Floating wind turbines
Lyse is planning the world's first deep-water wind farm off the island of Utsira in Rogaland, Norway.
DEEP SEA. Criteria for location of an offshore wind farm is excellent wind conditions and suitable water depth. The wind farm must be situated near a strong onshore power grid and near harbours and shipyards. (Illustration: Lyse)
The potential for offshore wind power is considered to be huge. The Norwegian company SWAY AS, is developing wind turbines for deep-water locations that will be tested out off the island of Utsira. Norway has the possibility of becoming a leading producer of renewable maritime energy, based on new Norwegian technology. Lyse Energi already develops onshore wind farms, and the company underlines that the planned offshore wind farm off Utsira, reflects Lyse’s ambition to be an innovative and socially-aware company.
Three steps on the way to full scale power production
During the offshore wind farm's pilot phase in 2009, Lyse Energi will build a 5 MW prototype floating wind turbine off the coast of Rogaland. In 2012 a demonstration farm with five wind turbines, will be built approximately five kilometres east of Utsira. The aggregate installed capacity is planned to be 25 MW. Eventually, the the wind farm will consist of 56 turbines approximately 17 kilometres west of Utsira with a total installed output of 280 MW and a power generation capacity of approximately 1.2 TWh.
Wind, water depth and onshore grid needed
The criteria for the location of an offshore wind farm are excellent wind conditions and suitable water depth. The wind farm must be situated near a strong onshore power grid and near harbours and shipyards. The level of conflict with affected parties must be acceptable and the farm must be built in cooperation with the local communities.
The tower and the turbin
The SWAY system consists of a 186-metre tower, of which 90 metres raise above sea level and 96 metres run below the ocean surface. The wind turbine is placed on top of the tower. The rotor be between 110-130 metres in diameter. The SWAY system uses a downwind rotor, which means the turbine house and tower are aerodynamically designed to limit the turbulence and reduction of wind velocities onto the rotor blades.
The assembly of the tower and wind turbine takes place onshore and the unit is then towed to the location at sea.This floating tower is anchored to the seabed by a tension leg and suction anchor. The anchor tension leg is fixed to the tower by a yaw mechanism which allows the entire windmill, including the tower, to rotate according the wind direction. Water depths of 120 to 400 metres are considered suitable for this type of floating wind turbine.
Transformer and transmission
A transformer is placed inside the tower and a sea cable from each individual turbine is hooked up in a transformer station for further transmission of power. A high-voltage cable will connect the offshore transformer station and the onshore power grid. To access to the wind turbines for maintenance, mechanics will use boats or helicopters. The unit can easily be disconnected from the sea bed and moved.The wind-power plant will have a lifetime of approximately 25 years, according to SWAY.
About SWAY AS:
SWAY AS was established in 2001 based up competence from floating maritime and offshore structures. The company patented their floating wind power system in 2002. Major owners are StatoilHydro, Inocean, Lyse, Scatec, Rosenberg yard, Gyldenlove Eiendom and Eystein Borgen
About Lyse Energi:
Lyse is a power company based in Jæren and Ryfylke, Norway. The company is owned by several municipalities in the western part of Norway.
For further information about the Utsira Offshore wind park:
Further reading:
Facts
A few hundred meters offshore, winds are twice as strong as on land in much of the world. Offshore wind energy has huge potential, and floating wind turbines is a promising technology. Such turbines are now being developed. They are meant to be used out at sea in deep waters, and they do not need to be permanently moored to the ocean bed.
Related Articles
The powerful connection
Troll WindPower is delivering the infield transmission system for offshore wind farms based on Norwegian offshore experience.
