Case Study: Planning offshore wind turbines along the coast of Normandy, France

The Multiannual Energy programme provides for the development of new offshore wind projects in France, including a 1-gigawatt (GW) project along the coast of Normandy.

This project was the subject of a public debate, at the end of which the area chosen for its implementation is located off the Cotentin (Manche department), more than 32 km from the coast and at least 40 km from the Vauban observatory towers of Saint-Vaast-La-Hougue. The perimeter of the project will be refined during the procedure. The planned wind farm, which will be ‘laid’ on the seabed, will consist of a maximum of 83 wind turbines with a height of approximately 260 m at the tip of the blade, covering an area of around 100 to 150 km². The competitive bidding process was launched in December 2020 to designate the future developer of the project, scheduled for 2022.

In accordance with the regulatory framework introduced by the ‘Law for a State at the service of a trustworthy society’ of 10 August 2018, the Ministry of Ecological Transition referred the matter in advance to the National Commission for Public Debate, in particular about the choice of location for the project. During the public debate, the issues relating to the Vauban fortifications of Saint Vaast-la-Hougue and the possible interactions between the inscription on the UNESCO World Heritage List of this part of the serial property and the wind farm project were raised.

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State Party:
France

World Heritage property:
Fortifications of Vauban

Criteria:
(i)(ii)(iv)

Year of inscription:
2008

Brief description:
Fortifications of Vauban consists of 12 groups of fortified buildings and sites along the western, northern and eastern borders of France. They are the best examples of the work of Sébastien Le Prestre de Vauban (163-1707), the military architect of Louis XIV. This series includes newly created towns, citadels, urban enclosures with bastions and bastioned towers. It also includes mountain forts, hill forts, a mountain battery and two mountain communication structures. These sites are inscribed as witnesses to the apogee of classical bastioned fortification, typical of Western military architecture. Vauban played a major role in the history of fortifications by influencing military architecture in Europe, but also on other continents until the mid-nineteenth century. Among the 12 sites which make up the serial property, considered to be the most representative of Vauban's work of exceptional architectural, territorial and landscape value, the site of Saint Vaast-La-Hougue includes the two tower-observatories of Tatihou Island and La Hougue.

See further details at: https://whc.unesco.org/en/list/1283

Impact assessment carried out for this project

The Government has launched a study on the issues relating to the preservation of the observatory towers of Saint-Vaast-La-Hougue, to inform the decision-making process. This is not strictly speaking an impact study of the project, which will be carried out at a later date by the developer, but an upstream study which aims to analyse the possibility of installing an offshore wind farm in the Manche department, without damaging the OUV of the observatory towers of La Hougue and Tatihou, which form part of the Vauban Fortifications World Heritage property.

Challenges identified during the impact assessment process

The first part of the study recalls the characteristics of this part of the property that contribute to the OUV of the Vauban site, notably in the formation of the landscape in which the towers are included in. Following a further assessment with relation to the criteria of inscription, it identifies the most remarkable viewpoints towards these two buildings from a heritage perspective and thus illustrates the different levels of sensitivity in the environment regarding its heritage dimensions. Photomontages are then established concerning the most significant viewpoints and panoramas. These visual simulations evaluate the interaction of the installation of the offshore wind farm with the perception of the observatory towers, based on fictitious siting choices of wind turbines, with the aim to minimize the possible impact of the wind farm on the towers. The study resulted in a landscape sensitivity map of the maritime area around the towers (see illustration below).

The second part of the study makes recommendations on how to locate a wind farm in the area to limit or control the visual effects. The analysis of the landscape sensitivities allows us to study six potential areas for the implementation of the project. The presented simulations ensure the avoidance, reduction and compensation measures with regard to the heritage values.

Summary on the outcome of the impact assessment

In conclusion, the study revealed that within 40 km of Saint-Vaast-la-Hougue there are undeniable interactions between the implementation of an offshore wind farm and the observatory towers of La Hougue and Tatihou. On the other hand, at a distance of more than 60 km, the risk of damaging the OUVof this part of the property is very low, if not zero. Furthermore, between these two distances, although visibility remains limited from several viewpoints, the wind turbines would clearly emerge from the battery of La Pernelle; a monumental panorama which offers a view of the great landscape and allows its formation to be appreciated. (See in the study: part 1 P1 EOL_VAUBAN Diagnostic Volet 1_2.pdf (developpement-durable.gouv.fr) and part 2 P2 EOL_VAUBAN Annexe Volet 2_2.pdf (developpement-durable.gouv.fr) (documents in French).

The most important lessons learned from this project include the fact that the study for the proper consideration of the issues relating to the preservation of the observatory towers of Tatihou and La Hougue was facilitated by the existence of prior documentation concerning the management, conservation and sustainable development of the property, drawn up by the managers of the Vauban sites (see also Parution du référentiel ‘Fortifications de Vauban’ - Réseau des sites majeurs Vauban (sites-vauban.org) (document in French).

Concerning challenges, particularly from a landscape and heritage context, the French Government decided to select for the project an area located more than 32 km from the coast to limit the visual impact of the wind farm from the coast. In addition, the selected area is located more than 40 km from the towers of Saint-Vaast-la-Hougue in order to avoid the area of high landscape sensitivity of the towers, in line with the recommendations of the landscape study. The area selected for the call for tenders is 500 km², whereas the park should only occupy approximately 100 to 150 km², so the pre-calculated distances may even be bigger, depending on the exact location chosen within the call for tenders.

In the further development of the project, the Government will ensure that the wind farm developer considers the landscape aspects in the planning and design of the wind farm project. Concerning the observatory towers of Saint-Vaast-la-Hougue, the developer will have to rely on the recommendations of the study commissioned by the Government, and particular attention will need to be paid to the viewpoint of La Pernelle.

Important lessons learned from the project

This is the first project in France for which a special study has been developed that consider the potential impacts of an offshore wind project on a World Heritage property. The lessons learned (particularly in terms of process and analysis methodology) will be used in France for future cases of similar projects.

One of the specificities of this type of offshore project is that the French Government (the Ministry of Ecological Transition) is temporarily in charge of the project and the studies are carried out directly on behalf of the Ministry, unlike for onshore wind projects. The analysis has led to the consideration of the landscape dimensions of the OUV of the property through a rigorous methodology that considered the different dimensions of the value of the site as a component of the World Heritage property ‘Fortifications of Vauban’, as well as the very careful mapping of the landscape sensitivities of the Saint-Vaast defensive barrier. The maps are also consistent with the elements produced by the manager during the drafting of the Vauban reference guide on the integrity of the property. (See also: http://www.sites-vauban.org/)

The positive outcomes from this experience included two particular challenges:

1. the definition of a large study area with six potential siting areas, allowing for an efficient evaluation of the different options for the realization of the project, taking into account environmental and technical constraints;
2. attention to project configuration options to limit or organize the visual impacts of the project.

The methodology used made it possible, both in the upstream opportunity study and the design study, to support avoidance, reduction, and compensation measures through plausible scenarios with regard to preserving a World Heritage property.