Faculty of Technical Sciences

This paper focuses on physical modelling of a novel Underground Pumped Hydro-electric Storage (UPHS) system for
storing energy. Potential energy is stored by pumping water into a shallow buried reservoir enclosed by a water-tight flexible
geomembrane. An updated reservoir geometry design is used to overcome previously seen issues with overstressing of the membrane
and at the same time to increase the storage capacity per unit area. A 2.5m diameter small-scale (1:100) 1g physical model of the
system was created using sand as overburden, and the laboratory test setup was used to demonstrate the conceptual behaviour and to
investigate energy loss characteristics of the system under repeated inflation-deflation cycles of the membrane reservoir. In addition,
interface testing has been carried out to investigate the interface shearing behavior between two different membrane types and sand
to further understand the interface shearing mechanisms and membrane wear occurring at full scale pressures. The physical smallscale
and lab tests will help to identify areas which need further attention.