Impossible to miss it. It stands at the end of a 5 kilometer long open track in the Osterild test center in northern Denmark. Its height is dizzying: 275 meters. “It’s the tallest offshore wind turbine model in the world right now,” says Allan Vesth, whose job is to check the monster’s compliance before it goes into production. In a few months, several clones of this device will be deployed at sea. They will be added to the hundreds of wind turbines already in operation off the Danish coast. “Another generation of devices, even more massive, is already pointing the tip of its blades”, specifies the specialist, with a smirk. Still at the project stage, some models even exceed the height… of the Eiffel Tower!
Seen from France, the contrast is striking. While in our country the deployment of offshore wind power remains sluggish, in Denmark, this type of infrastructure has long been part of the landscape. In this country of 5.8 million inhabitants, which does not have a single nuclear reactor, the authorities plan to cover 100% of energy needs with renewable sources by 2050. And, to achieve this, they are now turning to artificial islands surrounded by wind turbines. Imagine: 100 kilometers from the coast, in the middle of the North Sea, a structure the size of several football fields centralizing the production of electricity from multiple XXL turbine fields located nearby, before sending it by cable to several European countries in according to needs.
“This concept of an energy island covering the needs of several million people represents the future. It will play a major role in the gradual elimination of fossil energy sources in Denmark and Europe”, predicts Hanne Storm Edlefsen, in charge of developing this type of project at Energinet, the Danish gas and electricity transmission system operator. “On paper, these new kind of hubs have a lot of advantages,” admits Delphine Robineau, director of development for Europe at Copenhagen Offshore Partners, a company that invests heavily in the development of offshore wind projects all over the world. the world. Since the energy islands are located far from the coast, they are subject to fewer constraints (visibility, environment, fishing, navigation). This allows for more efficient installation. Especially since the wind blowing offshore is more stable than that encountered near the coast.
peace by the wind
The island is not only designed to receive and send electricity. This infrastructure can also use green energy to create and store hydrogen, like the Lhyfe company in France. Some would be piped to the mainland. Another would supply boats sailing nearby. Hydrogen would also be used to manufacture ammonia, a useful product for soil fertilization, or the propulsion of merchant ships. Eventually, several energy islands could be interconnected, thus gaining a geopolitical dimension. “The war in Ukraine made us aware of our weaknesses. A system of hubs connecting several countries would not only reduce our dependence on gas, but also stabilize energy prices and international relations”, explains Hanne Storm Edlefsen. Added to this peace by the wind is a final economic argument: the wind farms placed near the islands will undoubtedly create many jobs. This is enough to compensate for the current decline in the workforce in the fossil fuel sector. In the Danish port of Esbjerg, Jesper Bank, director of operations, is already preparing for this second wave. “The assembly and storage of wind turbines are taking up more and more space. In recent years, it has had to be expanded several times. At the moment, the offshore market is still immature. But in five years this will no doubt have changed. Many high value-added jobs will be created.”
Of course, not everyone is yet convinced of the indispensability of energy islands. “If you look closely, these platforms may only represent 5% of the infrastructure, the bulk being made up of nearby offshore wind farms. And we don’t yet know exactly what to put on them. The concept still needs to be studied,” said Brian Vad Mathiesen, professor at Aalborg University and specialist in renewable energies. But this vagueness does not prevent partner countries from coming forward. Thus Germany, the Netherlands and Belgium already want to “connect” to an energy island. And two implantation sites have been identified. The first is in the North Sea about 80 kilometers off Thorsminde, a town in Jutland. “To begin with, this artificial island will have a capacity of 3 gigawatts, corresponding to the electricity consumption of 3 million households, which is twice the amount of energy that all the offshore wind turbines in Denmark combined are capable of producing today” , says the Danish Energy Agency. This capacity will be expanded in phases up to a maximum of 10 gigawatts, which could eventually cover the electricity consumption of 10 million households. The second site is located in the Baltic Sea. This is the (real) island of Bornholm. The turbines placed off this small piece of land, about 15 kilometers from the coast, will have a capacity of 3 gigawatts, corresponding to the electricity consumption of 3.3 million households.
“The choice to operate a real island or to build one does not really matter. The idea is above all to make the best use of wind energy”, specifies a wind turbine manufacturer. The concept could also be replicated in other regions of the world due to the climate emergency. “If we fail to build 10 gigawatts of wind power within five years, the Old Continent will not achieve carbon neutrality in time,” agrees Brian Vad Mathiesen. “We must massively accelerate offshore wind power on a European and global scale. In France, it is better to carry out projects of 2 to 5GW than to multiply projects of 1 gigawatt or less to quickly reach 40 gigawatts” (the objective for France in 2050 set recently by Emmanuel Macron), notes Delphine Robineau. In Denmark, renewable energy specialists are already considering places where the island concept would make sense: off the coast of California or New York, on the east coasts of China and Brazil, between Australia and New Zealand…
“No technical reason prevents France from building an energy island one day”, slips a Danish expert. But is she really interested in doing so? “In one of its reports, the French network operator RTE plans to strengthen the European electricity network to cope with a future increase in demand. More specifically, it plans to double by 2035 its “capacity of interconnection” with neighboring countries. This leaves a priori room to consider an island made in France”, analyzes Delphine Robineau. “However, the benefits would probably not be as great as for Denmark given the geographical position of neighboring countries,” warns a specialist already. In the North Sea, the wind conditions remain exceptional. Moreover, the excessive depth of the Mediterranean would complicate the development of an island, whereas in the North Sea the shallow depth (30 to 40 m) makes it easier to create artificial structures.
“The Danish project is excessively expensive (28 billion euros for the only installation located in the North Sea). However, there is still a lot of offshore wind power to exploit in France before moving away from the shore. From our point of view view, France should first focus on the construction of parks before possibly moving to an energy island, says Nicolas Koenig, France director of European Energy, a company that supports the development of renewable energy projects. it takes three years in Belgium to carry out a project, four in the Netherlands, five in Germany, recalls another expert. In France, the installation of the first wind turbine at sea took ten years. Island or not, it is high time to shift into overdrive.”