From Coal to Coal

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Researchers have developed a new low energy and efficient process to convert CO2 from a gas into solid particles of carbon. In simple terms, they have found a way to turn carbon dioxide back into coal.

The research team led by RMIT University in Melbourne used liquid metals to turn carbon dioxide back into solid coal at room temperature, in a world-first breakthrough that could revolutionise carbon capture and storage. 

Published in the journal Nature Communications, the research offers an alternative pathway for safely and permanently removing the greenhouse gas from our atmosphere.

What makes this research especially significant is unlike other methods which usually require working at temperatures of hundreds of degrees Celsius making them energy-intensive and not commercially viable, the process is done at room temperature.

In addition, current technologies that focus on compressing CO2 into a liquid form and then injecting it underground have both economic and environmental drawbacks, notably possible leaks from storage sites.

RMIT researcher Dr Torben Daeneke said converting CO2 into a solid could be a more sustainable approach.

“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,” Dr Daeneke, an Australian Research Council DECRA Fellow, said.

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

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. Dr Esrafilzadeh said the carbon produced could also be used as an electrode.

“A side benefit of the process is that the carbon can hold 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.” 

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