Reducing emissions and removing greenhouse gases from the atmosphere are both crucial for achieving net-zero emissions and addressing climate change. It’s essential to develop improved sorbents for capturing carbon dioxide from the air, a process known as direct air capture.
Direct air capture using sponge-like materials to remove carbon dioxide from the atmosphere is one potential approach for carbon capture. However, current approaches are expensive, require high temperatures and the use of natural gas, and lack stability.
The University of Cambridge research team has recently developed an energy-efficient method for creating materials that can capture carbon dioxide directly from the air. The team used a low-cost approach similar to charging a battery to charge activated charcoal, commonly found in household water filters. This innovation shows great promise in overcoming the limitations of current technologies.
The researchers discovered that by charging the charcoal ‘sponge’ with ions that form reversible bonds with CO2, the material could effectively capture CO2 directly from the air. This innovative approach may offer a more energy-efficient method for capturing and storing CO2, as it requires significantly lower temperatures for CO2 release compared to current carbon capture methods.
“Capturing carbon emissions from the atmosphere is a last resort, but given the scale of the climate emergency, it’s something we need to investigate,” said Dr. Alexander Forse from the Yusuf Hamied Department of Chemistry, who led the research. “The first and most urgent thing we’ve got to do is reduce carbon emissions worldwide, but greenhouse gas removal is also thought to be necessary to achieve net zero emissions and limit the worst effects of climate change. Realistically, we’ve got to do everything we can.”
Activated charcoal is being investigated for its potential to capture and hold CO2 from the air. Researchers have found that charging activated charcoal with chemical compounds called hydroxides makes it suitable for carbon capture.
The charging process involves accumulating hydroxide ions in the pores of the charcoal, allowing it to effectively capture CO2 directly from the air.
The process of collecting CO2 from charcoal for purification and storage involves heating the material to break the hydroxide-CO2 bonds. Unlike traditional methods that require temperatures as high as 900°C using natural gas, the charged charcoal sponges developed by the Cambridge team only need heating to 90-100°C, which can be achieved using renewable electricity. This is made possible through resistive heating, resulting in a faster and less energy-intensive process.
While the materials have limitations, the researchers are actively working to increase the quantity of carbon dioxide that can be captured. They are optimistic that this approach could have implications beyond carbon capture, as the charcoal pores and inserted ions can be tailored to capture a variety of molecules.
“This approach was a kind of crazy idea we came up with during the Covid-19 lockdowns, so it’s always exciting when these ideas actually work,” said Forse. “This approach opens a door to making all kinds of materials for different applications, in a way that’s simple and energy-efficient.”
Journal reference:
- Huaiguang Li, Mary E. Zick, Teedhat Trisukhon, Matteo Signorile, Xinyu Liu, Helen Eastmond, Shivani Sharma, Tristan L. Spreng, Jack Taylor, Jamie W. Gittins, Cavan Farrow, S. Alexandra Lim, Valentina Crocellà, Phillip J. Milner & Alexander C. Forse. Capturing carbon dioxide from air with charged-sorbents. Nature, 2024; DOI: 10.1038/s41586-024-07449-2