OES-Environmental distributes metadata forms (questionnaires) to solicit information from developers involved in environmental monitoring around marine renewable energy project sites around the world. This page provides project descriptions, baseline assessment, post-installation monitoring, and links to available data and reports. Content is updated on an annual basis.

Paimpol-Brehat Tidal Demonstration Project

Project Site OES-Environmental

Title: Paimpol-Brehat Tidal Demonstration Project
Start Date:
August 01, 2011
Research End Date:
January 01, 2018
Technology Type:
Info Updated:
July 25, 2019
Project Status: 
Device never deployed
Project Scale: 
Installed Capacity: 
4 MW (each turbine 2 MW)

The Paimpol-Bréhat pilot project aimed to pave the way for the pre-commercialisation of tidal farms from 2017. At the initial stage of the project a prototype version of the 0.5MW 16m diameter OpenHydro device was installed and tested in 2011. Following this successful prototype testing, in 2015 OpenHydro completed the design and manufacture of two turbines for a grid-connected demonstration project (2 x 2MW turbines, 16m diameter).


The first turbine was installed on the 20th of January 2016 and the second turbine was installed on the 29th of May 2016. The turbines were installed using a dedicated barge designed by DCNS/OpenHydro. Once the barge was stabilized, the turbines were lowered to the seabed using an innovative winch system equipped with hydraulic motors.


During 2016 OpenHydro developed and built a power conversion system as part of the turbine control centre (TCC), housed in a subsea pressure vessel enclosure and mounted on the subsea base. The TCC is a power electronics apparatus which performs the dual functions of controlling the turbine to achieve optimum power output and converting the electrical output of the turbine to grid compliant power (however, these devices were never grid connected in the end).


OpenHydro released video footage of the installation of the first device: https://www.youtube.com/watch?v=Du7Jqscu3LE


Onshore Infrastructure: The substation that fed the electricity to the French grid is located close to the Arcouest Peninsula in Ploubazlanec.


Vessel Spread: Specifically designed catamaran barge (Triskell), a tug (Penfret) and a support boat.


The project was located 16km off the coast of Brittany, France in water depths of 35m.


Project Timeline: 

In January 2017 it was reported that the two turbines would need to be removed to replace a faulty part which prevented the system from operating correctly. It was discovered that corrosion of bolts and fasteners was the cause of the problem.


The first and second turbines were retrieved in April and July 2017 respectively for replacement of components that threatened the turbine’s resistance to corrosion. These turbines were never redeployed and the project was subsequently cancelled by EDF in 2018.

Key Environmental Issues: 

Key environmental issues include those relevant to other tidal stream developments such as:

  • Noise impacts during construction and operation
  • Disturbance to benthic habitats
  • Potential for collision with turbine blades


Available information on baseline studies and post-installation monitoring is provided in the table below. There is a lack of information available on the full extent of the baseline surveys and proposed monitoring to be carried out at the site, however a significant amount of additional work (e.g. marine mammal surveys) would likely have been carried out, but these have not been detailed due to the lack of information on their design.

Paimpol-Brehat Tidal Demonstration Project is located in France.

Baseline Assessment: Paimpol-Brehat Tidal Demonstration Project

General Description:

The following field surveys were undertaken (or commissioned by) the developer to inform baseline characterisation.

ReceptorStudy Description Design and Methods Results Status
  • Benthos

Drop down video monitoring at the project site and along the unburied section of the cable route

A total of 57 videos profiles were recorded using a HD video camera (Sony HD CX6) mounted on a weighted frame equipped with two lasers, a light and an altimeter. The suspended video frame was successively dropped and lifted for a few seconds, while the research vessel was in neutral but still moving with the current. The video profiles were thus positioned following a random sampling design. Instantaneous high resolution pictures were taken each time the frame hit the bottom (representing a total of 1455 snapshots) allowing the identification of benthic epifauna. Some megafauna taxa were also recorded when the video frame is flying about 1 m above the bottom.

During the 2012 survey (i.e. before the deployment of pilot turbines and the installation of the cable), 105 taxa were identified, including 91 invertebrate taxa and 14 benthic flora taxa. The benthic community was dominated by hard-bottom epifauna characteristic for the circalittoral zone, including ascidians, bryozoans, cnidarians, sponges and encrusting algae. Conspicuous mats of unidentified yellow and red social ascidians were present on most of the video profiles. Several identified species were of ecological interest, either because they were abundant at the tidal site while being considered to be rare in this region (e.g., the bryozoans Flustra foliacea, the cnidarians Sagartia elegans, Sertularia argentea and Tubulariidae sp.), or because they play important ecological roles as ‘engineer species’ (e.g. Laminaria macroalgae).


Post-Installation Monitoring: Paimpol-Brehat Tidal Demonstration Project

General Description:

The following monitoring activity has been undertaken at the site.

ReceptorMonitoring Program Description Design and Methods Results Status
  • Benthos

Monitoring of the artificial reef effect of the cable and concrete mattress cable protection

Monitoring will be carried out using drop down video at least once a year during the operational period of the turbines

Preliminary results showed that benthic colonisation is mainly composed with cirripeds, hydrozoans and ascidians. At least 2 introduced species (the ascidian Styela clava and the gastropod Crepidula fornicata) occur on the cable protection structures with significant abundances. Regarding the benthic colonisation on cable-stabilizing concrete mattresses, preliminary results showed that very few species have fixed on the structures after 6 months. However, a few individuals of young C. fornicata are already present. A large crustacean (young individual of Cancer pagurus) has been observed on one of the 2 investigated mattresses, suggesting that such artificial structure may act as potential new habitat for large vagile benthic fauna.

  • Plants

Areas of seagrass are present in the path of the cable route and so an experimental study involving transplantation of the seagrass, was carried out

Select an appropriate place for seagrass transplantation and move with care

The proved broadly successful, with growth of transplanted seagrass occurring. Zostera noltii and Zostera marina were both transplanted with Z. noltii yielding better results.

Reports and Papers N/A
Research N/A
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