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Innovation and sustainability in offshore wind Recyclable rotor blades, innovative foundation technologies and eco-friendly installation methods

Innovation and sustainability in offshore wind
Installation of RecyclableBlades at the offshore windfarm Kaskasi. Source: RWE/Matthias Ibeler

Our ‘From Hamburg to the world’ blog series profiles members of the EEHH network, focussing on their international activities or their activities which of great importance for the international energy sector.

Siemens Gamesa recently supplied the world’s first RecyclableBlades for RWE’s Kaskasi offshore wind farm. The first wind turbine to be equipped with these is already supplying green electricity. We report on this project in a joint interview with
- Marc Becker, CEO Business Unit Offshore, Siemens Gamesa Renewable Energy GmbH
- Sven Utermöhlen, CEO Offshore Wind, RWE Renewables GmbH

EEHH: What prompted Siemens Gamesa to bring the world’s first recyclable rotor blades to the wind market? How important is this step for the company's sustainability strategy?

Marc Becker: We aim to lead the way when it comes to sustainability. This includes taking a look at our own energy and resource consumption. That’s why we asked the Science Based Targets Initiative to confirm that our 2025 emission reduction targets meet the most ambitious 1.5°C scenario. By 2040, we aim to eliminate our emissions along the entire value chain, while ensuring that our turbines are 100% recyclable by then. This is already possible for many materials, such as steel and copper. Due to the design of rotor blades, different materials are bonded together with resin, which used to be a challenge, but we’ve now overcome this with our RecyclableBlade.

EEHH: Compared to previous rotor blades, what is the innovation behind the new, recyclable version and what are the benefits for the wind industry (e.g., project developers/turbine operators)? How are the materials recycled when the rotor blades have reached the end of their service life?

Marc Becker: Our RecyclableBlade uses a new resin that can easily be dissolved in a mild acid at the end of the rotor blade’s service life. The various materials in the blade, such as fibreglass and wood components, can then simply be separated out and returned to the material cycle. The recycled material can be used to make suitcases or cabinets for monitors, for example. And the best thing of all is that the production process remains the same and the material properties of the new resin are higher than those of the previous one. Turbine operators benefit because they reduce their carbon footprint and don’t produce any waste when they come to dismantle the turbines at the end of their service life but recover valuable raw materials instead.

EEHH: How come these recyclable rotor blades are being used commercially for the first time at the Kaskasi offshore wind farm? How many wind turbines will be equipped with these?

Sven Utermöhlen: RWE is a world leader in the offshore wind sector. Kaskasi is currently our sixth wind farm off the German coast. However, as members of society and a global offshore player, we’re also aware of the responsibility that comes with this, namely protecting the marine environment when building and operating our turbines, recycling materials and resources at the end of their service life and avoiding waste. Here too, we aim to be pioneers. Our Kaskasi offshore wind farm, located north of the German island Heligoland uses Siemens Gamesa’s recyclable rotor blades under operating conditions for the first time in the world. Around 85 to 90 percent of a wind turbine is already recyclable. Based on weight, the rotor blades are the most significant component to have so far been excluded from this.

We’re equipping a total of three turbines with RecyclableBlades and continuously monitoring these. This is a crucial step towards taking the sustainability of wind turbines to the next level, as well as only producing and using fully recyclable turbines in the long term. Recycling materials also helps to achieve climate neutrality. The Kaskasi wind farm is being built close to our existing offshore wind farms Nordsee Ost and Amrumbank West. So, we’re very familiar with the construction area and have already gained extensive operational experience. These are excellent prerequisites for the research projects and pilot applications that we’re implementing at Kaskasi.

EEHH: Several innovative technologies are celebrating their world premiere at the Kaskasi offshore wind farm. Please can you explain which other technologies and processes are being tested and used there?

Sven Utermöhlen: The use of recyclable rotor blades is just one example of how we test innovations in practice, thereby playing a key role in the further development of the offshore wind industry. At Kaskasi, we’ve used beside the conventional impact piling technology an innovative method for foundation installation. The so called Vibro Pile Driving technology has the potential to significantly reduce underwater noise. This is particularly good for the marine environment. We’re also testing foundation technology that is not yet commercially available. For the first time in the world, we’ve placed special steel collars around three monopile foundations on seabed level. This Collared Monopile has been designed based on a patent developed by RWE. We’re also testing a foundation with an expanding concrete ring that expands in the seabed. The expansion of this concrete ring at the base of the pile compresses the surrounding seabed. Both technologies are intended to significantly increase the stability of the foundations. We aim to prove by carrying out accompanying measurements and tests.

EEHH: And what is the current construction status of Kaskasi?

Sven Utermöhlen: We’re currently installing the wind turbines and gradually putting these into operation. We’re making good progress and have already supplied initial power to the grid. By the end of the year, all 38 turbines should be ready for operation. Kaskasi will then be able to supply the equivalent of over 400,000 households a year with green electricity. This is comparable to a large city such as Frankfurt am Main. Kaskasi is a visible sign of how RWE is driving the expansion of renewable energies in Germany. Faster offshore expansion is extremely important in order to simultaneously achieve climate targets and create more energy sovereignty.

EEHH: Recyclable rotor blades, innovative foundation technologies and eco-friendly installation methods. These are prime examples of how German and European wind companies are driving technological progress in the offshore wind industry. With regard to international business and the associated competition with market stakeholders from other countries, how would you describe the USP of German and European companies? What are the biggest challenges?

Marc Becker: The wind industry has grown in Europe. Our RecyclableBlade and Kaskasi wind farm illustrate the significant added value that Siemens Gamesa is simultaneously generating in several countries. The RecyclableBlade technology was developed in Aalborg, the rotor blades were manufactured in Hull and the nacelles come from Cuxhaven. The fact that these innovations originate in Europe, where a major chunk of the added value is created, means that we firstly ensure technological leadership and secondly control supply reliability ourselves. Instead of further increasing the pressure on domestic producers by means of additional payment elements in offshore tenders, I’d like our contribution to protecting the climate, securing the energy supply and creating jobs in structurally weak regions to be given greater recognition, while also being considered as part of more meaningful quality criteria for tenders.

Biography of Marc Becker

Biography of Sven Utermöhlen

Press release Siemens Gamesa

Press release RWE

About Jingkai Shi

Profilbild zu: Jingkai Shi

Hamburg is the model region for the energy transition and the Germany’s wind capital with connections all over the world. The local renewable energy sector is thus a key partner for the international energy industry. In my role as a contact person for international cooperation in renewables, I’m responsible for REH’s relations with international industry networks, support REH’s members in their international activities, and help Hamburg gain a stronger visibility and perception on the world stage by using social media.