Odfjell Oceanwind develops wind semi for harsh environments, heavier turbines

Offshore staff

BERGEN, Norway — Odfjell Oceanwind has introduced the Deepsea Star, a column-stabilized, steel semisubmersible for harsh environment floating offshore wind developments.

This is designed to accommodate the new generation of 15-MW and larger wind turbine generators (WTGs) that should become available from 2025 onward.

The platform, with center WTG tower, is at present undergoing basic design approval by DNV, based on Siemens Gamesa’s SG 14-236 DD wind turbine and application in the harshest environment locations globally for floating offshore wind.

Odfjell Oceanwind CEO Per Lund said, “The new design has successfully completed the model tank test, and our design team is now working in close collaboration with the WTG supplier and DNV to complete the qualification process to a basic design approval (BDA) level. Having a BDA qualified design for 15-MW WTG and a multi-locational, harsh environment design basis offer developers of seabed leases in tough locations to potentially cut significant time and reduce risk in their development programs. This is particularly the case for Scotwind, INTOG and [all in the North Sea region]. The Deepsea Star can also be optimized to site-specific metocean data.”

CTO Eystein Borgen added, “The center tower reduces the required displacement, which gives many benefits like reduced draft at quayside, lower environmental loads acting on the structure and reduced overall steel weight.

"Furthermore, it enables installation of tower and turbine on a floating structure. The bracing structures transfer the loads efficiently between the satellite columns and the tower. These loads are extreme for harsh environments and large WTGs, in particular when considering load scenarios like cross-sea waves and `split forces’ acting between the columns, torsion loads from the tower and mooring line failures. The symmetric design simplifies the supply chain and lends itself well to mass production, lowering the unit cost and increasing the supply chain efficiency which will be required to develop large wind parks in short time frames.”

Deepsea Star should be available for deployment from the mid-2020s. The design is under consideration for various oil and gas electrification projects in the North Sea, the company said.

02.28.2023