What are offshore energy sources

Offshore wind power in Germany

Opportunity for the climate - risk for the seas

Offshore wind power is an important renewable energy source. However, the construction, operation and maintenance of the systems put marine mammals, birds and fish at considerable risk. How much wind power can the North and Baltic Seas tolerate?

Offshore wind farms at sea pose a high risk for the marine environment - Photo: Kim Detloff

Offshore wind power is a key element in the generation of renewable energies. The federal government has formulated ambitious expansion targets through the Renewable Energy Sources Act (EEG) and wants to install around 15,000 megawatts of offshore generation capacity by 2030. Nevertheless, the expansion entails serious risks for marine nature. In particular, the underwater noise during the construction of the thousands of systems becomes an unpredictable burden for the already overused North and Baltic Seas. Only through careful spatial planning and more technical innovation can the energy transition at sea be made in a nature-friendly way.

The ecological impact is dramatic

Offshore pile driving - Photo: Research and Development Center FH Kiel GmbH

The construction, operation and maintenance of offshore wind turbines are associated with harmful effects on marine mammals, birds, fish and the communities on the sea floor (benthos). During the construction phase, it is particularly the intense noise exposure when driving the foundations that becomes a problem. The noise can injure harbor porpoises and fish or drive them out of key habitats. But sea and migratory birds are also affected. Their migration routes are cut by the wind power plants, important resting and feeding areas are lost and there is a risk of collisions with the rotors of the turbines. In this way, wind farms that were built in unfavorable locations become barely surmountable obstacles. This fact is particularly alarming, since the seas are already polluted and threatened in many ways. Overfishing, eutrophication and litter make marine ecosystems difficult to create. There are also a number of industrial activities such as shipping, gravel and sand mining, and the extraction of crude oil and natural gas. The cumulative extent of human activity in the sea leads to a rapid loss of marine biodiversity, the extent of which is difficult to predict.

Control and regulation necessary

How much wind power can the North and Baltic Seas tolerate? What role will offshore wind power play in the energy mix of the future? And how can the negative effects of the construction of wind turbines and their connection to the grid be implemented in a nature-friendly way? Central questions for the future of offshore wind power in Germany. However, there is currently no overarching concept. Numerous offshore projects have been approved to date and in many cases species and nature conservation have been given too little consideration, as a NABU study from 2014 showed. Climate protection and species protection are inseparable and must not be played off against each other. Rather, intact seas have an important influence on the climate crisis due to their natural climatic functions.

Therefore, NABU demands:

  • The expansion of offshore wind energy may only be advanced within the ecological limits of the North and Baltic Seas.
  • In future expansion scenarios, the actual space requirements of wind turbines must be taken into account. Concepts have to take into account the avoidance distances from seabirds to the turbines, habitat loss and collision risks.
  • Perspective expansion goals that go beyond today's EEG are only justified if other pressures on marine ecosystems (e.g. raw material extraction, fishing, shipping) are reduced at the same time.
  • The natural climate-relevant ecosystem services of the oceans, especially as carbon sinks, must be given greater consideration in spatial planning.

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