Visionary Wind Power RWE Offshore wind project "Thor"

REH met with Thomas Michel, COO of RWE Offshore Wind GmbH, to discuss Denmark's largest offshore wind farm Thor, the use of recyclable rotor blades, towers made of greener steel and a new life for foundation covers.

REH: RWE is currently constructing the Thor offshore wind farm in Denmark. Can you tell us a bit about how the project is going and what makes this wind farm so special?
Michel: Our Thor offshore wind farm is under construction 22 kilometres off the west coast of Jutland in the Danish North Sea. With an installed capacity of more than a gigawatt, it will be the largest offshore wind farm not only in Denmark, but the whole of Scandinavia once it is commissioned in 2027. Thor will generate enough green electricity to cover the annual needs of over one million Danish households.

Thomas Michel: "We will start installing the foundations in the coming months. They are currently stored in Eemshaven and will be shipped from there to the construction site at sea. The monopile foundations are up to 100 metres long and each tip the scales at up to 1,500 tonnes, equivalent to the weight of around 1,000 small cars. Starting in 2026, the 72 wind turbines will be erected on these foundations, each with a capacity of up to 15 megawatts. We will conduct turbine installation from the Danish port of Esbjerg. Siemens Gamesa is in charge of manufacturing the turbines. What makes this project so special is that we are having half of the wind turbines fitted with ‘GreenerTowers’. These steel towers have a lower carbon footprint. 40 turbines will be equipped with recyclable rotor blades."

REH: So the Thor offshore wind project will involve recyclable rotor blades and GreenerTowers. Can you describe the underlying technology and the goals that RWE is pursuing?

Thomas Michel: "RWE is a world leader in the offshore wind sector. However, as members of society and a global offshore stakeholder, we’re also aware of the responsibility that comes with this: for example, 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. Offshore wind turbines already have one of the best carbon footprints of all power generation technologies. But we must bear in mind that tower production accounts for around a third of all life cycle carbon emissions from wind turbines. The use of greener steel is therefore an important step towards making electricity generation from wind energy even more sustainable. We are therefore delighted that RWE is the world’s first company to use GreenerTowers from Siemens Gamesa. The steel sheets in these towers are made from more environmentally friendly steel, which produces around 63 percent less CO2 emissions than conventional steel. Green power and scrap steel instead of iron ore are used to decarbonise steel production.

Established recycling methods already exist for many components. Until now, though, it has been more difficult to recycle the materials used in the rotor blades. A novel type of resin with a special chemical structure enables the separation of materials used in Siemens Gamesa's recyclable rotor blades. This involves a process that protects the properties of the individual materials and enables their reuse in the automotive industry or in consumer goods, to name just two applications. We are already operating the world's first fully recyclable rotor blades at our German offshore wind farm Kaskasi and will install them not only at Thor but also at Sofia, our offshore project off the British coast."

REH: Are you considering any other innovative approaches to make the Thor wind farm even more sustainable?

Thomas Michel: "The aim of our offshore projects is to contribute to sustainability – and not just in the production of electricity. At Thor, for example, we are installing reusable foundation covers during the construction phase, in addition to recyclable rotor blades and GreenerTowers. This enables us to reduce waste and increase recyclability.
The covers are used as a temporary but essential solution to protect against seawater, rain and bird droppings until the wind turbine towers are installed on the monopile foundations. The covers are usually disposed of once the wind farm is up and running, as they are purpose-built for a specific offshore project. Our covers in the Thor project are built by the Dutch company Circular Covers B.V. and are made of glass fibre reinforced composite panels that are bolted to a steel frame. With this design, we can now adapt the panels for reuse with different sizes of monopile. The steel can also be recycled at the end of its service life.

REH: Will RWE also include the reusable foundation covers in future offshore wind projects?

Thomas Michel: "The individual composite cover panels can last around 15 years or even longer, depending on how often the diameter needs to be adjusted. The 72 panels for Thor were already installed in an offshore wind farm off the coast of the Netherlands. RWE is the world’s first company to reuse these covers. And because we want to continue conserving resources and avoiding waste going forward, we will do what we can to use these covers for other RWE offshore projects as well."

REH: Qualitative criteria should be more relevant in the allocation of land for offshore wind farms instead of – or in addition to – just the question of pricing. How do you view this development and where do you see the challenge?

Thomas Michel: RWE endorses the EU’s Net-Zero Industry Act, which provides for the establishment of resilient and sustainable supply chains for the European energy transition and the application of qualitative criteria in future renewable energy auctions. But energy supply still needs to be affordable and secure. The pace of offshore expansion must be maintained as well. The introduction of quality criteria must also consider cost efficiency and the necessary flexibility in the procurement of components, while also minimising red tape. It is also important to compensate for additional costs that may be incurred due to the introduction of qualitative criteria – bilateral contracts for difference (CfDs) and sufficiently high bid caps would be helpful here."

Thank you very much for the interview!

Our guest:
Dr Thomas Michel, Chief Operating Officer (COO), RWE Offshore Wind GmbH
- 1999-2008 Doctorate (Dr Ing.) in Electrical Engineering, Technical University of Berlin, Vordiplom in Industrial Engineering, Technical University of Darmstadt, Diplom in Industrial Engineering, Technical University of Dresden
- 2009-2023 various (management) positions at Vattenfall, E.ON and RWE in the offshore wind sector
- Since 09.2023, COO at RWE Offshore Wind