Flexibility Potential in the Nepalese Power System: A Diagnostic Analysis

Nepal's power system, dominated by run-of-river hydropower, faces a critical seasonal flexibility challenge, characterized by significant energy surpluses in the wet season and severe power deficits in the dry season. This study conducts a comprehensive flexibility assessment of the Integrated Nepal Power System (INPS) to quantify these operational gaps and evaluate the role of storage hydropower as a mitigating solution. Using the FlexTool, a power balance simulation was performed on a single-node model of the INPS. The analysis reveals that in the 2025 base case, the system fails to serve 5.68% of the annual demand while simultaneously curtailing a massive 5.22 TWh of variable renewable energy (VRE). A sensitivity analysis demonstrates that increasing the share of storage hydropower is highly effective; a generation mix with 35% storage capacity virtually eliminates loss of load and reduces VRE curtailment by 76%. Future scenarios for 2030 indicate that achieving national capacity targets is crucial, but even then, a storage share of 20-30% will be required to maintain reliability under high-growth and policy-driven demand scenarios. The findings underscore the need for a capacity expansion planning with strategic investment in seasonal storage to ensure flexibility and efficient use of renewable resources in Nepal's power system.