## 3 Results
### Plant Model Results  
The efficiency results and CO\({}_{2}\) capture performance of the benchmark SMR plants without CO\({}_{2}\) abatement and with CO\({}_{2}\) capture employing MDEA absorption, as well as the GSR and GSPOX H\({}_{2}\) production plants and the GSPOX H\({}_{2}\)-power co-production schemes, are shown in Figure 12. Efficiency results are indicated attending to the definitions presented in Section 2.3. It can be seen that when steam exports are neglected in the calculation, the equivalent efficiency reduction is greatest for the unabated SMR plant, while it remains unchanged for the GSPOX H\({}_{2}\)-power plants (since there are no steam exports). The equivalent efficiency penalty for CO\({}_{2}\) capture with MDEA absorption amounts to approximately 7.9%-points (when accounting for steam exports). As discussed, this penalty originates from the fact that a fraction of the H\({}_{2}\) produced must be invested to provide heat to the reformer. Since the operation is carried out with a high S/C ratio of 4, the steam turbine low-pressure stage output is comparatively reduced. Furthermore, LP steam must be sent to the MDEA stripper reboiler for solvent regeneration, neglecting the efficiency benefit of steam export attained in the unabated SMR plant. When the energy from exported steam is neglected as a useful by-product, the energy penalty of the MDEA process reduces to only 4.5%-points: the LP steam produced is fully utilized for solvent regeneration in the CO\({}_{2}\) stripper reboiler. Simulation results in this work yield a significantly higher hydrogen efficiency for the SMR with MDEA capture process relative to what has been presented by [PERSON] et al. [11]. Reformer inlet and outlet conditions are identical, yet apparently, the fuel demand to satisfy the reformer balance is notably smaller, yielding a higher H\({}_{2}\) output. Equivalent efficiency on the other hand is close to the value reported by [PERSON] et al. [43], albeit the fact that in the present work no LP steam exports are considered for this model and the H\({}_{2}\) is compressed to 150 bar. Given  
Figure 12: Efficiency and CO\({}_{2}\) capture results for the different cases. the higher steam turbine output in these works, it is concluded that in these earlier works a larger portion of the final H\({}_{2}\) product is combusted to generate more steam for the turbine in the reformer heat recovery network in order to minimize electricity imports to the plant, therefore attaining a comparatively lower amount of H\({}_{2}\) product. Since the GS-based plants are modeled assuming substantial electricity imports, the SMR model with MDEA CO\({}_{2}\) capture is designed to generate only sufficient steam for the reformer and stripper column demands. Regarding the GS-based plants, as predicted by [PERSON] et al. [22], the integration of GS clusters for H\({}_{2}\) production results in a substantial increase (in this work up to 11.6%-points) of the H\({}_{2}\) efficiency relative to conventional SMR. As discussed earlier, this is a consequence of the higher reforming temperature that shifts the SMR reaction to the products side (consequently reducing the S/C ratio), as well as a more effective heat recovery network, minimizing the heat losses in the plant. On the other hand, for the GS plants with electricity imports (cases GSR-H\({}_{2}\) and GSPOX-H\({}_{2}\)), similar results are obtained for the plants operating at a reactor pressure of 32.7 bar. Approximately the same amount of steam must be raised for the GSPOX prior to the WGS unit, leading to a similar H\({}_{2}\) production (around 0.5%-points higher for the GSPOX). A sensitivity study regarding the cluster operating pressure is carried out and shown in Figure 13, to assess the effect on the efficiency of the reduced equilibrium conversion resulting from higher pressures in the GSR process.