The currently most important cable in Germany: The “Suedlink” electricity highway is one of the most important projects in the German energy transition

Suedlink is one of Germany's central infrastructure projects and plays a crucial role in implementing the energy transition. As a high-voltage direct current (HVDC) transmission line, Suedlink will take on the task of efficiently transporting wind energy from the windy north to the energy-hungry south of the country. Developed and planned by the transmission system operators TenneT TSO and TransnetBW, the project is an integral part of the electricity network development plan.

Background and necessity

The energy transition in Germany aims to significantly increase the share of renewable energies in the electricity mix and at the same time to phase out nuclear energy and coal-fired power generation. While wind energy is produced on a large scale on land and at sea in the north of Germany, the south of the country relies on this energy to meet its needs, especially after the last nuclear power plants have been shut down and the coal phase-out is planned by 2038 at the latest.

Without efficient power lines like Suedlink, there is a risk of network bottlenecks and instabilities in the power grid. The even distribution of the energy generated is crucial not only for security of supply, but also for the stability of electricity prices.

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Technical details and route

Length and capacity

Suedlink will have a total length of around 700 kilometers and offer a transmission capacity of 4 gigawatts. This output corresponds to that of four large nuclear power plant blocks and can theoretically supply up to ten million households with renewable energy.

Routing

The route runs through six federal states: Schleswig-Holstein, Lower Saxony, Hesse, Thuringia, Bavaria and Baden-Württemberg. It consists of two main compounds:

First connection

Starts in Brunsbüttel (Schleswig-Holstein) and ends in Leingarten (Baden-Württemberg).

Second connection

Starts in Wilster (Schleswig-Holstein) and leads to Bergrheinfeld (Bavaria).

Interestingly, both lines merge under the Elbe and only branch out again in southern Germany to reach their respective end points.

technology

Suedlink uses high-voltage direct current (HVDC) transmission, a technology that is particularly suitable for transporting large amounts of energy over long distances. Compared to AC lines, DC transmission has the advantage of lower energy losses and allows for better control of the energy flow. At the end points of the route there are converter stations that convert direct current into alternating current in order to feed it into the regional distribution network.

Progress and challenges in construction

Current status

The start of construction on Suedlink has been delayed several times. Commissioning was originally scheduled for 2022. According to current plans, completion is now expected at the end of 2028. Despite the delays, construction work is already underway in several sections. For example, the first cable laying has begun in Lower Saxony and Baden-Württemberg.

Technical and logistical challenges

Laying the underground cables represents a significant technical challenge. The route must, among other things, cross rivers, highways and existing infrastructure. At such crossings, special drilling methods are used to lay the cables at depths of up to 200 meters, such as when crossing under the Elbe near Glückstadt or in the salt mine near Heilbronn.

In addition, the construction work must be carried out in such a way that the disruption to farmers and residents is minimized. This includes temporary use of agricultural land and strengthening of roads to carry the heavy construction vehicles.

Approval process and public participation

Another factor for the delays is the extensive planning and approval procedures. Since the route runs through numerous private properties, extensive coordination and compensation measures are necessary. Citizen groups and environmental groups have raised concerns about the impact on the environment and the local economy. In order to do justice to these, extensive environmental impact assessments were carried out and alternative routes were examined.

Economic and ecological aspects

Costs and financing

The total costs for Suedlink are estimated at around ten billion euros. This investment is financed through network fees, which are ultimately borne by electricity consumers. In the long term, however, the project is intended to help stabilize or even reduce electricity prices by reducing network bottlenecks and minimizing the need for expensive compensation measures.

Contribution to the energy transition

Suedlink offers significant ecological advantages. By transporting wind energy from the north, the share of renewable energy in the south of Germany can be significantly increased. This supports national climate goals and contributes to reducing CO₂ emissions. The use of underground cables also reduces visual impact on the landscape and minimizes potential interference with wildlife habitats.

Critical voices and support

Concerns and protests

Despite the general recognition of the need for Suedlink, there is resistance from the population. Citizens' initiatives fear negative impacts on agriculture, soil and groundwater. Some farmers worry about crop failures and long-term damage to their fields. There are also concerns about electromagnetic fields and their potential health effects.

Political support and compromises

Politicians have tried to take these concerns into account. After heated discussions, it was decided to lay the lines primarily as underground cables, even though this is more expensive and complex than overhead lines. This compromise was intended to increase acceptance among the population and speed up construction.

Federal and state governments emphasize the importance of Suedlink for security of supply and the successful implementation of the energy transition. Without the route, power outages and increased dependence on fossil fuels could result.

Future impact and significance

Integration into the European power grid

Suedlink is not only important for Germany, but also for the European power grid. Through the improved north-south connection, Germany can strengthen its role as an energy hub in Europe. This enables more efficient exchange of energy with neighboring countries and supports the integration of renewable energies at the European level.

Technological progress

The project sets standards in the application of modern transmission technologies. The experiences gained from building and operating Suedlink can influence future infrastructure projects and contribute to the further development of HVDC technologies.

Contribution to climate neutrality

In order to achieve the climate goals and achieve climate neutrality by 2045, the expansion of renewable energies and the associated infrastructure is essential. Suedlink is a central element in ensuring the necessary electricity transport and making the energy supply sustainable.

Symbol of change in German energy policy

Suedlink is more than just a major technical project; it is a symbol of the change in German energy policy. Despite the challenges and resistance, the project shows how ambitious goals can be achieved through cooperation between politics, business and society. The successful implementation of Suedlink will make a significant contribution to driving forward the energy transition, ensuring security of supply and achieving Germany's climate goals.

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The SuedLink and SuedOstLink are important infrastructure projects in Germany that were developed as part of the energy transition to efficiently transport renewable energy from the wind-rich northern regions to the energy-intensive southern regions.

North-south power line – Image: Federal Network Agency

SouthLink

Purpose and structure

SuedLink is a high-voltage direct current (HVDC) transmission line that runs approximately 700 kilometers. It is primarily intended to transport wind energy from northern Germany to southern Germany, providing a total output of 4 gigawatts.

Course

The route begins in Brunsbüttel and Wilster in Schleswig-Holstein and ends in Großgartach in Baden-Württemberg and Bergrheinfeld in Bavaria. The route runs through several federal states, including Lower Saxony, Hesse and Thuringia.

Construction and completion

Construction has been delayed several times, with completion scheduled for the end of 2028. The construction work includes laying over 2,400 kilometers of underground cable.

Costs and challenges

The costs are estimated at around ten billion euros. Laying underground cables minimizes the impact on the landscape, but is more expensive than installing overhead lines.

SuedOstLink

Purpose and structure

The SuedOstLink is also an HVDC line that is around 540 kilometers long. It is intended to transport wind power from Saxony-Anhalt, Brandenburg and Mecklenburg-Western Pomerania to Bavaria.

Course

The route begins in Wolmirstedt near Magdeburg and ends at the Isar site near Landshut in Bavaria. It runs through Saxony-Anhalt, Thuringia and Bavaria.

Construction and completion

Construction is scheduled to be completed by 2027. Cables are mainly laid underground to minimize impact on the environment.

Meaning

The SuedOstLink is an important part of the energy transition in Germany and has been classified as a “project of common interest” by the EU.

Common aspects

Both projects are crucial for securing electricity supply in southern Germany after the phase-out of nuclear power and coal. They contribute to the stability of the German power grid and help avoid bottlenecks.

The projects are politically prioritized and are intended to promote the integration of renewable energies, which is crucial for achieving Germany's climate goals.

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