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The involvement of green hydrogen in energy transformation is getting global attention. This assessment examines the hydrogen production and its utilization potential in one of the hydropower-rich regions, Nepal under various demand growth and technology intervention scenarios by developing a power grid model of 52 nodes and 68 transmission lines operating at an hourly time-step. The model incorporates a grid-connected hydrogen storage system as well as charging stations for electric and hydrogen vehicles. The least-costly pathways for power grid expansion at the nodal and provincial levels are identified through optimization. The results show that 32 GW of installed capacity is required to meet domestic electricity demand and 14 GW more hydropower should be exploited to completely decarbonize the transport sector by 2050. For maintaining 50% shares of hydrogen vehicle in the transport sector and meet government electricity export targets, Nepal requires 5.7 GW, 12 GW and 23 GW of the additional electrolyzer, hydrogen storage tanks and storage-based hydropower capacities respectively. For a given electricity demand, introducing hydrogen systems can reduce the capacity requirements of hydro storage by storing surplus power generated from pondage run-of-the-river and run-of-the-river hydropower during the rainy season and using it in the dry season. • Integrated hydrogen energy storage system and charging stations within a power grid model. • 14 GW of additional hydropower plant is required to completely decarbonize the transport sector. • Huge storage-based hydropower is exploited only in export-oriented scenario. • Share of storage-based hydropower decreases with a reduction in hydrogen system cost. • Hydrogen system reduces power curtailment from pondage run-of-the-river and run-of-the-river hydropower. [ABSTRACT FROM AUTHOR]

This paper presents a new modeling approach to incorporate operational characteristics of different types of hydropower in long-term power sector models. The existing literature and methods were reviewed, and the mathematical formulation of the developed model is presented. The model is then used to analyze the future power generation mix of Nepal, a country with huge untapped hydro resources, as a case study. The possible power sector development pathway has been assessed through three different electricity demand growth rate scenarios. The optimal deployment of indigenous hydro and renewables is further evaluated by developing zero-emission scenarios as a conceivable policy to strengthen national energy security. The sensitivity analysis of governing parameters and evaluation of simulation results was performed to validate the model. Simulation results for capacity and generation mix along with emission level and total power system costs have been discussed for each scenario. Power dispatch and operation schedule determined as a result of optimization take account of the seasonal variations of river inflow and operational benefits of hydropower. Sensitivity analysis is carried out to examine the impact of construction cost, availability factor and water storage capacity on total cost, capacity requirements and optimal operation of hydropower. • Represented different types of hydropower in dynamic power sector model. • Detailed analysis of the future power generation mix of Nepal. • Optimized the operation schedule and water storage strategy of hydro Pondage run-of-the-river and hydro storage. [ABSTRACT FROM AUTHOR]

Climate change significantly impacts hydrological systems resulting in hydropower generation uncertainties. In this study, a high-resolution glacio-hydrological model is coupled with an hourly-resolution power grid model to evaluate the climate change influences on hydropower generation across Nepal. Four climate future scenarios namely Cold-Dry, Warm-Dry, Cold-Wet, and Warm-Wet are developed to compare the changes in water availability and optimal power system with historical climate. The total flow increases for the wet scenarios (+11.4% under Cold-Wet for the Koshi basin), compared to the dry scenarios (−24.6% under Warm-Dry for the Karnali basin) for all the major river basins in Nepal. The results illustrate the distribution and magnitude of changes in total water availability and power generation are not proportional for dry and wet scenarios as a ∼20% reduction of water availability in the dry scenarios only results in a ∼2–3% decrease in electricity generation. The capacity requirements of hydro storage decrease by 7.2 GW for Cold-Wet and 6.8 GW for Warm-Wet scenarios compared to historical climate indicating higher capacity requirements in dry scenarios. Larger impacts observed at higher altitudes suggest more attentive adaptation strategies in developing climate-resilient hydropower systems. Results suggest that Nepal should not be entirely focused on exploiting its hydropower potential but rather diversifying the generation mix including solar PV and hydrogen technology. For the least-cost power system expansion, the Warm-Wet climate appears to be the most desirable and a cost savings of about 3.76 billion USD in hydropower development can be realized if better adaptation strategies are employed. [Display omitted] • Climate change impacts on hydro-dominated power systems in a high-mountain country. • Coupling of glacio-hydrological model and a high spatial-temporal power grid model. • Adaptation strategies for surplus electricity management are more critical in wet scenarios. • Storage hydro capacity needs drop by 7.2 in Cold-Wet & 6.8 GW in Warm-Wet scenarios. • Employing adaptation strategies results in cost savings of about 3.76 billion USD. [ABSTRACT FROM AUTHOR]