Germany and Europe have set themselves the goal of achieving a climate-neutral economy by the middle of this century. Offshore wind energy plays a central role in this, as it reliably supplies large quantities of clean energy and reduces dependence on fossil fuels. The Offshore Wind Energy Act (WindSeeG) sets specific expansion targets: 30 gigawatts by 2030, 40 gigawatts by 2035 and 70 gigawatts by 2045. To achieve these ambitious targets, the new governing coalition of CDU/CSU and SPD plans under the coalition agreement to provide targeted support to German shipyards in the production of offshore converter platforms.
Structure and benefits
Offshore wind energy not only includes the construction of wind farms consisting of the generation infrastructure (foundations, turbines and cabling within the farm), but also the necessary transmission infrastructure. Offshore converter platforms are a central component of this transmission infrastructure. They consist of a foundation structure (jacket) with piles and an upper structure (topside) in which the technical equipment for high-voltage direct current (HVDC) transmission is housed.
Offshore wind turbines usually generate electricity in the form of alternating current (AC). As alternating current is transmitted over long distances with high losses, the offshore converter platforms convert this electricity into direct current (DC) - a more efficient form of energy transmission over long distances. On land, the electricity is then converted back into alternating current and fed into the power grid. Through this conversion, these offshore converter platforms significantly reduce transmission losses and make a decisive contribution to the efficient and economic utilisation of offshore wind energy.
The HVDC systems (including the offshore converter platforms) are installed and operated in Germany by the transmission system operators (TSOs), i.e. Tennet, Amprion and 50Hertz in the offshore sector. For the next expansion stage of offshore wind energy in Germany, powerful 2-gigawatt converter platforms are planned for the first time. These new platforms mark a technological leap, as they offer twice the transmission capacity of previous systems and make the connection of large wind farm clusters to the mainland more efficient.
Construction of the first 2 GW platforms will start in 2026; the first commissioning is planned from 2029, for example for the BalWin4, LanWin2 and BalWin3 connection systems from TenneT or the BalWin1 and BalWin2 connection systems from Amprion. A total of 21 of these 2 GW converter platforms are to be built in the German North Sea and Baltic Sea by 2042. This will specifically align the transmission infrastructure with the ambitious offshore expansion targets and create the basis for feeding large amounts of wind power into the German electricity grid.
Legal framework and regulation
The planning and construction of HVDC systems (including the offshore converter platforms) is subject to a complex regulatory interplay of various laws.
The Energy Industry Act (EnWG) requires the transmission system operators to construct and operate the offshore connection lines in accordance with the grid development plan (NEP) and the area development plan.
The NEP is developed jointly by the transmission system operators and determines the specific locations and commissioning dates for the offshore connection lines based on the area development plan, which defines the individual offshore areas and generation capacities. The NDP is reviewed, publicly consulted and approved by the Federal Network Agency every two years. The approved NEP is incorporated into the Federal Requirements Plan by the legislator. Only projects in the Federal Requirements Plan are subject to accelerated planning and approval procedures. The approval of an individual converter platform itself is then in turn the responsibility of the Federal Maritime and Hydrographic Agency (BSH) and is subject to the WindSeeG.
However, the other components of the HVDC system are not subject to the WindSeeG per se. For example, the onshore converter platform is subject to authorisation under the Federal Emission Control Act (BImSchG) and is therefore not approved by the BSH. The different responsibilities for the individual components increase the complexity of the overall process and make coordinated harmonisation essential.
Key technology and bottleneck in the energy transition
In countries such as the Netherlands or the UK, the electrical energy from offshore wind farms is usually transmitted directly to the mainland via an alternating current line. In Germany, on the other hand, the use of offshore converter platforms is necessary, as German wind farms are often much further away from the coast in international comparison - in some cases up to 100 kilometres. At these distances, the use of alternating current is inefficient as too much energy is lost. This is why high-voltage direct current transmission is used to significantly reduce such losses.
The demand for HVDC technology will continue to increase in the future, as wind turbines are not only becoming larger and therefore able to produce more electricity but are also being built further and further away from the coast.
At the same time, no converter platforms are currently being produced in Germany. The only shipyard in Europe that currently produces foundation structures (so-called jackets) for such offshore converter platforms is the Dragados shipyard based in Cadiz, Spain.
This is causing concern in the industry, as converter platforms could become a bottleneck in the expansion of offshore wind energy. At the end of 2024, the BSH had already announced various delays in the installation of HVDC systems - some of them lasting up to two years. The timely expansion of production capacities for converter platforms and cable systems is therefore crucial to keep pace with the expansion of offshore generation. Delays in construction may oblige the transmission system operators to make compensation payments in accordance with Section 17e EnWG.
New developments
After former Federal Minister of Economics Robert Habeck had already spoken out in favour of supporting German shipyards entering the converter market with guarantees, the federal and state governments have launched a special guarantee programme for the construction of converters and converter platforms. This programme provides for the federal and state governments to secure up to 80 percent of the contractual guarantees to be provided (advance payment, performance and warranty guarantees) by means of deficiency guarantees. The aim of the special guarantee is to cushion financing bottlenecks in the construction of converter platforms as part of the accelerated energy transition.
The coalition agreement between the CDU/CSU and SPD also takes up this idea. It states:
"We will support the entry of German shipyards into the production of offshore converter platforms, for example through guarantees."
Furthermore, politicians have announced that they will create the necessary infrastructure, such as heavy load areas and harbour facilities, or expand existing infrastructure. The federal government also intends to provide funds to promote the development and expansion of production capacities - for example through the joint task "Improvement of the regional economic structure" (GRW).
The National Ports Strategy adopted in March 2024 also emphasises investment in suitable ports for the construction of converter platforms as an important measure to strengthen the German ports industry and thus Germany as a business location.
German shipyards also want to utilise the political tailwind. Some German shipyards are planning to enter the construction of converter platforms and are investing in the expansion or securing of corresponding production areas.
Outlook
It remains to be seen whether and to what extent the support measures announced by the new German government will be successfully implemented, enabling German shipyards to participate in the further expansion of offshore wind energy. In view of the ambitious expansion targets for offshore wind power set out in the Offshore Wind Energy Act, there is a considerable need for additional offshore converter platforms. A rapid ramp-up in production is therefore necessary to prevent the lack of converter platforms from becoming a bottleneck for the expansion of offshore wind energy in the future.
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