Offshore wind farms

REpower 5MW wind turbines D4 (nearest) to D1 on the Thornton Bank

Main article: List of offshore wind farms

As of 2008^[update], Europe leads the world in development of offshore wind power, due to strong wind resources and shallow water in the North Sea and the Baltic Sea, and limitations on suitable locations on land due to dense populations and existing developments. Denmark installed the first offshore wind farms, and for years was the world leader in offshore wind power until the United Kingdom gained the lead in October, 2008 with 590 MW of nameplate capacity installed.^[47] The United Kingdom planned to build much more extensive offshore wind farms by 2020.^[48] Other large markets for wind power, including the United States and China focused first on developing their on-land wind resources where construction costs are lower (such as in the Great Plains of the U.S., and the similarly wind-swept steppes of Xinjiang and Inner Mongolia in China), but population centers along coastlines in many parts of the world are close to offshore wind resources, which would reduce transmission costs.

On 21 December 2007, Q7 (later renamed as Princess Amalia Wind Farm) exported first power to the Dutch grid, which was a milestone for the offshore wind industry. The 120MW offshore wind farm with a construction budget of €383 million was the first to be financed by a nonrecourse loan (project finance). The project comprises 60 Vestas V80-2MW wind turbines. Each turbine's tower rests on a monopile foundation to a depth of between 18-23 meters at a distance of about 23 km off the Dutch coast.

Transporting large wind turbine components (tower sections, nacelles, and blades) is much easier over water than on land, because ships and barges can handle large loads more easily than trucks/lorries or trains. On land, large goods vehicles must negotiate bends on roadways, which fixes the maximum length of a wind turbine blade that can move from point to point on the road network; no such limitation exists for transport on open water. Construction and maintenance costs per wind turbine are higher for offshore wind farms, motivating operators to reduce the number of wind turbines for a given total power by installing the largest available units. An example is Belgium's Thorntonbank Wind Farm with construction underway in 2008, featuring 5MW wind turbines from REpower, which were among the largest wind turbines in the world at the time.