| Abstrakt: |
Underground energy storage plays an important role in electric energy supply systems. Hydroelectric power schemes are important undertakings that can make use of underground space and storage of energy. Reversible hydro power plants are one of several technologies that allow to store energy, by pumping water from a lower reservoir to an upper reservoir during periods of lower energy consumption. This technique makes it possible for hydro power plants to take advantage of their power capacity at any time of the year, regardless of rainfall. New reversible hydro power plant developments that make use of deep underground reservoirs are called UPHS, underground pumped hydroelectric scheme. Just as in conventional "above the ground" reversible hydro power plants, during periods of low energy demand, the surplus of electrical energy can be used to transfer water from an underground lower reservoir to an upper reservoir (which can also be underground) which is stored in the form of potential energy. In this paper, we describe the first UPHS system in the world, the Socorridos hydroelectric scheme, developed in Madeira Island, and its feasibility from a geotechnical point of view. This hydroelectric project is equipped with reversible units with a difference in height of about 450 m between the upper and the lower reservoirs. The host rock mass consists of volcanic formations, which include basalts, breccias, tuffs, and deposits. For the characterization of the rock mass, empirical systems were used, with special emphasis to the novel VRS system for volcanic formations. Additionally, in situ dilatometer tests were performed to characterize the rock mass. A 3D finite element model of the complex underground cavities, including only the lower reservoir and the pumping station cavern, was developed using the software Abaqus. The numerical results of the model are in good agreement with the field monitoring results. [ABSTRACT FROM AUTHOR] |
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