Optimal integration of hybrid pumped storage hydropower toward energy transition

Abstract

This study explores the advantages of combining variable renewable energy sources like solar and wind with a pumped storage hydroelectric (PSH) system for grid integration. The hybrid modeling systems considered in this study consist of four distinct schemes and seasons to ensure their adaptability to real-world conditions. Each scheme is defined by specific rules and algorithms, including those without PSH, with PSH, with PSH adjustments, and with an optimized schedule for the PSH storage system. The last scheme of daily simulation with an optimization solver is used to optimize the integration of PSH with a hybrid power system that uses solar and wind energy as primary renewable sources by minimizing the daily operating costs. The optimal value is derived from the minimized operating costs and incoming and outgoing energy accumulation. The dispatch system includes load demand satisfaction considering the intermittent nature of solar and wind sources and demand fluctuations presented with a hybrid system of PV solar, wind turbines, PSH, and other power generators as backup. Limitations of the study include considering various factors influencing the integration of a PSH unit, such as different ecological and geographical conditions, distinct atmospheric data, and varying load and 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 while meeting the same load patterns. Namely, it can be inferred from the tested schemes that PSH plays a crucial role in facilitating the transition to sustainable energy sources. This is evident through project financing results, which indicate a favorable positive Net Present Value (NPV) and a relatively short payback period of 5 years. Furthermore, Scheme 4 demonstrates the potential for a substantial 84 % reduction in CO₂ emissions during the summer season, and daily costs can be significantly lowered by over 90 % across all seasons. Overall, two simplified net present value and payback period estimation models have shown feasible project financing for a simulation period of 25 years with an interest rate of 10 % for the combined PSH and hybrid system.