."

Barriers to conversion

One advantage sustainable liquid fuels could have over the electrification of transportation is that they could use the existing gasoline and diesel infrastructure, like engines, pipelines and gas stations. Additionally, the barriers to electrifying airplanes and ships - long distance travel and the high weight of batteries - would not be problems for energy-dense, carbon-neutral fuels.

Although plants reduce CO2 to carbon-rich sugars naturally, an artificial electrochemical route to CO has yet to be widely commercialized. Among the problems: Devices use too much electricity, convert a low percentage of CO2 molecules, or produce pure carbon that destroys the device. Researchers in the new study first examined how different devices succeeded and failed in CO2 electrolysis.

With insights gained, the researchers built two cells for CO2 conversion testing: one with cerium oxide and the other with conventional nickel-based catalysts. The ceria electrode remained stable, while carbon deposits damaged the nickel electrode, significantly shortening the catalyst's lifetime.

"This remarkable capability of ceria has major implications for the practical lifetime of CO2 electrolyzer devices," said DTU's Graves, a senior author of the study and visiting scholar at Stanford at the time. "Replacing the current nickel electrode with our new ceria electrode in the next generation electrolyzer would improve device lifetime."

Road to commercialization

Eliminating early cell death could significantly lower the cost of commercial CO production. The suppression of carbon buildup also allows the new type of device to convert more of the CO2 to CO, which is limited to well below 50 percent CO product concentration in today's cells. This could also reduce production costs.

"The carbon-suppression mechanism on ceria is based on trapping the carbon in stable oxidized form. We were able to explain this behavior with computational models of CO2 reduction at elevated temperature, which was then confirmed with X-ray photoelectron spectroscopy of the cell in operation," said Michal Bajdich, a senior author of the paper and an associate staff scientist at the SUNCAT Center for Interface Science & Catalysis, a partnership between the SLAC National Accelerator Laboratory and Stanford's School of Engineering.

The high cost of capturing CO2 has been a barrier to sequestering it underground on a large scale, and that high cost could be a barrier to using CO2 to make more sustainable fuels and chemicals. However, the market value of those products combined with payments for avoiding the carbon emissions could help technologies that use CO2 overcome the cost hurdle more quickly.

The researchers hope that their initial work on revealing the mechanisms in CO2 electrolysis devices by spectroscopy and modeling will help others in tuning the surface properties of ceria and other oxides to further improve CO2 electrolysis.

Facts, background information, dossiers
More about Stanford University
  • News

    Tiny light detectors work like gecko ears

    Geckos and many other animals have heads that are too small to triangulate the location of noises the way we do, with widely spaced ears. Instead, they have a tiny tunnel through their heads that measures the way incoming sound waves bounce around to figure out which direction they came fro ... more

    Efficient electrochemical cells for CO2 conversion

    Scientists at Stanford University have developed electrochemical cells that convert carbon monoxide (CO) derived from CO2 into commercially viable compounds more effectively and efficiently than existing technologies. Their research provides a new strategy for capturing CO2 and converting i ... more

    A new way of generating ultra-short bursts of light

    Although critical for varied applications, such as cutting and welding, surgery and transmitting bits through optical fiber, lasers have some limitations - namely, they only produce light in limited wavelength ranges. Now, researchers from the Ginzton Lab at Stanford University have modifie ... more

  • Videos

    Stanford researchers send text messages using chemicals

    Researchers have built a machine that texts sends messages using common chemicals. This system could be used in nanoparticle communication or to send secret notes. more

    Pop science: Stanford engineers stop soap bubbles from swirling

    The spinning rainbow surface of a soap bubble is more than mesmerizing – it’s a lesson in fluid mechanics. Better understanding of these hypnotic flows could bring improvements in many areas, from longer lasting beer foam to life-saving lung treatments. more

    America’s Nuclear Waste – No Solution in Sight

    America’s nuclear waste is accumulating at over seventy sites in 39 states – but there is no clear way forward for its final disposal.An international cast of experts explains how the U.S. nuclear waste program arrived at gridlock – and suggest some steps that may be taken to move the progr ... more

More about Technical University of Denmark
  • News

    Double graphene sandwich provides protection against corrosion

    ”Normally it’s not a huge success that not a damn thing has happened after 120 days.” These words belong to Professor Peter Bøggild after a four-month period where a novel type of anticorrosion coating was tested. The nanomaterial graphene plays a crucial role in this new type of coating. F ... more

    Squeeze to remove heat

    Move over, vapor compression cooling technology. Emerging "elastocaloric" refrigeration is potentially much more efficient and, unlike vapor compression, relies on environmentally-friendly refrigerants. In elastocaloric materials a change in mechanical stress can create a change in temperat ... more

    Chemist develops X-ray vision for quality assurance

    It is seldom sufficient to read the declaration of contents if you need to know precisely what substances a product contains. In fact, to do this you need to be a highly skilled chemist or to have genuine X-ray vision so that you can look directly into the molecular structure of the various ... more

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE