The excavators are at work, trenches are being dug, and vast lengths of cable are being brought in and laid through complex logistics; slowly but surely, the SuedLink route is taking shape. The electricity highway, transporting energy from wind turbines in the north of Germany to the south, is scheduled for completion by 2028. It is an important component of the energy transition, not just for Germany, but ultimately also for Europe as a whole. The project is currently receiving plenty of media attention due to its numerous construction sites. But this is just a fleeting glimpse, because in a few years’ time, when the work is complete, these heroes of the energy transition will once again become “invisible, quietly providing valuable services as underground cables.
No country is an island – especially when it comes to climate protection and energy supply. By 2050, the EU aims to have reduced its greenhouse gas emissions by 80 percent compared to 1990. Renewable energy represents an important pillar supporting this goal, as it is hoped that it will cover at least 27 percent of energy consumption by 2030. To make this a reality, a Europe-wide energy system is needed. Therefore, national electricity grids across Europe are interconnected via cross-border lines, known as “interconnectors”: mega-projects in which high-performance cables are indispensable.
Cable systems for higher voltages
However, the transformation of the energy system has meant that even larger volumes of electricity are now being transported over ever longer distances – a task for which the power grids were not originally designed, explains the German transmission system operator Amprion. This is why Europe urgently needs grid expansion. The energy supply must be secured in the long term, as well as being made sustainable and affordable.
And this is already happening. For example, through the construction of the SuedLink, which carries electricity from northern Germany to southern Germany. Covering a distance of 700 kilometres, 525-kilovolt cables are currently being laid for high-performance extra-high-voltage direct current (HVDC) transmission. They can transport up to 2 gigawatts of power via a single system and are – according to cable manufacturer Prysmian – “less susceptible to the extreme weather events that are occurring more and more frequently”. Cable systems that are designed for higher voltages and with large conductor cross-sections also offer an ideal technical solution for transmission over long distances and high performance with minimal land use.
The SuedLink cables measure 15 centimetres in diameter and consist, among other things, of an inner semiconducting layer, which serves as a barrier to avoid leakage between the layers. The structure also includes cable insulation, fibreglass elements, welded aluminium foil and an outer sheath. The conductor is made of copper. The two cable suppliers NKT and Prysmian are producing a total of 2,420 kilometres of cable for SuedLink. The fabricated cable sections are up to two kilometres in length. The supply network will cost a total of around ten billion euros. Once it has been completed, it will supply electricity to about ten million households. This makes it the largest infrastructure project for the energy transition in Germany.
A key component of the energy transition
Construction of the 540-kilometre-long SuedOstLink, connecting the eastern part of Germany with the south, began in 2024. The line is scheduled to come into operation at the end of 2027. It will also use 525 kilovolt cables, and is a key component of the energy transition. Here too, robust high-performance cables are needed.
This year, the transmission system operator Amprion celebrated the symbolic groundbreaking for the German A-Nord underground cable link. The project is also of major importance for the economy of North Rhine-Westphalia. “The approximately 300-kilometre A-Nord underground cable route is a main artery of the energy transition and will in future transport two gigawatts of wind power from Emden in East Frisia to Meerbusch-Osterath in North Rhine-Westphalia,” explains Amprion. A-Nord will supply electricity to around two million people.
Together with the Ultranet DC connection, it will form an approximately 600-kilometre wind-power corridor, set to carry two gigawatts of wind energy from 2027. Construction in Lower Saxony already began in 2023.
EU: Project of common interest
NordLink is seen as a flagship project of the European energy transition – a transmission link connecting Norway and Germany. The European Union has granted it the status of a “Project of Common Interest”. Its goal is to balance periods with little sun or wind and make green energy available safely and affordably across the EU.
NordLink already links the hydropower capacity of Norway with Germany’s wind power, enabling the exchange of renewable energy and helping to cut CO2 emissions, according to transmission system operator TenneT. “For example, when Germany produces a surplus of wind energy, it can be transferred to Norway via NordLink. The water reservoirs in Norway then act as natural storage for this wind power.” Conversely, when demand is high, Germany can import hydropower from Norway. With a capacity of 1,400 megawatts (MW), NordLink can supply renewable energy to more than 3.6 million German households.
Energy supply without borders
The idea of building interconnectors to exchange renewable energy across borders is not new: As early as 2008, the Dutch and Norwegian power grids were linked by the NorNed cable. The 450 kV high-voltage line is 580 kilometres long and has a capacity of 700 MW. The NorNed cables enhance the security of supply in both the Netherlands and Norway.
The BritNed cable has also been in operation since 2011. Two submarine cables span the 260-kilometre distance between the Netherlands and Great Britain. The BritNed link, manufactured by ABB, has a transmission capacity of 1 GW.
Electricity highway connecting continents
The next step is to link continents: The EuroAfrica Interconnector will feature the world’s longest submarine cable – almost 1,400 kilometres in length, and laid at depths of up to 3,000 metres, making it also the world’s deepest. This high-voltage direct current (HVDC) transmission line will connect the power grids of Greece, Cyprus and Egypt. Initially, the energy highway between Europe and Africa will have a transmission capacity of 1,000 MW. Commissioning is scheduled for 2028–2029. And as with many other interconnectors, these cables will have to withstand the harshest conditions – yet will continue their vital work unseen: the invisible heroes.
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