Use the force of the tides and the swell to generate electricity. The idea is not new. Faced with the inexhaustible force of our oceans, science has long tried to capture it. In Brest (Finistère), the construction group Legendre has just presented a prototype of a sea wall equipped with a wave energy system. The structure could thus convert the force of the waves into electricity. For this project, the Rennes company is accompanied by the marine renewable energy specialist Geps Techno and Ifremer. “The objective is to combine port or coastal protection and energy production”, explains Vincent Legendre, chairman of the executive board of the Breton group Legendre, referring to “a world first”.
Large-scale trials in the harbor of Brest
The principle is to equip a port or coastal protection breakwater, already existing or new, with an oscillating flap to convert the force of the waves and the swell into electricity. The shutter also helps to absorb the force produced by the impact of the waves. After tests in the basin, the prototype of the “positive energy” breakwater called Dikwe was submerged for larger-scale tests in the harbor of Brest, on the Ifremer sea test site, in Sainte-Anne- du Portzic. “For the moment, we are very satisfied with the behavior in resistance and in production of the prototype”, indicated Quentin Henry, project manager for the Legendre group.
First, a 1/15th scale prototype was tested in the Ifremer wave basin in Brest. According to initial calculations, the device captures up to 60% of wave energy. The prototype installed in the harbor of Brest, on a 1/4th scale, measures almost 4.5 m high and wide, and 6 m deep. It is a kind of metal box equipped on one of its sides with an oscillating flap. Its cost, between study, design and installation, is around one million euros.
The third stage of the project, scheduled for 2024, will consist of carrying out full-scale tests. The prototype dike, built in concrete this time, will then be able to produce in the order of a megawatt.