Figure to Figure show the profiles of O2 concentration and CO2 loading of the solvent along the absorber length for each case, along with bulk temperature and the predicted oxidative MEA degradation rate. The results presented are intersection averages of each modelled absorber section (1 to 100). The high O2 concentration seen at the top of the absorber occurs due to the rapid dissolution of O2 into the liquid phase over the final section of the absorber. A lower lean loading in itself does not appear to largely affect oxidative degradation rates. This is due to the order of the degradation reaction with respect to O2 being low at 0.47, so an increase in the concentration of dissolved O2 will have a progressively smaller impact on the degradation rate and the subtle effect of increased solubility and unloaded MEA concentration at lower lean loadings appears eclipsed by the much more dominant effect temperature has on the reaction rate. More critically, and an entirely novel observation, is that, by the same virtue, total MEA degradation rates within the absorber are approximately comparable over the range of flue gas O2 concentration studied. While increasing O2 concentration will increase the concentration of O2 in the solvent, the resulting increase in MEA degradation is muted by the low reaction order. However, O2 leaner flue gases have increased concentrations of CO2 in post-combustion applications; in the absence of intercooling, the high CO2 concentration will tend to lead to higher temperatures in the absorber as more energy is released by the exothermic reaction between MEA and CO2 per unit of flue gas processed. As the oxidative degradation reaction is strongly influenced by temperature, the increase in bulk temperature throughout the absorber present in low O2/high CO2 concentration flue gases appears to, at least partially, offset the effect of decreased dissolved O2 concentrations; this is clearly illustrated in Figure . This is most prominently observed in the cases with intercooling included, with a 30-80% decrease in oxidative degradation predicted. This indicates that regardless of the CO2 capture rate or loading, intercooling can be an effective measure for reducing solvent degradation rates. This must, however, be considered in conjunction with the increased CAPEX and operational requirements that result from including intercooling. Notably, a 43% increase in oxidative degradation in the absorber packing is seen when comparing the 100% added capture and 95% gross capture CCGT cases at 0.1 mol/mol lean loading without intercooling in both cases. This is the result of increased temperatures in the absorber at the higher CO2 capture fractions. Comparable degradation rates can be seen between the same 95% case and the 100% added capture case (with intercooling), a novel conclusion which indicates that intercooling may be a particularly potent mechanism for reducing solvent degradation in CCGTs at high CO2 capture fractions despite giving a minor increase in SRD in the cases presented in Table (likely due to decreased reaction rates at lower solvent temperatures). Likewise, the intercooler arrangment presented here does not represent an optimum; further benefits may be observed by revising return temperatures or the inclusion of an additional intercooler, which may have benefits outwith reducing oxidative degradation as this optimisation may allow a marginally higher lean loading to be utilised while maintaining the same CO2 capture performance, reducing thermal degradation. Figure and Table detail the predicted total and location-specific MEA degradation rates in the CO2 capture process. As MEA reacts rapidly with oxygen, the majority of the oxidative degradation occurs within the absorber internals, with the absorber sump and downstream equipment contributing minimally as the remaining dissolved O2 in the solvent is consumed. The effect is more prominent in O2-rich flue gases as a higher concentration of dissolved O2 is carried over into the absorber sump. For the 100% added CO2 capture cases, i.e. lean loadings of 0.1 mol/mol, thermal degradation increases by a factor of 3 to 4 due to the increased temperatures experienced by the solvent in the regeneration system. The increase in reaction rate due to increased temperatures outstrips the decrease from the reduced carbamate concentration in leaner solutions, resulting in the net increase in degradation seen, albeit dampened to some degree. This indicates that a designer should utilise the lowest regeneration pressure that will achieve the required trade-offs between solvent degradation, energy efficiency and CAPEX. This is clearly shown in Figure which details the distribution of MEA thermal degradation at key plant locations. A grouping of degradation profiles by lean loading is immediately apparent, with minimal difference seen between the three processes analysed. The assumed residence times for each piece of equipment are available in Appendix A. Figure Illustrates the consumption of O2 dissolved within the solvent once direct contact with the flue gas ceases. The degradation framework assumes that once the solvent exits the absorber packing and enters the sump (modelled as a continuously stirred tank reactor), it is no longer in contact with O2 from the flue gas. From this point onward, degradation occurs indirectly through previously dissolved O2. For clarity, only the CCGT cases are shown; however, the EfW and SMR cases follow similar trends and can be seen in Appendix B.