Is it possible to build wind farms on former opencast mining sites sooner than has been the case up to now? Are freshly recultivated areas already stable enough? Ruhr University Bochum, engineering office J?rss-Blunck-Ordemann (JBO) and RWE are investigating this in a joint research project. Soils that are still young usually need to settle for several years before they can be cultivated. Modern wind turbines weigh up to 6,500 tonnes. Therefore, recultivated areas are usually only built on after up to 15 years.

On the initiative of RWE, the experts will now be investigating an operating area at the Inden opencast mine for three years. There, they want to select the most complex possible subsoil for the research project. Then the field test is due to begin with gravel and sand to be piled up on a circular area with the radius of a wind turbine. The earth masses weigh as much as a wind turbine including its foundation. Measuring devices in the soil will subsequently record any geomechanical changes. Computer calculations based on data from the field tests and accompanying geotechnical laboratory investigations will be carried out. They will not just model the settlement of the subsoil under the dead weight of the wind turbine, but also the effect of wind loads on the ground around such a turbine.

Christian Vogt, responsible for developing wind farms at RWE: “Together, we want to push ahead with the expansion of wind power and also use more difficult locations for this purpose. We are thus very pleased that the Federal Ministry for Economic Affairs and Climate Protection is supporting our project, thereby helping to examine to what extent and under what conditions the use of freshly recultivated areas is possible. In the Rhenish mining area alone, we want to build 500 megawatts of additional renewables capacities by 2030 to advance the energy transition.”

Torsten Wichtmann, Professor of Soil Mechanics, Foundation Engineering and Environmental Geotechnics at Ruhr University Bochum: “We are confident that we can reliably assess the suitability of sites on freshly recultivated areas using computer simulations, which we want to confirm using the test fill in Inden. This innovative project combines our many years of expertise on wind turbine foundations and soil mechanics issues in the recultivation of former opencast mines.”

With the “Innovations for the energy turnaround” project group, the Federal Ministry for Economic Affairs and Climate Protection promotes research and development projects on wind energy that also deal with the development of sites that are difficult to access. The research project in the Inden opencast mine is being supported with 683.345 euros.* The Ruhr University Bochum is to receive a large part of the money. It is the first project to systematically investigate the suitability of freshly filled-in opencast mining areas.

by evwind