Catalytic Combo Converts CO2 to Solid Carbon Nanofibers [View all]

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https://www.bnl.gov/newsroom/news.php?a=121635

Catalytic Combo Converts CO₂ to Solid Carbon Nanofibers
Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material
January 11, 2024

UPTON, NY—Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Columbia University have developed a way to convert carbon dioxide (CO₂ ), a potent greenhouse gas, into carbon nanofibers, materials with a wide range of unique properties and many potential long-term uses. Their strategy uses tandem electrochemical and thermochemical reactions run at relatively low temperatures and ambient pressure. As the scientists describe in the journal Nature Catalysis, this approach could successfully lock carbon away in a useful solid form to offset or even achieve negative carbon emissions.

“You can put the carbon nanofibers into cement to strengthen the cement,” said Jingguang Chen, a professor of chemical engineering at Columbia with a joint appointment at Brookhaven Lab who led the research. “That would lock the carbon away in concrete for at least 50 years, potentially longer. By then, the world should be shifted to primarily renewable energy sources that don’t emit carbon.”

As a bonus, the process also produces hydrogen gas (H₂ ), a promising alternative fuel that, when used, creates zero emissions.

Capturing or converting carbon
The idea of capturing CO₂ or converting it to other materials to combat climate change is not new. But simply storing CO₂ gas can lead to leaks. And many CO₂ conversions produce carbon-based chemicals or fuels that are used right away, which releases CO₂ right back into the atmosphere.

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Here’s the thing I keep coming back to. Coal is essentially a large quantity of pure carbon with some impurities. We burn/burned it producing CO₂ and energy. So, this technology essentially reverses the process, taking CO₂ and converting it back to carbon. Now, how much energy does that take? (Presumably at least as much energy as we got from burning the coal, which we used extremely inefficiently.)

So, to reverse things on a grand scale, say, convert 120ppm of CO₂ to carbon nanofibers would require, let’s call it 3 times the amount of useful energy that we produced by burning it in the first place. On the other hand, pumping CO₂ into basalt does not have to pay back that chemical energy debt.