Retrofitting hollow fibre carbon capture systems to decarbonise surface transport

On-board carbon capture and storage (CCS) is being recognised as an essential transitional solution for transport decarbonisation. However, due to inherent space constraints, retrofitting current CCS technology to vehicles is challenging. Herein, the feasibility of a novel hollow fibre carbon capture system impregnated with a carbon xerogel for on-board CCS was assessed. The working capacity of four carbon xerogels with varying surface area/surface groups, over ten temperature swing adsorption (TSA) cycles, was studied in a packed bed adsorption unit (PBAU). The highest-performing carbon xerogel (i.e. CX) was deposited inside a hollow fibre support to form the hollow fibre adsorption unit (HFAU). Under typical vehicle exhaust gas compositions (i.e. 14 vol% CO2 + 3 vol% H2O balanced in air) and at mild operating conditions (i.e. adsorption at 25 °C, 1 atm; desorption at 125 °C, 1 atm), the HFAU exhibited a 1.3 times greater working capacity than the equivalent PBAU (i.e. 4.7 mmol g−1 and 3.5 mmol g−1, respectively), due to minimized mass transfer limitations. In addition, the results obtained were used in a study that compared hollow fibre carbon capture systems and packed bed carbon capture systems designed to be retrofitted to three transport scenarios: (1) a light-duty vehicle (car/van); (2) a large regional delivery truck; and, (3) a ferry. For scenarios 2 and 3, the findings of the study showcased the potential of retrofitting a hollow fibre carbon capture system to these large surface transport modes. However, for scenario 1, despite obtaining a hollow fibre carbon capture system that was 3.5 times smaller, 5.7 times lighter and 6.6 times cheaper than the packed bed carbon capture system, it cannot be feasibly retrofitted without significant improvements in weight. Furthermore, a short-hand simplified heat exchange approach was presented to obtain the TSA operation temperatures of the carbon capture systems.