North Sea ‘energiser’

World first offshore energy island central to Denmark’s green energy transition

Wind turbines will be central to Denmark’s green energy island situated North Sea. Credit: Shutterstock/TwiXteR

Early this year (February) the Danish government took the bold move to develop the world’s first artificial island specifically for the capture of green energy. The energy island will be located in the North Sea, around 80 km off the Danish west coast, where, according to energy-focussed fund management company Copenhagen Infrastructure Partners (CIP), “conditions for green energy production based on offshore wind are optimal”.

The island will have a minimum capacity of 3 gigawatts when it starts operating in 2033, with potential for expansion to 10 gigawatts of offshore wind. When running at full capacity the island should be able to supply 10 million households with their energy needs.

According to the Danish Energy Agency, the island’s exact design has not yet been determined. It noted, however, that an island expected to handle 3 gigawatts of offshore wind will likely be the size of at least 120,000 m2 – equivalent to 18 football fields and when expanded, 64 football pitches.

No stranger to wind turbine technology, Denmark has been a leading pioneer in its evolution over the past centuries. And in the early 1990s, it became the first country to establish an offshore wind farm using locally manufactured turbines.

The energy island will be situated west of Jutland in the North Sea, around 80 km from the town of Thorsminde.

The North Sea is an important shipping region and is situated between Norway and Denmark to the east, the UK to the west and Germany, The Netherlands, France and Belgium to the south. Many of Europe’s largest ports, such as Rotterdam and Antwerp, as well as the UK port of Felixstowe are situated either on or close to the North Sea. It is also home to some of the business shipping lanes in the world such as the Dover Strait.

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With MarineTraffic you can view the current status of ships in the North Sea. An energy island is planned 80 km off the Danish coast

MarineTraffic AIS data reveals that in November this year alone Europe’s biggest port, Rotterdam, received 437 containerships, whilst Antwerp and Felixstowe received 314 and 60 containerships respectively.

The North Sea is an active offshore oil drilling region and has around 170 active rigs, and so tanker activity is prevalent. 

The Belgian port of Antwerp saw 1327 tankers arrive at its terminals in November, 75 at Rotterdam, and 82 at the UK port of Fawley, shows MarineTraffic data.

The North Sea island represents an excellent opportunity for the dredging and offshore supply industries, both during the energy islands’ construction and then its operational life. If a land-based island, as opposed to a platform, is realised then extensive dredging will be needed to create the structure (the North Sea has a mean depth of 95 m). Further, cables will need to be laid to conduct the electricity generated by the turbines to the mainland for consumption. 

The tendering process is scheduled to commence next year (2022). CIP announced on 30 November that it has signed an agreement with dredging giants, Boskalis and Deme, renewables development and management company Acciona and Danish international contractor, MT Højgaard International. Known as the Njord Group, the five companies together plan to bid for the Danish project.

Further, in the future tankers may well be deployed to transport the green hydrogen that is planned to be created with any excess electricity generated by the turbines. By process of electrolysis, water (H20) is split into its components of hydrogen and oxygen. The liquid hydrogen can then be captured and transported to the mainland or beyond by ship. 

It’s a fuel that’s been earmarked as a potential route to reduced emissions. And a Danish paper written by Jacob Østergaard electrical engineering professor at the Technical University of Denmark (DTU), Professor Nicolaos Antonio Cutululis from DTU’s Wind Energy department, and Professor Frede Blaabjerg from Aalborg University, sees the benefits of shipping the product. They write in a joint editorial: “On the energy islands, we can convert part of the power into hydrogen, which is much cheaper to transport. For example, we can do this by building power-to-x systems in the turbines, so that the wind turbine can convert the energy into hydrogen when there is no need for electricity.”

Pilot projects for the shipment of ultra-cold liquified hydrogen, which has a boiling point of -252.8 °C, are popping up around the globe. One such vessel is Japan’s Kawasaki Heavy Industries-built LPG tanker Suiso Frontier, launched in December 2019.

Image credit: Hirotaka Kinoshita,

And in early 2020, it was announced that Korean company – Hyundai Heavy Industries (HHI) Group – together with Hyundai Glovis, became the first to receive an Approval in Principle to build a commercial liquefied hydrogen carrier.

Norway’s Wilhelmsen is leading a project to construct zero emission hydrogen vessels. The company aims to be an integral part of the development of hydrogen for marine applications in Norway and also internationally. “We can make Norway the Silicon Valley for maritime hydrogen globally”, says its senior vice president, Industrial Investments at Wilhelmsen, Jan Eyvin Wang.

All of these projects are due to be realised well before the energy island commences operations in the next decade.

This is not the only energy island that Denmark is planning. On the Baltic Sea, the natural island of  Bornholm will host electrotechnical facilities to capture energy generated by offshore wind farms (supplying 2 gigawatts) of energy situated off the coast.

The energy islands are being created in response to the Danish Climate Agreement of June last year, which requires the country to cut greenhouse gas emissions by 70% by 2030 from 1990 levels.

The Danish government is already finding markets for its green electricity, and late last month, it signed with Germany an MoU to establish an offshore grid connection which would include the North Sea land.

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