Browsing by Author "Pitso, Khiba"

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    Design of a standalone hybrid solar-wind system with pumped hydro storage along Likhaebaneng river in Quthing District, Lesotho
    (National University of Lesotho, 2024) Pitso, Khiba; Khaba, L; Makhele, M
    Extending the power grid to all villages in Lesotho, a country characterized by rugged terrain comprising mountains and hills, is nearly financially unfeasible. Consequently, the nation suffers from escalating poverty due to insufficient access to electrical energy. The most viable and sustainable solution to provide electricity to unelectrified areas is to harness the renewable resources abundant in such regions. However, many renewable energy technologies face intermittency issues because they rely on natural resources with diurnal and seasonal patterns for power generation. Thus, it is necessary to consider complementary energy storage systems. The pumped hydropower plant emerges as a viable option for hybrid systems seeking efficient energy storage solutions. The present study examines the planning of a pumped hydroelectric power station situated in the Quthing district, Lesotho, utilizing the resources of the Likhaebaneng River, and the solar radiation and wind resources available in the area. The research site is positioned at Latitude -30.352244 and Longitude 28.160639, while the river under consideration boasts an average flow rate of 0.3 cubic meters per second and a gross head of 301 meters. The pumps, powered by both solar and wind power, are employed to pump water from the lower reservoir to the upper reservoir via a succession of 14 cascaded reservoirs. The turbine utilized for this generation process is the 5 kW Turgo turbine. In the study area, the average scaled annual solar insolation and wind speeds are measured at 5.19 kWh/m²/day and 4.85 m/s at 30 m above ground level (a.g.l), respectively. The hybrid optimization model for electric renewables (HOMER) software was employed to model, simulate, and optimize the hybrid system consisting of solar, wind, and hydropower. The chosen optimized system in this study, featuring a maximum wind power output of 3,000 kW and a maximum PV power output of 4,568 kW, demonstrated a Net Present Cost (NPC) of $46.48 million and a levelized cost of energy (LCOE) of $0.2053 per kWh, which is equivalent to M3.80 per kWh. The system annually generates 8,074,658 kWh from solar resources, constituting 58.2% of the total production. Additionally, 5,797,867 kWh per year is generated from wind resources, accounting for 41.8% of the solar / wind system's total annual energy production of 13,872,525 kWh while 2,228,537 kWh is generated from PHES annually with the efficiency of 84.15 %. The consumption amounts to 8,764,589 kWh per year, resulting in an excess energy production of 28.9%.