This technology can effectively capture CO2 from trucks and buses

Capturing CO2 directly in the trucks’ exhaust system.


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For the world to stay within the safety threshold of an increase in average temperature agreed by virtually all governments, the transport sector needs to be decarbonized. The transportation sector is a significant contributor to total man-made CO2 emissions from the burning of fossil fuels.

Essentially diminishing CO2 emissions from transport won’t be simple, as the rate of emission decreases has eased back. Different areas have cut missions since 1990, yet as individuals become progressively mobile, CO2 emanations from transport are increasing.

Continuous efforts are going on to reduce CO2 emissions in the transportation sector. EPFL scientists have just taken a new step. They have developed a new concept that could cut trucks’ CO2 emissions by almost 90%.

The technology captures CO2 directly in the trucks’ exhaust system and liquifies it in a box on the vehicle’s roof. The liquid CO2 is then delivered to a service station, where it is turned into conventional fuel using renewable energy. 

In collaboration with the Industrial Process and Energy Systems Engineering group, scientists propose to combine several technologies to capture CO2 and convert it from a gas to a liquid in a process that recovers most of the energy available onboard, such as heat from the engine. In their study, the scientists used the example of a delivery truck.

In the first place, the vehicle’s flue gases in the fumes pipe are cooled down, and the water is isolated from the gases. CO2 is then isolated from different gases (nitrogen and oxygen) with a temperature swing adsorption framework, using metal-organic systems (MOFs) adsorbent, which are specially intended to retain CO2.

Those materials are being developed by the Energypolis team at EPFL Valais Wallis, led by Wendy Queen. Once the material is saturated with CO2, it is heated so that pure CO2 can be extracted from it.

Fast turbocompressors created by Jürg Schiffmann’s research facility at EPFL’s Neuchâtel campus use heat from the vehicle’s engine to compress the extracted CO2 and transform it into a liquid. That fluid is put away in a tank and would then be able to be changed over go into conventional fuel at the service stations using renewable electricity.

The whole process takes place within a capsule measuring 2 m x 0.9 m x 1.2 m, placed above the driver’s cabin. 

François Maréchal, at EPFL’s School of Engineering, said“The weight of the capsule and the tank is only 7% of the vehicle’s payload. The process itself uses little energy because all of its stages have been optimized.”

The calculations show that a truck using 1 kg of conventional fuel could produce 3kg of liquid CO2. Only 10% of the CO2 emissions cannot be recycled, and the researchers propose to offset that using biomass.

Scientists noted, “The system could theoretically work with all trucks, buses and even boats, and with any fuel. The advantage of this system is that, unlike electric or hydrogen-based ones, it can be retrofitted to existing trucks to neutralize their impact in terms of carbon emissions.”

The project is being coordinated by the Industrial Process and Energy Systems Engineering group, led by François Maréchal, at EPFL’s School of Engineering. The patented concept is the subject of a paper published in Frontiers in Energy Research.


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