New humidity-driven membrane to help remove CO2 from air

New Delhi, July 19: An ambient-energy-driven membrane that efficiently removes carbon dioxide (CO2) out of the air has been developed by UK researchers, revealed a study on Friday.

While CO2 is the main contributor to climate change, as humans release about 40 billion tonnes into the atmosphere every year, separating the greenhouse gas from the air is very challenging due to its dilute concentration.

The study, published in the journal Nature Energy, explained that dilute separation processes are challenging due to the low concentration and high energy requirements.

The team, collaborating with several universities, utilised natural humidity differences to drive the membrane, overcoming energy and kinetic challenges.

“Direct air capture will be a key component of the energy system of the future,” said Dr. Greg Mutch, from the Royal Academy of Engineering.

“In our work, we demonstrate the first synthetic membrane capable of capturing carbon dioxide from the air and increasing its concentration without a traditional energy input like heat or pressure. I think a helpful analogy might be a water wheel on a flour mill. Whereas a mill uses the downhill transport of water to drive milling, we use it to pump carbon dioxide out of the air,” he added.

The team tested a new CO2-permeable membrane with a variety of humidity differences applied across it. When the humidity was higher on the output side of the membrane, the membrane spontaneously pumped CO2 into that output stream, the researchers said.

Further, using advanced techniques like X-ray micro-computed tomography, the membrane’s structure was precisely characterised, and density-functional-theory calculations identified unique carriers that transport both CO2 and water.

This innovative approach harnesses the energy from humidity differences to drive CO2 through the membrane from low to high concentrations.