CO2 Rail Company is a US based firm which was founded as recently as 2020. Since then, the company has managed to develop rail-based, self-powered direct air capture (DAC) technology. The technology developed actually works by removing excess carbon dioxide from the ambient air using the rail network, purpose-built rail equipment and sustainable, train-generated regenerative braking energy with no external energy inputs required. What’s more exciting is that it could even make diesel-fuelled trains nearly carbon neutral.
Despite being based in the US, CO2 Rail are working alongside researchers from the University of Sheffield to design carbon-capturing equipment which can be used on specialist rail cars placed in operational trains. Direct Air Capture is proving to be a promising solution to the current global climate crisis and the company plans to begin construction of its first DAC units in 2023.
Although CO2 Rail have not yet targeted passenger railways, they have had meetings with some of the bigger rail freight operators. Peter Styring, Professor at the Department of Chemical and Biological Engineering 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 necessity to mitigate the worst effects of climate change. Who pays for the technology can be anyone such as the government or private industries who take a net zero pledge. More and more companies, like Microsoft, Google parent company Alphabet and Disney say they commit to become carbon-neutral and purchase contracts to offset their emissions for millions of tonnes.”
How it works
The capture of CO2 from the air is a cyclical process, explains Bachman. It works by using large intakes of air that extend up into the slipstream of the moving train to move ambient air into the large cylindrical CO2 collection chamber. After grabbing air, the air chamber is closed up with hatches, and the desorption process to take the CO2 out of the air is initiated. The air goes through a chemical process that separates the CO2, and the carbon dioxide-free air then travels out of the back or underside of the car, re-entering the atmosphere. After a certain amount of CO2 has been captured, the chamber is closed and the CO2 is collected, concentrated, and stored.
The chamber is designed to collect one day’s worth of CO2, says Bachman. One cycle of capture depends on speed, a faster train absorbs more CO2 and reaches capacity quicker. For a faster train, the air collection takes around 45 minutes, slower trains around an hour or 1.5 hours. The desorption cycle to capture the CO2 takes approximately 5 or 10 minutes. By collecting the air with the speed of the train running, there is no need for the energy-intensive fan systems that are necessary with stationary Direct Air Capture operations.
The air collection chamber takes up 85 percent of the CO2Rail car’s space. The rear 1.5 metres (5 or 6 feet) is a 15 tonne CO2 reservoir. That small reservoir is emptied in a regular CO2 tank car when there is a crew change or fuelling stop.
Each CO2 Rail car is capable of removing between 10-20 tonnes of CO2 each day. Indeed, some of the CO2 captured could be used to carbonate your drink, or used as feedstock for the production of chemicals, synthetic fuels or refrigerants.