[en] 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.
