In a paper published in the journal Frontiers in Energy Research, the researchers propose capturing carbon dioxide from a truck's exhaust pipe and turning it liquid, which is stored in a tank on the vehicle's roof. This liquid carbon dioxide can then be delivered to a service station where it can be reused in various ways, including being turned into conventional fuel.
The carbon dioxide capture works by first cooling the gases which are emitted from the exhaust pipe. Special absorbent materials developed at EPFL could separate the carbon dioxide from other gases like nitrogen and oxygen. When it is full, the absorbent material is then heated to extract the carbon dioxide, and heat from the vehicle's engine is used to compress the carbon dioxide and turn it into liquid. That liquid can then be stored in a box attached to the vehicle's roof until it can be deposited at a service station when the truck refuels.
The system is more appropriate for large vehicles like trucks or buses than for cars as it is rather bulky, requiring a 2-meter-long capsule and weighing 7 percent of the total payload of a truck. However, the researchers calculate that 90 percent of carbon dioxide emissions could be recycled in this way.
The system is only a concept at the moment, and the researchers estimate that it will take several years to realize the system in the real world. The next step is to develop a prototype of the system to test out the experimental elements in practice.