Interim storage of wind power

The goal of the project is to analyze the possibility of an interim storage of wind power by using underground pump storage stations in old mining areas. From the geomechanical point of view the feasibility of the foresaid idea depends on the static stability of the underground openings which must be excavated to store the water in an upper and lower basin, to connect the basins by a pressure shaft, to install the turbine and generator in an underground cavern and to guaranty the infrastructure for the all over operation by mine drifts. The static stability of underground openings depends on rock and rock mass strength, geology, tectonic elements, stress-strain and hydraulically behaviour of rock and rock mass, the primary stress field, the depth of the underground openings, the distance of excavations to old mining areas, the excavation method and last but not least the reinforcement. Taken into account the foresaid bearing values geomechanical calculations based on empirical, analytical and numerical computations are done for an underground storage system which is characterized by parallel drifts with a cross section area of about 30 square meters. Because only few respectively no informations regarding the geomechanical behaviour of the site specific rock mass are available, the calculation is defined by a very row estimation. Nevertheless it was estimated, that there are no basements which answer back the assessment, that the basic feasibility of the project is given. Regarding to the quality and amount of reinforcement needed to guaranty the static stability further investigations of the site specific situation are heavily demanded.