Empirical Analysis and Geomechanical Modelling of an Underground Water Reservoir for Hydroelectric Power Plants

Abstract

The European Union policy of encouraging renewable energy sources and a sustainable and safe low-carbon economy requires flexible energy storage systems (FESSs), such as pumped-storage hydropower (PSH) systems. Energy storage systems are the key to facilitate a high penetration of the renewable energy sources in the electrical grids. Disused mining structures in closed underground coal mines in NW Spain have been selected as a case study to analyze the construction of underground pumped-storage hydropower (UPSH) plants. Mine water, depth and subsurface space in closured coal mines may be used for the construction of FESSs with reduced environmental impacts. This paper analyzes the stability of a network of tunnels used as a lower water reservoir at 450 m depth in sandstone and shale formations. Empirical methods based on rock mass classification systems are employed to preliminarily design the support systems and to determinate the rock mass properties. In addition, 3D numerical modelling has been conducted in order to verify the stability of the underground excavations. The deformations and thickness of the excavation damage zones (EDZs) around the excavations have been evaluated in the simulations without considering a support system and considering systematic grouted rock bolts and a layer of reinforced shotcrete as support system. The results obtained show that the excavation of the network of tunnels is technically feasible with the support system that has been designed.

Prediction of water source and water volume of underground reservoir in coal mine under multiple aquifers

“…In particular, in recent years, all sectors of society have paid increasingly more attention to the ecological environment, forcing enterprises to continually carry out technological innovations to fundamentally solve the problem of water resources protection and utilization, thus achieving the goal of 'zero discharge' and 'optimal utilization' of mine water (Hannan & Broz 1976;Cao et al 2019;González-Quirós & Fernández-Álvarez 2019;Li et al 2019;Zhao et al 2019;Jiao et al 2020). Underground reservoir has the characteristics of no land occupation, large storage capacity and small evaporation loss (Hannan & Broz 1976, Menéndez et al 2019Fan et al 2020;Menéndez et al 2020;Song et al 2020;Wang et al 2020a, 2020b, 2020c, Yao et al 2020Yang et al 2020). Shendong Mining Area of China took the lead in carrying out the practice of water resource preservation during mining, covering the storage, purification, and recycling of groundwater reservoir water resources, which reasonably solves the problem of coordination between ecological protection and coal mining in the mining area, and achieves significant economic and social benefits (Gu 2015;Cao et al 2019).…”

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.…”

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].…”