The impact of pumped hydro energy storage configurations on investment planning of hybrid systems with renewables

The pumped hydro energy storage (PHES) systems can be installed in various configurations depending on the specific geographical and hydrological conditions. Closed -loop PHES systems are off -stream and have no natural inflow to the system. However, open -loop systems are on -stream and have natural inflows to the upper and/or lower reservoirs. In this study, we develop two -stage stochastic programming models for various PHES configurations to investigate how the choice of PHES configuration impacts the sizing decisions and costs of a hybrid system that includes a renewable power generator co-operated with PHES. Our numerical results show that using a PHES facility instead of a conventional hydropower system reduces the expected system cost and mismatched demand significantly. Open -loop PHES facilities perform better than closed -loop PHES and seawater-PHES facilities, dramatically lowering the need for fossil fuels in demand fulfillment. The most cost-efficient PHES configuration is when there is natural inflow to the upper reservoir. Using solar energy instead of wind as the renewable source significantly increases the requirement for larger upper reservoirs in on -stream open -loop PHES facilities, while reducing the expected system cost for all configurations.