Floating offshore wind uses turbines mounted on platforms that float on the sea surface and are held in place by mooring lines anchored to the seabed. Conventional offshore turbines stand on foundations fixed to the seabed, which become impractical and expensive as the water gets deeper.
How it works
The turbine itself is similar to a fixed-bottom offshore model. The difference is the floating structure beneath it. The main designs are:
- Spar buoy: a long, ballasted cylinder that sits deep in the water, like a fishing float. It needs very deep water.
- Semi-submersible: a wide platform on several columns, partly under water. It works in moderate depths and can be assembled in port and towed out.
- Tension leg platform: a buoyant base pulled down by taut vertical tethers.
Because the platforms can be built in harbour and towed to site, less heavy work is needed at sea. The cost per unit of electricity is still higher than for fixed turbines, as the industry has not yet reached large-scale production.
UK projects
| Project | Location | Capacity | Status |
|---|---|---|---|
| Hywind Scotland | Off Peterhead, 95–120 m depth | 30 MW (5 turbines, spar buoys) | Generating since October 2017 |
| Kincardine | Off Aberdeen | 50 MW (semi-submersibles) | Fully operating since 2021 |
| Celtic Sea (Round 5) | Off south Wales and south-west England | Three sites of up to 1.5 GW each | Agreements for lease signed by March 2026 |
The Crown Estate’s Round 5 is the first leasing round in England and Wales designed for floating wind. Equinor, Gwynt Glas (EDF power solutions and ESB) and Ocean Winds (EDPR and ENGIE) hold the three sites, which The Crown Estate says could be generating by the mid-2030s.
Why it matters
Much of the strongest wind around Britain blows over deep water, particularly off Scotland and in the Celtic Sea. Floating turbines open up those areas, and sites further from shore are less visible from the coast. The challenges are cost, port capacity for assembly, grid connections and sharing the sea with fishing fleets.
Read more: TotalEnergies Launches Floating Wind Pilot to Supply the Culzean Gas Platform.