As the degree of functionalization increases and working capacity decreases, greater stability enhancement is necessary to achieve the same cost. For instance, 0.05HP-PEI requires only a slight stability improvement over unmodified PEI, whereas 0.15HP-PEI requires significantly higher stability (Fig. , middle panel). If the sorbents are only used for a short amount of time before replacement, the unmodified PEI results in a lower cost of CO2 capture due to its higher working capacity (Fig. , right panel). However, as the sorbent usage time is extended, the umodified PEI will degrade more than the modified HP-PEIs. The results presented in Fig. reflect a scenario in which the unmodified PEI loses 50% of its capacity in two years, consistent with the deactivation timeline observed in Climeworks amine sorbents as described by Deutz et al. However, the PEI degradation rate will depend on the selected cycle parameters and environmental factors, such as humidity, temperature, and the concentration of other air contaminants. To account for this variability, we included results for several PEI degradation rates in Fig. , providing both a sensitivity analysis and guidance for processes with different observed degradation rates.