Analysis and optimization of solar-pumped hydro storage systems integrated in water supply networks

A new strategy for the integrated management of water and energy in large water supply networks with the aim of reducing the energy costs of the energy intensive water facilities via the installation of photovoltaic plants is proposed. To address the non-dispatchability of photovoltaic systems, the integration of pumped hydroelectric storage plants based on the upgrading of existing pumping stations is also proposed. As case study, the proposed integrated solution is applied to two different pumping stations: the “Basso Flumendosa” pumping station, which is also candidate for the conversion to a pumped hydroelectric storage section due to its low utilization factor, and the “Monteleone-Roccadoria” one. A mathematical model is developed with the objective of maximizing the energy self-consumption. Different photovoltaic and turbine sizes are investigated to assess the achievable self-sufficiency rate and economic performance. The effect of the availability of the pumping station for storage purposes and the shape of the daily demand curves on the main result parameters are also evaluated. The results demonstrate that self-sufficiency rates higher than 65% are achievable only with the integration of the pumped hydroelectric storage section. Full self-sufficiency of the two pumping stations can be reached but a reduction of the profitability occurs.