Young et al. showed that for both KOH with calcium looping and MgO looping, the costs increase rapidly if the starting scale is below 0.5 MtCO 2 /yr. Meanwhile, the starting scale does not seem to be as critical for the modular technologies, such as temperature vacuum swing adsorption or KOH with BPMED regeneration, as it is expected that they can easily be scaled up (or scaled out). However, there are many important insights that are currently missing and can be extracted from the operation of these plants, e.g., material replacement, material degradation, optimal spacing between air contactors, 135 process response and operational control, that can be beneficial for optimizing the DAC unit and whole system's setting. Also, the starting scale is expected to impact how many doublings can be achieved in a technology's development, which is critical to reducing cost via technological learning.