When it comes to carbon capture and storage, researchers have been getting creative by turning carbon dioxide into everything from carbon monoxide (CO) for the use in industrial processes to oxalic acid for processing rare earth elements. Now, it seems they are going back to its source, turning it into solid coal.
Back to carbon particles
In a world-first breakthrough, a research team led by RMIT University in Melbourne, Australia developed a technique that can convert CO2 back into particles of carbon, decreasing pollution by removing greenhouse gases from our environment.
The 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 have many technical and safety issues and are also very costly.
"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 Dr. Torben Daeneke, RMIT researcher and an Australian Research Council DECRA Fellow.
To date, CO2 has only been converted into a solid at extremely high temperatures, making it industrially unviable.
The novel technique is an electrochemical one. It consists 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."
Better yet, the researchers say 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," said lead author, Dr. Dorna Esrafilzadeh, a Vice-Chancellor's Research Fellow in RMIT's School of Engineering.
"The process also produces synthetic fuel as a by-product, which could also have industrial applications."
The study was published in the journal Nature Communications.