Reflection Phenomena in Underground Pumped Storage Reservoirs

Abstract

Energy storage through hydropower leads to free surface water waves in the connected reservoirs. The reason for this is the movement of water between reservoirs at different elevations, which is necessary for electrical energy storage. Currently, the expansion of renewable energies requires the development of fast and flexible energy storage systems, of which classical pumped storage plants are the only technically proven and cost-effective technology and are the most used. Instead of classical pumped storage plants, where reservoirs are located on the surface, underground pumped storage plants with subsurface reservoirs could be an alternative. They are independent of topography and have a low surface area requirement. This can be a great advantage for energy storage expansion in case of environmental issues, residents' concerns and an unusable terrain surface. However, the reservoirs of underground pumped storage plants differ in design from classical ones for stability and space reasons. The hydraulic design is essential to ensure their satisfactory hydraulic performance. The paper presents a hybrid model study, which is defined here as a combination of physical and numerical modelling to use the advantages and to compensate for the disadvantages of the respective methods. It shows the analysis of waves in ventilated underground reservoir systems with a great length to height ratio, considering new operational aspects from energy supply systems with a great percentage of renewable energies. The multifaceted and narrow design of the reservoirs leads to complex free surface flows; for example, undular and breaking bores arise. The results show excessive wave heights through wave reflections, caused by the impermeable reservoir boundaries. Hence, their knowledge is essential for a successful operational and constructive design of the reservoirs.

Parametric assessment of hydrochemical changes associated to underground pumped hydropower storage

“…An UPHS has in principle less surface impact on landscape and land use as at least, one of the reservoirs is underground. In addition, if an abandoned mine is used as underground reservoir (Pummer and Schüttrumpf, 2018), UPHS may help for a better economic transition for local communities after the cessation of mine activities. However, in this case considered here, concerns may arise about environmental impacts and efficiency of the plant linked to the water exchanges occurring between the underground reservoir and the surrounding porous medium.…”

Transient Simulation of Underground Pumped Storage Hydropower Plants Operating in Pumping Mode

“…Pummer et al [17] analyzed the reflection phenomena in underground pumped storage reservoirs. The results shown excessive wave heights through wave reflections.…”

Numerical study of the Martelange mine to be used as underground reservoir for constructing an Underground Pumped Storage Hydropower plant

“…UPSH possibilities have been investigated in different parts of the world: The Netherlands (Min, 1984), Singapore (Wong, 1996), USA (Allen et al, 1984;Severson, 2011), Germany (Beck and Schmidt, 2011;Zillman and Perau, 2015;Alvarado et al, 2016), Belgium Poulain et al, 2018), Spain (Menéndez et al, 2017), South Africa (Winde and Stoch, 2010a, b;Khan and Davidson, 2016;Winde et al, 2017), Finland and Australia (Academy of Science of South Africa, 2018). However, there are no bibliographical evidences of constructed UPSH plants.…”