Offshore wind power
Offshore wind power or offshore wind energy is the generation of electricity through wind farms in bodies of water, usually at sea. Due to a lack of obstacles out at sea versus on land, higher wind speeds tend to be observed out at sea, which increases the amount of power that can be generated per wind turbine. Offshore wind farms are also less controversial than those on land, as they have less impact on people and the landscape.
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. Floating wind turbines for deeper waters are in an earlier phase of development and deployment.
As of 2022, the total worldwide offshore wind power nameplate capacity was 64.3 gigawatt. China, the United Kingdom, and Germany account for more than 75% of the global installed capacity. The 1.4 GW Hornsea Project Two in the United Kingdom was the world's largest offshore wind farm. Other large 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. A big advantage of offshore wind power compared to onshore wind power is the higher capacity factor meaning that an installation of given nameplate capacity will produce more electricity at a site with more consistent and stronger wind which is usually found offshore and only at very few specific points onshore.
History
Capacity
Europe is the world leader in offshore wind power, with the first offshore wind farm 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, Sweden, Finland, Ireland, Spain, Norway and Portugal.
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.
The history of the development of wind farms in the North Sea, as regards the United Kingdom, indicates three phases: coastal, off-coastal and deep offshore in the period 2004 through to 2021. Through the development of offshore wind power the Baltic Sea is expected to become a major source of energy for countries in the region. According to the Marienborg Declaration, signed in 2022, all EU Baltic Sea states have announced their intentions to have 19.6 gigawatts of offshore wind in operation by 2030.
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.
In 2022, the offshore wind industry marked its second-largest yearly growth, adding 8.8 GW and increasing global capacity to 64.3 GW—a 16% rise from the previous year. The Global Wind Energy Council anticipates a significant expansion, projecting an additional 380 GW by 2032 to reach a total of 447 GW. However, market challenges in Europe and the US could slow progress, with only a third of the anticipated capacity expected to be installed between 2023 and 2027.
Costs
In 2010, the US Energy Information Agency said "offshore wind power is the most expensive energy generating technology being considered for large scale deployment".The 2010 state of offshore wind power presented economic challenges significantly greater than onshore systems, with prices in the range of 2.5-3.0 million Euro/MW.
That year, Siemens and Vestas were turbine suppliers for 90% of offshore wind power, while Ørsted A/S, Vattenfall and E.on were the leading offshore operators.
In 2011, Ørsted estimated that while offshore wind turbines were not yet competitive with fossil fuels, they would be in 15 years.
Until then, state funding and pension funds would be needed.
At the end of 2011, there were 53 European offshore wind farms in waters off Belgium, Denmark, Finland, Germany, Ireland, the Netherlands, Norway, Sweden and the United Kingdom, with an operating capacity of 3,813 MW, while 5,603 MW was under construction.
Offshore wind farms worth €8.5 billion were under construction in European waters in 2011.
In 2012, Bloomberg estimated that energy from offshore wind turbines cost per MWh.
Costs of offshore wind power are decreasing much faster than expected.
By 2016, four contracts were already below the lowest of the predicted 2050 prices.
Offshore wind projects in the United States cost US$4,000 per kilowatt to build in 2023, compared to US\$1,363 per kilowatt for onshore wind farms. The cost of offshore wind has increased by 36% since 2019, while the cost of onshore wind has increased by only 5% over the same period.
Some major U.S. projects have been stymied due to inflation even after subsidies became available from the Inflation Reduction Act.
Future development
The Organisation for Economic Co-operation and Development predicted in 2016 that offshore wind power will grow to 8% of ocean economy by 2030, and that its industry will employ 435,000 people, adding $230 billion of value.The European Commission expects that offshore wind energy will be of increasing importance in the future, as offshore wind is part of its Green Deal. The development of the full potential of Europe's offshore wind energy is one of the key actions in the Clean Energy section of the Green Deal.
By 2050, the expectation is that the installed offshore wind power capacity will reach 1550 GW on a worldwide scale. Compared to the capacity of 2017 that corresponds to an 80-fold increase.
One of the advancements that characterises the current development within the offshore industry are technologies that allow for offshore wind projects further off the shore where wind availability is higher. In particular, the adoption of floating foundation technologies has proved to be a promising technology for unlocking the wind potential on deeper waters.
A main investor for Europe has been the European Investment Bank. The EIB has been investing in offshore renewable energy, co-financing around 40% of all capacity in Europe. Since 2003, the EIB has sponsored 34 offshore wind projects in Europe, including facilities in Belgium, Denmark, Germany, France, the Netherlands, Portugal, and the United Kingdom, totaling more over €10 billion in loans. The EIB funded €3.7 billion in maritime renewable energy between 2019 and 2023 and has future plans for financing of wind farms.
Economics
The advantage of locating wind turbines offshore is that the wind is much stronger off the coasts, and unlike wind over land, offshore breezes can be strong in the afternoon, matching the time when people are using the most electricity. Offshore turbines can also be located close to the load centers along the coasts, such as large cities, eliminating the need for new long-distance transmission lines.However, there are several disadvantages of offshore installations, related to more expensive installation, difficulty of access, and harsher conditions for the units.
Locating wind turbines offshore exposes the units to high humidity, salt water and salt water spray which negatively affect service life, cause corrosion and oxidation, increase maintenance and repair costs and in general make every aspect of installation and operation much more difficult, time-consuming, more dangerous and far more expensive than sites on land.
The humidity and temperature is controlled by air conditioning the sealed nacelle.
Sustained high-speed operation and generation also increases wear, maintenance and repair requirements proportionally.
The cost of the turbine represents just one third to one half of total costs in offshore projects today, the rest comes from infrastructure, maintenance, and oversight.
Costs for foundations, installation, electrical connections and operation and maintenance are a large share of the total for offshore installations compared to onshore wind farms.
The cost of installation and electrical connection also increases rapidly with distance from shore and water depth.
Other limitations of offshore wind power are related to the still limited number of installations.
The offshore wind industry is not yet fully industrialized, as supply bottlenecks still exist as of 2017.