Improving carbon capture

02 February 2019

POWER-STATION

Power stations are a major source of greenhouse gas emissions

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A new technique that makes the process of carbon capture 24% more energy-efficient, has been announced by scientists in the US...

Climate change is a reality that is already impacting our lives in many ways: we’re seeing melting ice caps, warming of the oceans, and the occurrence of extreme weather events more often. Carbon dioxide, or CO2, released by industry, vehicles and almost anything powered by fossil fuels such as oil, natural gas and coal is the main culprit.

And while some debate whether it is real or not, or who’s responsible for taking action, scientists are pursuing research that aims to achieve two things: reducing our emissions; and reverting some of the damage already done.

One way to reduce the damage is to scavenge back carbon dioxide that has either already been released or is about to be released into the atmosphere by ‘filtering’ emissions and extracting the gas. This is called carbon capture and it's this line that scientists from the Oak Ridge National Laboratory in Tennessee, USA, are taking.

The Oak Ridge team are using a molecule called bis-iminoguanidine, which was actually first documented by German scientists at the turn of the 20th century. Added to a liquid solution which contains CO2, the molecules dissolve and bind with the CO2 before solidifying and falling to the bottom of the liquid. This solid, with the CO2 sequestered inside, can be separated from the liquid and the scavenged CO2 is released from the powder by heating to 90 degrees Celsius. This regenerates the bis-iminoguanidine molecules, which can be re-used in the same way up to a hundred times.

The new research shows how using bis-iminoguanidine like this leads to a 24% improvement in the carbon capture process. “The new compounds are up to two times better than previous compounds in extracting the CO2 from solution, and the temperature needed for the process is almost 10 times lower,” says Neil Williams, lead author of the paper published in Chem. Moreover, since these compounds can be reused over and over again, there are even more savings of materials and costs.

Since costs are the main reason why carbon capture technology has been slow to catch on, the new results are encouraging. And although it is still in the early stages, the Oak Ridge National Laboratory team believe the process will eventually be used on a large scale.

“It is very important to remember that all of these technologies are little steps, but obviously going in the right direction in order to reduce the emissions of CO2 in the atmosphere,” adds University of Cambridge chemical engineer David Fairen-Jimenez.

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