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Separate topic · Evidence-based

Wind turbines
and the marine environment.

Wind power is a low-carbon energy source. That does not exempt large offshore installations from documenting their local and cumulative impacts – particularly near Wadden Sea National Park and the UNESCO World Heritage Site.

Our principle
What we state as fact must be supported by evidence. What we do not yet know must be investigated.
01 Conclusion

Green energy.
The same burden of proof.

The EU's Joint Research Centre assesses wind power as an energy source with low life-cycle greenhouse-gas emissions. At the same time, research and government reports document impacts from construction noise, foundations, cables, corrosion protection, blade wear, vessel traffic and the displacement of existing activities.

The impacts are not identical for every project. They must therefore be assessed for the specific area and cumulatively – not only turbine by turbine or project by project.

EU JRC: Sustainability Assessment of Wind Energy (PDF)

Documented

Wind is a low-emission energy source

The JRC reports average life-cycle emissions of approximately 7.4 g CO₂e/kWh for onshore wind and 17 g CO₂e/kWh for offshore wind.

Documented

Local impacts exist

Research has recorded underwater noise, displacement of wildlife, physical changes to habitats and emissions of materials.

Still uncertain

The cumulative long-term impact

Several official studies point to gaps in knowledge about chronic and cumulative effects on populations and ecosystems.

02 The Wadden Sea

10–12
million

A global
hub for
migratory birds.

UNESCO states that up to 6.1 million birds may be present in the Wadden Sea at the same time and that 10–12 million migrate through the area each year. UNESCO lists wind farms among the activities that may affect the World Heritage values.

Under the common Wadden Sea policy, wind farms are not permitted within the World Heritage property itself. Installations outside it can only be accepted if the area's ecological and landscape values are not harmed. Cable crossings must be minimised and bundled, and impacts on birds and marine mammals must be limited.

UNESCO requires direct, indirect and cumulative effects to be included when assessing projects that may affect World Heritage.

UNESCO: Wadden Sea
UNESCO: Wind-energy policy around the Wadden Sea
UNESCO: Assessing impacts from renewable energy

03 Documented impacts

Research and authorities

What do we
already know?

Here we distinguish between recorded impacts and questions that still lack long-term or site-specific answers.

Close-up of rain erosion and damage to the leading edge of a wind-turbine blade
Actual leading-edge erosion on a wind-turbine blade caused by raindrops. Photo: Belzona Polymerics Ltd. / Wikimedia Commons. CC0 1.0.

Blades

Plastic from leading-edge erosion

A peer-reviewed DTU study estimates approximately 30–540 grams of eroded plastic per blade per year across its overall range, and approximately 80–1,000 grams offshore. For Denmark's wind-turbine fleet, the study estimates approximately 1.6 tonnes per year under the assumptions of the model.

DTU, 2024: Erosion and Microplastic Emission from Wind Turbine Blades (PDF)

Foundations

Metals and other substances

Germany's Federal Environment Agency identifies potential emissions from corrosion protection, cooling and antifouling systems, coatings, operating fluids and accidents. One technical example in the report calculates approximately 38 kg of aluminium per foundation per year from a particular type of coating; the figure does not automatically apply to every wind farm.

Umweltbundesamt, 2024: Hazardous substances from offshore wind

Marine mammals

Harbour porpoises are displaced during pile driving

At Horns Rev II, harbour-porpoise acoustic activity was reduced very close to the construction site following pile driving. The study detected a negative response out to an average distance of 17.8 kilometres. It documents a temporary local impact, not in itself a lasting decline in the population as a whole.

Brandt et al., 2011: Horns Rev II

Birds

Species-specific displacement and collision risk

The Wadden Sea Quality Status Report describes divers as particularly sensitive to offshore wind and reports avoidance at distances exceeding ten kilometres. It also identifies collision risk, attraction to light and disturbance from maintenance vessels. Responses vary between species.

Wadden Sea Quality Status Report: Energy

Ocean physics

Foundations affect vertical mixing

Measurements at two German wind farms indicated increased vertical mixing, altered stratification and nutrient transport. The researchers also stress that natural variability makes the precise impact difficult to isolate.

Floeter et al., 2017: Pelagic effects in the stratified North Sea

Subsea cables

Biological responses to magnetic fields

A 2026 systematic review found behavioural or physiological responses in 66% of the 67 studies included, frequently in fish and crustaceans. The authors also highlight major knowledge gaps concerning chronic effects on populations and ecosystems.

James, Ghodsi & Ford, 2026: 35-year synthesis of submarine cable EMF

Questions for DN

Does the same
precautionary
princip apply?

DN requires a small local brown-shrimp fishery to document its impact on the Wadden Sea. That is a legitimate requirement.

But will DN impose the same requirement for concrete, site-specific and independent evidence on the far greater industrialisation of the North Sea?

Burden of proof

Show the evidence
here as well.

  1. 01

    What materials, surface treatments and operating fluids are used in blades, foundations, cables and platforms?

  2. 02

    What material losses and chemical emissions are expected under local marine and weather conditions over the installations' service life?

  3. 03

    How are particles, metals and other substances measured in water and sediment before, during and after construction?

  4. 04

    How are bird migration, harbour porpoises, fish, crustaceans, the seabed, currents and sediment affected?

  5. 05

    How is the cumulative impact of all existing and planned wind farms, cables, vessels and closed sea areas calculated?

  6. 06

    If the precautionary principle is to be applied to four small fishing vessels, why should it not be applied at least as consistently to large industrial installations?

04 Source archive

Open sources

Read them yourself.
Check our claims.

Every principal factual statement on this page can be traced to research, government reports or UNESCO. The sources describe recorded impacts as well as limitations and contrary findings.

World Heritage

UNESCO: Wadden Sea

World Heritage values, bird numbers, integrity and known impacts.

The other main issue

The fishing case has
its own complete page.

The mine-related prohibition, DN, the lawyers' letter, the fishers, the evidence and the complete timeline are gathered on the fishing-case page.

Go to the fishing case →