Increasingly, CO2 capture fractions above 95% up to, or slightly above, 100% added CO2 capture is the focus of emerging research. Mullen et al. provide a detailed analysis of the currently available literature, critically assessing seven modelling studies and six pilot plant facilities where CO2 capture fractions over 95% were achieved. The authors identify lean loading as the critical factor to ensure thermodynamically efficient operation at increased CO2 capture fractions. Lean loading must be sufficiently low to provide a strong driving force of absorption at the top of the absorber despite decreased CO2 concentrations, a consideration typically absent or insufficiently considered in the current literature. As well as increasing the absorption rate throughout the absorber, low lean loadings facilitate increased cyclic capacity of the solvent (CO2 absorbed per unit of solvent), minimising the quantity of water to be moved through the system and maximising rich loading. These factors will contribute to a decreased energy requirement for solvent regeneration, and, as will be explained later, higher regeneration pressures will reduce compression duties. Where the importance of low lean loadings was recognised, solvent regeneration to the loadings required is typically mismanaged. Michailos and Gibbins describe what has been termed the desorber "inflection point". They present a modelling study using a 35% wt. MEA solution on a flue gas representative of a commercial CCGT and study 95% and 99% gross CO2 capture fractions over a range of lean loadings and absorber packing heights. They show that as lean loadings decrease under constant stripper pressure and incoming rich loading conditions, the energy requirement for regeneration per unit of CO2 captured, known as the specific reboiler duty (SRD), increases exponentially below a low loading value that depend on the specific conditions. This phenomena has historically led to the conclusion reducing lean loadings and, by extension, increasing CO2 capture fractions will result in exponential increases in SRDs. However, Michailos and Gibbins showed that the inflection point can be shifted to lower lean loadings by increasing the stripper pressure, noting, though, that reboiler temperatures will increase proportionately as a result. This change in inflection point loading arises because the rapid increase in SRD corresponds to the point where the water vapour to CO2 ratio in the reboiler rises to a level at which it cannot be condensed to near-equilibrium partial pressure and temperature with the incoming rich solvent at the top of the stripper column. This leads to increasing levels of water vapour in the CO2 at the top of the column, representing a significant heat loss. An increase in stripper pressure shifts the vapour liquid equilibrium (VLE) in the reboiler towards lower vater vapour/CO2 ratios for a given lean loading, at the expense of higher reboiler temperatures. Mullen et al. build upon the work of Michailos and Gibbins by completing an in-depth techno-economic assessment on 100% added CO2 capture for both an SMR and a CCGT using a 35% wt. MEA solution. They find that, although the thermal efficiency of the process decreases and the cost of the product increases relative to achieving 95% CO2 capture fractions, the effect is modest and is primarily due to the increase in the absolute quantity of CO2 captured rather than any non-linearity in the specific cost to capture CO2 as the CO2 capture fraction increases. The authors further conclude that, for the assumed conditions of this study, unless the cost of negative emission technologies with permanent CO2 storage falls below 184 £/tCO2, increasing CO2 capture fractions to 100% of the added CO2 is the most economical method of fully decarbonising a CCGT. Mullen et al. also show that the CO2 intensity of the counterfactual to hydrogen combustion, i.e. natural gas combustion, means that the cost of CO2 avoided falls as the CO2 capture fraction increases for the SMR process considered, despite the increase in product cost. Mullen et al. suggest two design changes to achieve 100% added CO2 capture: increased reboiler operating pressures and, by extension, temperatures, which facilitate efficient solvent regeneration for low lean loadings, and, in the CCGT case, a moderately increased absorber packing height, from 20m to 24m, to increase the mass transfer area. Although moderate from a process and technological perspective, these two design changes will expose the solvent to previously largely unexplored process conditions, with higher regeneration temperatures, lower lean loadings and increased duration of exposure to the oxygen content of the flue gas. Each of these process modifications may lead to an increase in specific solvent degradation rates. Mullen et al. note that this is a knowledge gap and assumes an MEA consumption rate of 2 kg/tCO2, quoting experience from MEA-based pilot plant studies, which report a range of 0.17 -1.5kg/tCO2 . This manuscript uses emerging models developed by Braakhuis and Knuutila, two co-authors, to shed light on the effect on MEA degradation rates of the process conditions thought to be thermodynamically beneficial when operating at 100% added CO2 capture. MEA will degrade when exposed to oxygen-rich atmospheres (oxidative degradation) or high temperatures (thermal degradation) . Unless effectively controlled, solvent degradation products in the circulating solvent can reduce CO2 capture performance, increase atmospheric emissions and operational costs and accelerate equipment corrosion . Degradation causes a loss of solvent directly while further solvent losses may occur as part of solvent reclaiming, which is required for sustained operation to remove all degradation products at the rate they are formed and maintain constent solvent health. One of the main degradation mechanisms for MEA is carbamate polymerisation, often referred to as thermal degradation. This mostly occurs at elevated temperatures within the CO2 capture process, most notably within the stripper sump and reboiler, where temperatures often exceed 120 o C for extended periods. It also occurs when the solvent is descending through the stripper packing and during pre-heating of the solvent, albeit for relatively short periods and at lower temperatures than the reboiler. When the carbamate, formed when CO2 reacts with MEA, is subjected to increased temperatures ring closure and dehydration occur to form 2-oxazolidinone (OZD). OZD is sensitive to nucleophilic attacks and reacts with MEA, forming dimers, oligomers, imidazolidinones, and other cyclic compounds. The cyclisation of the carbamate leading to the formation of OZD is the rate-limiting reaction. This rate was found to be dependent on both temperature and CO2 loading. Higher CO2 loadings have been shown to increase degradation rates, possibly by forming more of the carbamate or increasing the availability of proton donors, which can catalyse dehydration. A detailed review of thermal degradation methods is available in Braakhuis et al. .