Optimal operation of pumped hydro storage-based energy systems: A compendium of current challenges and future perspectives

Over the past decade, energy storage in renewable energy-dominated systems has received increasing interest. Effective energy storage has the potential to enhance the global hosting capacity of renewable energy in power systems, accelerate the global energy transition, and reduce our reliance on fossil fuel-based generation. Pumped hydro storage (PHS) is the most common storage technology due to its high maturity, reliability, and effective contribution to the integration of renewables into power systems. Accordingly, it is essential to achieve the optimal operation of energy systems combined with PHS. Therefore, this paper comprehensively reviews recent efforts toward the optimal operation of PHS-based energy systems (PHS-BES), considering the diversified energy sources, configurations, grid connectivity, and research directions. The evaluation criteria for the optimal operation of these systems are mathematically addressed and discussed. Moreover, methods of solving the studied problem are categorized and several improvements are suggested. It is observed that more flexible energy policies are urgently needed to encourage new investments in PHS, and the existing environmental and social criteria require further research. Moreover, the hybridization of PHS with other storage devices should be further investigated, and the development of robust hybrid methods for solving the optimal operation of PHS-BES, especially for real-time applications, is highly promising. Based on an in-depth analysis, this paper provides a compendium of real-world research and industry-oriented challenges, and presents future research and industry trends for the optimal operation of PHS-BES.