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Freight Trains With Carbon Capture Cars? Researchers Say It Could Work

Specially adapted cars could be roaming carbon cleaning machines, researchers say.

There’s no one way that we’re going to fight climate change, it’s going to take a bunch of stuff. From changing the types of cars we drive to looking at the materials we use and the way they’re made and meaningfully protecting what we haven’t already ruined, there’s no silver bullet or a single thing that solves it. So getting creative about what we can do to help is important.

This is why I bring you the following: Trains that huff carbon out of the air. Direct air capture of carbon is kind of the dream, in the sense that the most obvious way to deal with there being too much CO2 in the air is to, well, take it out. Carbon sequestration (making it into blocks or pellets and getting it back into the ground, not the atmosphere) does work but the problem is capturing CO2 out of the air is really energy intensive.

Energy has to come from somewhere and a lot of the time that’s a fossil fuel source or carbon capture has to only take place at a limited site that has access to renewables when ideally you’d be moving the capture devices around. Say, on a train.

A rendered image of the proposed carriage, showing it as part of a train, with air flowing through the direct capture device as the train moves

Big freight trains cover a lot of ground, displacing a lot of air and creating a lot of energy during braking events. That’s why scientists have proposed that trains might be the perfect place to put carbon capture devices.

The idea is that the movement of the train replaces the need to pump air through the devices, by having it naturally flow in. That’s a big energy saving compared to having to force air through, as a start. Then the specially created carriages will use solar panels and batteries that store energy recovered from the train’s brakes to run the chemical and mechanical devices that filter CO2 out of the air, turn it into a liquid, and store it in tanks ready to be pumped out and disposed of when the train stops.

Efficiency is essential for it to work and the researchers say that, at scale, it would run at about 93%, as a process. So for every 100 molecules of CO2 captured out of the air, only seven would have been put out. For direct air capture, that’s pretty incredible and it could be a genuine game changer in climate solutions if it was rolled out on a global scale.

The IPCC, which does plenty of climate reporting, says we need to take 1,000 gigatons of CO2 out of the atmosphere in the next 78 years in order to stop the earth from getting hotter than it should be. That’s a big demand, so if the scientists are right these trains could make a meaningful contribution. Their numbers say that the cars could be capturing 0.45 gigatons by 2030, 2.9 gigatons by 2050, and 7.8 gigatons by 2075.

Every car, they say, could capture up to 3,306 tons of CO2 per year. Of course, this is a theoretical technology right now but it’s proposing using things we know work already; direct air capture is real, just not very efficient, regenerative braking and solar power are technologies we already use in our cars and homes. So, although this isn’t happening yet it is a pretty cool idea of a way we could make a meaningful difference.

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