## 4 Results and Discussion
### Comparative Summary and Suitability  
Each system demonstrates distinct advantages aligned with specific sustainability goals. Solar thermal and PV systems stand out for their extremely low GHG emissions during operation, although both require significant energy input during component manufacturing, particularly for batteries and heat exchangers, as discussed in previous sections. Biogas systems, while relying on consistent organic feedstock, offer the unique advantage  
Figure 13: Midpoint environmental impact analysis (ReCiPe 2016) for biogas-based electricity generation at DEI Agra. of converting waste into usable energy and fertilizers, effectively contributing to a circular economy. However, the presence of gas impurities and the complexity of anaerobic digestion require careful design and operational controls. Table 4 encapsulates the comparative summary with key environmental and technical characteristics of the three renewable energy systems. It shows that solar thermal offers the lowest cradle-to-grave emissions and damage scores, making it ideal for rural/off-grid electrification. Solar thermal excels for steady heat supply but carries higher embodied energy and modest GHG. Biogas provides dispatchable power and waste valorization, with moderate CED and life cycle damage driven by methane and digestion emissions. Based on the analysis and discussion, it can be recommended since the solar thermal systems are particularly well-suited for industrial or institutional facilities in high solar irradiance regions (e.g., Africa, Middle East, India, South America, etc. ), where there is consistent sunlight and a significant demand for process heat or space heating. They are ideal for applications like solar cooking, water heating, and pre-heating boilers in industries. Solar PV systems, on the other hand, are highly effective in off-grid rural areas or remote islands where extending the electricity grid is economically unfeasible (e.g., Sub-Saharan Africa or remote villages in Northeast India). Their modularity and decreasing costs make them attractive for home electrification and telecom towers. However, the results should be interpreted as typical technology baselines for sunny temperate regions. In extremely arid zones with high dust loads or in high-tech waste management economies, midpoint scores for water consumption and end of life processing may differ. Biogas systems are most relevant in agrarian or livestock-dense regions (e.g., Denmark, Netherlands, rural Punjab, or the midwestern United States, etc.) where large quantities of organic waste are available. They can be used for cooking fuel, electricity generation, and organic fertilizer production, creating a circular economy around farm and municipal waste. Impact of End-of-Life Options on Endpoint Score  
Table 5 summarizes the results for the BAS, OLR, and CLR. Moving from BAS to CLR cuts the panel's endpoint score by 55% and the battery's endpoint score by 58%. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Metric** & **Solar Thermal** & **Solar PV** & **Biogas** \\ \hline GHG Emissions & Moderate (0.6 kg & Very low (0.05 kg & Low-to-moderate (0.2 kg \\  & CO\({}_{2}\)-eq/kWh) & CO\({}_{2}\)-eq/kWh) & CO\({}_{2}\)-eq/kWh) \\ CED & 230 kJ primary/kWh & 21,700 kJ primary/kWh & 1406 kJ primary/kWh \\ Life cycle damage & 1.25 mPt/kWh & 72.45 mPt/kWh & 18.8 mPt/kWh \\  & Dependent on solar irradiance, & Weather-dependent, & Feedstock-dependent, \\ Reliability & Storage needed for night or & Battery backup helps, but & Consistent supply of \\  & low sun. & adds cost. & organic waste required. \\  & Minimal direct emissions in & Minimal direct emissions, & Methane leakage (high \\  & operation, & E-waste from panel & global warming potential), \\  & Used Therminol fluid & disposal. & H\({}_{2}\)S, NH\({}_{3}\) in digestate; \\  & disposal. & & digestate reuse. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparative summary of solar thermal, solar PV, and biogas systems.