16/04/2021

EVOLUTION OF OFFSHORE FOUNDATIONS

Foundations represent a major factor of any offshore wind farm: supporting the wind turbines are in a very challenging environment, and foundations often account for a large portion of the total project cost. Selecting the right kind of foundations is hence key for the economic viability of any project.

Only a few locations can be selected for offshore wind farms, with limitations due to the maximum depth of the seabed (greater depth means higher cost) and the distance to coast (greater distance increases the size and the power of the turbines that can be deployed but also, typically, increases the depth). The trend is moving to place these installations farther from the coastline than ever before.

Different foundation technologies can be deployed, including Gravity-Base Structures (GBS), Monopiles, Tripods, Jackets and, more recently, Floating. Among these, monopiles stand out for both frequency and versatility at different seabed depths. Due to their simplicity and adaptability, Monopiles are currently being selected in more than 60% of all offshore wind installations.

Monopile design has constantly improved to accommodate more and more demanding wind-farms: diameter, thickness and length have steadily increased for supporting higher and heavier turbines installed at greater depths. As an example, Monopiles for a 6-7 MW turbine are typically 330’ long, with bottom sections diameter and thickness of 30’ and 4” respectively for a total weight often exceeding 1,650T. However, offshore wind turbines capacity will certainly increase in the near-mid term, with 12-14 MW turbines already being tested: the required so-called XXL Monopiles are expected to weigh up to 3,300T reaching 40-50’ diameter and 5½” thickness at their bottom sections.

The manufacturing challenges

Offshore foundations are large plates rolled into cans and cones, assembled and welded into large structures reaching up to 400’ in length. With thicknesses approaching 5½” at 30-40’ diameter, it becomes critical to minimize the amount of circumferential welding, hence minimizing the number of workpieces needed to achieve the desired total structure length which leads to using larger plates, up to 15’ in width.

Fabricators of these huge parts need to overcome two main manufacturing challenges: managing the increasing ratio between diameter and thickness (higher ratios lead to workpiece instability and deformations compromising the rolling accuracy) and handling highly unbalanced tapered plates required for large diameter conical sections with angle up to 14° (used to transition from bottom to top sections of the Monopiles).

All the above makes off-shore foundations rolling operations very challenging indeed!

Stay ahead of the Market with DAVI!

High performance and reliable rolling solutions are essential, with serial production requiring high accuracy and repeatability while guaranteeing operators safety and minimized downtime.

DAVI has been leading this market since 2007, when a dedicated Wind Energy Division was created, with many cutting-edge technologies developed in partnership with the main players in the Sector. Dedicated feeding and handling accessories are continuously being updated to provide fabricators with the most advanced equipment allowing them to gain a competitive edge in a dynamic environment where increasingly challenging workpieces have to be manufactured every year.

DAVI’s market dominance is confirmed by more than 300 installations operating in the Wind Energy Industry worldwideThis represents a market share close to 60%. Don’t miss out, stay ahead with DAVI!