This work explores the advantages of combining variable renewable energy sources including solar, wind and hydropower with a pumped storage for grid integration. The grid's capacity to accommodate the solar photovoltaic (PV) and wind energy sources is limited by their instability. However, this system instability can be overcome by integrating these renewable sources into a Pumped Storage Hydropower (PSH). This work explored the complementarity of PV-wind-hydropower with a pumped storage system to provide an adequate, stable and reliable power generation from Mukungwa hydropower considering the intermittent nature of solar sources, wind sources and the demand fluctuations. The availability of resources, proximity to hydropower infrastructure, and land constraints directly determine the least-cost technology mix. Limitations of the study include considering various factors influencing the integration of PSH unit, such as different ecological and geographical conditions (flat terrain, poor geology, or high sediment loads and is inapplicable in ecologically protected areas with legally binding environmental flow requirements, distinct, varying load demand patterns, which may result in different outcomes in different situations. The results show that using the developed model to optimally schedule the integration of PSH with renewables and the hybrid system in each season provides significant cost savings and CO2 emissions reductions. Firstly, the coefficient is defined to measure the system power output complementarity. The size of optimization model based on power output complementary coefficient is then developed for the integration of wind and PV into the PSH system. This method is applied to determine the optimized sizes and sites for PV and wind power plants to be integrated into Mukungwa hydropower. The system complementarity benefits are investigated based on the optimization results. Using the defined algorithm of scheme two that is described as without PHS and with PHS, it can be seen that the cost profile of scheme two is biased towards higher profitability due to lower injection into the grid and higher withdrawal from the grid in the simulation. The results showed that power plant location plays a critical role in PV and wind size optimization. The joint operation of PV, wind and a PSH system enhances the output power complementarity benefits.
Niringiyimana et al. (Mon,) studied this question.