Underground water caverns for the storage of renewable energies in the open-cast mining reservoir – this future scenario of a new pumped storage plant in the Rhenish Opencast Mining Area Garzweiler, Hambach and Inden was investigated by Tractebel Hydroprojekt GmbH in a concept study on the energy re-use of opencast mining waste holes in North Rhine-Westphalia.
In the study commissioned by the state of North Rhine-Westphalia, extensive basic studies in the fields of geology, hydrology and hydrogeology were carried out as well as a site analysis in which about 25 topographically possible pumped storage sites in the open-cast mining region were identified and evaluated. In various basic technical concepts, it was examined to what extent a new pumped storage plant could be integrated into the future regional planning of the state government, which provides for permanent flooding of the opencast mining remaining holes after the end of coal mining. The most attractive pumped storage option in terms of storage is the concept of an underground cavern reservoir located in the area of the deep-lying residual hole sole as a sub-basin in the open-cast mining reservoir, which was later filled with water. The associated upper basin would be built either at the edge of the remaining hole or on a higher artificial dump. With such a PSW plant, drop heights of up to 600 m could be generated in the open-cast mining area. The Hambach opencast mine with the deepest remaining hole would be the most suitable location. In any case, the planning, construction and operation of a pumped storage plant offers a future perspective for the open-cast mining region after the end of mining. Since the north-south new line planned by the Federal Network Agency would run close to the Rhine district, a pumped storage plant located there would be ideal for the intermediate storage of the wind energy fed in the north of the country.
Matthias Feldmann - Munich