32 - Drees & Sommer

PROJECT MANAGEMENT FOR OFFSHORE GRID CONNECTIONS
Collection and safe transmission
of offshore power
Generating wind power on the open sea places the maximum demands on people, material
and management. And the same challenges apply to low-loss transmission to consumers.
Since 2010, as a member of a consortium, Drees & Sommer has been supporting the planning
and realization of grid connections for wind farms in the North Sea.
Legislators in Germany have recognized
the potential of wind power, in particular
of offshore wind farms. The German
Federal Government’s energy concept
provides for 35 percent of electricity
consumption to be covered by renewable
resources by 2020. Over the following
decades, this share is to continue to rise,
reaching 80 percent in 2050.
Wind power will play a key role in the
expansion of ‘renewables’ (see graphic
on right). But there is only very limited
space for wind farms on land and their
profitability – even in elevated areas
of the highlands or on the coast – is
relatively limited. So what better than
to go where wind and weather come
together: on the open sea.
Bringing the electricity of the future
safely to the consumer
Generating power off the coast is one
thing. Getting it as safely as possibly to
consumers on the mainland – and with
minimum transmission loss – is quite
another. The first challenge here is the
transmission lines themselves, which
are often up to 200 kilometers long and
which, when transmitting alternating
current, are not good conductors. For
this reason, the current is converted into
direct current on a floating converter
platform. A relatively new technology
called high-voltage direct current (HVDC)
transmission then takes it from there to
a transformer station on land, where it is
converted back into three-phase current
before being fed into the grid. This is a
clear demonstration of how offshore wind
power depends on a well-functioning
infrastructure on land.
12 13
Gigawatt
The potential for renewables is enormous, with offshore wind power, in particular, promising high growth rates
Water power, total
Jahr
Land-based wind power Offshore wind power Bio mass, total Photovoltaics
Source: SRU – Sachverständigenrat für Umweltfragen,
„Wege zur 100 % erneuerbaren Stromversorgung“,
Sondergutachten January 2011 (condensed version)