Operators, owners, and planning offices are considering dismantling wind turbines without replacing them, or choosing not to repower them. This is due to the discontinuation of state EEG subsidies in Germany, economic considerations that have to do with continuing operations, and even the development of scrap metal prices. Recycling turbine components is thus playing an increasingly important role. Motivated and innovative entrepreneurs are needed to develop environmentally sound ways to dismantle existing plant and implement holistic standards in line with a low-carbon solution.

This will create space for indispensable framework conditions such as legal security, occupational health and safety, and sustainability. At the same time, the same entrepreneurs will have to close the information gaps that still exist among decision-makers, planning offices, demolition and waste disposal companies and owners when it comes to recycling the materials used in the production of wind energy. This particularly applies to rotor blades whose construction is complex.

Rotor blades: does a complex composition necessarily mean complex recycling?

Rotor blades account for only a fraction of the weight of a wind turbine but account for nearly a quarter of the manufacturing costs: high manufacturing costs are a major issue because the blades are subject to a high-frequency development process and also, to a lesser extent, generate a certain amount of production waste. This means that not only old disused rotor blades present a recycling challenge, but also the production waste, which comprises complex materials such as

  • reinforcement fibres, 
  • a polymer matrix (consisting of thermosets such as epoxies, polyesters, vinyl esters, polyurethanes, and thermoplastics),
  • sandwich cores (e.g., balsa wood)
  • surface coatings (e.g., polyethylene and polyurethane)
  • and metals (such as copper wiring and steel bolts).

Glass-fibre reinforced plastic (GRP) is used in numerous areas due to its positive properties. Because of its high strength, flexibility, and processing ease it is popular in the shipbuilding and automotive industry, as well as being used in the production of rotor blades for wind turbines. But, until now, the possibilities for recycling it have been limited. Dumping GRP waste in landfill sites has been prohibited in Germany since 2005 and incinerating it is only permitted to a limited extent.

From demolition to recycling

The successful and economically responsible way to recycle wind turbines involves the following critical steps:

  • employing the right team for the wind turbine in question
  • removing the foundations, crane assembly areas, access roads, and subterranean cables
  • recycling rotor blades made of GRP / CFRP (glass fibre or carbon fibre reinforced plastics) and disposing of them correctly
  • direct sales and marketing support for selling the wind turbines
  • consultancy, market research, and regulatory support

Turning a rotor blade into cement

Once they have been dismantled, rotor blades are sawn up and transported in containers to pre-treatment sites where the solid metal components are separated out and the rotor blade fragments crushed down even more. This material is then transported to a factory, where other impurities are removed before being mechanically processed and homogenised to produce a usable granular raw material substitute with a grain size of < 40 mm. The silicate contained in the glass fibre replaces sand in cement factories and the material is recycled to produce an intermediate product known as cement clinker, which is then mixed with gypsum and ground into cement. So, cement produced in this way can be produced without using sand which is scarce around the world.

This is still far from perfect, and a lot remains to be done ...

At this point, the most responsible way to recycle the silicate in the GRP involves the use of suitable process engineering and thermal pre-treatment within the cement factory although this is also the costliest way to recycle this valuable material both from an ecological and economic perspective. However, the end goal has to be to ensure that the fibres really are reused as part of a genuine circular economy. Both the paper industry and specialist carbon fibre processing firms are already showing how this can be done.

Involving private companies in this process presupposes an economic feasibility on a large industrial scale, which is precisely where the real challenge begins. The market price of carbon fibres, which is twenty-fold higher, as well as the (economic) possibility of making investments that had previously not been considered profitable for fibre optic connections would seem to make a recycling process both compelling and economically reasonable. Nevertheless, so far, many entrepreneurs are not ready to also recycle glass fibre composites and to design these thermosets in a way that they can be used till the end of their life cycle. There is also still a lack of imagination when it comes to considering the use of glass fibres for other applications (such as furniture and kick plates) to give them a genuine “second life”. Dealing with the increasing recycling demand will require an urgent rethink on the part of both the public and the economy.


This text is from the new "German Wind Power Magazine" from the German Wind Energy Association (BWE). Read the first issue of the magazine here for free.