4sea, Climate Politics, Energy, Oceans

Development of wind farms on the high seas: a new challenge for the international law of the sea

 This article is part of the 4sea project.

Climate change and growth of the world population is finally making us create a common wake-up call about to be taken serious: the use of fossil fuels must be reduced. As a result of this, development of renewable energy is gaining ground. For a long time, renewable energy has been developed land-based, however there is now a growing trend for renewable energy to be developed in the sea. Because of the benefits of offshore renewable resources, sea is becoming a playing field for new developments. For example, as for wind energy, marine winds are more abundant, stronger, and blow more consistently than land winds.

For years, wind offshore turbines were constructed only in territorial seas and exclusive economic zones, due to technical reasons. Indeed, fixed wind structures required low sea-depth. To answer growing international demand for cleaner energy and thanks to technology development, we are now very close to see wind farms being installed on the high seas, particularly floating wind farms. [1]

Maritime Zones under the International Law of the Sea

The freedom of constructing wind farms on the High Seas

The United Nations Convention on the Law of the Sea (UNCLOS) referred to as the Constitution of the Sea does not provide for a proper regime for wind energy. This is not surprising because in 1982, when the Convention was elaborated, offshore wind farm was not yet a widely spoken subject.

UNCLOS describes the high seas as a “res communis”: all countries can use and exploit them so long as they respect conditions laid down by rules of international law. In other words, according to the principle of freedom of the high seas, exploitation of wind by States is free. This raises several concerns.

Potential designs for floating wind energy structures

Potential sea-grabbing of the High Seas by developed States

Development of wind farms by States on the high seas could call into question the principle of non-appropriation of the high seas by States. According to this principle, no State may validly purport to subject any part of the high seas to its sovereignty. [2] By creating such structures, States ensure that no other States will operate in the same area and the area around, for safety concerns. One could argue that this would result in practice in a creeping appropriation of the location. Only developed countries can pretend to construct offshore wind structures so far, and that imply a “sea-grabbing” by wealthy countries at the expense of the rest of the world.


This was not considered as a prominent issue in the field of oilrigs, but it is with wind turbines. Due to wind farm sprawl and the required separation between wind turbines, wind farms tend to be extremely large. Moreover, unlike oilrigs conceived for a limited period of time, wind turbines are quasi-permanent structures. Consequently, the high seas would no longer be considered as a source of unlimited resources but as a limited source of space.

Uncertainties as to the impacts of wind farms on the marine environment

Implantation of turbines raises the issue of its conciliation with environmental standards involving a change of natural habitat, causes a change of sediment dynamics and has impacts upon fishes, marine mammals and birds. [3] On the basis of UNCLOS, States have created different kinds of marine protected areas throughout international organisations. Establishment of protected areas does not per se exclude the possibility to develop wind farms in the same place. However, some of them are so fragile that construction of wind farms is inconceivable at the same location. Some scientists claim that development of wind farms could also create some potential benefits for the marine environment, acting as a reef and marine reserve from fisheries for certain species. [4]

Conflicts with other uses of the High Seas

Real-Time Marine Traffic, on Wednesday 20th December 2017

Development of wind farms on the high seas would create big risks of collision with other users of the seas. There is no obligation for developers of floating wind farms on the high seas to establish safety zones or other safety measures around installations. Informal and unregulated development of wind farms could lead to collision with fishing or pleasance boats, bunkers or tankers and thus to human and environmental disasters. A regime that replicates the regime of oil platforms (establishment of a 500m-safety zone) [5] would not be enough. Wind turbines need a proper regime of safety zones as they take up a lot more space than oilrigs. There is thus an urgent need to develop a regime for safety zones on the high seas as floating installations are now a reality.

Reviewing the International law of the Sea as an emergency

As demonstrated, international law is not sufficient to deal with development of offshore wind energy. We therefore call for a new development of the International Law of the Sea. The ideal solution would be to revise UNCLOS or to develop a new convention on the role and space needed by offshore wind energy. However, change and creation of international agreements is very lengthy and rarely deliver concrete achievements. Another solution would be to use soft law by developing standards and guidelines though appropriate international organisations. We recommend this solution. That had been developed in certain fields, especially for norms for navigation signaling around wind farms and experience shows that standards have been widely applied. Developing international standards would be helpful for the standardization of the industry of offshore industry and thus for its development and also for investment security. Standards for the marine spatial planning could also be developed. Indeed, a real international standardized system of marine spatial planning would assure an equitable development of wind farms all around the world.

About the author: Lucie Rollini has been member of CliMates for 3 years. She holds a Master in International Law from La Sorbonne University (Paris) and a LL.M Degree in Maritime Law from the University of Southampton (UK). Now trainee lawyer, she is based in Paris and she is completing an internship at the OECD, Nuclear Energy Agency.


This article has been written in the context of 4sea. 4sea, a project about the importance of the world oceans, addresses the interdependence between the oceans and climate change, entraining everyone to become ocean lovers – for now through articles and videos on this blog and in November on our own platform. 4sea is a joint project between the youth organisations CliMates, Youth for Ocean and Vitamin Sea. Love it? Stay tuned for our platform!


[1] ClimateWire, ‘Floating Wind Turbines Set to Conquer Deep Ocean’ (Scientific America, 3 January 2012) accessed 6 September 2017.
[2] UN General Assembly, Convention on the Law of the Sea (UNCLOS), 10 December 1982 Article 89, available at: http://www.refworld.org/docid/3dd8fd1b4.html %5Baccessed 23 January 2018]
[3] OSPAR Commission, Assessment of the environmental impact of offshore wind-farms (2008) See <http://qsr2010.ospar.org/media/assessments/p00385_Wind- farms_assessment_final.pdf> accessed 10 August 2017.
[4] Mark P Simmonds, Vicki James January, ‘Is there a conflict between cetacean conservation and marine renewable-energy developments?’ (2010) Wildlife Research, 37, 691.
[5] Hossein Esmaeili, The Legal Regime of Offshore Oil Rigs in International Law, (second edition in 2017, United Kingdom, Ashgate/Dartmouth).

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