The two currently available archetypes of DAC include absorption-and adsorptionbased systems. A key requirement for DAC systems is a low pressure drop in the contactor. This is necessary as vast volumes of air must be processed in order to capture a meaningful amount of CO 2 . For absorption-based technologies, this achieved by a cross-flow column design. This is where the gas flow is perpendicular to the downflowing liquid. However, the fundamental mechanism of this design are still under investigation, also the design and construction standards have not been developed. As a result, ideal operating conditions are still to be established. Adsorption-based systems aim to tackle the pressure drop issue by replacing conventional packed beds with monolithic contactors, which are a generally established concept. However, the TVSA variant is more complex and large scale production may be challenging due to the requirement of maintaining vacuum conditions. These design issues may hinder the deployment of DAC due to its inability to compete with other technologies.