Download WindpowerUpdate 15 - Nordex

phoria to Reality
For some time now, one concept has been electrifying the
wind energy sector: everyone is talking about “offshore”.
Hardly a day goes by without yet more apparently major contributions
being added to the public debate on the use of our
oceans. But only some 100 MW of capacity are currently installed
off the coasts of Europe. This represents approx. 0.4 % of
installed wind power capacity worldwide. And in Germany?
Nothing doing. To date, the precautionary principle has prevented
even the smallest steps offshore. So where does the
euphoria come from?
Experts from the Danish consulting company BTM-Consult
estimate the wind energy potential for the European seas at up
to 125,000 MW. They reckon that German coastal areas alone
could provide 20,000 MW. Huge against the backdrop of the present
25,000 MW of installed capacity – worldwide! According
to Greenpeace expertise, if the German offshore potential is
optimally used, a good half of the electricity consumption in
Germany can be covered alone by wind power generated at
sea. Yet, according to estimates by the German Wind Energy
Institute, the offshore market will not take off until the second
half of this decade. Then finally in Germany too. Just in time to
compensate for the lack of space onshore. German wind energy
companies which, unlike Nordex, are not involved in foreign
markets have to trust this forecast.
Nevertheless, the advantages of offshore operation are
obvious: thanks to the strong and more constant winds at sea,
higher yields can be obtained than onshore. At the same time,
the machines are subjected to lower strains as a result of reduced
turbulence. The consequence: reduced wear on the turbine.
The real challenges are technical in nature. Adapting the
machine to offshore conditions does not present a major
problem: the electrotechnical units are moved from the foot to
the head of the unit and the machine house protected against
the saline atmosphere by means of a dehumidifier. The additional
costs involved are quire reasonable. However, the situation
is different for the foundation and for installation. This is
where the main cost blocks are involved which make an
offshore project up to 50 % more expensive than wind parks
onshore. Gravity foundations are used today for projects realised
in shallow coastal waters. But the future lies 30 to 40 kilometres
offshore, at water depths of down to 40 metres. Here
different methods have to be used, such as the monopile or tri-
The market for wind turbines will grow by approx.
20 % per annum in the coming years. Especially in
Spain, the USA, France and Great Britain. The German
market too will continue at a high level in the next few
years.
However, another topic also has to be considered:
offshore application. By the year 2006, wind parks with
a capacity of several thousand MW could be created in
European coastal waters alone.
pod – much more expensive foundations. So the aim pursued
by manufacturers of wind turbines is clear: installation of the
maximum possible yield potential on each foundation. This
is why Nordex is developing a new, large turbine in the
5-MW class. The objective is to make the costs per kW specific
to offshore operation both calculable and economical.
In addition to this, the installation concepts at sea are based on
platforms and ships with lifting devices which independently
raise themselves above the surface of the water, thereby offering
a stable working platform. These too are unsuitable for transport
in heavy seas and cannot work continuously. This means
that the actual process of erection must be made faster and so
more cost-favorable.
In Germany, it is high time for the first pilot projects to be
realised if a breakthrough is to be made in the offshore market.
These will enable manufacturers and partner companies to gain
initial experience with offshore units. It is not only the wind
energy sector and the shipyard industry that will benefit. 6 million
tons of steel are needed to build the units solely to exploit
the German offshore potential of 20 gigawatts. This is approximately
equivalent to the quantity of sheet steel produced annually
throughout Europe.
No. 15 ı December 2002 13