Optimization of sizing and operation of pumped hydro storage plants under current and future economic scenarios

Hydro power plants are among the most mature technologies for power production. To optimally manage possible overgeneration from non-programmable renewable energy sources, such as photovoltaic power plants and wind power plants, a Pumped Hydro Storage (PHS) plant can be employed as both a storage device (pumping mode) and a power production technology (turbine mode). To this aim, this paper deals with the optimization of the sizing and operation of a PHS plant that interacts with a power generation system consisting of different power production technologies. The national power production system and electric energy demand of Sweden are used as a case study and a PHS plant is sized and managed to fit conventional hydraulic sites as well as abandoned mines to be used as reservoirs. First, this paper develops a methodology suitable to identify the optimal size and operation strategy of the PHS plant, by means of the simultaneous use of two algorithms: surrogate modeling optimization algorithm and mixed integer linear programming algorithm. Then, this paper analyzes different present and future scenarios of electricity production, demand, and cost, in order to assess the energy and economic feasibility of PHS plants. The analyses carried out in this paper demonstrate that PHS plants are highly recommended with high overgeneration from photovoltaic power plants or wind power plants. This situation is a likely scenario thanks to green energy transition strategies. The return on investment of the most cost-effective solutions in the future scenarios ranges from 8.5 % to 11.6 %. In all the investigated scenarios, the results indicate that PHS is mainly employed to meet domestic electricity demand.