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  • Writer's pictureSarah Whiteford

9 of the Largest Offshore Wind Farms

There’s been a lot of news about increasingly large wind farms such as the planned Empire Wind and Beacon Wind projects off the east coast of the United States. We even wrote about those projects in a recent news article about the Equinor/bp partnership. Both Beacon and Empire could produce up to 2.4 GW each, with an estimate of 1 MW powering 700 homes, these two projects could power an estimated 3,360,000 homes combined. That got us curious about other large wind farms, so let’s take a look at some of the largest wind farms around the world, what’s in the pipeline, and how many homes these projects can power.

What is offshore power?

At its heart, offshore power is simply power that is generated on the ocean. This power can be in the form of solar, wind, or even waves. Wind and waves are more powerful the farther you move from shore, so wind farms are moving farther and farther out. Locating turbines farther out from land also means new wind farms cannot be seen from shore, maintaining the shoreline view. Today we’ll take a look at some of the largest offshore wind farms - we plan to take a broader look at offshore power in the future.

Largest offshore wind farms

Hornsea 1. Image Credit:

The current title holder for largest offshore wind farm is Hornsea 1, with a total capacity of 1.2 GW of power. It’s 120 km off the coast of Yorkshire in the United Kingdom and consists of 174 turbines, the last completed in October 2019. It’s spread over 407 square kilometers and holds the title for the first offshore wind farm to produce more than 1 gigawatt of electricity. The Ørsted developed project uses Siemens Gamesa 7 MW turbines that together can power over a million households. The wind farm is supplied with 4G/LTE coverage to improve operational efficiency and keep workers in contact with the shore.

Ørsted’s Borssele 1&2 and 3&4 come in second and third place as the largest energy producing wind farms. Borssele 1&2 is a 752 MW project located in the Dutch North Sea and is the first use of Siemens Gamesa’s 8 MW offshore turbines. Installation of all 94 turbines was completed in just 5 months from April to October 2020. They are 200 meters tall with rotor diameters of 167 meters. Located off the Dutch province of Zeeland, Borssele 1&2 will power around a million Dutch households. DEME Offshore provided Sea Installer and Sea Challenger jack-ups for turbine installation, with the Innovation doing the foundation work. Van Oord provided the Nexus for cable-laying duties. Borssele 3&4 is also in the Dutch North Sea, and is comprised of 77 turbines provided by MHI Vestas for a total of 731.5 MW. The 9.5 MW turbines will provide a total of 3,000 gigawatt hours of power per year, to at least 825,000 Dutch households. 3&4 currently provides power, but is not yet fully complete.

East Anglia ONE under construction. Image Credit: Wikipedia, user Pontificalibus.

East Anglia ONE is about 43 km from shore, located between the United Kingdom and the Netherlands, connected to Bramford, England. Initial capacity was 1.2GW, which would have put it in line with Hornsea 1, but subsidies were insufficient and it was scaled down to its current capacity of 714 MW. It consists of 102 Siemens gearless turbines rated at 7 MW each. They use jacketed foundations in water depths of 30-40 meters. There are future plans for three additional sites, East Anglia TWO, East Anglia THREE, and East Anglia ONE North that will add 900, 1200, and 800 MW of power, respectively.

Largest offshore wind farms under construction

Hornsea 2 is the largest planned project with a potential capacity of up to 1.8 GW. The location is about 400 square kilometers in the Hornsea area off the UK coast. Dong Energy will build 174 turbines for the site, beginning installation in 2021 with power in 2022, making it the largest wind farm in the world.

Seagreen Alpha and Bravo are two phases of development of a wind farm off the coast of Scotland. Their combined capacity will be 1.075 GW and started in January 2020. Commercial operations should commence in 2024, about 27 km from the coastline of Angus.

Wind turbine at Moray East. Image Credit: Moray East.

Moray East is also under construction near Scotland, consisting of 100 turbines at 9.5 MW each for a total of 950 MW of power. According to Offshore Engineer, “The offshore wind farm is being developed by Moray Offshore Windfarm East Ltd (MOWEL), which is a joint venture company owned by Ocean Winds ( 56.6%) Diamond Green Limited (33.4%) and CTG (10%).” It is the country’s largest infrastructure project. Expected completion is 2022 with savings of 1.4 million tons of CO2 each year.

The previous three wind farms are currently under construction, but the below wind farms are still in the planning stage. We’ll talk about a few of the important projects in the pipeline. That being said, here is the largest planned wind farm:

Planned wind farms

South Korea has a $43.7 billion project for what will easily be the world’s largest wind farm when completed. The planned size is 8.2 GW, almost 7 times the size of Hornsea 1. The project brings together 33 public and private entities and is expected to create about 120,000 jobs. Scheduled completion is by 2030 and will help South Korea reach their target of 12 GW of offshore wind capacity by 2030.

IJmuiden Ver (IJVER) is another massive wind farm planned to help reach the Dutch 4 megaton CO2 reduction by 2030 with offshore wind. Located approximately 80 kilometers offshore, the expected capacity is at least 4 GW. The Netherlands has about 1GW of capacity with 3.5 GW planned by 2023, leaving an additional 7 GW needed. IJVER is expected to produce more than half the deficit.

The United States has lagged behind in the offshore wind power department, with only one operational site: Block Island. This lone wind farm is off the coast of Rhode Island and features 5 Haliade 6 MW turbines for a total of 30 MW of capacity. The U.S. is moving quickly to catch up with three new sites, each with multiple projects. The Coastal Virginia Offshore Wind project is a 2,640 MW project expected to be completed in 3 equal phases of 880 MW. Two sites near New York are also being planned: Empire and Beacon. Equinor recently released a statement they are partnering with bp to develop Empire Wind 2 and Beacon Wind 1. Each location will provide more than 1,200 MW of power with 90 turbines each. The wind turbines will be between 10-15 MW each; judging from the rough numbers, the newest 13 or 14 MW turbines will likely be installed.

Wind turbine blade ready for installation. Image Credit: GroundSure.

What about the turbines?

We thought you might be interested in learning more about the turbines. The first offshore turbines ever installed were at the Vindeby offshore wind farm in 1991. They produced about 0.45 MW of electricity and were 35 meters tall with a rotor diameter of 35 meters. The current largest turbines are made by Siemens Gamesa, producing up to 15 MW of electricity. As you can imagine with a capacity 33 times the original, they are monstrous with a 222 meter rotor diameter. With turbines getting so large, vessels are being specially designed to handle them. If you want to learn more about how turbines are installed on the ocean, check out our article “How are offshore wind turbines installed?”.

As technology advances and we continue to look for greener solutions to our power needs, the offshore power industry will grow. There are some huge wind farms in the works, with ever increasing turbine sizes. We’re excited to be in front of this new chapter in energy, supporting the dynamically positioned vessels that install and service wind turbines, cables, and their foundations.

Happy Friday!


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