Japan\'s first floating platform for offshore wind turbines developed by Sasebo HI

1. offshore floating wind turbine platform developed September 8, 2009
Sasebo, Japan
Sasebo Heavy Industries is proud to announce the successful completion of the world’s
first large scale steel/concrete hybrid Spar-type floating wind turbine platform.
The hybrid Spar platform was developed jointly by Kyoto University, Sasebo Heavy
Industries, Toda Corporation and Nippon Hume.
After testing of a 1/100 scale model in 2007 and a 1/20 model in 2008 in a deep-sea water
tank, the time had come for a large scale model testing at an offshore site.
Precast concrete was assembled to the upper part steel structure in one of Sasebo’s
shipbuilding docks. The completed Spar-type platform, measuring 12.5 meters in length of
which 7 meters below water surface, was then transported to its testing location about 20
meters from Sasebo’s outfitting quays and tethered with three mooring cables to the
seabed.
the offshore floating wind turbine platform model, measuring 12.5 meters in length
inset: general arrangement

2. Although the objective of this particular test was to verify the performance of the platform
in offshore conditions, for demonstration purposes a household-size wind turbine was also
installed and generating electricity, brought ashore through an underwater power cable.
Sasebo Heavy Industries shipyard, where the offshore platform was assembled and floated
During the two week testing period surge, heave and pitch were measured and the floating
platform was found to perform extremely well under the various wind, wave and current
conditions. Accordingly, Sasebo and its partners intend to immediately proceed with the
development of a full scale model, including a two-megawatt wind turbine, to be tested at
an offshore site in the Kyushu area of Japan. Commercialization of the floating offshore
platform is targeted in three to four years.
The concept of the Spar floating platform itself is taken from the offshore oil/gas industry,
where this technology is already well proven. Also, a similar platform for wind turbines is
already being tested full-scale in Norway. The uniqueness of the Sasebo type is its
steel/concrete hybrid structure, which is believed to be the most cost-effective and
easy-to-build design.

3. offshore wind in Japan
Japan has been slow in developing its wind energy resources, but it is expected that, also
spurred by Prime Minister Hatoyama’s ambitious goal of a 25% emission reduction from
1990 levels by 2020, demand for wind generated power will increase drastically in the near
future. Especially in Europe and the US, recently offshore wind has garnered a lot of
attention. Winds at sea are stronger and more stable, NIMBY, noise and visual pollution
obstacles can be avoided, and transportation of large turbines is easier and more
economical over sea than over land. Still, there are many hurdles to be overcome. Some are
related to the turbine design itself, but a major issue is also the type and installation of
foundations. Today’s offshore wind turbines are still installed on piles fixed in the seabed in
shallow waters of up to 20 meters depth. However, the further one goes offshore, or in
countries like Japan where the waters immediately become very deep, such piles are
technically and economically not feasible. In such cases the solution is a floating type
platform construction, such as the one now under development by Sasebo Heavy
Industries.
graph showing water depths around Japan between 100 and 200 meters in grey,
where floating type platforms will be required for the development of offshore wind

4. Sasebo Heavy Industries
Sasebo Heavy Industries, located in the most western part of Japan, is one of Japan’s oldest
shipyards. Established in 1889 as one of the shiprepair and shipbuilding yards of the
Imperial Navy, it was given into civilian hands in 1946. Part of its well-known history is the
delivery of the “Nissho Maru” in 1962, the world’s largest tanker to that time.
Today the company is still active in both newbuilding and shiprepair, of both commercial
and naval vessels. The main repair dock can accommodate ships up to 400,000 dwt.
shiprepair at Sasebo Heavy Industries
The Business Development Department within Sasebo Heavy Industries is working on
projects and new businesses beyond the company’s traditional activities, but that are still
within the scope of shipbuilding or heavy industries manufacturing. Focus is on
technologies and business fields related to “environment and energy”.
The company’s smaller docks are very suitable for the mass production of floating
platforms for wind turbines such as the one now under development.