Heerema’s new offshore floating wind installation method allows floaters (the buoyant, bottom part of floating offshore wind installations) to be constructed on land before being shipped to location. After arrival, they are installed by crane using Heerema’s floating installation frame to lift the floaters from the vessel (click here to see video). During that process, they are submerged under the weight of the frame as permanent guy wires are attached to the seabed foundations. Later, the wind turbines themselves are installed on to the floaters.

According to Heerema, the new installation method helps cut engineering, procurement and construction costs, reducing the levelised cost of energy. The floaters’ volume and weight are reduced by removing the need for wet-towing, it explains. Also, as the floater is lifted directly from the ship, both the floater and wind turbine can be optimised for in-place conditions. Furthermore, a low-tech floater design is possible by integrating installation requirements such as ballasting provisions into reusable installation tooling, removing the requirement to build these features into each floater.

It notes that by removing the need for in-port assembly of the floater and wind turbine, there is less space and draught required in the port and reduced quayside capacity, which helps avoid one-off major investments in port areas.

Heerema also claims that by removing time-consuming and highly weather-sensitive wet tows and mooring connections, higher throughput can be achieved on floating wind projects. ‘The floating to floating installation method means floater and wind turbine campaigns can be decoupled, reducing supply-chain pressure, and resulting in a more efficient process,’ it says.

Aker Solutions unveils three innovative floating wind foundation designs

Meanwhile, Aker Solutions has introduced three new floating wind foundation designs – YFloat, CONFloat-Omega and CONFloat-7C – that it claims maximise energy production, simplify construction and reduce maintenance. All three have passive ballast systems and are able to support turbines that are 15 MW and larger, says the company.

The first, YFloat, is a steel floating substructure. ‘Its symmetrical design facilitates efficient pre-fabrication with the option of local assembly, reducing material usage and simplifying the manufacturing process,’ says Aker. It also offers ‘scalability that facilitates higher power generation’ and lower cost.  

The second design, CONFloat-Omega, is a circular concrete floater concept featuring a moonpool at its centre and an offset turbine and tower. It is specifically designed for harsh environmental conditions, with ‘the concrete material and robust construction ensure high resistance to fatigue and minimal maintenance requirements’, according to Aker.

CONFloat-7C, the third design, draws on the company’s CONDEE designs, with a seven-cell configuration featuring a centralised turbine and tower. The CONFloat-7C has been designed to float at a lower draught for installation and integration of the tower and wind turbine generator (WTG), as well as commissioning and completion of the fully assembled structure (ie floater and WTG). This design allows for greater flexibility in selecting execution sites and ports, particularly in regions with limited water depth, such as areas around the UK, Scotland, and other parts of Europe and the world, notes Aker.

Aker Solutions’ new floating wind foundation designs – (left to right) CONFloat-Omega, YFloat, and CONFloat-7C  

Photo: Aker Solutions