Three options must be considered when wind turbines (WTGs) reach the end of their feed-in tariff support under the Renewable Energy Sources Act (EEG) in Germany: repowering, continued operation or decommissioning of the turbine. While repowering requires planning and licensing permission, technical and economic aspects are crucial for continued operation. Repowering i.e. replacement of an old by a new more powerful turbine makes sense if it serves to significantly reduce the number of WTGs and boost yield. Moreover, operators, property owners and municipalities can continue putting proven sites to good commercial use. What’s more, the acceptance of the local residents is also higher in the case of repowering sites.
If a wind turbine can no longer be used to generate electricity because it is taken out of service or repowered for reasons of age, it is dismantled and disposed of, and the property is restored to its original condition. In general, dismantling and deconstruction are mentioned in the building permission and the lease agreement. Disused wind turbines must be dismantled rapidly, at low-cost and without compromising the environment. At present, disassembly by the dismantling teams is a complicated process – it takes a good four weeks to dismantle a single turbine. Rotor blades, nacelle and generator are lifted from the tower by a crane, disassembled into their individual parts on the ground and then professionally recycled and/or disposed of.
Many materials can be recycled from the dismantled wind turbines such as copper from the cables or steel from the steel tower segments. Most time-consuming is the dismantling of concrete towers: they are cut into segments using a sawing process, blown up or torn down by a special height demolition process on site and then recycled. The recycling material can be used for road construction. The rotor blades are usually shredded and used as substitute fuel in the cement industry. About 80 to 90 percent of a wind turbine can be recycled. However, there are still challenges and optimisation potentials.