The Impact of Hydrogeological Features on the Performance of Underground Pumped-Storage Hydropower (UPSH)

Estanislao Pujades,Alain Dassargues,Angelique Poulain,Philippe Orban,Pascal Goderniaux

doi:10.3390/app11041760

Abstract

Underground pumped storage hydropower (UPSH) is an attractive opportunity to manage the production of electricity from renewable energy sources in flat regions, which will contribute to the expansion of their use and, thus, to mitigating the emissions of greenhouse gasses (GHGs) in the atmosphere. A logical option to construct future UPSH plants consists of taking advantage of existing underground cavities excavated with mining purposes. However, mines are not waterproofed, and there will be an underground water exchange between the surrounding geological medium and the UPSH plants, which can impact their efficiency and the quality of nearby water bodies. Underground water exchanges depend on hydrogeological features, such as the hydrogeological properties and the groundwater characteristics and behavior. In this paper, we numerically investigated how the hydraulic conductivity (K) of the surrounding underground medium and the elevation of the piezometric head determined the underground water exchanges and their associated consequences. The results indicated that the efficiency and environmental impacts on surface water bodies became worse in transmissive geological media with a high elevation of the piezometric head. However, the expected environmental impacts on the underground medium increased as the piezometric head became deeper. This assessment complements previous ones developed in the same field and contributes to the definition of (1) screening strategies for selecting the best places to construct future UPSH plants and (2) design criteria to improve their efficiency and minimize their impacts.

Highlights

Renewable energies, such as solar or wind, may not be sufficiently efficient since they are intermittent and random, and their production of electricity is not adapted to the demand [1,2,3,4]
Despite the fact that all the pumped water can be discharged into the underground reservoir, the results showed that water exchanges were higher than in the other scenarios, which indicates that the interaction betwe1e1notfh1e6 Underground pumped storage hydropower (UPSH) plant and the surrounding materials, and the impact on the groundwater, was high
Despite the fact that all the pumped water can be discharged into the underground reservoir, the results showed that water exchanges were higher than in the other scenarios, which indicates that the interaction between the UPSH plant and the surrounding materials, and the impact on the groundwater, was high

Summary

Introduction

Renewable energies, such as solar or wind, may not be sufficiently efficient since they are intermittent and random, and their production of electricity is not adapted to the demand [1,2,3,4]. For this reason, they must be combined with energy storage systems (ESSs) [5] that allow for balancing the production and the demand [6]. The excess of electricity during low demand periods is stored in the form of potential energy by pumping water from the lower to the upper reservoir. PSH plants can only be installed in relatively steep areas [16]

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Conclusion