To minimize the impact of the energy source, direct air capture processes are typically proposed to be located in regions with low-carbon-footprint grid mixes or powered directly by renewable electricity or waste heat, which makes the U.S. grid mix carbon footprint (461 kg CO2/MWh in 2020) an inaccurate representation. Thus, here we use an average of the five states with the lowest carbon footprints (171 kg CO2/MWh) throughout the analysis (Tables ). Using waste heat could further reduce the thermal carbon footprint. Combining the energy and sorbent carbon footprints provides a total carbon footprint. When the sorbent degrades over time, there is a minimum carbon footprint when the decreasing sorbent carbon footprint and increasing energy carbon footprint balance each other (Fig. , right panel). The location of this minimum carbon footprint will influence the optimum sorbent replacement time. Two important conclusions can be made from these results. (1) Sorbent degradation can unintentionally lead to high carbon footprints, especially when carbonintensive energy sources are used. (2) Sorbent capacity fade must be included in DAC economic modelling to determine the replacement time that leads to the highest climate benefits.