From German Bight to German bytes

Frankfurt am Main will need significantly more electricity in future, not least because increasing numbers of new data centres – which are large-scale consumers – are locating there. This power is set to be generated primarily by wind farms located out in the North Sea. But how is it to get from there to the data centres in central Germany? Amprion is upgrading and expanding its grid to make sure it can. This article describes the key stations along the way.

The link via which electricity will flow from the offshore North Sea wind farms via Hanekenfähr (1) to Frankfurt (4), where it will supply consumers such as the world's largest Internet node DE-CIX (5), is more than 600 kilometres long. Amprion is consequently upgrading the grid at a number of different locations. This includes the line section between Dortmund-Kruckel and Dauersberg (2) and the Kriftel transmission substation in the Taunus region (3). Some 100 or so weather stations are also to be installed between the River Ems in the north-west and the River Main to help manage weather-dependent operation of the overhead power lines


Grid connection system

Welcome, wind power!

Offshore wind power is becoming increasingly important. One of Amprion's responsibilities is to connect new wind farms in the North Sea to the onshore electricity grid. The power will initially flow as direct current through up to 280 kilometres of submarine and underground cables until it reaches the city of Lingen in the Emsland region. It's here that Amprion will build a converter station by 2028. These are high-tech installations that convert direct current to alternating current, the standard form of electricity on the grid. “There's no more room for them on the site of the existing transformer substation Hanekenfähr,” says grid planner Christian Klein. The new facilities are therefore being built on a plot of land approximately one kilometre away. An overhead line that has until now been used to feed power from a nuclear power plant to this transformer substation will connect the converter and the Hanekenfähr substation. But this nuclear plant will be taken off the grid at the end of 2022. This will free up transmission capacity at this grid node, which will then be able to be redeployed to transmit wind power.


Weather Monitoring stations

Natural cooling

Grid optimisation first, then expansion: this is the principle Amprion is following as it examines the possibilities for transmitting more electricity between Hanekenfähr and Frankfurt using existing lines. One method of achieving this goal is, for example, “weather-dependent operation of overhead lines”. It is founded on the phenomenon that enables conductor cables to carry more current without overheating when outside temperatures are low. Amprion’s grid planners want to take advantage of this natural cooling effect. Around 100 monitoring stations installed between Emsland and the Rhine-Main area are to deliver the necessary weather data. “They are the basis for accurate forecasts that show how much the conductor cables can be loaded under the prevailing weather conditions,” says Lars Henter, Head of Power Circuit Capacity at Amprion. Based on this data, algorithms employed in the Brauweiler System Operation and Control Centre determine at which times more current can flow through the lines. In this way, power surges can be cushioned – and we gain additional time in which to carry out necessary expansion work on various route sections.


Grid expansion

New lines with greater capacity

Amprion is expanding an existing 126-kilometre route between Dortmund-Kruckel and Dauersberg in the Rhineland-Palatinate. It is at the heart of the future power supply line set to bring wind power from the north to the Rhine-Main region. Instead of the previous 220 kilovolts, the new overhead line will operate at 380 kilovolts. In combination with new conductor cables, the line will be able to transmit around five times the amount of power. The expansion work is like performing open-heart surgery. “Despite the measures being carried out, the power supply for the Hagen-Siegen conurbation must not be interrupted,” says grid planner Bastian Lüttecken. Amprion experts have to reroute the supply in the sections affected via field-installation cables or run it over temporary pylons that they erect adjacent to the existing route. In addition, one section of the route runs through mountainous terrain, and the foundations for the pylons have to be anchored in the bedrock – no easy feat. The connection between Dauersberg and the Rhine-Main area already exists.


Kriftel substation

Grid nodes with tasks full of tension

The Kriftel transformer substation, located in the Taunus region, is one of the most important grid nodes in the Greater Frankfurt area. It connects the transmission grid – which will in future operate at a voltage of 380 kilovolts – with the 110-kilovolt distribution grids in the region. New transformers perform this task. Another important function of the substation is to provide what's known as “reactive power”. With their help, voltage fluctuations in the grid can be compensated. Until now, this has been done by generators in large power plants – but these are being taken off the grid as part of the energy transition. “Our two state-of-the-art reactive-power compensation devices in Kriftel are already making an important contribution to system security,” says Dmitrij Kamenshikow, Head of Grid Stability at Amprion. We are talking about a mechanically switched capacitor with damping network (MSCDN), which can control the voltage especially under heavy grid load conditions, and a static synchronous compensator (STATCOM), which compensates short-term voltage fluctuations in the grid. These two pieces of equipment complement each other. Together they form the most high-performance hybrid plant for reactive power compensation in the German grid.


Boomtown Frankfurt am Main

Green power for mainframes

Frankfurt is not only a financial metropolis; it's also considered the Internet capital of Europe. No other city in Europe is home to so many data centres. Their energy requirements are growing continuously. “We have received connection requests for the period between now and 2028, that mean a power demand increase of up to 3.5 gigawatts,” says Dr Ralph Pfeiffer, Amprion's Head of Regional Grid Planning. That's roughly equivalent to the output of seven medium-sized offshore wind farms. “This additional demand is driven entirely by data centres,” Pfeiffer adds. In order to process the increasing amounts of data, the performance of mainframe computers is also increasing. Running and cooling these more powerful systems means greater power consumption. And the data centres get this power from local distribution grids, which in turn are connected to the transmission grid. Amprion is currently tracking a dozen projects in the region with the goal of supplying them with green electricity.

New data centres increase power demand, says Dr Ralph Pfeiffer, Head of Regional Grid Planning at Amprion.

New data centres increase power demand, says Dr Ralph Pfeiffer, Head of Regional Grid Planning at Amprion.

Winners of digitalisation: the DE-CIX Internet node is where all the different threads of communication come together.


DE-CIX Internet node

The networkers

Without them, the Internet wouldn't work: DE-CIX operates the largest Internet node in the world in Frankfurt. More than 1,000 network operators, Internet service providers, content providers and company networks link up here to exchange data. “Our equipment is spread across 37 data centres located in Frankfurt,” says the company's CEO Harald A. Summa. In addition to DE-CIX, each power system operator has other customers they supply and who also require a lot of energy. The power requirements of data centres are enormous. Summa is certain that the number of such centres in Frankfurt will continue to grow. After all, digitalisation is still in its infancy. “In Frankfurt alone, there are plans to build nigh on ten new data centres in the near future,” he reveals. Hundreds of new facilities will be added across Germany in the next few years. This will also increase the need to transmit the electricity required to run these many new data centres around the country.

Winners of digitalisation: the DE-CIX Internet node is where all the different threads of communication come together.

3 questions for
Harald A. Summa

CEO of the DE‑CIX Internet node

Why is the Internet node with the highest data throughput in the world located in Frankfurt of all places?

When we founded DE-CIX in the mid-1990s, Frankfurt was the only city in Germany with a fi bre-optic network. Such infrastructure is crucial for transmitting large volumes of data. We exploited what was back then a key asset of Frankfurt to connect clients with us.

How important is a reliable power supply for the computers?

If our Internet node suff ered an outage, it could have serious consequences for the entire economy. This is why we place exceedingly high demands on the data centres we work with. They have to guarantee an uninterruptible power supply – comprising several circuits supplied by diff erent power utilities. Of course, all of this presupposes reliable, secure power grids.

How are data traffic volumes developing?

The volume of data being transmitted is growing non-stop. Every year, we invest between four and six million euros to create additional computer capacity. This increases the level of power consumption – even if the latest-generation equipment uses far less electricity than previous generations of IT equipment. And the ongoing Covid-19 pandemic has upped traffi c levels even further: video conferencing traffic alone has increased by 50 per cent and led to 10 per cent growth in data throughput in Frankfurt. In 2020, we surpassed the symbolic milestone of 10 terabits per second for the fi rst time here in Frankfurt. This is equivalent to the amount of data needed to stream 2.2 million high-defi nition videos all at the same time.

TextHeimo Fischer
PhotosGetty Images, Daniel Schumann, E.ON-Netz (Detlef Gehring, 2008), shutterstock, DE-CIX