A visualisation of the team's design.Retrofitting direct air capture tech to trains to recover CO2 could help us get back on track in the fight against climate change, a study carried out at the University of Toronto has found.


The tech is already well established, but stationary, ground-based facilities require a lot of land. This has historically led to many residents in the areas near to proposed sites objecting to their construction, the researchers say.

“It’s a huge problem because most everybody wants to fix the climate crisis, but nobody wants to do it in their backyard,” said co-author Prof Geoffrey Ozin, director of the solar fuels group at the University of Toronto.

“Rail-based direct air capture cars would not require zoning or building permits and would be transient and generally unseen by the public.”

Direct air capture systems typically extract CO2 from the atmosphere via a series of chemical reactions that occur as air passes through them. This captured CO2 can then be stored in a liquid reservoir until it can be sequestered underground in porous rock formations.

The team’s proposed design could be fitted to existing trains and uses a large vent to take in air. This makes it much more efficient than the energy-intensive fan systems used in stationary facilities.

A visualisation of the team's design.
A visualisation of the team's design. © Joule/Bachman et al

According to their calculations, the researchers say that an average freight train fitted with their system could remove up to 6,000 tonnes of carbon dioxide per year – an amount comparable to that emitted by 250 medium-sized family cars over their lifespans.

It would also be significantly cheaper to operate than other currently available direct air capture systems and would require far less construction work than stationary facilities as the rail network is already in place, they say.

“The infrastructure exists,” said Ozin. “That's the bottom line. All you need to do is take advantage of what is already available.”

The research was published in the journal Joule.

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Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.