Commercial Oscillating Water Column Marine Power Plant Commissioned

One of the world’s first breakwater wave power stations was commissioned this July by Ente Vasco de Energia (EVE), an energy agency in the northern Basque region of Spain. The €2.3 million ($3.3 million) project in Mutriku uses oscillating water column technology developed by Voith Hydro’s Wavegen, based in Inverness, Scotland. The technology is integrated into a concrete power station built on a breakwater or coastal protection project (Figure 6).

6. A breakwater breakthrough. Spanish agency Ente Vasco de Energia in July commissioned a 296-kW breakwater wave power station based on oscillating water column technology that uses 16 Wells turbines. The plant produces power by harnessing pressure differentials created by wave oscillations and converting that rotational energy into power. Courtesy: Voith Hydro

Essentially, waves create oscillations on the water’s surface in a partially submerged hollow chamber that’s open at the bottom. The oscillations continuously compress and decompress an air column above the chamber. The difference in pressure converts the rotational energy to electricity via a turbine-driven generator. The 296-kW offshore installation at Mutriku has 16 Wells turbines—a fixed-pitch machine with only one direction of rotation. As Voith Hydro notes, “therefore, the rotor is symmetric with respect to the rotation plane.”

The Mutriku plant was modeled on Wavegen’s prototype decade-old Limpet plant installed on the island of Islay, off the west coast of Scotland. Results from testing at that grid-connected commercial-scale plant will also be used at the larger 4-MW Siadar Wave Energy Project on the west coast of the Isle of Lewis in Scotland, which Voith Hydro is developing with RWE npower, with funding from the Scottish government.

EVE noted that the total investment for the project was €6.7 million—less than half of which was used to build the plant. The project was also the only marine energy project supported by the European Commission’s 6th Framework Program.

—Sonal Patel is POWER’s senior writer.