With the Wind Energy at Sea Act, the
German government set the framework for further expansion of offshore wind
energy in Germany: Installed capacity is to increase to at least 30 GW by 2030
and as much as 70 GW by 2045. However, this requires more than just new wind
farms. More powerful high-voltage direct-current (HVDC) transmission systems must
be built to transport electricity over long distances. The increase in transmission capacity to
two gigawatts represents a decisive technological leap, as more wind farms can now
be connected to the grid via the new systems. Siemens Energy's recently
implemented projects had a transmission capacity of 900 megawatts (MW). Siemens
Energy used a "bipolar configuration" design to create the two-GW
systems, meaning they can effectively operate at twice the voltage and transmit
twice the power. The new projects are among the world's first offshore grid
connections of this type.
Siemens Energy's scope of supply consists
of two converter platforms at sea and two associated stations on land. The wind
turbines generate alternating current and feed it into the converter platforms,
which convert the alternating current into a direct current. Only in this way
can large amounts of energy travel the long distance of around 390 kilometers (242
miles) each to the two converter stations on land via a direct current cable. The converter stations on land are being built near Wehrendorf
in Lower Saxony and Westerkappeln in northern North Rhine-Westphalia.
European
technology for the energy transition
Siemens Energy will manufacture all major
high-voltage equipment for the two connection systems, such as converter
technology, transformers, and switchgear, in Germany and will assume the
systems’ complete maintenance for a period of 10 years. This includes
services to ensure cyber security and transport logistics, such as the
provision of service ships and helicopters. The Spanish consortium partner,
Dragados Offshore, is responsible for the construction and offshore
installation of the associated platforms. Construction will take place at the
company's shipyard in Cadiz, Spain.
In addition, the systems are designed to
be integrated into multi-terminal-systems in the future. Instead of pure
point-to-point connections, several direct current connections could converge
in one station. These direct-current grids on land and on the high seas (as
offshore hubs) are intended to bring electricity to consumers more flexibly and
quickly. The converter systems will then act as electricity hubs at the grid
nodes that transmit the electricity according to the demand situation.
The connection systems are expected to transmit
power as early as 2029 and 2030, supporting Germany's accelerated energy
transition goals.