Grid Access
Huge offshore platforms
are needed to transmit
offshore wind power
to the shore. Their construction is sensational
in size, material, and
logistics. A report from
the yard.
Text: Onno Groß Photos: Kay-Uwe Rosseburg
The Art of
Illustration: Bridgemanart
Building a
Colossus
The topside of the HelWin 1 platform
is as tall as the Colossus of Rhodes –
together with its substructure, it’s
almost as tall as London’s Big Ben.
Living Energy · No. 7 | November 2012 47
Grid Access
Denmark
Germany
Flensburg
SylWin
Husum
BorWin
HelWin
Heide
Substation Büttel
DolWin
Cuxhaven
Substation Hagermarsch
Stade
Wilhelmshaven
Germany
Delfzijl
Netherlands
Rorichmoor
Substation Diele
Giants in the Ocean
HVDC converter platforms are cuttingedge links between offshore wind parks
and onshore power grids, converting
the turbines’ AC power into direct current
for low loss transmission to onshore
HVDC converter stations.
BorWin 1 (400 MW)**
BorWin 2 (800 MW)*
DolWin 1 (800 MW)**
DolWin 2 (900 MW)**
DolWin 3 (900 MW)X
HelWin 1 (576 MW)*
HelWin 2 (690 MW)*
SylWin 1 (864 MW)*
* Siemens (contract)
** Other provider (contract)
X
Tendering
48 Living Energy · No. 7 | November 2012
I
nevitably, the Colossus of
Rhodes comes to mind. As the
Greeks once must have done
before one of the Seven Wonders of
the Ancient World, I am marveling at
the enormous structure that is being
created in the Nordic Yards hangar
in Wismar: an eight-deck construction,
almost the size of a soccer field and
filled with technology. How can something this large ever be anchored in
the sea?
This massive construction, assembled
in one of Europe’s biggest covered
dockyards, is the HelWin 1, a so-called
HVDC (high-voltage direct-current)
converter platform for the transformation of alternating into direct current on sea. It will serve to link the
many offshore wind turbines in the
North Sea with the onshore grid. The
name HelWin is derived from the Ger-
man outpost in the North Sea, Heligoland. In its vicinity, 85 kilometers off
the coast, the HVDC converter platform
will be anchored more than 20 meters
below sea level in 2013.
Placing this steel monster – 35 meters
high, 72 meters long, 51 meters wide –
in the choppy North Sea, that’s the
real technological challenge. To achieve
this feat, the platform is being built
in two parts: the topside, in which the
technological apparatus is encased,
and the base frame, the foundation
on the bottom of the sea. They will be
transported separately to their location and assembled at sea.
Shipyard Craftsmanship
In the dock on the Baltic Sea coast,
a base frame for an HVDC converter
platform has already been completed
and placed on board a ship. The di-
Graphics: independent
Substation Dörpen / West
mensions are again gigantic, considering that many thousand tonnes of
steel went into the base frame’s construction. In shallow waters, for instance off the English coast, many wind
turbines use a simple steel anchoring
system called Monopile. But the German wind turbines are located much
further out in the open sea, beyond
the Wadden Sea and out of sight of the
coastline. Here, the turbines have to
be installed on a tripod or a jacket, also
known as a lattice tower, to weather
the tides. And they have to be extremely tall, since waves can – once or twice
in a century – pile up to 20 meters
high in a North Sea gale.
From a distance, the basement on the
wharf resembles a climbing frame
with its towering cranes, spokes, and
reinforcements. However, when
standing in front of it, you simply face
a bulky mess of pipes rising into the
sky. On closer inspection, I can make
out the five strong support pipes
forged from the best offshore steel,
each pipe wall 8 centimeters thick,
­almost the length of a ballpoint pen.
The shipyard workers are standing
in front of the huge grid, displaying
apparent pride in their work. The steel
construction was executed with the
utmost care, since the base frame will
have to provide a solid support for
the HelWin HVDC converter station.
Seven hundred shipyard workers at
Nordic Yards are involved in building
and setting up the offshore platform.
It takes three times as many working
hours to assemble the platform as to
build a container vessel. But as yet
they’re still sailing in uncharted waters with the construction of offshore
platforms. Vitaly Yusofov, owner and
chairman of Nordic Yards, assures me
that, “the dockyard has a long tradition and is already experienced in
building drilling platforms.” He aims
to be an important partner for maritime special orders.
The shipyard craftsmanship is also
noticeable in the hangar where the
HVDC converter platform is being
built. My exploratory visit of the topside takes me over a couple of stories.
In the lower parts lie two gigantic clean
rooms full of transistors – they are the
core of the offshore converter station.
Then I head onwards through the climatic chambers which will later be
used for cooling and air cleaning,
through the workshops, passing the
rooms for IT and the cabins for a crew
of 20, and all the way up onto the top
roof. Up here, cranes and a heliport
have been installed, giving an idea of
the working routine out on sea. The
gulls are still missing, but the sea view
from almost 50 meters altitude is sure
to be overwhelming.
Unmapped Territory
A construction of this scale with complex HVDC transmission is globally
still unmapped territory. During the
assembly, the most cutting-edge mi-
crotechnology is subjected to higher
dust loading. “This calls for strong
­logistics, so that all components can be
fitted quickly,” says Christian Schmitt,
Project Manager at Siemens, and explains the challenge to me. The procedure has to be organized in a sensible
way and at the same time set the standards for future constructions. At
Siemens in Hamburg, 300 employees
from the offshore department are busy
optimizing the logistics to speed up
the assembly of such offshore platforms.
The HVDC converter platform HelWin 1
is not the only order in the Baltic Sea
shipyard’s book. Actually, with a capacity of 576 megawatts, it is the smallest of four Siemens constructions currently under way. Three additional
HVDC converter platforms desperately
needed to connect the wind farm to the
grid are SylWin 1 (­ 864 MW), BorWin 2
(800 MW), and HelWin 2 (690 MW).
Colossal Proportions
70 m
35 m
22 m
Big Ben
23 m
Human
Soccer Field
Living Energy · No. 7 | November 2012 49
Grid Access
cent of the power requirement. Great
Britain plans to raise the proportion
of wind energy to 25 percent of the
­total, covered by up to 48.6 gigawatts
from offshore wind farms. In the latest planning phase – the so-called
Round 3 – the wind turbines will be
increasingly built at greater distances
from the coastline and thus need an
HVDC connection. An estimated 160
wind farm clusters will spring up all
over Europe in the near future.
Connecting these wind farms is a
­logistical challenge, also for the network provider TenneT who commissioned the platforms. The Dutch
company will connect the North Sea
wind turbines to the grid. “It’s exciting at the moment,” confirms Wilfried
Breuer, Senior Manager for offshore
projects at TenneT. Comparable to the
work of an urban planner, he has to
distribute wind farm clusters, transformer platforms, direct current and
three-phase current connections,
and converter stations onshore in
the tight exclusive economic zone of
Germany. “In ten years’ time, we will
have implemented nearly all future
plans in network development, I’m
sure about that.” Tim Dawidowsky of
Siemens is equally optimistic: “Although we’ve been facing some difficulties with our first projects, I am
convinced we will hardly remember
these initial teething problems in ten
years’ time. Offshore wind energy
will become a success story.”
BorWin is the second-largest of four HVDC converter platforms that Siemens will install in the North Sea to link
the wind farm to the German power grid.
Pioneer Projects in the North Sea
20 – 25
> 100
(in kilometers)
350
Average
capacity
750
(in megawatts)
20 – 35
Water depth
(in meters)
Platform
20 – 40
2,000 – 2,500
(in tonnes)
10,000 – 15,000
AC solutions in Great Britain
50 Living Energy · No. 7 | November 2012
DC solutions in Germany
A Profitable Future Market
Compared to a three-phase current
cable, HVDC technology transmits
power almost without loss. If you take
sea cables more than 80 kilometers
long, this technology is the mandatory
solution. Add Europe’s ambitious
goals for the move to sustainable energy sources and the need to find an
alternative to nuclear power to the
equation and what you get is a profitable future market. Germany aims to
generate 10 gigawatts from offshore
wind farms by 2020 – this will require
about 3,000 wind turbines – and to
raise the output by 2030 to a total of
25 gigawatts. This will match 15 per-
Photos: Ulrich Wirrwa, Kay-Uwe Rosseburg Graphic: independent
From the
coast
“All offshore projects a long distance
from the coast need high-voltage
­direct-current transmission,” says
Tim Dawidowsky, CEO Business Unit
Transmission Solutions of Siemens
Energy. “Without these new power
highways, Germany will not be able
to meet its goals set for the expansion
of renewable energy sources.”
Siemens has installed more than 860
turbines in the sea, totaling approximately 2,500 megawatts of installed
offshore capacity.
Worshipping the Wind
Network provider TenneT has announced investment obligations of
currently €6 billion in the offshore
segment. In the northern Baltic Sea,
an HVDC route will power energy
via the HelWin 1 HVDC converter platform to the converter station in
Schleswig-Holstein. Significant lengths
of cables, both underwater and onshore, will be needed to transmit power
from the wind farms. In the southern
part of the route, off the island of
­Borkum, two further direct current
connections have been projected.
In addition, the move towards renewable energy sources in Germany is
­being backed by roughly 3,800 kilometers of new transmission lines and
optimization of 4,400 kilometers of
existing routes onshore.
Ultimately, there will be a new HVDC
offshore grid that will transmit power
from the sea via the coastlines to all
over Europe. Gigantic colossi like the
HelWin 1 platform are an indispensible part of it. The lighthouse on the
Greek island of Rhodes was once built
to honor the sun god Helios. In the
north, present-day architects rather
seem to worship the wind. p
Onno Groß, a science journalist from Hamburg,
writes regularly about maritime issues for news­
papers and magazines such as National Geographic,
Financial Times Deutschland or Handelsblatt.
860 Siemens Wind
Turbines to Date
The platform’s base frame is made of thousands of tonnes of steel.
The boom in wind energy started
about ten years ago. Helped along by
the Renewable Energy Act of 2000, the
number of wind turbines increased
rapidly. More than two dozen building
applications for the windy North and
Baltic Sea have been submitted to the
Federal Maritime and Hydrographic
Agency (BSH); so far 8 gigawatts of installed capacity have been granted.
2010 saw the commissioning of the
first test area, alpha ventus just off
Borkum. In May 2012, Baltic 1, the first
wind farm in the Baltic Sea, followed
suit: Here, 21 Siemens wind turbines
produce enough energy to power
a medium-sized town. Worldwide,
Tim Dawidowsky (center), CEO Business Unit Transmission
Solutions, at the Nordic Yards in Wismar.
Living Energy · No. 7 | November 2012 51