UNEXPLODED ORDNANCE - Wind Energy Network

SPONSORS OF STEEL FOUNDATIONS
Supplying offshore wind turbine
foundations
The UK offshore construction industry
is probably the best suited to provide
offshore wind developers with the
adequate supply of foundations.
It is based on decades of offshore
experience, strong traditions of
marine engineering as well as
an outstanding track record for
innovation.
It is an area where it is probably the easiest
to secure a large share of the UK content.
However, it is also a segment of the supply
chain that has been consistently overlooked
in the UK by developers, the Government
and industry experts.
Steel or concrete
When we talk about foundations, there
are largely just two materials to chose
from – steel or concrete. We believe that
steel is going to be the main material for
offshore wind foundations in the coming
10-20 years.
Future large offshore wind developments
are about scale, speed and repeatability.
In other words, the offshore wind supply
chain will need to deliver a large number of
foundations in a very short timeframe and
to find a way to transport and install them
safely and cheaply. And this is where steel
wins over concrete.
While concrete gravity based structures
have some benefits, concrete
foundations are very large and heavy,
their transportation in big numbers is very
questionable and their installation requires
lots of seabed preparation.
Waterfront construction
capacity
There is also not nearly enough waterfront
construction capacity to produce them
in large numbers. They will have certain
market share in areas where a steel
foundation can’t be used due to some
conditions, but we don’t see how these
structures can be supplied in hundreds
every year.
Oil & Gas industry experience
This also matches the experience of
the Oil & Gas industry where concrete
foundations are typically used for gigantic
platforms like Thor in Norway.
While offshore wind farms go further
from shore, into deeper water and use
larger turbines, the jacket or space frame
foundations become the solution of choice.
Jacket structures
Jacket structures are easily adaptable for a
range of turbines, sea floor conditions and
water depth. They also give some flexibility
as to the installation arrangement that
can be driven piles, drilled piles or suction
buckets. The installation process can
also be optimised to expand the offshore
window while using not so expensive
vessels. Finally, they can be produced in a
mass-manufacturing fashion.
These are the core points underlining our
approach to the offshore wind market as a
foundations supplier.
AQUIND
AQUIND has developed an innovative
three-legged jacket foundation for offshore
wind turbines that they call Triton.
This design is primarily targeted at wind
turbines in the 5-6MW range and water
depths of between 30m and 60m, but can
also be used in shallower waters.
It covers most of Round 3 and STW wind
farms. The foundation has a number
of novel features aimed at reducing
installation costs and enabling installation
to take place in rougher sea conditions
than is often possible. Triton has been
demonstrated to work for both sand and
clay seafloors.
Third party analysis
An analysis by a third party has also
shown that Triton will work with a range of
leading 5 and 6MW turbines. AQUIND
is continuing to expand the list of design
cases.
A different approach
Triton has also been developed
specifically with low cost mass production
in mind. Conventional Oil and Gas offshore
Jackets are all of a bespoke design and
hence by necessity tend to be constructed
by traditional manual methods. Such an
approach is not feasible for the offshore
wind industry as it would be both too costly
and time consuming. A typical Oil and
Gas Jacket can take 18 month or more to
construct. A different approach is required
when over 5,000 offshore wind turbine
foundation are required by Round 3 areas
in the next ten years.
To achieve these levels of production,
they look to reduce the number of
structural elements and joints while
also standardising these elements and
operations as far as possible. This is
where the company works with a number
of steel suppliers to see if they can use as
much as possible lower cost off-the-shelf
rolled products rather than custom-made
tubulars.
Offshore wind strategy
This leads to the second part of their
strategy in offshore wind. The group
plans to build a new 36,000m2 automated
manufacturing plant at its Hadrian Yard
in Wallsend. This will be the most optimal
offshore construction location for many
of the Round 3 projects. The company’s
target is to achieve the throughput of
100,000te of jacket foundations per year
(approximately 3 Triton foundations per
week).
The new plant will be able to produce any
type of jacket foundation, including Triton,
as well as modules and foundations for
substations and other offshore structures.
Undercover facility
Most importantly, the new facility will allow
building complete structures undercover,
without weather interruptions and with a
minimum impact on surrounding areas.
The North Tyne Council granted planning
consent in September 2012. OGN has
also been approved for a £4.5m Regional
Growth Fund Grant, which is expected to
provide over 700 long term sustainable jobs.
Aquind
www.ogn-group.com
Click to view more info
www.windenergynetwork.co.uk
43