Environment Science & Technology

Carbon Capture: Turning Carbon Dioxide back into coal

Researchers have developed a new method of carbon conversion using liquid metals to turn carbon dioxide back into coal.
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Researchers have developed a new method of carbon capture using liquid metals to turn carbon dioxide back into coal. The breakthrough could revolutionise carbon-capture and storage. 

The team of researchers led by RMIT University, Melbourne, have developed a revolutionary new technique that can efficiently convert CO2 from a gas to solid particles of carbon. 

The research — published in Nature communications — offers the potential for a safe way to permanently remove greenhouse gas from the atmosphere. 

Current technologies for carbon capture and storage focus on compressing CO2 into a liquid, which is then injected underground. The implementation of this method has been restricted by engineering challenges, economic viability and environmental concerns regarding leakage. 

(RMIT University)

Dr Torben Daeneke — Australian Research Council DECRA Fellow — believes that converting CO2 to a solid could be a more sustainable alternative: “While we can’t literally turn back time, turning carbon dioxide back into coal and burying it back in the ground is a bit like rewinding the emissions clock.

“To date, CO2 has only been converted into a solid at extremely high temperatures, making it industrially unviable.

Daeneke continues: “By using liquid metals as a catalyst, we’ve shown it’s possible to turn the gas back into carbon at room temperature, in a process that’s efficient and scalable.

“While more research needs to be done, it’s a crucial first step to delivering solid storage of carbon.”

The method behind carbon capture and conversion

Lead author, Dr Dorna Esrafilzadeh, a Vice-Chancellor’s Research Fellow in RMIT’s School of Engineering, developed the electrochemical technique to capture and convert atmospheric CO2 to storable solid carbon.

A schematic illustration showing how liquid metal is used as a catalyst for converting carbon dioxide into solid coal ( RMIT University)

To convert CO2, the researchers designed a liquid metal catalyst with specific surface properties that made it extremely efficient at conducting electricity while chemically activating the surface.

The carbon dioxide is dissolved in a beaker filled with an electrolyte liquid and a small amount of the liquid metal, which is then charged with an electrical current.

The CO2 slowly converts into solid flakes of carbon, which are naturally detached from the liquid metal surface, allowing the continuous production of carbonaceous solid.

Esrafilzadeh says the carbon produced could also be used as an electrode: “A side benefit of the process is that the carbon can hold an electrical charge, becoming a supercapacitor, so it could potentially be used as a component in future vehicles.

“The process also produces synthetic fuel as a by-product, which could also have industrial applications.”

Australian Research Council DECRA Fellow Dr. Torben Daeneke and Vice-Chancellor’s Research Fellow Dorna Esrafilzadeh, RMIT University ( RMIT University)

The research was conducted at RMIT’s MicroNano Research Facility and the RMIT Microscopy and Microanalysis Facility, with lead investigator, Honorary RMIT and ARC Laureate Fellow, Professor Kourosh Kalantar-Zadeh (now UNSW).


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