Odfjell Oceanwind has launched its Deepsea Star platform designed to host 15MW and larger turbines in floating offshore wind farms.
The Deepsea Star is a column-stabilised, semi-submersible steel design with centre turbine tower, designed to take the weights and loads from the 15MW turbines becoming available for floating wind from 2025 onwards.
The model is undergoing the Basic Design Approval from DNV based on Siemens Gamesa’s SG 14-236 DD turbine and a multi-location design basis which includes harsh environment locations relevant for floating offshore wind globally.
“With the Deepsea Star we have compiled Odfjell’s 50 years learnings from operating semi-submersible structures in harsh environments with 20 years’ experience in designing floating wind solutions.
“Stepping up to the 15MW turbines makes floating wind relevant for larger utility-scale wind parks and will be a significant contribution to lowering the LCoE in the coming years,” said CEO of Odfjell Oceanwind Per Lund.
He added: “The new design has successfully completed the model tank test and our 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 15MW 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 programmes.
“This is particularly the case for Scotwind, INTOG and Utsira Nord. The Deepsea Star can also be optimised to site specific metocean data.”
In the design of theplatform for bigger turbines, the centre 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 transfers the loads efficiently between the satellite columns and the tower.
These loads are extreme for harsh environments and large turbines, in particular when considering 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 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, said the company.