Researchers at RMIT have developed a new method for quickly converting carbon dioxide into solid carbon, which can be stored indefinitely or turned into useful materials. The technology works by bubbling CO2 up through a tube of liquid metal, and it’s designed to be easy to integrate into the source of emissions.
Reducing carbon dioxide emissions is crucial for the future of the planet, and a major part of that may involve finding ways to capture it at the point of emission. Current methods in development include filtering the gas through absorbent materials like magnetic sponges, bubble-like membranes, zeolite foam, or materials made of clay or coffee grounds.
The RMIT team’s new system uses liquid metal, specifically an alloy called Eutectic Gallium-Indium (EGaIn), which is heated to between 100 and 120 °C (212 and 248 °F). Then, carbon dioxide is injected into the mix, and as the bubbles rise, the CO2 molecules split into flakes of solid carbon. These float to the top, making it easy to collect the material.
The team says that the design of the system should be relatively easy to scale up and implement at the point of emission. The reaction occurs quickly and efficiently, and the heat required is also relatively low, and could be supplied by renewable sources. All of these are improvements on the team’s earlier work, which required more hands-on steps.
But perhaps the biggest advantage is that the end result is solid carbon. Many other forms of carbon capture keep it as gaseous CO2, which can be trickier to store and transport, and prone to leak back into the air. Even attempts to stash it underground, where it can turn back into solid rock within a few years, isn’t foolproof, with large proportions remaining in gas form, ready to belch back out if the seal is broken.
Solid carbon, on the other hand, is stable, and could be stored more or less indefinitely without risk of leakage. The team says this could be buried again, or, more promisingly, used for other industrial applications, such as making concrete.
The next steps for the team are to scale up the system to a modular prototype that’s about the size of a shipping container.
The research was published in the journal Energy & Environmental Science, and the team demonstrates the technique in the video below.
Source: RMIT
