Elsam is still very interested in building offshore wind farms even though the newly-elected Danish Government has decided to stop the development of three of five scheduled offshore demonstration wind farms. In an interview with Ritzau on 23 January 2002, Elsam's CEO Mr Høstgaard-Jensen says Elsam is ready to compete for the projects should they be put out to tender.

Elsam is the owner of the world's so far largest offshore wind farm that will be built at Horns Rev in the North Sea this summer. Elsam was also ordered by the former government to build the offshore wind farm south of the island of Læsø. This project, however, and the offshore projects at Omø Stålgrunde and Gedser Rev have been dealt the Government's deathblow.

"The consequences of the new Government's decision are still not clear to us but it seems that Elsam will be relieved of the order to build the offshore wind farm south of Læsø", says Mr Høstgaard-Jensen.

For some time Elsam has worked on a study mapping the environmental impacts of a wind farm at Læsø. Mr Høstgaard-Jensen expects the Læsø project be put out to tender and it will only be natural for Elsam to tender for the project.

"Environmental-friendly energy plants are of our main interest and the production of electricity at such plants is our core business area. If the construction of these farms is to take place in a liberalised market, we shall tender for them even if there are several bidders", says Mr Høstgaard-Jensen.

Mr Peter Høstgaard-Jensen
Chief Executive Officer
Elsam A/S.

A2SEA is currently testing the first of the vessels, the "Ocean Hanne". A2SEA is a sub-supplier of Vestas' which is to supply and operate the two crane vessels for sea transport and lifting jobs in connection with the installation of the turbines at Horns Rev,.

"Ocean Hanne" which departed from Ørskov Shipyard in Frederikshavn just before the Christmas holidays, was tested in the Bay of Ålbæk around the turning of the year. Turbine lifts were simulated: the vessel was jacked up on

its four legs and the main crane lifted a load, already on board the vessel. See below.

The results of the tests showed that under the wind and wave conditions on the day of the test, the vessel was very stable and the lifting job was carried out without problems. "Ocean Hanne" continued to the Port of Esbjerg to make a series of tests at Horns Rev as well.

It soon became clear that the vessel's winch was not sufficiently powerful to secure the vessel's position under the more harsh conditions in the North Sea. Nevertheless, a number of tests were carried out just like in the Bay of Ålbæk and the vessel's required lifting capacity seemed acceptable. At present, "Ocean Hanne" is at the Port of Esbjerg to solve the winch problems. Once these problems are solved, the thorough tests at Horns Rev will continue.

Ocean Hanne was tested in the Bay of Ålbæk around the turning of the year. Turbine lifts were simulated

The main contractor for the foundations, MT Højgaard, has joined forces with Mammoet, a Dutch company, for the job of constructing the foundations on site. For this purpose, Mammoet is currently building a completely new vessel that - by means of four legs - can lift itself out of the water, a so-called jack-up vessel.

To be able to operate under extreme weather conditions at Horns Rev it has proven necessary to make the legs very robust. The picture shows one section of a total of three sections, which form one jack-up leg. The legs will be approx. 33 m long and the cross-section 3.5 ´ 3.50m. Each leg will have a so-called spud can which is 8 ´ 8m and weighs approx. 70 tonnes.

In principle, the vessel's hull - which is also the jack-up vessel's work platform - is a rectangular box 100m long, 33m wide and 7m high. In the picture a section of the hull is being loaded onto a barge that will transport the hull section to the main shipyard where the hull will be assembled (other sections and the jack-up legs). Section size: 16.5m wide, 7m high and 8 m long.

When ready for operation, the jack-up vessel will carry ten monopiles (approx. 1,500 tonnes) and other equipment for driving the turbine foundation piles.

Manufacturing of one section for a jack-up leg

Section of the hull, ready for shipment from sub-supplier's to Mammoet's

In connection with the environmental monitoring programme initiated for the Horns Rev project it was decided to follow the migration of seals in the area to examine whether the construction of the wind farm may have an undesired impact on seals' lives in the Wadden Sea.

During a kick-off meeting led by Marine Biologist Svend Tougaard, held at Fanoe Rescue Station, 15 men were instructed in the demanding work of capturing the seals. What makes it so hard and demanding is that the seals are not so curious that they swim into the nets voluntarily. In fact, they fight aggressively!

When the men arrived at the site, the seals were lying on a sand bar on the northern tip of the Island of Fanø. Half the group of men rushed to the bar in a fast rescue boat. It was a beautiful winter morning with temperatures around the freezing point and it was quite a cold experience. Within a few minutes all seals were captured in a net and put in individual nets (bags) in which they couldn't move but weren't hurt either.

The furs of the seals were then brushed thoroughly. The furs were extremely greasy - as are the hairs of all those who do not wash regularly - and it was necessary to clean and dry the furs to be able to attach the transmitters correctly.

[photo: seals are not tamed animals and they defend themselves vigorously when approached by humans]

After a couple of hours of struggling with marking the seals they were released one by one, and watching their behaviour was very exiting. The first seal released rushed to the sea and swam off. Another one moved slowly towards the sea, turned his head and glanced at the men as if to check out his watchmen.

Later on, the positions of the seals were registered on the computer and at present at least one of the seals has already been in the wind farm area to check it out. 

 
Picture in large format

The migration of the ten seals will be monitored from now till May where the transmitters will no longer send out signals due to exhausted batteries. The transmitters will fall off in the autumn when the seals shed their fur.

The first four seals (of a total of ten) were fitted with transmitters at the first "seal hunt" in early January 2002.

It was necessary to clean and dry the furs to be able to attach the transmitters correctly.

The transmitter is glued to the fur

Seals are not tamed animals and they defend themselves vigorously when approached by humans.

All turbines are fitted with cable tubes, also known as J-tubes. The purpose of the tubes is to protect and keep the cable in position at the transition piece between the turbine foundation and the seabed in which the cable is washed.

Primarily due to installation aspects the foundation supplier has wished to change the initial design of the J-tube from a design based on steel to a design using plastics (PEH). To verify that the new J-tubes were suitable for use in the harsh marine environment at Horns Rev a series of design tests were carried through. Firstly, these tests were aimed at verifying the tubes' ability to resist the pressure from the erosion protection of the foundations and, in addition, the ability to resist possible collision with drifting objects.

Later, tests were carried out on an installed J-tube to verify whether the structure was stable during pulling of the real cable. The first test was executed by pulling a steel wire through the J-tube. The tractive effort had been pre-defined by the cable supplier.

To conclude the test series, a final full-scale test was made. All tests had satisfactory results and a solution was chosen for the J-tubes.

Compression test of J-tubes

Full-scale test.

Two red marking lights have now been installed on the Horns Rev prototype turbine erected in Tjæreborg (see the Horns Rev Newsletter of December 2001).

The lights have been installed to carry out thorough tests; not least the rather advanced candela control. The Danish Civil Aviation Administration make test flights in the area under different weather conditions to test the marking lights.

The lights are not automatic and will be removed after the necessary tests.

Marking lights have now been installed on the Horns Rev prototype turbine erected in Tjæreborg.

Our Newsletter of November 2001 describes the problems with the driving of foundation piles for the substation. There has been no news to report since then. A schedule will be drawn in the near future for the driving of the remaining piles.

The platform is under construction at HBG Steel Structures in Holland, the main contractor. In the coming two months they will be very busy preparing for the start-up of the technical installations in March.

The main steel structure for the platform topside during installation. The heli-platform and facade panels will be fitted to the substation while it is still at the workshop.

The Alstom 170 kV wind farm transformer unit unloaded at HBG's berths.