Van Oord to install 62 jacket foundations for Saint-Brieuc OWF
Van Oord will install 62 jacket foundations and foundation piles for the Saint-Brieuc offshore wind farm (OWF). 190 pin piles will be used at the 75 square kilometres site, 16,3 kilometres off the coast of Brittany, in France.
Many of the more convenient offshore wind farm locations in Western Europe are already being exploited. Thus, the remaining sites tend to present more logistical difficulties, explaining why they have not yet been built on. Saint-Brieuc bay is one of these more difficult locations for two reasons. Van Oord will handle the transportation and installation of the 62 jackets and the marine substation.
First, the designated coastal area has a particularly uneven and rocky seabed, with rock strengths exceeding 100 MPa. Ultimately, Van Oord will need to drill through about 4 kilometres of rock. Second, both tide and weather conditions are harsh in this area, with a tidal range of 12 metres, extremely strong currents, as well as heavy Atlantic swell and high waves.
Aeolus and Dive Drill
Despite these difficult conditions, Van Oord plans to use the offshore installation vessel Aeolus. Following a tender phase, BAUER Group was selected as contractor to develop the Dive Drill for this project, a hydraulically powered drill that will operate entirely below the surface of the water. Lowered down through a temporary casing, the drill is removed once it is at the goal depth anda pin pile is inserted. Then, the oscillator raises the casing to the surface while grout is injected into the opening.
Frank Haehnig Managing Director BAUER, stated: “The Dive Drill can handle all kinds of soil and rock conditions to allow installation of any kind of pile in the seabed. The need to use sustainable drilling equipment in challenging soil conditions and a harsh environment drove our decision to develop the Dive Drill. Using components from our existing equipment portfolio and combining them with new and innovative ideas has produced a solution that satisfies the project requirements.”
The wind farm is commissioned by Ailes Marines SAS, a subsidiary of Iberdrola. With an investment of 2.4 billion euros, it is Brittany’s first large-scale offshore wind farm, and one of the first of its kind in France. Once commercialisation begins in 2023, it is estimated that it will produce 1,820 gigawatt hours (GWh) per year, thanks to a total installed capacity of 496 megawatts (MW) from 62 Siemens Gamesa turbines each generating 8 MW of power. This should supply green energy to 835,000 people.