Offshore Installations
See also: Offshore wind power, List of offshore wind farms, and Lists of offshore wind farms by countryEurope is the leader in offshore wind energy, with the first offshore wind farm being installed in Denmark in 1991. As of 2010, there are 39 offshore wind farms in waters off Belgium, Denmark, Finland, Germany, Ireland, the Netherlands, Norway, Sweden and the United Kingdom, with a combined operating capacity of 2,396 MW. More than 100 GW (or 100, 000 MW) of offshore projects are proposed or under development in Europe. The European Wind Energy Association has set a target of 40 GW installed by 2020 and 150 GW by 2030.
As of February 2012, the Walney Wind Farm in United Kingdom is the largest offshore wind farm in the world at 367 MW, followed by Thanet Offshore Wind Project (300 MW), also in the UK. The London Array (630 MW) is the largest project under construction.
| Wind farm | Capacity (MW) | Country | Turbines and model | Commissioned | References |
|---|---|---|---|---|---|
| Walney | 367 | United Kingdom | 102 × Siemens SWT-3.6 | 2012 | |
| Thanet | 300 | United Kingdom | 100 × Vestas V90-3MW | 2010 | |
| Horns Rev II | 209 | Denmark | 91 × Siemens 2.3-93 | 2009 | |
| Rødsand II | 207 | Denmark | 90 × Siemens 2.3-93 | 2010 | |
| Lynn and Inner Dowsing | 194 | United Kingdom | 54 × Siemens 3.6-107 | 2008 | |
| Robin Rigg (Solway Firth) | 180 | United Kingdom | 60 × Vestas V90-3MW | 2010 | |
| Gunfleet Sands | 172 | United Kingdom | 48 × Siemens 3.6-107 | 2010 | |
| Nysted (Rødsand I) | 166 | Denmark | 72 × Siemens 2.3 | 2003 | |
| Ormonde | 150 | United Kingdom | 30 × REpower 5.0 | 2011 |
Offshore wind turbines are less obtrusive than turbines on land, as their apparent size and noise is mitigated by distance. Because water has less surface roughness than land (especially deeper water), the average wind speed is usually considerably higher over open water. Capacity factors (utilisation rates) are considerably higher than for onshore locations.
The province of Ontario in Canada is pursuing several proposed locations in the Great Lakes, including the suspended Trillium Power Wind 1 approximately 20 km from shore and over 400 MW in size. Other Canadian projects include one on the Pacific west coast.
As of 2010, there are no offshore wind farms in the United States. However, projects are under development in wind-rich areas of the East Coast, Great Lakes, and Pacific coast.
Installation and service / maintenance of off-shore wind farms are a specific challenge for technology and economic operation of a wind farm. Service vessels have to be operated nearly 24/7 (availability higher than 80% of time) to get sufficient amortisation from the wind turbines. Therefore special fast service vehicles for installation (like Wind Turbine Shuttle) as well as for maintenance (including heave compensation and heave compensated working platforms to allow the service staff to enter the wind turbine also at difficult weather conditions) are required. So-called inertial and optical based Ship Stabilization and Motion Control systems (iSSMC) are used for that.
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