Wind turbines that reach the end of their service and operational life need to be dismantled. The same applies when a replacement by a new, more powerful turbine is planned as in the case of so-called repowering. The approval procedure already stipulates that wind turbines must eventually be completely dismantled and the grounds upon which they are erected be restored to original condition. In view of the fact that, as of 2021, thousands of turbines will no longer be eligible for subsidies under the German Renewable Energy Sources Act (EEG – see p. 16), the issue of dismantling is set to become increasingly relevant. As the German Wind Energy Association (BWE) explains: “The dismantling conditions are usually outlined in the building permit and clarified in the lease agreement”. Federal state legislation regulates “the form in which the building permit authorities ensure compliance with this mandatory requirement”. In some federal states the dismantling costs must be covered by a surety prior to the start of the project.
Secondary market for old systems not very lucrative
There is a secondary market for old turbines. They can be sold abroad, for example, where they can continue to produce electricity. However, as experts point out, the market is changing: older mid-sized turbines are already failing to finding buyers and revenues from their sale are also decreasing. This trend is all the more likely to continue if more turbines are dismantled as of 2021. Operators, therefore, will incur costs for dismantling and disposal as standard practice.
Turbines are always dismantled with the aid of a crane, whereby the individual components are dismantled one-by-one from top to bottom, taking due account of occupational safety and environmental aspects, starting with the rotor blades and the nacelle. Concrete towers can be dismantled either with the aid of a wrecking ball or so-called demolition shears. Blasting is another suitable option, also for the foundations. Furthermore, it is possible to use a jackhammer attached to an excavator instead of the shovel to break up the foundations, which detaches the concrete from the steel reinforcement, after which the metal and concrete can be recycled separately. The concrete, for example, can be crushed to a certain size in a crushing plant before being used to construct such things as access roads to new wind turbines.
Rotor blades that are not to be resold or used as spare parts are cut into transportable pieces on the ground and transported away for further processing. If water is used during the cutting process, any dust or sludge is collected at source. Other components, such as gears or bearings, can also be refurbished and reused as used spares. The use of used spare parts is particularly useful in continued operation plants, which need to be run as cost-efficiently as possible. All other materials and components are recycled. According to the BWE, “80 to 90 percent of the components, such as the metal-bearing turbine components, the electrical system in its entirety as well as the foundations and tower (steel, copper, aluminium and concrete components), can be recycled in established recycling cycles”.
Currently, the composite materials from which the rotor blades are made continue to present a recycling challenge. They usually consist of glass fibre or carbon fibre reinforced plastics. However, as the BWE points out, these are “nothing new for the recycling industry, as boat hulls, aircraft parts and other fibre composite components are also disposed of. In addition to thermal recycling, the industry is also putting a lot of work into the developement of new raw material recycling concepts”.
Four short questions for Bernd Weidmann
How does the secondary market work?
Primarily via online platforms that bring buyers and sellers together. It is important to consider who is actually behind the ads – brokers or operators?
Turbines are almost exclusively purchased abroad.
Which components are easiest to resell?
Bernd Weidmann: Often it is gearboxes, control elements, transformers, switch cabinets and generators from different manufacturers. Some systems which use permanent magnets also use neodymium, an extremely valuable raw material. Our advice is not to dispose of this material carelessly. There is great demand for it on the market and thus the potential of minimising dismantling costs.
Is there a demand for complete systems?
Bernd Weidmann: Yes, the trend is for 1.5–3 MW turbines. Smaller systems are often sought after as a way of acquiring large components or replenishing spares holdings.
Many more will be offered for sale as of 2021 ...
Bernd Weidmann: That’s correct: prices for complete systems will certainly fall, hence our tip to offer systems and large components for sale at an early stage. It can take several months to conclude a sales contract.