MEI researchers find cleaner, greener way to remove CO2 from air
Researchers at the Melbourne Energy Institute have found a new approach to direct air capture that can run on zero emission renewable energy.
Meeting the targets of the Paris Agreement is now out of reach without technologies to actively remove carbon dioxide from the atmosphere, according to the latest report from the Intergovernmental Panel on Climate Change.
The catch is, most existing negative emission technologies, such as direct air capture, require a high energy input from non-renewable sources – potentially releasing even more greenhouse gas emissions into the atmosphere in the process.
Researchers at the Melbourne Energy Institute have found a prospective way to address this, through a new approach to direct air capture that can run on zero emission renewable energy.
The new approach makes use of engineered ‘nanocatalysts’ to capture carbon dioxide and regenerate at a lower temperature, paving the way for the use of renewable energy sources, such as solar hot water.
“This technology puts direct air capture into a different perspective. Without radical changes, it simplifies the process and makes a huge difference by using renewables,” says Associate Professor Kathryn Mumford, the Institute’s Program Leader for Hydrogen and Clean Fuels.
Mumford and Research Fellow Masood S. Alivand have been working on the technology since 2019. A provisional patent was filed in 2021, and the pair’s research findings were published this year in Nature Communications.
In typical direct air capture processes, carbon dioxide is extracted from air using either a solid adsorbent or liquid solvent. For solvent-based processes, after carbon dioxide is separated the liquid must be brought to a very high temperature to remove the captured carbon dioxide so that the solvent can be recycled and reused.
This boiling step in the process requires high energy input, making it impractical in most cases to use renewable energy sources such as solar.
Through the new approach, advanced “water-dispersible nanocatalysts” are added to the chemical solvent that can regenerate at a much lower temperature – at around 88 degrees Celsius compared to the usual 120-140 degrees.
“This lower operating temperature paves the way for hot water streams from green and renewable energy sources, such as solar hot water, or those already available in the processes, such as hot process water streams, thereby significantly reducing operating costs,” explains Alivand.
Additionally, only a small amount of the nanocatalyst is needed for the process to be effective – less catalyst, and less energy input means a huge reduction in cost.
The new technology is likely to be an attractive option for cement and fertiliser production companies, natural gas refineries, and high-emission industries in the power generation sector. It could also be a game-changer for remote areas like deserts, where renewable energy may be the only accessible source, Mumford says.
The research further contributes to Australia’s zero emission portfolio and its objectives to make direct air capture technologies economically feasible, and accelerate their massive-scale deployment to a capacity of 1-4 gigatonnes per year by 2050.
Prototyping is now underway with partners to trial direct air capture systems that use the nanocatalyst and are equipped with solar panels, enabling continuous operation powered by renewable energy.
For more information, please contact Associate Professor Kathryn Mumford, MEI Program Leader on Hydrogen and Clean Fuels (mumfordk@unimelb.edu.au) or Research Fellow Masood S. Alivand (m.sheikhalivand@unimelb.edu.au).