3rd International Conference on Ocean Energy, 6 October, Bilbao

Paimpol-Bréhat: Development of the First Tidal Current Array in

P. Brun 1, L. Terme 2 and A. Barillier 3

1Hydro engineering centre Electricité de France Savoie Technolac 73 373 Le Bourget-du-Lac Cedex E-mail : [email protected]

2Hydro engineering centre Electricité de France Savoie Technolac 73 373 Le Bourget-du-Lac Cedex E-mail : [email protected]

3Hydro engineering centre Electricité de France Savoie Technolac 73 373 Le Bourget-du-Lac Cedex E-mail : [email protected]

Abstract 1. Introduction In order to launch the development of tidal current energy in French waters, EDF has decided to This paper presents the stages of development of EDF develop a pilot farm of TCEC (Tidal Current first tidal current project in French waters; the Paimpol- Energy Converters) by 2012. The main purpose of Bréhat project. The objectives and key features of the this project is to set up an overall framework for the project are first described. implementation and operation of such marine The process for site selection is explained. renewable energy production site. The technology selection is explained and a brief EDF decided in 2008 to develop the site of Paimpol- presentation of OpenHydro’s technology is provided. Bréhat in North and selected The surveys undertaken for the Paimpol-Bréhat project OpenHydroGroup Ltd., an Irish energy company as are presented together with key findings. the technology partner for implementation of the The final tidal array layout is presented taking into tidal array. account all the constraints identified. The Paimpol-Bréhat project consists of a The grid connection architecture and characteristics are configuration of 4 machines with 0,5 MW capacity described. per unit for 2,5 m.s -1 (0,85 MW peak capacity per Details regarding EIA and including the challenges of unit), an offshore subsea converter, a 15km 10kV the administrative procedures are given. DC transmission line for grid connection and an on shore substation. The implementation schedule is shown and the critical The major specificity of the project is its path identified. environmentally friendly characteristics. The paper presents the Paimpol-Bréhat project This paper does not present the economic aspects of the development focusing on the site and technology project; which is considered to be a pre-industrial selection, the consent, the field investigation and demonstration. surveys, the technical studies (including R&D 2. Objectives and main characteristics of the developments and environmental impact project assessment) and the administrative authorization In order to launch the development of tidal current process. energy in French waters and to assist in meeting the The design is described and in particular the 2020 target for renewable energy, EDF has decided to technical options selected are explained taking into construct a demonstration tidal farm by 2012. account environmental context, consent by The main purpose of this project is to set up an overall stakeholders, technical and administrative context. framework for the implementation and operation of a Keywords: OpendHydro, Paimpol-Bréhat, Tidal current demonstration tidal farm to include: array. • Full-scale test of a TCEC array,

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• Validation of EDF modelling tools including OpenHydro Group Ltd. is an Irish company whose wake effect and energy yield calculations, business is the design and manufacture of the Open- • Environmental Impact Assessment and Centre Turbine. This unique and simple device is Environmental Monitoring Program, designed to extract marine renewable energy from tidal • Optimisation of offshore installation process, streams in a simple and environmentally benign Development of consent process with all manner. The machine has a single moving part and is stakeholders, situated directly on the seabed, with no part of the • Development of administration, legal and structure visible from the surface and deep enough so taxation framework. as not to pose a hazard to shipping. OpenHydro deployed their first 6m tidal turbine in 3. Site selection and consent by stakeholders 2006 at the European Marine Energy Centre (EMEC) EDF R&D and Hydro Engineering have already carried in Orkney, Scotland. OpenHydro installed a 10m out several surveys and feasibility studies on the turbine in the Bay of Fundy in Nova Scotia, Canada viability of tidal energy in French waters together with last November 2009. upfront dialogue with all the stakeholders. Through The Paimpol-Bréhat project involving OpenHydro these studies, two sites were shortlisted, the first technology requires extensive research and located in Northern Brittany and the second in development prior to the finalization of the project Normandy (Cotentin). design, construction and commissioning. The following development is necessary due to the site conditions and EDF decided in July 2008 to develop the Northern the decisions made by EDF: increase the installed Brittany site, which is located off Bréhat Island, mainly capacity of each machine (and therefore the size of for acceptability and consent reasons in addition to the turbine to 12 m and venturi to 16m), adapt the favourable grant support structures available in geometry of the turbine and characteristics of the Brittany. subsea base. The key features of the 16m machines are as follows: • Turbine weight 100t, Barfleur • Subsea base weight 490t, • Subsea base dimensions 21x23m. A number of technical studies have currently been Paimpol-Bréhat performed for the development of the larger 16m turbine focusing the improvement of efficiency for blades and venturi and for generator and mechanical parts. To allow the engineering teams to trial their designs and also for the project to mitigate the risk it is planned to install a machine in spring 2011, not connected to the grid; one year before the commissioning of the full Figure 1 : Location of PAIMPOL-BREHAT project demonstration tidal farm (4 turbines).

The strong acceptance that the project currently receives was achieved primarily due to permanent consultation with key stakeholders and this consultation was undertaken at a very early stage of the project. The main stakeholder is the local committee of fishermen; all discussions between this committee and EDF were decisive regarding the location of the machines (layout, depth) and the cable route and protection. The requests of all other stakeholders (oyster farm owners, authorities in charge of environment, environmental associations, riparian and municipality) were also considered and taken into account to adapt the project design. 4. Technology selection After a multi criteria analysis (economical, financial, Figure 2 : 10m OPENHYDRO machine view CAD technical, feedback of first prototypes, willingness to collaborate) and a pre-qualification process, EDF Tidal energy has a number of important benefits selected OpenHydro as the technology partner for including predictability of energy generation but also it implementation of the tidal array. This selection was is seen as having minimal impacts both made among 5 short-listed developers: OpenHydro, environmentally and socio-economically. It is Marine Current Turbines (MCT), Hammerfest Storm, important for this specific project to demonstrate these Tidal Generation and Lunar Energy. characteristics:

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• the tidal array has no significant negative impact on socio-economic activities due to it being located in a fishing reserved area, as agreed with

fishermen; Parc hydrolien • each turbine is supported on a tripod subsea base foundation directly deployed on the seabed,

which limits the area of contact and does not N require any seabed preparation; • the turbine has no requirement for oils or lubricants; • the turbine has a large open centre which Figure 4 : Geological map provides an exit route for marine life. The results of the marine investigations can confirm the feasibility of machine installation and allow the cable 5. Surveys to be buried on the stretch close to the shore (it will lay EDF completed a number of field investigation and on the seabed on the rest of the route). It is surveys as part of the feasibility studies from 2005 to demonstrated that the level of impact of the project on 2008. Further survey work was completed in early the environment is low and can be mitigated. 2009. These investigations are listed as follows: • Tidal velocity measurements using Acoustic 6. Layout Doppler Current Profilers (ADCP), The layout of the tidal farm has been one of the most • Bathymetry and Geophysics (magnetometer, challenging aspects of the project to date; the crucial seismic refraction, material sampling), question was the following: how to design the optimum • Environmental surveys, machine position taking into account: • Inspection by divers, • Current velocities (magnitude and direction), • Geotechnics: boreholes at the onshore site. • Minimization of the wake effect, • Optimisation of the output generation, The marine investigations provide a good knowledge of • Navigation constraints and in particular the physical characteristics of the project area: fishermen ships’ draught, • Depth at the deployment area is between –35m • Micro relief and angular tolerance (rolling and and –40m (from chart datum), pitching), • The deployment area is generally flat but the • Accuracy for machine installation on the seabed. level variability can reach 1 to 2 meters locally, • The seabed is quite chaotic on the cable route Using a local numerical model and a numerical 2D but a suitable path can avoid the rocky peaks, flow model (TELEMAC) developed by EDF, the • The geology is globally homogenous: granite on optimum location was proposed as a compromise the deployment area without significant among all the constraints. sedimentary deposits and granite covered locally by sediments on the cable route,

The cable route approaching the shore crosses a sandy beach.

-21 à -13 -25 à -21 -29 à -25 -32 à -29 -34 à -32 -37 à -34 -39 à -37 N -42 à -39 -44 à -42 -50 à -44

Figure 5 : Layout

Figure 3 : Bathymetry map Figure 6 : levels of the machines

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7. Grid connection For the electrical aspects, the main difficulties were to Many alternatives were reviewed in 2008 for energy develop high performance - high reliability coils and conversion and grid connection and after a detailed connections even immerged in sea water. review it was decided to implement an offshore subsea For the hydrodynamics aspects, performing a full converter. optimisation process based on CFD calculation has The subsea converter will be on the seabed near to the made huge improvements. The full set of parameters turbines using similar foundations and will be equipped and dimensions were introduced as variable in the with power converter and turbine control system. The software, associated with site specific constraints components of this converter will be: (manufacture, volumes…) and allow to evolve on their • Subsea base including the base, the ballast, the full range of dimensions, until a maximum were found recovery system, for the chosen objective function (maximum peak • Water-proof housing containing the power power, maximum annual energy…). electronics, control system and cooling system, The comparison of various maximum and the convergence tendency of the parameters bring • Conversion system consisting of rectifiers, invaluable information for future developments and busbars and DC/DC converters. design optimisation considering manufacturing costs

and constraints. Due to the need of development (overall electrical system for the energy conversion), it was decided to set For the offshore substation, which is a world first for an up a partnership with the French electrical company, industrial project, the main challenges are to implement CONVERTEAM. The main challenges consist of high tech equipment in a confined and subsea waterproofing of the housing and to minimize environment, with strong access limitations. maintenance due to the high costs linked with offshore This offshore substation requires specific procedures interventions (vessels mobilisation). for layinf and retrival due to the number of cables

connected to it, as well as a perfect watertighness and The export cable to shore is designed to operate at reliable cooling system. 10kV DC. An European call for tender for this package The specificity of the TCEC power output, with will be launched in summer 2010. variable voltage – variable frequency and the choice of a DC connection to shore required specific design, in terms of protections and equipment redundancy. In particular, the number of HF transformers and serial connexion were defined in order to improve reliability and reduce development risks.

Finally, the interfaces between the TCEC and the common offshore substation required high level simulation models in order to avoid eddy currents and define appropriate type of connection to the ground and Figure 7 : 3D view of tidal current array performing protection system. 8. Technical developments 9. EIA Every little part of the project requires more or less An extensive EIA was carried out and completed in development and innovative solutions to deal with the early 2008; this was based on the feasibility studies challenge of new technologies, harsh environment, performed. The main results are summarized as limited budget and large uncertainties. follows: • During the deployment stage, the impact is For the TCEC, the development has been made limited in duration and localized, progressively, by implementing new solutions on scales • During the operation stage the impacts are models, on 6m turbines tested in Scotland (EMEC), and assessed as being minor, on the 10m turbine tested in Canada (Fundy Bay). Remaining work includes the acoustic impact of the Every domain has been reviewed in order to improve machines and the converter in particular on marine mainly the reliability, the efficiency and the cost, but mammals. also by considering the manufacturing process, the environmental impact or the maintenance operations. For the mechanical aspects, the main challenges are the performance of the circumferential bearings, with aim to reduce friction and wear, the respect of low tolerance on air gap and the manufacturing constraints for such huge equipment.

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The critical paths are linked to administrative procedures and to technical innovation; these create delay risks for the project which are difficult to mitigate. 12. Conclusion This first tidal project developed in French waters is a pre-industrial project but regarding certain aspects such as the increase in size of the machines, the offshore power conversion and the administrative procedure it could be classified in the prototype family.

EDF wishes with this project to launch the French tidal Figure 8 : View of the Launay beach: point of cable farm industry and has the following ambitious targets: connection to the shore • Obtain technical feedback of the selected technology, The mitigation measures are primarily focused on sea • Reach a successful full scale test of the tidal users (fishermen, oyster farms owners). A detailed current array using an offshore submarine environmental follow up is planned during machine test converter, stage, commissioning and first years of operation. • Validate the modelling tools (wake effects, energy captured), 10. Administrative procedures • Optimise offshore installation and maintenance Previously no specific rules and legislation for marine process, tidal energy had been established and the only • Confirm the consent and acceptability process, possibility was to use the existing legislation. The main • Develop the Environmental Impact Assessment applicable administrative procedures are as follows: and Environmental Monitoring Program, • A declaration under the Electricity Act, • Demonstrate the need for change within the • An authorization under the Water Act, administrative procedures and contribute to • A concession authorizing the occupancy of the improving the regulations. marine State property, • Several authorizations pursuant to urban A number of the targets have already been achieved but planning necessities (including building permit), two key issues and challenges are still to be completed: • Procedures necessary pursuant to the the technological development and the completion of environmental legislation (EIA incl. Natura administrative procedures. 2000 file), • Associated public enquiries, Acknowledgements • A convention between EDF and the electricity EDF kindly thanks the Local Fisheries Committee of company in charge of distribution (ERDF), -Paimpol for its assistance in particular during technology and site selection, OpenHydro for the The administrative procedure is a significant challenge quality of technical partnership and the Brittany and it must be noted that national and regional Regional Council for supporting the project. authorities are on the learning curve, many rules and restrictions are overlapping and marine media is very References complex regarding regulation and number of stakeholders. [1] L. Terme, N. Gérard, C.T. Pham, S. Saviot, P. Brun. (2009): Tidal current turbine demonstration farm in 11. Implementation schedule Paimpol-Bréhat – Detailed design, Internal EDF The approximate implementation schedule can be document - France. summarized as follows: [2] C.-T. Pham, V. Martin. (2009): Tidal current turbine

2006 2007 2008 2009 2010 2011 2012 demonstration farm in Paimpol-Bréhat (Brittany): tidal PRELIMINARY STUDIES characterisation and energy yield evaluation with INVESTIGATIONS FEASIBILITY STUDY Telemac. Proceedings of the 8th European Wave and DETAILED DESIGN EIA Tidal Energy Conference, Uppsala, Sweden. TECHNOLOGICAL DEVELOPMENTS PROCEDURES BARGE AND TEST MACHINE PROCUREMENT [3] P. Brun, A. Barillier. L. Terme, S. Barr (2009): Paimpol- AND MANUFACTURING CABLE PROCUREMENT, MANUFACTURING Bréhat: development of the first Tidal current array in AND INSTALLATION TESTING NON CONNECTED MACHINE France, Proceedings of Hydro 2009 conference, Lyon MACHINES PROCUREMENT AND France. MANUFACTURING INSTALLATION / CONNECTION TESTING AND COMMISSIONING

Figure 9 : Simplified implementation schedule

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