Offshore wind power or offshore wind energy is the deployment of wind farms sited in bodies of water. Higher wind speeds are available offshore compared to on land, so offshore farms’ electricity generation is higher per amount of capacity installed, and NIMBY opposition is typically weaker.
Unlike the typical use of the term “offshore” in the marine industry, offshore wind power includes inshore water areas such as lakes, fjords and sheltered coastal areas as well as deeper-water areas. Most offshore wind farms employ fixed-foundation wind turbines in relatively shallow water. As of 2020, floating wind turbines for deeper waters were in the early phase of development and deployment.
As of 2020, the total worldwide offshore wind power capacity was 35.3 gigawatt (GW).United Kingdom (29%), China (28%) and Germany (22%) account for more than 75% of the global installed capacity. The 1.2 GW Hornsea Project One in the United Kingdom was the world’s largest offshore wind farm. Other projects in the planning stage include Dogger Bank in the United Kingdom at 4.8 GW, and Greater Changhua in Taiwan at 2.4 GW.
The cost of offshore has historically been higher than that of onshore, but costs decreased to $78/MWh in 2019. Offshore wind power in Europe became price-competitive with conventional power sources in 2017. Offshore wind generation grew at over 30 percent per year in the 2010s. As of 2020, offshore wind power had become a significant part of northern Europe power generation, though it remained less than 1 percent of overall world electricity generation.
Europe is the world leader in offshore wind power, with the first offshore wind farm (Vindeby) being installed in Denmark in 1991. In 2009, the average nameplate capacity of an offshore wind turbine in Europe was about 3 MW, and the capacity of future turbines was expected to increase to 5 MW.
A 2013 review of the engineering aspects of turbines like the sizes used onshore, including the electrical connections and converters, considered that the industry had in general been overoptimistic about the benefits-to-costs ratio and concluded that the “offshore wind market doesn’t look as if it is going to be big”. In 2013, offshore wind power contributed to 1,567 MW of the total 11,159 MW of wind power capacity constructed that year.
By January 2014, 69 offshore wind farms had been constructed in Europe with an average annual rated capacity of 482 MW. The total installed capacity of offshore wind farms in European waters reached 6,562 MW. The United Kingdom had by far the largest capacity with 3,681 MW. Denmark was second with 1,271 MW installed and Belgium was third with 571 MW. Germany came fourth with 520 MW, followed by the Netherlands (247 MW), Sweden (212 MW), Finland (26 MW), Ireland (25 MW), Spain (5 MW), Norway (2 MW) and Portugal (2 MW).
At the end of 2015, 3,230 turbines at 84 offshore wind farms across 11 European countries had been installed and grid-connected, making a total capacity of 11,027 MW.
Outside of Europe, the Chinese government had set ambitious targets of 5 GW of installed offshore wind capacity by 2015 and 30 GW by 2020 that would eclipse capacity in other countries. However, in May 2014 the capacity of offshore wind power in China was only 565 MW. Offshore capacity in China increased by 832 MW in 2016, of which 636 MW were made in China.
The offshore wind construction market remains quite concentrated. By the end of 2015, Siemens Wind Power had installed 63% of the world’s 11 GW offshore wind power capacity; Vestas had 19%, Senvion came third with 8% and Adwen 6%. About 12 GW of offshore wind power capacity was operational, mainly in Northern Europe, with 3,755 MW of that coming online during 2015. As of 2020 90% of the offshore global market was represented by European companies.
By 2017, the installed offshore wind power capacity worldwide was 20 GW. In 2018, offshore wind provided just 0.3% of the global electricity supply. Nevertheless, just in 2018 an additional amount of 4.3 GW of offshore wind capacity was employed on a worldwide scale. In Denmark, 50% of the electricity was supplied by wind energy in 2018 out of which 15% was offshore. The average size of turbines installed was 6.8 MW in 2018, 7.2 MW in 2019 and 8.2 MW in 2020.