Our key tasks

We are primarily tasked with providing power transmission services, system services and facilitating the energy market. Our core tasks follow from our appointment as grid operator under the Dutch 'Elektriciteitswet' (E-wet) and the German 'Energiewirtschaftsgesetz' (EnWG).


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TenneT presents Hub and Spoke concept for large scale wind energy on the North Sea.

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Our grid

TenneT manages the high-voltage grid in the Netherlands and large parts of Germany. TenneT transmits electricity at 110,000 volts (110 kV) and higher. With over 22,500 kilometres of high-voltage lines, we cross borders and connect countries.

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Grid maps

Maps of our onshore and offshore high-voltage grid.

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Electricity market

The energy sector is developing rapidly. The process of European market integration began some years ago. Its purpose is to create a single European market that enables market parties to trade gas and electricity across national borders easily and efficiently.

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Transparency data

We provide transparency data on our operations on our Dutch and German transparency page and on ENTSO-E. 

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Our vision is to be one of the most transparent Transmission System Operators (TSO) in Europe and thereby creating value for society. In this Energy Insights section we present selected energy related topics and show data, information and valuable insights. 


Energy transition

Wind turbines and solar panels are the physical signs of consumers’ growing desire for clean, renewable energy.

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TenneT is a leading European electricity transmission system operator (TSO), with activities in the Netherlands and in Germany. We strive to ensure a reliable and uninterrupted supply of electricity in our high-voltage grid for some 41 million people.

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We are TenneT

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alpha ventus

First German offshore grid connection



  • 66 km long and 62 MW capacity
  • 6 km onshore cable
  • 60 km offshore cable

Grid connection point

  • substation Hagermarsch (110 kV) Germany

Status of project

  • online since may 2009

About the project

alpha ventus

A few coastal offshore wind farms are implemented as AC connections. They are connected to the German grid via the nearest grid connection point. The first wind farm realised by TenneT for such a grid connection, was alpha ventus. This offshore test field is a joint venture of E.ON, EWE and Vattenfall, located 45 kilometres in linear distance to the coast of Borkum, an island in the North Sea.

Already in 2007, underground horizontal channels were drilled underneath the dunes and the mudflats along the coast of the North Sea island of Norderney for the connection of alpha ventus. In spring 2008, the 1.5 kilometres long ductworkwas completed in the soil of Norderney. At the same time the new Hagermarsch substation was erected onshore and connected to alpha ventus.

At the end of May 2008, the cables for the connection of alpha ventus were pulled in the empty conduit system. In summer 2008, the six kilometres of landcable as well as the 60 kilometres of subsea cable were installed.

Laying the cables in the North Sea confronts technology and employees with big challenges: Kilometres of cables weighing several tons have to be laid and installed by jetting up to three meters deep into the seabed. Depending on the characteristics of the sea bed the subsea cables were installed using various methods. The subsea cables weigh 53 kilogram per lineal meter.

This requires special ships which are capable of transporting the cable, previously wound onto enormous turntables, then paying it out into the sea. There are only few of these special ships which are capable of transporting several thousands of tons of cable.

This 110 kV grid connection system was put into service in May 2009.


Cornelia Junge

Pressereferentin - Projektkommunikation Offshore

0049 (0)5132 89-2357

alpha ventus

This 110 kilovolt grid connection system was put into service in may 2009.

Project downloads

Factsheet alpha ventus (german) (394 KB, pdf, 05/08/2016)

Die erste Offshore-Netzanbindung in Deutschland

Category: Brochures
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Die Naturschutzprojekte von TenneT (german) (785 KB, pdf, 08/02/2016)

Aufwertung der Lebensräume von zahlreichen Pflanzen- und Tierarten

Category: Brochures
Die Naturschutzprojekte von TenneT (german) Download Download

Also interesting

TenneT Offshore brochure

"Energie von See an Land" brochure about TenneT offshore projects and technology (german only)

Offshore projects in Germany

Our other german offshore projects.

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Media footage

Your way to our pressfootage.

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