Researchers test new way to remove carbon dioxide from air

30 July, 2024

A new method to pump carbon dioxide out of the air has been put to the test by scientists from the UK and New Zealand

This story was first published on the VUW website - read the full story.

More than 35 billion tonnes of carbon dioxide (CO₂), the main contributor to climate change, are released into the atmosphere each year. Scientists investigating ways to "capture" some of this gas have landed on a new method that they believe could see CO₂ extracted from the air and potentially reused in carbon-neutral manufacturing processes.

Professor Patricia Hunt, from the School of Chemical and Physical Sciences at Te Herenga Waka Victoria University of Wellington, and a MacDiarmid Institute Associate Investigator, says extracting CO₂ from the air is a "challenging" puzzle to solve.

"Some CO₂ can be captured at source - for example, from the smokestacks of factories and power plants that burn fossil fuels. However, once CO₂ is in the atmosphere it's significantly harder to extract.

"The first problem is that air is mostly nitrogen and oxygen, and we need to select and then capture CO₂, which is only present in tiny amounts - about 0.04 percent. The next step is concentrating the CO₂, which requires significant energy," she says.

Professor Hunt and researchers from the UK hit upon an approach that doesn't require huge amounts of energy.

They developed and tested a CO₂-permeable synthetic membrane, a bit like a high-tech filter. The membrane system was designed to "hijack" the energy generated by differences in humidity between dry air on one side of the membrane and wet (humid) air - made wet by the introduction of water - on the other side, she explains.

In the lab, the researchers were able to exploit this energy to pump CO₂ out of the air, avoiding the need for an external energy source.

Results of the research, led by Professor Ian Metcalfe from Newcastle University, are published in Nature Energy.