Renewables Windmill recycling: Status quo, challenges and opportunities

8 Reading Time

Wind power is the backbone of the German energy transition - but what actually happens to wind turbines when they reach the end of their service life? Many wind turbines have also reached the end of their service life in Germany in the coming years. This raises important questions for the wind energy industry: How can materials such as concrete, steel and, above all, the problematic rotor blades be recycled sustainably? Which standards should be applied? And how can the individual components be usefully reused?

There are no binding standards yet, but innovative solutions are now developing on the market that revolutionise recycling and exploit the potential of wind power more holistically - and above all more future-proof.

The current situation

With almost 29,000 wind turbines, wind energy in Germany now accounts for almost a third of all electricity generation - and the trend is increasing .¹ This is also because wind turbines are becoming bigger and more efficient and can thus produce more electricity: In 2023, the average wind turbine was already 10 per cent more powerful than a year earlier, while the average size of the wind turbine blades, also known as rotor blades, increased by 6 per cent over the same period.²

But as the number of modern wind turbines increases, so does the need for sustainable solutions for dismantling old wind turbines. After all: Wind turbines have an estimated service life of 20 to 30 years, after which they must be dismantled again by the respective operator and replaced with new turbines if necessary.

In Germany, around half of the wind turbines are now over 15 years old, and a quarter are already over 20 years old. As a result, almost 15,000 of German wind turbines have already reached at least half of their service life.³ Germany is therefore facing a major dismantling wave in the coming years - and this brings its own challenges.

Big, bigger - and even better?

Modern wind turbines are becoming ever larger in the course of so-called “ repowering ”: Older wind turbines will be replaced after their service life by more powerful models with significantly larger dimensions: While the average diameter of the rotor blades was still 95 metres in 2013, it was already almost 150 metres at the beginning of 2024.

And the height of the towers is also increasing steadily, with an average hub height of 150 metres.⁴ This means that modern wind turbine towers are now almost as high as Cologne Cathedral - the third highest church in the world.

Comparison of wind turbine sizes

klimaVest: Die Grafik zeigt die Rotorendurchmesser der Windräder auf See.

Today, this quickly results in a total height (hub height plus rotor radius) of around 220 metres in assembled condition. Some projects go even further: A wind turbine development in Lusatia is planning a wind power plant with a hub height of 300 metres and rotor blades that are over 100 metres long - a globally unique project that aims to reach new heights in the wind power industry.⁵

The background to this growth dynamic: Modern wind turbines are expected to be up to seven times more powerful than their predecessors. The aim is to significantly reduce the size of many wind farms and still increase their overall performance. This development improves energy yield, but also increases material requirements and makes dismantling more difficult once the wind turbine has exceeded its service life.

Turn old into new: The challenge was

If a wind turbine needs to be dismantled, there is above all a question: What happens to the old windmill? This issue is currently playing a major role, as more and more wind turbines will soon reach the end of their subsidised service life.

Most of this question is quite easy to answer - about 90 percentto be precise. This is the proportion of materials in a wind turbine that can be easily recycled and reused, whether for further wind power projects or in other industries. These 90 percent are primarily the wind turbine tower: It consists primarily of a concrete base fitted with a steel cap. Both materials can be easily recycled, for example, the concrete is often used in split, i.e. crumbled form for road construction. And if the mild steel does not show any signs of wear or rust, it can also be used for further construction projects without problems.

It only becomes a real problem for the remaining around 10 percent of the entire wind turbine: the blades. They consist of a complex material mix of balsa wood and plastics, which are reinforced with glass or carbon fibres. These materials ensure stability and weather resistance during operation, so that the blades can withstand all weather conditions even at speeds of up to 400 km/h.

The stability this material mix brings ultimately creates difficultiesin the recycling process: For recycling the rotor blades, the glass and carbon fibres would have to be separated from the plastic again. So far, however, there are only a few and very elaborate and expensive methods for this. For many operators, such procedures are therefore often not the first choice.

Abtransport eines Windradflügels auf einem Lastwagen

This is why the recycling problem has often been ignored so far: Dismantled blades were in some cases left unused on fields for years.⁷ In many other cases, the glass fibre-reinforced rotor blades in particular are often used as replacement fuel or deposited abroad - solutions with which Peter Kurth, President of the BDE Waste Management Association, is not at all satisfied. He regards these forms of recycling as an annoying wasteof resources: “The recyclable materials have to be returned to the cycle instead of simply burning them,” says Kurth.⁸

A study by the Federal Environment Agency from 2022 has shown that almost 400,000 tonnes of waste will be generated by glass fibre-reinforced plastics in rotor blades over the next 20 years alone. Wind turbine blades therefore generate a large amount of waste, but it doesn't have to be any.

Organisations such as the Waste Management Association or the German Wind Energy Association are therefore actively committed to the construction of wind turbines that can be better recycled and returned to the recyclable material cycle - not least against the backdrop of an ever-increasing awareness of sustainability. After all, sustainable wind energy production also contributes to this.

Mandatory industry standards are missing

The recycling problem is also supported by the absence of clear standards that provide clear - and above all mandatory - guidelines at federal level. Much more so, it is the individual municipalities that decide which standards operators must follow when constructing and dismantling wind turbines. On this basis, the authorities ultimately also issue the respective authorisations. The only obligation for operators is to guarantee disposal in accordance with the German Circular Economy Act.10

The provisional standard DIN SPEC 4866 came closest to such an industry standard: It was developed in cooperation with the Industrial Association for Repowering, Dismantling and Recycling of Wind Turbines e.V. (RDRWind), the Federal Environment Agency and the German Institute for Standardisation and published in 2020. This standard provides guidelines for dismantling, dismantling and recycling and has become one of the top 10 industry standards.11 Although it has made a significant contribution to standardising and professionalising the dismantling process, However, it has also been implemented as standard by only a few federal states and municipalities so far - but not by all.

However, this preliminary standard is not the end when it comes to standardisation in the wind energy industry: Projects such as the DIN working group “Demolition Work” are currently developing a DIN standard and - equally promising - a quality mark based on DIN SPEC 4866. Both projects are intended to ensure greater transparency and comparability on the market.12 For operators as well as authorities, municipalities and neighbours, the quality mark could serve as a transparent starting point in the future to obtain information on compliance with safety requirements and the environmental compatibility of the respective dismantling processes, among other things.

Investing in wind power

Wind power investments 2025: Expertise is valuable in stormy times

Wind power as an investment is becoming increasingly popular, and the market has grown considerably in recent years. But a larger, more competitive market can also overheat more quickly. We have compiled the basics of this investment class for everyone who needs an overview.

To the overview article on wind power investments

From rotor blade to terrace plank: The innovative power of recycling technology

And the market has also been changing on the technological side for some years now: Among other things, innovative companies are working on sustainable solutionsto simplify recycling processes and recycle blade waste. One example of this is Novo-Tech: The German company, based in Saxony-Anhalt, processes old rotor blades into terrace decking and other elements for outdoor use. The wings are combined with material residues from the wood industry for this purpose. For example, Novo-Tech recycles around ¹,000 tonnes of rotor blades annually - and this with 100% green electricity.13

In addition to recycling, other companies on the market also produce wind turbines or individual wind turbine elements from more environmentally friendly materials. The Swedish startup Modvion stands out here in particular: The company designs and manufactures wind turbine towers made from pure wood. Up to 144 layers of plywood are pressed and assembled into a tower in individual modules.14 Following a prototype that Modvion built on the Swedish island of Björkö in 2020, the first commercial wooden wind turbine construction for the Swedish energy company Varberg Energie followed in 2023. With a total height of 105 metres, the tower is probably the largest wooden wind turbine in the world, according to the company.

But there is a problem here: For the most difficult part to recycle - the blades - models made of glass- and carbon-fibre-reinforced plastics continue to be used. The sustainable added value of wooden wind turbines thus ends here at a current altitude of just over 100 metres.

A solution to this problem has been developed by the German start-up Voodin Blade Technology, which manufactures the traditionally difficult-to-recycle rotor blades entirely from wood. This will not only reduce the CO2 emissions associated with production by 78%, but also the costs by as much as 20%.15 The rotor blades are made of veneered laminated wood. By using computer-controlled CNC milling machines, the manufacturing process can also be more specifically automated, which contributes to lower manufacturing costs. Production can therefore also take place closer to the wind farms themselves. This ensures shorter transport distances and thus more effective CO2 savings.

In mid-2024, the first wooden Voodin rotor blades were installed at a German wind farm in Breuna. The next step is to produce and install larger blades with a length of 60 to 80 metres. Jorge Castillo, co-founder of Voodin, is very optimistic: "Over the last two years, we have carried out hundreds of laboratory tests to perfect the blade material. According to all our tests, our blades are even more durable than the existing fibreglass blades, as they exhibit less fatigue and are proven to withstand all types of onshore weather conditions extremely well," Castillo explains.

Thinking holistically about the wind energy industry

Wind power is a central and indispensable component of the German energy transition, but its sustainability potential must be considered holistically in the future - not only with regard to energy production itself, but also beyond. Innovative and promising solutions are developing on the market to make future recycling of the plants and thus the entire life cycle of wind turbines more environmentally friendly.

Binding standards and greater transparency can also help to overcome the growing challenges of the wind energy industry in the future - and to further expand its contribution to an all-round sustainable energy economy.

¹ electricity report (2024). Wind energy in Germany.
https://strom-report.com/windenergie/

² Deutsche Windguard (2024). Status of onshore wind expansion in Germany. First half of 2024. P. 6.
https://www.windguard.de/Statistik-1-Halbjahr-2024.html?

³ Wind and Solar Agency (2024). Dismantling and recycling.
https://www.fachagentur-windenergie.de/themen/rueckbau-und-recycling/

⁴ Deutsche Windguard (2024). Status of onshore wind expansion in Germany. First half of 2024. P. 6.
https://www.windguard.de/Statistik-1-Halbjahr-2024.html?file=files/cto_layout/img/unternehmen/windenergiestatistik/2024/Halbjahr/Status%20des%20Windenergieausbaus%20an%20Land_Halbjahr%202024.pdf

⁵ MDR (2024, 20 September). Largest wind turbine in the world: Laying the foundation stone in Lausitz for 400-metre giants.
https://www.mdr.de/wissen/naturwissenschaften-technik/windkraft-firma-aus-dresden-baut-hoechstes-windrad-der-welt-100.html

⁶ Federal Environmental Office (2022, 26 September). Rotor blade preparation and recycling of fibre composite materials.
https://www.umweltbundesamt.de/themen/abfall-ressourcen/produktverantwortung-in-der-abfallwirtschaft/windenergieanlagen/rotorblattaufbereitung-recycling-von#undefined

⁷ Deutschlandfunk (2024, 26 October). Disposal problem for rotor blades.
https://www.deutschlandfunk.de/recycling-windraeder-100.html

⁸ Tagesschau (2023, 6 July). Recycling industry sees a waste problem with wind turbines.
https://www.tagesschau.de/wirtschaft/recycling-branche-warnt-vor-muellproblem-windraeder-100.html

⁹ Federal Environmental Office (2022, August). Final report: Development of decommissioning and recycling standards for blades. S. 125.
https://www.umweltbundesamt.de/sites/default/files/medien/479/publikationen/texte_92-2022_entwicklung_von_rueckbau-_und_recyclingstandards_fuer_rotorblaetter_0.pdf

¹⁰ Wind on Land Specialist Agency (2023, July). In a nutshell: Dismantling and recycling.
https://www.fachagentur-windenergie.de/fileadmin/files/Veroeffentlichungen/Rueckbau/FA_Wind_Kompaktwissen_Rueckbau_und_Recycling_07-2023.pdf

¹¹ Renewable energies (2021, 6 September). DIN SPEC 4866 success report.
https://www.erneuerbareenergien.de/technologie/betrieb/rdrwind-erfolgsbilanz-der-DIN-SPEC-4866

¹² Institute for Regenerative Energy Management (2023, 7 September). RDRWind focuses on professionalisation through standardisation and standards.
https://www.iwr.de/ticker/repowering-demontage-und-recycling-von-windturbinen-rdr-wind-setzt-auf-professionalisierung-durch-normung-und-standards-artikel5791

¹³ EnergyWinch (2023, 8 October). Supporting the circular economy.
https://energiewinde.orsted.de/trends-technik/windraeder-recycling-rotorblaetter-novo-tech-terrassendielen-cradle-2-cradle