Newcastle University researchers have made a breakthrough in the fight against climate change by developing a membrane that uses ambient energy to extract carbon dioxide (CO2) from the air. This innovative technology addresses the significant challenge of direct air capture (DAC), identified as one of the “Seven chemical separations to change the world.”
The Challenge of Direct Air Capture
Carbon dioxide is the primary driver of climate change, with approximately 40 billion tons released into the atmosphere annually. However, capturing CO2 directly from the air is notoriously difficult due to its low concentration of about 0.04%.
According to Prof Ian Metcalfe, the Royal Academy of Engineering Chair in Emerging Technologies at Newcastle University, “Dilute separation processes are the most challenging separations to perform.” The low concentration of CO2 makes the chemical reactions needed for its removal very slow, and concentrating it requires substantial energy.
Innovative Solution
In collaboration with colleagues from Victoria University of Wellington, Imperial College London, Oxford University, Strathclyde University, and UCL, Newcastle researchers have tackled these challenges with their new membrane process.
They harnessed naturally occurring humidity differences to drive the pumping of CO2 out of the air, overcoming the energy hurdle. The presence of water also sped up the transport of CO2 through the membrane, addressing the kinetic challenge.
Published in Nature Energy, the research highlights the first synthetic membrane capable of capturing CO2 from the air and increasing its concentration without traditional energy inputs like heat or pressure. Dr. Greg A. Mutch, a Royal Academy of Engineering Fellow at Newcastle University, explained, “Direct air capture will be a key component of the energy system of the future, essential for capturing emissions from sources that cannot be easily decarbonized.”
The Importance of Separation Processes
Separation processes are integral to modern life, from food production to medicine and energy. They are also crucial for minimizing waste and environmental remediation, such as capturing CO2 directly from the air.
In a circular economy, these processes will become even more vital, potentially providing CO2 as a feedstock for making hydrocarbon products in a carbon-neutral or even carbon-negative cycle. DAC is essential for meeting climate targets, such as the 1.5 °C goal set by the Paris Agreement.
The Humidity-Driven Membrane
Dr. Evangelos Papaioannou, Senior Lecturer at Newcastle University, described how the team tested a new CO2-permeable membrane with varying humidity differences. When the humidity was higher on the output side, the membrane spontaneously pumped CO2 into that stream. Using advanced imaging techniques, the team precisely characterized the membrane’s structure, allowing robust performance comparisons with other state-of-the-art membranes.
Molecular-Scale Modeling
A critical aspect of the research was modeling the membrane processes at the molecular level. Using density-functional-theory calculations, the team identified carriers within the membrane that uniquely transport both CO2 and water. This interaction allows the energy from a humidity difference to drive CO2 through the membrane from a low to a higher concentration.
Prof Metcalfe emphasized the collaborative effort over several years, acknowledging the support from the Royal Academy of Engineering and the Engineering & Physical Sciences Research Council. This groundbreaking work represents a significant step forward in developing sustainable technologies to combat climate change.
Related Article: Rethinking The Tree Of Life: Viruses Became Our Genes
