A wide variety of concepts at the prototype stage
Wave energy converters are systems for recovering the energy generated by the waves and transported by the swell to return it, usually in the form of electricity. Four types of installation are possible: on a coastal structure, floating or seabed systems near the coast in water depths of less than 20 m, or floating offshore systems. Over the last 200 years, a wide variety of concepts have been developed, based on different operating principles and mechanisms. Some extract potential energy from the swell while others exploit its kinetic energy. Some demonstration units have been deployed at sea, but none of these concepts has reached the maturity and cost-effectiveness required to move beyond the demonstrator stage.
Technological tests and developments still needed
The transition to industrialisation still requires testing and technological development efforts to address the following issues:
- Increasing efficiency by improving power electronic equipment used for energy conversion;
- Innovating in the field of materials (use of composites, piezoelectricity or other physical conversion phenomena);
- Improving the robustness of components and subsystems (such as mooring lines) against fatigue and extreme loadings;
- Developing control and monitoring systems to optimise maintenance operations;
- Controlling installation and logistics costs;
- Identify and limiting social and environmental impacts.
A pioneering and structured approach
These strategic priorities to ensure the take-off of a sector currently handicapped by high production costs are identified at European level, in the Strategic Energy Technology Plan, and shared at international level. In order to make the most of its opportunities, the wave energy sector has innovated in comparison with other ORE sectors by applying the design approach based on the validation of predefined stages (or phase-gate), which is widely used in the aeronautics industry in particular. This approach is based on the selection of performance criteria and indicators that each new concept must meet in order to “universally” estimate that a level of technological maturity has been reached. This approach proves to be crucial in order to support any investment in a technology considered to be at risk. The Scottish, European and US public funds, which spend 100 million pounds, euros and dollars a year respectively, are already applying it. France has never yet reached the order of magnitude of these levels of investment. However, consolidating the future of wave power means hearing the strong arguments in favour of the availability of this energy: a technically exploitable potential on the French Atlantic coast of over 10 GW, overseas territories all with a highly exposed coastline, and the almost universal suitability to provide an uninterruptible power supply for uses or activities offshore (instrumentation, aquaculture, extraction, etc.).
No specific R&D on wave energy, but cross-cutting themes
Although France Energies Marines has not yet launched a specific study on wave energy subject, the results of cross-cutting projects can be applied to wave energy converters.
The work on site characterisation focuses on the interaction of winds, waves and currents in the water column to assess the wave energy resource (HYD2M project). They are also interested in the influence of waves on fixed structures to determine the forces to be considered in the design, and the potentially devastating conditions encountered during extreme events such as hurricanes (DIME and CARAVELE projects). Several projects carried out by the Institute provide solutions to the exploitation of wave energy: design of semi-tensioned mooring lines (POLYAMOOR and MONAMOOR projects), monitoring of mooring lines (MHM-EMR project) and behaviour of export power cables (OMDYN, OMDYN2 and DYNAMO projects).
The potential environmental impacts of wave energy converters are studied with: experiments to assess the effect of electromagnetic fields from subsea cables on coastal ecosystems (SPECIES project), passive acoustic monitoring of benthos (BENTHOSCOPE and BENTHOSCOPE2 projects), characterisation of biofouling on underwater components (ABIOP and ABIOP+ projects) or quantitative assessment of metals released into the marine environment from galvanic anodes (ANODE project).
France Energies Marines is co-developing the open source software suite DTOcean+ dedicated to the design and optimisation of tidal and wave energy systems at the farm scale. Our teams have thus developed three flagship modules: site characterisation, foundations and moorings, environmental and societal acceptability (DTOCEANPLUS project).
Representation and participation in wave energy R&D networks
The Institute is involved in several international projects and working groups whose objective is to support R&D on ocean energies in order to develop this sector:
- Support for the implementation of the European strategic plan for tidal and wave technologies (OCEANSET project),
- Technology Collaboration Program to provide an accurate view of the entire sector (TCP/OES),
- Monitoring the environmental effects of the development of these energies (OES-Environmental).
Photo credit: CorPower Ocean
Advanced design tools for ocean energy systems innovation, development and deployment
Dynamic umbilicals for floating marine renewable energies technologies - Phase 2
Durable and flexible polyamide moorings for offshore renewable energies
Consideration of biofouling using quantification protocols useful for engineering
Design and metocean: modelling and observations of extreme sea states for offshore renewable energies
Dynamic cable monitoring
Monitoring of polyamide mooring lines
Support implementation of the ocean energy component of the SET-Plan
Collaborative initiative for monitoring the environmental effects of ocean energy development
Subsea power cables interactions with environment and associated surveys
Technology Collaborative Programme on Ocean Energy Systems
Accounting for biofouling through established protocols of quantification
Quantitative evaluation of metals released into the marine environment from the galvanic anodes of ORE structures.
Understanding and monitoring of ORE impacts on the benthic compartment via a measurement platform dedicated to passive acoustic
High-resolution local analysis of wave and breaking variability from satellite imagery
Optimal Design Tools for Ocean Energy Arrays
Dynamic umbilicals for offshore renewable energies
Coordination and participation in expert panels on ORE
Ecosystem approach of the impact of offshore wind farms
Marine life monitoring
Offshore renewable energies farm optimisation
Resource and site characterisation
Training in the field of offshore renewable energies
Yann-Hervé De Roeck
Deputy Executive Director
Published on 02/11/2020