Wind energy from the deep sea
Current offshore technology is largely based on its onshore counterpart, despite the significant differences in conditions and environment. The aim of the DEEPWIND (Future deep sea wind turbine technologies) project was to develop a new and reliable wind energy technology that is less costly than existing offshore wind energy. The design was a floating vertical axis wind turbine comprising a long vertical tube in the water, a vertical axis rotor on top of this tube, a generator at the base and a seabed mooring system. An aeroelastic modelling suite calculated the effects of external loads on the wind turbine, floater, power transmission and loads transmitted to the seabed via the mooring system. Researchers developed a proof-of-principle prototype 1 kW wind turbine to demonstrate the principle under near-to-realistic operating conditions with a two-bladed rotor. They also used it to study floater kinematics under controlled conditions in a test basin laboratory and with combined wind simulation to examine performance of the inclined rotor. The inbuilt monitoring system provided data about movements of the rotating components and submerged parts. Researchers also analysed the power transmission, mooring and torque absorption components relative to environmental conditions such as wind, waves and currents. In parallel, DEEPWIND drew up a plan to scale up the 5 MW conceptual design to a 20 MW design. The project also developed computer code for the blade pultrusion manufacturing process, generator and wind turbine coupling, and turbine control simulation. DEEPWIND results have shown that vertical axis wind turbines combined with deep sea-based technologies exposed to gusty winds far from the coast are better tolerated than existing horizontal-axis wind turbines. Furthermore, this concept has acquired increased momentum from public awareness, thereby pushing the technology one step closer to commercialisation.
Keywords
Wind energy, deep sea, wind turbines, DEEPWIND, aeroelastic, floater kinematics