Offshore wind power refers to the construction of wind farms in large bodies of water to generate electric power. These installations can utilize the more frequent and powerful winds that are available in these locations and have less aesthetic impact on the landscape than land based projects. However, the construction and the maintenance costs are considerably higher.
Siemens and Vestas are the leading turbine suppliers for offshore wind power. Ørsted, Vattenfall and E.ON are the leading offshore operators.
As of October 2010, 3.16 GW of offshore wind power capacity was operational, mainly in Northern Europe. According to BTM Consult, more than 16 GW of additional capacity will be installed before the end of 2014 and the UK and Germany will become the two leading markets. Offshore wind power capacity is expected to reach a total of 75 GW worldwide by 2020, with significant contributions from China and the US.
The UK's investments in offshore wind power have resulted in a rapid decrease of the usage of coal as an energy source between 2012 and 2017, as well as a drop in the usage of natural gas as an energy source in 2017.
In 2012, 1,662 turbines at 55 offshore wind farms in 10 European countries produced 18 TWh, enough to power almost five million households.
As of September 2018 the Walney Extension in the United Kingdom is the largest offshore wind farm in the world at 659 MW.