A Train that captures CO2 from atmosphere

In recent years, efforts have been made to promote the use of public transport as much as possible. Above all, a lot of value has been given to the train. But not only for the transfer of passengers, but also for goods, since it is much less polluting than transporting and bringing the same load by truck. For this reason, a team of scientists from the University of Toronto has designed a train whose carriages can collect carbon dioxide (CO2) from the atmosphere. Thus, not only would emissions be reduced, but those that already exist would be cleaned up.

In the paper, "Direct Rail-Based Airborne Carbon Capture," researchers from the University of Toronto and the University of Sheffield, along with US-based start-up CO2Rail (DAC) could remove 3,000 tonnes of carbon dioxide out of the atmosphere per year, a figure that could double in the medium term as technology improves.

Currently, this carbon dioxide capture is done at fixed stations. The problem is that these require the acquisition of a large amount of land, as well as many permits that are very difficult to obtain. In addition, they are frowned upon by the population that lives in the surroundings. All of this is a problem that would be easily solved with this train, which keeps moving while doing invisible work. As they say, you kill two birds with one stone.

What is CO2rail?

CO2Rail Company is a US-based startup founded in 2020 that has developed rail-based, self-powered Direct Air Capture ("DAC") technology that removes excess carbon dioxide from ambient air using the network global railway, purpose-built railway equipment and sustainable regenerative braking energy generated by trains without the need for external energy inputs.

Why is CO2 so harmful?

Carbon dioxide, as well as other greenhouse gases, are not dangerous per se. In fact, they are very necessary. If they were not in the atmosphere, much of the solar radiation that hits the Earth's surface and is reflected back into space would be lost, resulting in great cooling. Without them, our average room temperature would be -18°C, so we can be very grateful for this demonized effect.

The problem is that human activity has led to levels of CO2 and other similar gases rising far above what is necessary. In the last century, we have gone from about 300 parts per million of carbon dioxide to 415 ppm. The number does not stop rising and global warming began to be dangerous a long time ago.

That is why it is important to reduce emissions while trying to capture and store some of the carbon dioxides that has already been released into the atmosphere. There are natural mechanisms to achieve them. For example, it is precisely the work that trees do on Earth or Posidonia meadows in the sea. But its effect begins to be insufficient. You have to design artificial mechanisms and this is where the train designed at the University of Toronto comes into play.

A train to clean the environment

The train designed to capture CO2 from the atmosphere has carriages with vents through which air enters in large quantities. Thus, as its designers have explained in a statement, "the need for fan systems with large energy consumption used by stationary direct air intake systems" is eliminated.

On the other hand, once a sufficient amount of carbon dioxide is captured, the chamber is closed and the collected carbon dioxide is collected, concentrated, and stored in a liquid reservoir until it can be emptied. To do this, the train takes advantage of crew changes or fuel supply stops.

Finally, the carbon dioxide-free air exits the rear or bottom of the train and returns to the atmosphere. By repeating this on each trip, such a train could capture and store up to 6,000 tons of gas per year.

It should be noted that the CO2 that is released from the train at the corresponding stops is directed to one of the tanks located for this purpose throughout the world. It is there that carbon dioxide from stationary installations is also directed, but in this case, it is much simpler.

Now, unfortunately, money is essential even when it comes to saving the planet. Therefore, these scientists have also worked hard on the economic calculations of their inventions. Thus, they have seen that "the projected cost at scale would be less than $50 per ton." Therefore, it is not only efficient and beneficial for the planet, it is also very economical.

How does the train wagon work?

As a train equipped with a CO2Rail car moves, air propagating upward in the wake pushes ambient air into a cylindrical CO2 collection chamber.

The air then moves through a chemical process that separates its CO2, before the CO2-free air is exhausted out the back or under the car into the atmosphere.

Once a sufficient amount of CO2 has been captured in the collection chamber, it is concentrated and stored in a liquid reservoir.

Liquid can be emptied from the train at a crew change or refuelling stop to be transported to the circular carbon economy or to nearby geological landfills.

Professor Peter Styring, director of the UK Center for Carbon Dioxide Utilization at the University of Sheffield and co-author of the research, said: "The direct capture of carbon dioxide from the environment is increasingly becoming an urgent need to mitigate the worst effects of climate change.

The technology will collect significant amounts of CO2 at much lower costs and has the potential to achieve an annual productivity of 0.45 gigatons by 2030, 2.9 gigatons by 2050 and 7.8 gigatons by 2075, with each car having an annual capacity of 3,000 tons of CO2 in the short term.

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