Sustainability Report 2017

Our Business

We are consistently working on the Success of the Energy Transition

As a transmission system operator, we ensure the electricity supply for around 18 million people in the north and east of Germany. Our high voltage grid has a power circuit length of approximately 10,200 kilometres. We keep up the condition of the lines and substations through efficient maintenance and repair, expand our grid based on the need and ensure the electrical balance between energy consumers and producers in our grid area at all times. Over 1,000 employees at eight locations ensure that electricity flows 24/7 in Berlin, Brandenburg, Hamburg, Mecklenburg-Western Pomerania, Saxony, Saxony-Anhalt and Thuringia.

With the energy transition, the energy system has fundamentally changed. Increasingly, renewable energies are fed into our grid, either directly or via the distribution grids, and have to be transported via our lines. Already today, the share of renewable energies in electricity consumption in the 50Hertz grid area is calculated at over 53 percent. And this share will continue to grow. The 50Hertz grid is prepared to keep the region stable and provide a secure supply of power also in the future – because we are dedicated to successfully shaping the energy transition.

Our Electricity oscillitates at 50Hertz

50Hertz primarily transmits the energy in its grid using alternating current. This current changes its flow direction 100 times per second. Technically speaking, the current oscillates at a frequency of 50 hertz. Fluctuations in electricity generation and consumption have an impact on the frequency. The frequency falls if there is a power deficit and increases if there is a power surplus. To ensure that the frequency is always in the range of 49.8 and 50.2 hertz, we constantly balance the oscillations. In doing so, we always keep the system stable.

Claudia Dalbert, Dr Frank Golletz, Johannes Kempmann und Rainer Schmittdiel at the commissioning of the Wolmirstedt substation Energy Minister of the State of Saxony-Anhalt, Prof Dr Claudia Dalbert, commands the commissioning of the Wolmirstedt substation via radio transceiver. To her left, 50Hertz Chief Technical Officer, Dr Frank Golletz, to her right, Johannes Kempmann, Chief Technical Officer of Städtische Werke Magdeburg, and to the far right Rainer Schmittdiel, Managing Director of Avacon Netz GmbH.

Our Business is exciting

As a transmission system operator, we transport the electrical energy over great distances at high voltages of 150, 220 and 380 kilovolt (kV). The distribution grid operators distribute the electrical energy in their respective region at a high voltage <= 110kV. Between high and extra-high voltage, the transformers convert the electrical energy from one voltage level to the other. Particularly energy-intensive industrial plants are connected directly to our high voltage grid, for example steel works.

Roles of 50Hertz: grid owner, system controller, market facilitator and trustee We shape our social mandate efficiently, safely and sustainably. In doing so, we have to fulfil various roles.

Grid Ownership

We are constantly adapting and expanding our transmission grid according to needs, keep it in operating condition and repairing damage caused by age or severe weather, for example. In 2017 we fully connected the Southwest Interconnector from Bad Lauchstädt in Saxony-Anhalt to Redwitz in Bavaria to the grid. The Southwest Interconnector is a 380 kV transmission line. It leads from the Bad Lauchstädt substation to the Vieselbach substation near Erfurt in Thuringia and from there via the Altenfeld substation to the Redwitz substation. The section in Bavaria is constructed by the transmission system operator TenneT.

Southwest Interconnector

The Southwest Interconnector mainly transports renewable energies from the north to the large consumption centres in the south of Germany. Its construction was funded by the European Union as a “project of common interest” (PCI) and financially supported up to a total of EUR 100 million. The reason is that the Southwest Interconnector also improves system security at the European level. The two power circuits of the line, which totals almost 200 kilometres in length, (161 km in the 50Hertz grid area, 31 km in the TenneT grid area) can now transfer an additional 5,000 megawatts (MW) from north to south.

During the planning and construction of the Southwest Interconnector, 50Hertz not only faced technical challenges. At times, citizens in the affected regions of Thuringia protested vehemently against the construction of the route. We have learned a lot from it.

Read more in our section "Commitment and Cooperation"

In the Baltic Sea, the connection between two offshore wind farms, the so-called “Combined Grid Solution”, is currently being built. This interconnector is considered to be the first of its kind worldwide to be used to connect wind farms at sea in order to connect the transmission grids of two countries. Thus, wind farm infeed and power trading will be combined. To this end, 50Hertz is connecting the Danish Kriegers Flak wind farm to the German Baltic 2 wind farm and will connect them to the transmission grid together with the Baltic 1 wind farm. The special thing about this project is that the Danish and the German grids will not operate on the same frequency – they do not oscillate synchronously. Therefore, a so-called double converter will have to be interposed. This is currently being built on land in Bentwisch near Rostock. This project is also funded by the European Union to the sum of EUR 150 million.

When expanding the grid, 50Hertz operates sustainably and protects natural resources and the environment. We only build as many lines as are really needed. Out of a sense of responsibility for nature and the environment, we balance any necessary interventions in nature with appropriate compensation measures and give habitats and cultural landscapes back to society.

Read more in our section "Environment".

The Energy Transition is a Challenging Task

In the “Energy Transition Outlook 2035” study, we examined various development scenarios for the energy transition. The focus of consideration was on checking whether the planned grid expansion would also meet needs even if the energy transition develops along a path other than is currently envisioned. The study clearly showed that all of the grid expansion measures planned by 50Hertz are suitably dimensioned for all development paths.

System Control

By keeping the production and consumption of electrical energy in balance at all times in our grid area, we ensure an optimal power flow and a smooth transition to our neighbouring transmission system operators and distribution grids. This is a particularly challenging task in our grid area, because more generation capacity from renewable energy sources is installed than from conventional power plants. In particular, wind power plays a major role. On 28 October 2017, we registered a new infeed record to our grid of 14,266 MW of wind energy. The infeed quantity is constantly changing at short intervals. The same is true for the infeed from photovoltaic systems to our grid. This differs from hour to hour and depends on the weather. In 2017, for example, the daily values on 07 June were between 0 MW and 7,200 MW. Through constant control, infeed and consumption are kept in balance and the security of the electrical system as a whole is ensured.

Stabilisation of the costs of congestion management

In spite of the further renewable capacity additions of 2,100 MW in 2017, we were able to keep the congestion management costs at the previous year’s level. The newly built Southwest Interconnector affects congestion management by 50Hertz positively. After the first two circuits of the line were connected to the grid in 2015, we were able to save about EUR 80 million in redispatch costs the next year. When the second circuit was commissioned in September 2017, the Southwest Interconnector finally went into full operation after 15 years of planning and construction. The redispatch cost savings came to EUR 181 million in 2017.


million euros

in redispatch cost savings due to the
Southwest Interconnector in 2017.


Congestion Management and Redispatch

On particularly wind and solar-intensive days, more power is traded than can physically be transported by the grid. In order to ensure system security even in such situations, conventional power producers who are the spatially near a grid bottleneck, are instructed to reduce their power. At the same time, power generation on the other side of the grid bottleneck is activated. This so-called redispatch is complex and cost-intensive, because while the electricity producers in the north and east of Germany are shut down, reserve power plants in the south of Germany or Europe are powered up at the same time. The costs incurred by the power plants are compensated. If this is not enough to resolve grid congestion, the generation of electricity from renewable energies must also be restricted through infeed management. This also leads compensation payments made to producers of renewable energy. The total costs are the so-called congestion management costs.

Chart costs of congestion management according to section 13 para. 1 and para. 2 EnWG

Grid expansion has a positive effect

Without the Southwest Interconnector, 50Hertz would have been able to transport far less power from the north and east of Germany to the south. As part of the congestion management, we would have had to restrict cost-effective power plants in the 50Hertz grid area and instead, switch to power plants in Bavaria and Austria. Over the next few decades, more plants for the production of renewable energies will be built in our grid area. In view of this and the upcoming nuclear power phase out, the completion of this line is an important milestone on the way to a successful energy transition.

Furthermore: On our company website, we provide live information on the current status of the savings and the current transport performance for the Southwest Interconnector.

Balancing group management

Electricity is freely tradable. Traders, power distributors, producers and grid operators are assigned to difference balancing groups in the 50Hertz grid area. Within each individual balancing group, power infeed and consumption are held in balance on a quarter-hourly basis. If balancing groups are not balanced, deviations from the overall balance arise, which we balance. To do so, we take excess amounts of electricity from or add balancing energy to the balancing group. Corresponding balances are invoiced monthly with those responsible for the balancing group. We maintain the balance between infeed and consumption for the sum of all balancing groups at all times. We use balancing energy to do so.

Market Facilitation

Similar to traffic, electricity also flows across borders – and we want to improve the international electricity flow. Due to our central location in Europe, we are predestined for this. 50Hertz is directly connected to the high voltage grids of Denmark, Poland and the Czech Republic as well as our German neighbours, and works closely with the operators of these grids. We are committed to the development of a European internal energy market and are working to achieve this in numerous initiatives, collaborations and projects. 50Hertz also has shares in the European Energy Exchange (EEX) in Leipzig and thus indirectly also in the European Power Exchange (EPEX) in Paris.

One of the two phase shifter transformers being discharges at the Röhrsdorf substation.

Phase Shifter Transformers

Phase shifter transformers (PST) are used to control the power flows. You can imagine a phase shifter transformer as an adjustable valve. In a line network, this valve changes the energy flows and distributes them around. Thus, the overloading of individual lines can be avoided and lines with lower loads can be used. Currently, 50Hertz operates two PST in Röhrsdorf at the transition to the Czech grid. Another is under construction in Vierraden at the transition to the Polish grid.

Together with our neighbours and the market participants, we develop energy market products that facilitate the efficient use and control of the grids and the energy system.

We also take on new challenges: Thus, the increased infeed of wind energy in the 50Hertz grid area placed an increasingly heavy load on the interconnectors to Poland and the Czech Republic. This resulted in loop flows, in which power from the north of Germany sought a way to Bavaria and Austria via Poland and the Czech Republic. 50Hertz agreed with the transmission system operators PSE in Poland and CEPS in the Czech Republic, to better control these cross-border power flows: Therefore, phase shifter transformers (PST) were installed at the coupling points to these neighbours’ control zones. This has allowed us to efficiently control the power flows in the 50Hertz grid area, exploit transmission potential as fully as possible and significantly improve free power trading in Europe.

50Hertz is already a pioneer for the integration of volatile renewable energies. That is why we are developing solutions with over 70 partners in the “WindNODE” project, with which large quantities of renewable energies can be integrated into the system while keeping the electricity grids stable.

You can also read our section “Committed Partner”.

Discussion on the subject "EU Clean Energy Package". Among others, Boris Schucht, CEO of 50Hertz is sitting on the stage. Discussion on regional cooperation on the Brussels stage. CEO Boris Schucht is there, too. He is presenting the 50Hertz perspective In front of 150 guests from politics, industry and society.


In addition, the German legislator has transferred the responsibility for coordinating and processing legal levy systems to promote environmentally-friendly technologies to the transmission system operators. These include, among others, the Renewable Energies Act (EEG) levy and the Power and Heat Cogeneration Act (KWKG) levy. We collect these levies as a trustee, administrate these and coordinate their distribution to the recipients. If the producers does not market electricity from renewables directly, we sell this electricity on the power exchange. By doing so, we integrate renewable energies in the electricity market transparently.