Underground Pumped-Storage Hydropower (UPSH) at the Martelange Mine (Belgium): Underground Reservoir Hydraulics

Abstract

<jats:p>The intermittent nature of most renewable energy sources requires their coupling with an energy storage system, with pumped storage hydropower (PSH) being one popular option. However, PSH cannot always be constructed due to topographic, environmental, and societal constraints, among others. Underground pumped storage hydropower (UPSH) has recently gained popularity as a viable alternative and may utilize abandoned mines for the construction of the lower reservoir in the underground. Such underground mines may have complex geometries and the injection/pumping of large volumes of water with high discharge could lead to uneven water level distribution over the underground reservoir subparts. This can temporarily influence the head difference between the upper and lower reservoirs of the UPSH, thus affecting the efficiency of the plant or inducing structural stability problems. The present study considers an abandoned slate mine in Martelange in Southeast Belgium as the lower, underground, reservoir of an UPSH plant and analyzes its hydraulic behavior. The abandoned slate mine consists of nine large chambers with a total volume of about 550,000 m3, whereas the maximum pumping and turbining discharges are 22.2 m3/s. The chambers have different size and they are interconnected with small galleries with limited discharge capacity that may hinder the flow exchange between adjacent chambers. The objective of this study is to quantify the effect of the connecting galleries cross-section and the chambers adequate aeration on the water level variations in the underground reservoir, considering a possible operation scenario build upon current electricity prices and using an original hydraulic modelling approach. The results highlight the importance of adequate ventilation of the chambers in order to reach the same equilibrium water level across all communicating chambers. For fully aerated chambers, the connecting galleries should have a total cross-sectional area of at least 15 m2 to allow water flow through them without significant restrictions and maintain similar water level at all times. Partially aerated chambers do not attain the same water level because of the entrapped air; however, the maximum water level differences between adjacent chambers remain relatively invariant when the total cross-sectional area of the connecting galleries is greater than 8 m2. The variation of hydraulic roughness of the connecting galleries affects the water exchange through small connecting galleries but is not very influential on water moving through galleries with large cross-sections.</jats:p>

Economic aspects of introducing pumped-storage hydroelectric power plants into the mine dewatering system for distributed power generation

“…Implementation of a PSHPP in the power system of mining enterprises is the subject of research in a number of works [3][4][5][6][7][8][9][10][11][12][13]. [3][4][5] consider application of the PSHPP to water drainage during open pit mining operations; [6][7][8][9][10][11][12][13] look into pumped-storage equipment use at water intake facilities of underground mine workings.…”

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

“…Therefore, no previous pumping was considered before the start of the activity of the plant. Certain authors considered that, initially, the underground reservoir must be empty [50] because previous works needed to adapt the mine to be used as an underground reservoir, and this adaptation requires dewatering it. However, it was proven in a previous investigation that the differences between considering a previous pumping or not are negligible and only occur during the early periods [33].…”

Technical and Economic Aspects of Electric Energy Storage in a Mine Shaft—Budryk Case Study

“…Many studies on the use of abandoned mines for energy storage are described in the literature. For example, they refer to thermal energy storage [13,14], compressed air energy storage [15][16][17], underground pumped hydroelectric energy storage [16,[18][19][20][21][22][23], and gravity energy storages with suspended weights in mine shafts [24].…”