Engineering Ocean

TenneT plant artificial island in the North Sea for offshore wind parks

An artificial island in the North Sea could in the future collect the power of offshore wind parks and convert to DC. This idea has introduced the network operator TenneT. The island has 6 km2 large and at the same time serve as a distribution and hub for EU offshore wind electricity grid.

The idea of an island of that will connect wind farms in the North Sea, is daring: the Dutch network operator TenneT, which is responsible among other things for the grid connection of wind farms in the North Sea, wants to pour on the island in the Dogger Bank. This is a more than 300 km long Shoal in the middle of the North Sea. The island should merge the complete generated electricity from several wind farms, there convert it into DC and then forward via undersea cable to the participating countries.

TenneT plant artificial island in the North Sea for wind parks
Power cable on the beach of Norderney: so far offshore wind farms over large submarine cables are connected to the Mainland. An island located in the North Sea could immediately serve as connection for several wind farms. Photo: Tennet

The Netherlands, Great Britain, Belgium, Norway, Germany and Denmark are those participating countries for TenneT. “It will be very important to separate time their goals due from borders and to accept that offshore generated electrons transfer not necessarily in their own country for these six European North Sea States”, explained Mel Kroon, Chief Executive Officer of TenneT, the international project.

Island as a hub for trade in electricity

The TenneT plan foresees to use the island in the Dogger Bank as a hub for the trading of electricity in the connected countries. The transmission capacity of the DC power connections will be not only for the transmission of the Windengerie, but should also be used for international electricity trading. Thus, a distribution and hub into a North Sea grid is created from offshore wind farms and international connections.

TenneT plant artificial island cable
A power cable in the North Sea: the grid connection of offshore wind farms is complicated and expensive. Photo: Tennet

The Dogger Bank sand bank is fairly centrally located in the North Sea. Their ends are each just over 100 km away from the Danish and the British coast. But above all, the Dogger Bank is an extremely flat region, where the average 94 m deep North Sea. At the shallowest points of shoal, there are only 13 m to the bottom.

30 gigawatts Capacity for 10 million people

The part where the island will be built, is not deep with up to 20 m and “there is a lot of wind”, “A European infrastructure in the North Sea can cut significantly the cost of wind power.”

2030 already could start the construction of the island, 20 years later, it should be ready for use together with the necessary wiring. The networked island could offer a capacity of 30 gigawatt about ten million people with clean energy.

Island with runway, Harbour and apartments

And it’s the networked Island: multiple converters, a runway for aircraft, a port and apartments for about 2,000 employees built on about 6 km2. Also, the spare parts for the wind turbines of the surrounding wind farms to store on the artificial island, so turbines, rotor blades, towers and high-voltage equipment.

TenneT plant artificial island
Wind farm in the North Sea: currently, the wind farms on some long routes with the Mainland must be connected. Photo: Tennet

TenneT is clear: “the shallow water, the construction costs of wind farms and the island are less.” By connecting the same conditions are created with the island also for the far shore wind farms, as in off-shore wind farms. This means especially: lower costs.

But even for offshore wind farms, it was not always easy to feed their electricity into the grid. Often, wind parks are indeed ready, can deliver but no electricity because the grid connection is missing. But in the meantime, TenneT has caught up: 2015 went so many offshore wind farms in the North Sea as ever on the network.