We have a new ally to eliminate CO2: train cars converted into rolling tanks capable of "hunting" it

kilometers of railway lines. And that's counting only those managed directly by Adif. Throughout such a network, more than twice the distance that separates Kansas and Madrid, thousands of trains loaded with goods and passengers circulate every year, a flow so intense that we have learned to see it as something routine.

But… What if those trains were used for something more than moving people or containers? What if they helped us reduce our environmental footprint and combat climate change ?
It may seem like a contradiction, but in the United States there is a company convinced that the formula would not only be effective in removing carbon dioxide from the atmosphere, but would also allow it to be done more efficiently and at a lower cost than with fixed installations.

After all — they reason — we already have a large part of the way advanced: we have an extensive network of railways and locomotives that, in addition to moving, generate energy.
What the US firm CO2 Rail is proposing is to use special cars designed, literally, to "hunt" CO2 as they move through the country's extensive tangle of tracks.

Its dynamics are relatively simple and, a priori — from what the company explains — efficient: the CO2 Rail wagons are equipped with large grilles through which the air is filtered as the train moves forward and with chambers in which, With the help of a chemical process, the CO2 is separated. When that filtering phase is complete, the clean air is blown back out the back of the cylinder and the carbon dioxide is safely stored in a liquid reservoir.

Simple. And with some important advantages. Or at least that is what the parents of the prototype emphasize. By taking advantage of the speed of the train, CO2 Rail cars do not need the powerful fans built into stationary CO2 removal plant designs to filter the air.

Another of its pluses is that the system takes advantage of the operation of the train itself during braking maneuvers for its supply. Instead of allowing the energy generated by friction to dissipate as heat, the prototype uses it to power the filtration system.
It's a waste. Each complete braking maneuver generates enough energy to power 20 average homes for a day, so we are not talking about an insignificant amount”, details E. Bachman, founder of CO2 Rail. According to the calculations of the researchers — New Atlas specifies — if it could capture it at almost all the stops of all the trains in the world, we would obtain 105 times more energy than that generated by the Hoover dam during the same period.

Those who investigate the system have already taken stock and calculate that an average freight train equipped with special CO2 Rail wagons could eliminate up to 6,000 tons of CO2 per year at a cost that, from the outset, would improve that of other solutions that have been putting on the table. "The projected cost to scale is less than $50 per ton , which makes the technology not only commercially feasible, but attractive," Bachman claims.

As New Atlas points out , the goal of Climeworks , the promoter of the world's largest direct CO2 capture plant, is for the cost per ton of carbon removed to reach $100. In the case of the Australian Southern Green Gas , an invoice of 72 dollars per ton is pointed out.
The use of special railcars would also have other key advantages . Perhaps the main one is that it relies on an infrastructure that already exists, the extensive railway network, and saves the space that fixed plants do need, both for their installations and for the renewable energy sources from which they are supplied. A clear example has just been left by the design of 1PointFive : in addition to the filtering center itself, it is supported by plants with wind turbines or solar panels.

And where will the CO2 end up once filtered? The idea is to empty the tank taking advantage of the stops for the change of crew or the replenishment of the railway itself. Its last stop, its promoters point out: the circular economy of carbon or nearby places of geological sequestration.
Every 12 hours the onboard CO2 tank is emptied into a tank car located at the station [...]. This should not be a challenge, as the CO2 Rail cars are designed for around 24 hours of continuous operation before need to be unloaded and the drivers have to rotate about every eight hours," Bachman tells Interesting Engineering .

"We could get a positive feedback loop where encouraging rail to widely deploy these direct capture railcars could further decrease carbon emissions because rail is about five to six times more efficient than trucks," he says .

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