An interesting article about the commercial experience and potential regarding design, construction and installation of foundations at the Amrumbank West, Sandbank, Eneco Luchterduinen and WindFloat Atlantic offshore wind farms. Read it here: http://bit.ly/_Article_CommercialProjectExperience

1. Offshore Wind Turbine Foundations
and Commercial Project Experience
www.foundations-offshore.com
Foundations for offshore wind turbines
are one of the key areas of development
for the growth of the wind industry into
deeper waters. There has been a sustained
research effort over recent years to design
and implement new foundation technologies
and to build on already successful designs,
such as monopiles.
Amrumbank West Offshore Wind Farm
The Amrumbank West Offshore Wind Farm is
being constructed by E.ON in the North Sea
off the coast of Germany. It is approximately
37km North-West of the German Island of
Helgoland, which will be used as an operations
and maintenance base.
In total the wind farm will cover an area of 2km2
,
with 80 turbines installed at a depth of 20-25
metres. The 80 turbines, which will give the
wind farm a capacity of 288MW, will be Siemens
SWT-3.6-120 Turbines, rated at 3.6MW each.
The foundations used for the project are
monopile foundations, the first of which was
installed in January 2014. The wind farm is
scheduled to be completed and enter service
in autumn 2015.
Three different ports are being used during the
construction phase, with Esbjerg, Denmark
as an installation base for turbines, Hoboken,
Belgium as a base for the substation, and
Cuxhaven, Germany as the installation base for
foundations.
The grid connection point for the wind farm is
the Helwin2 (beta) converter station (offshore),
and the Buttel onshore substation. The cable
landing point is at the German coastal town of
Busum.
The design, construction and installation of the
foundations were collaborative processes, with
a number of firms involved in the supply chain.
The initial detailed design and certification
process was carried out by Danish company,
Ramboll, and they were also responsible for the
development of the turbine foundation structure
for BSH standards application, the work taking
place between 2010 and 2011.
MPI Adventure installs the first turbine at the Amrumbank West
Offshore Wind Farm. Source: MPI Offshore

2. Offshore Wind Turbine Foundations and Commercial Project Experience
www.foundations-offshore.com
The manufacture of the monopile foundation
and transition pieces was undertaken by SIF
Group of the Netherlands, and Smulders
group of Belgium, Euskal Forging of Spain was
contracted to fabricate and supply 160 transition
piece flanges and 80 monopile flanges for the
new double hull monopile design.
MPI Offshore Ltd was originally contracted
to install the foundations, at the same time
as carrying out installation work at Humber
Gateway. Ballast Nedam was also contracted
to aid installation work while the contracted
vessel, MPI Discovery, continued work at
Humber Gateway. MPI Offshore has also
been contracted to install the turbines atop the
foundations, and carried out the first installation
early in 2015, with the MPI Adventure vessel set
to continue installation work until the autumn
and completion.
Sandbank Offshore Wind Farm
Source: Vattenfall
The Sandbank wind farm is another North Sea
construction, which is located around 90km
off the coast of the island of Sylt. The project
is being financed by a joint investment from
Vattenfall and StadtWerke Miinchen (SWM),
with a total investment value of 1.2 billion Euros.
Aspecial project company has been established
for the purpose of managing the construction,
with Vattenfall owning 51% and SWM 49% of
the shares.
The Wind farm will cover an area of 66km2,
with 72 turbines, in water depths between 25
and 37 metres, giving a capacity of 288MW.
Construction is planned to start in summer 2015,
with completion set for 2017. The wind farm
has been downsized from initial plans, it seems
likely that this was due to the limited remaining
connection capacity in the SylWin1 converter
station, but it has the potential to be extended in
the future to approximately 500MW. The project
area has room for a further 64 wind turbines, 24
of which have already received approval.
Siemens SWT-4.0-130 win turbines will be
installed at the site, supported by monopile
foundations. MPI Offshore have been
contracted to install the turbines, and Siemens
Wind Power will be responsible for operations
and maintenance for the first five years. The
monopile foundations and transition pieces
are being fabricated by EEW Special Pipe
Constructions GmbH, and they will be installed
by Bilfinger Construction GmbH.

3. Offshore Wind Turbine Foundations and Commercial Project Experience
www.foundations-offshore.com
Vattenfall and SWM also worked together on the
nearby DanTysk Offshore Wind Farm, which began
construction in 2013 and will be commissioned on
the 30th of April 2015. The wind farm also has
a capacity of 288MW and Siemens Wind Power
will also be responsible for O&M for the first five
years. A new service concept will be tested at the
two wind farms, with one service vessel servicing
both wind farms. The vessel will house workshops
and accommodation for 30 technicians, and will
be positioned permanently between the two wind
farms, with personnel transferred to and from the
vessel via helicopter.
Eneco Luchterduinen Offshore Wind Farm
The Eneco Luchterduinen Offshore Wind Farm is
a Dutch project currently under construction, which
will see 43 wind turbines providing a capacity of
129MW, 23km off the Dutch coast near Noordwijk
and Zandvoort. The wind farm is jointly-owned by
Eneco and Mitsubishi, who acquired a 50% stake
as part of a long-term cooperation agreement with
Eneco.
The 43 turbines will be V112-3.0 MW models
supplied by Vestas, and will be installed by main
contractor, Van Oord, which has an EPCI contract
to carry out full construction of the wind farm. This
may be slightly unusual in the industry, as the
owners of the wind farm are usually responsible for
development, but in this case all responsibility has
been handed over to Van Oord. The company has
used its new transport and installation vessel, the
Aeolus, to install the foundations on the site since
August 2014, and the Aeolus also completed the
first turbine installation in early April 2015.
One of the most interesting aspects of this
development is the foundations that were used,
which consisted of a monopile foundation and
Foundation installation at Luchterduinen Offshore Wind Farm.
Source: Eneco
transition piece manufactured together,
rather than as two separate components.
SIF Group were contracted to fabricate the
foundations, which the turbines will be
attached to directly, using an innovative
technique that has previously only been applied
in a few smaller cases.
One of the biggest challenges of this design is
the flange at the top of the foundation pile where
the turbine is connected. The impact of the pile
driver had potential to cause issues, so a flange
was designed with a horizontal outer edge for
driving purposes, and a slight downward slant
towards the inside. This ensured that the surface
to which the bolts will be attached to connect the
turbine remained intact during the driving
process. Euskal Forging of Spain was contracted
to manufacture and supply the flanges for this
purpose.
Construction will continue in the coming months,
and the wind farm is expected to be operational
by August 2015.