## 6 Simulation and Analysis
### Results and Analysis  
#### 6.3.1 Carbon Emission Analysis  
Using FP-RIES as a reference, the carbon emissions are calculated based on the load demands in the rapid, steady, and green development scenarios, as depicted in Figure 7. The growth rates of the carbon emissions in all three scenarios closely mirror the load growth rates. The highest-emission scenario is the rapid development scenario, reaching 11,266.7 tons in 2040, followed by the steady-development scenario (10,840.6 tons) and the green-development scenario (10,426.7 tons). Upon comparing Figure 7 with Figure 6, it becomes evident that the carbon emissions of FP-RIES in all three scenarios are more  
Figure 6: The 2020–2040 regional carbon emission constraints for building clusters for carbon peaking. than double the carbon emission constraints. Because FP-RIES relies entirely on fossil fuels without any low-carbon technologies, it results in uncontrolled carbon emissions. It is clear that relying on FP-RIES for the energy supply cannot meet the low-carbon requirements for achieving carbon-peaking goals. Figure 8 presents the carbon emissions of HP-RIES and CP-RIES under different operating strategies of FEL and FTL, both with and without carbon emission constraints. Optimization is conducted for both CP-RIES and HP-RIES with and without carbon emission constraints, as indicated in Tables 8 and 9 and Figure 8. Table 8 displays the carbon emissions of CP-RIES in the \"electricity-based heating\" mode in the green development scenario from 2020 to 2040. It is evident that the carbon emission constraints have no impact on CP-RIES because of its highest renewable energy penetration, and Figure 8 illustrates that its carbon emissions remain below the carbon emission constraints set by the carbon-peaking  
From Table 9 and Figure 8, it is clear that carbon emission constraints significantly influence the environmental performance of HP-RIES in all the scenarios. The emissions are notably lower when there are carbon constraints compared to when there are no constraints, indicating that carbon constraints have a suppressive effect on the emissions of the hybrid renewable energy and traditional fossil energy RIESs. Additionally, as confirmed by numerous other studies, the FEL and FTL operating modes determine different energy-supply-scheduling methods, thereby directly affecting the environmental performance of the energy system [45; 46]. The optimization results reveal that in all three development scenarios, the carbon emissions of HP-RIES and CP-RIES in the FEL mode are significantly lower than those in the FTL mode. The negative percentages described in Table 8 indicate the reduction level of FEL relative to FTL, reaching over 30% at the maximum. Figure 8 provides a comprehensive illustration of the impacts of the carbon emission constraints, RIES system configuration, and operating modes on carbon emissions in the scenarios of rapid, steady, and green developments. It is evident that as carbon emission constraints progressively strengthen in these scenarios, the carbon emissions of all the RIES systems exhibit a decreasing trend. This suggests that the carbon emission constraints, as defined by the carbon-peaking implementation pathway, have a significant suppressive effect on carbon emissions. Furthermore, the emissions of HP-RIES in the FTL mode are notably higher than the carbon emission constraint line. Even with carbon emission constraints, they cannot meet the carbon-peaking target. In contrast, HP-RIES in the FEL mode can achieve the carbon-peaking target under carbon emission constraints, and without constraints, it remains below the constraint line until 2032, gradually surpassing it later. An intriguing observation is the changing relative positions of the emissions of HP-RIES in the FEL mode and CP-RIES in the FTL mode in different scenarios for carbon emission constraints.