Offshore wind power: Islands are to serve as energy distribution stations

With so-called energy islands in the North Sea and Baltic Sea, Denmark and Belgium have big plans for electricity from wind power. But there are still some hurdles.

Wind farms supply electricity for the mainland. With the so-called energy island, Denmark and Belgium want to better bundle the electricity generated offshore and distribute it on land. 
(Image: PHOTOCREO Michal Bednarek/

By 2050, 260 gigawatts of electrical power from wind power should be installed in the North Sea alone. At least that’s what the North Sea countries decided according to the Federal Ministry of Economics – without Great Britain. However, in order to get the electricity ashore and also to distribute it to the European grids, it is not enough to pull at least one cable from each individual marine wind farm to the shore.

This would work far better via a few, but centrally located islands in the North and Baltic Seas. As nodes, they collect the electricity from many offshore wind farms and transmit it to the coasts of several countries with just a few cables. If they are also connected to each other, the flow of energy can be regulated even better as needed. “Hub and spoke” is the name of this principle of the star-shaped arrangement of transport routes from individual suppliers, the wind farms, to a node, the hub.

In the North Sea, Denmark and Belgium are each striving to be the first in the world to implement such an energy island off their coasts. It is not clear which of the two will win the race. Both are needed anyway.

In June 2020, the Danish parliament passed a national climate plan that provided for the establishment of two energy islands. One of the two islands is Bornholm in the Baltic Sea, which is already an important hub for offshore wind power networks. However, its counterpart in the North Sea has yet to be filled up.

From 2030, three gigawatts of electricity from offshore plants in the region should be available on Bornholm. Not only Denmark will benefit from this, but also Germany. Federal Economics Minister Robert Habeck and his Danish counterpart Dan Jørgensen agreed to jointly develop the offshore project “Bornholm Energy Island”. The agreement provides that Germany will have a direct connection to the island with a 470-kilometer cable.

The artificial energy island in the North Sea will be rebuilt around 80 kilometers off Jutland. At least 28 million euros are estimated for the 46-hectare island. From 2033, three gigawatts of electricity from 200 wind turbines should be available. This would supply around three million households. With almost six million inhabitants, all Danish households would be supplied with this alone.

In a further expansion stage, Denmark could supply 10 gigawatts from here with even more wind turbines from 2040. But there must first be enough buyers, and the necessary connections must also be installed in the sovereign waters of the other neighboring countries.

However, off the coast of Jutland, the wind power is not only to be collected and passed on. In fact, the Danes are also planning to install power-to-X systems there, in which they can also produce additional fuels from electricity, water and air. On the one hand, this allows excess electricity to be stored and, on the other hand, the fuels can be sold as fuel to shipping, aviation or for heavy goods vehicles .

Plans for the Belgian counterpart were pushed ahead with far less publicity. At the beginning of October, the Belgian network operator Elia internationally announced that there will be a new artificial island, Princess Elisabeth Island, 45 kilometers off the Belgian coast. As a hub, it is intended to provide a maximum of 3.5 gigawatts of electricity from the wind farm of the same name. After all, the planning has progressed so far that a building tender is currently being prepared.

Construction should start as early as 2024, and completion is planned for 2026 – earlier than the Danish counterpart. However, full connection capacity will probably not be available until around 2030. From then on, Princess Elizabeth Island would be the central hub for planned connections between England, Denmark and the rest of Europe.

In view of the alleged sabotage of the Baltic gas pipelines Nord Stream 1 and 2, the Belgian government is apparently more concerned about the security of the power cables than the Danish executive. “It is more important than ever for us to protect these critical infrastructures from sabotage and attacks,” said Vincent Van Quickenborne, Belgium’s Minister for the North Sea. The Belgians are now also investing in surveillance of the Belgian sovereign zone using cameras, drones, the tracking of foreign ships and regular security analyses.

But in order to really be able to use the enormous energy of the two sea areas, which together cover one million square kilometers, as planned, many bureaucratic hurdles still have to be removed, such as uniform approval processes and rules for technical procedures that go beyond the sovereign borders of the countries.

In the course of the immense expansion of offshore energy, however, some scientific assumptions will probably have to be reconsidered, as a study by the Helmholtz Center Hereon showed. According to this, the lee of large wind farms still hinders the mixing of seawater at a distance of 70 kilometers and thus the availability of nutrients and the growth of plankton.

The wind yield could also be lower than expected. Because the more turbines there are in a region, the less they rotate because not enough wind flows from the atmosphere from above. According to a study commissioned by Agora Verkehrswende, effective hours could shrink from the current average of around 4,000 hours per year to just 3,000 to 3,300 hours.

So it remains exciting to see how the ambitious plans to expand wind power in the North and Baltic Seas will come true. Because plans can still be changed.


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