Floating offshore wind
Wind turbines mounted on buoyant platforms moored to the seabed, enabling wind farms in water deeper than about 60 m where fixed foundations become uneconomic.
Roughly 80% of the world's offshore wind resource lies in water deeper than 60 m (IEA Offshore Wind Outlook 2019), including the coasts of Japan, Korea, California, Norway, the Mediterranean and much of the Atlantic margin. Floating platforms unlock these areas.
The main platform concepts:
- Spar-buoy: a deep ballasted cylinder, very stable but needing deep water at the quayside for assembly (Hywind Scotland, Hywind Tampen)
- Semi-submersible: three or four columns linked by pontoons, shallow draft and assembled in port (WindFloat Atlantic, Kincardine)
- Tension-leg platform (TLP): held down by taut tendons, small footprint but demanding anchors
- Barge: wide, shallow hull with damping pool
Platforms are held by catenary chain, synthetic rope or taut moorings with drag-embedment, suction or driven-pile anchors, and connected by dynamic inter-array cables designed for motion fatigue.
Pilot farms have performed well: Hywind Scotland (30 MW) reported capacity factors above 50% in several years. Global installed capacity was still only about 250–300 MW by 2024, and costs remain high, with reported LCOE for pre-commercial projects often in the USD 150–250/MWh range. NREL ATB and DNV expect convergence toward fixed-bottom costs as serial production, port infrastructure and larger turbines mature, though timelines have slipped amid cost inflation. The turbine controller must also be re-tuned, since standard pitch control can amplify platform motions.
Related terms
All terms →- Offshore wind
Wind turbines installed in seas or large lakes, usually on fixed foundations in water up to about 60 m deep, exploiting stronger and steadier winds than onshore sites.
- Pitch control
Rotation of wind turbine blades about their long axis to change the angle of attack, used to regulate power above rated wind speed, start up, and stop the rotor.
- Yaw system
The motors, gears, bearing and brakes that rotate a wind turbine nacelle about the tower axis to keep the rotor facing the wind.
- Capacity factor
The ratio of the energy a power plant actually produces over a period to the energy it would produce running at full nameplate capacity for the whole period.
- LCOE (Levelized Cost of Electricity)
The constant price per MWh that recovers all lifetime costs of a power plant, discounted to present value, divided by its discounted lifetime output.