Fire and coal

Scientists succeed in turning carbon dioxide back into coal

Image credit: Vasiliy Chernyshov |

A research team from RMIT University in Australia have harnessed liquid metals to turn carbon dioxide back into solid coal – a breakthrough that offers an alternative pathway for safely and permanently removing the greenhouse gas from our atmosphere.

Scientists from the Melbourne-based university developed a new technique using a liquid metal electrolysis method which efficiently converts CO2 from a gas into solid particles of carbon.

This solution offers a more viable approach than many of today’s carbon capture and storage systems that compress CO2 into a liquid form with the aim of injecting it underground.

These approaches, however, have many technical and safety issues and are also very costly. There are also environmental concerns about leaks from the storage sites.

RMIT researcher Dr Torben Daeneke, also an Australian Research Council DECRA Fellow, 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,” said Daeneke.

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

This novel technique created is an electrochemical one, consisting of a specially-designed liquid metal catalyst that sees carbon dioxide from gas slowly converted into solid flakes of carbon.

“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,” said Daeneke.

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

As well as Daeneke’s emphasis on the technique being a breakthrough for the storage of carbon, lead author, Dr Dorna Esrafilzadeh also added the carbon produced by the technique 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,” she said.

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

E&T recently explored six promising carbon reuse ideas currently under development.

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