Full speed ahead on foundation pile driving at Walney
Good planning and favorable weather conditions have given a good start for the foundation activities at Walney. Up till 20 May, some 21 monopiles have been installed in the seabed, and the installation process is now becoming more and more routine, and the members of the installation team and the team on site in Barrow know the sequence of operations and what to do.
The first transition piece in place
Further, the first transition piece was installed 8 May 2010 at 06.00, and since then a further five transition pieces have been successfully placed on the top of the monopiles.
The transition pieces are transported to the location two at a time by the feeder barge Vagant. From Vagant, the installation vessel Goliath places the first transition piece on top of a monopile, while the second transition piece is temporarily stored on board Goliath, and Vagant can then return to Barrow for a new load of transition pieces.
Goliath finishes the installation of the transition piece and makes sure that the transition piece is placed completely vertical by means of support jacks. At this vertical position the grout material is injected and after 10 days of hardening, the transition piece has gained the strength needed to carry a turbine, but long before that, Goliath has left for a new transition piece installation. According to the time schedule, the last transition piece should be placed in September 2010.
Blessed with good weather conditions
Essential for this process is the good weather which has been most favourable up till now. During the first 1½ installation months, the wave and wind conditions have only stopped construction activities in a total of some seven days, but only for short periods of half a day. This allows the installation vessel Goliath and assisting vessels to operate almost 24 hours a day.
Taking design faults on wind turbine foundations into consideration
During the winter of 2009/2010, it became clear for the offshore wind industry that the construction method, used for other offshore wind farms, of grouting transition piece and monopile together with special concrete was not as durable as expected. As a result of this, it was decided to adjust the foundation design at Walney 1. The adjustment consists of welding rings on the inside of the transition piece and the outside of the monopiles, also called "Shear keys". At Walney 2, a solution has been chosen where the top of the monopiles is conically shaped. Thus, a future vertical load will squeeze the concrete together in a downward direction and prevent the transition piece from sliding down.
Preparations for the transport and installation of the offshore substation
Before the power from the Walney 1 wind farm can be sent onshore, it has to be gathered and the voltage stepped up from 34 kV to 132 kV. This will take place at the offshore substation to be placed inside the area of the wind farm.
The 1,100-tonne offshore substation together with the 1,000-tonne jacket foundation is right now being prepared at Bladt Industries in Aalborg, Denmark, for the transport over the North Sea. The barge is expected to leave Aalborg 31 May, and the actual installation at Walney is expected to take place from 7-15 June 2010.
Here the jacket will be placed in its position and four 60-metre long steel piles will be placed in the corners to keep the jacket in position. When the jacket has been vertically leveled, the jacket and piles are grouted together. When the grouting has hardened, the transformer platform can be placed and welded in its position.
The lifting operation of the jacket and the transformer platform will be performed by the Heavy Lift Vessel Rambiz.
Due to the nature of these operations, both the transport on open sea and the heavy lifts needed for the installation are very dependent on favorable weather conditions. When the offshore substation is in place, the commissioning will begin and ensure that the offshore hook-up and commissioning of the offshore substation are completed in due time from June to October 2010.
Onshore cable installation for Walney 1
Onshore, the cable installation work for Walney 1 is progressing. On approx 2/3 of the onshore cable route, cable ducts have already been installed.
Onshore substation installation Walney 1
The reactor for the onshore substation has arrived and was successfully placed on its final position on the onshore site in Heysham. The reactor is one of the major components on onshore site.
Besides, the reactor also other work on site continues. The filter compound is 95% completed for the contractor to arrive with the equipment in mid-May. Also the building brick work is 90% completed – with snagging lists ongoing.
Cable installation for Walney 2
For Walney 2, the land owner agreements are ongoing – the first agreements are expected in a few weeks, and the first geotechnical investigations are planned for mid-May. Together with Network Rail it was agreed how to proceed with the necessary railway crossing. This will be done as an open cut solution.
First turbines have arrived at the pre-assembly site in Mostyn
At the moment, Siemens Wind Power is working on the finalization of the establishment of facilities at the pre-assembly site in Mostyn, North Wales.
Components for six turbines, including tower, nacelle, hub, transformer unit and power unit and 15 blades have already arrived at the pre-assembly site. The pre-assembly of the wind turbines is scheduled to start on 29 May, and the first turbine is expected to be in position by the second half of June.
Go ahead for an extension of the Walney Offshore Windfarm
On 11 May 2010, The Crown Estate announced that DONG Energy has been awarded an extension of the project area within which the new capacity will be constructed. DONG Energy who holds a 74.9% part in the Walney Offshore Windfarm has not decided if, how or when to develop this option, which potentially could comprise a capacity of 750MW. Should DONG Energy choose to use the 3.6MW turbine currently used for Walney 1 & 2, it could potentially include some 200 turbines in this extension. Any extension must commence the statutory consenting process as the extension will require a full, new planning application, including an environmental impact assessment and a full consultation. The Crown Estate will only grant a lease allowing construction to start when statutory consents have been obtained from appropriate decision-making bodies.
The Walney Offshore Windfarms
The Walney Offshore Windfarms project is located approximately 15km west of Barrow-in-Furness in Cumbria. The project consists of Walney 1 and Walney 2 each with 51 - 3.6MW turbines, giving a total capacity of the Walney project of 367.2MW. The rotor diameter of the turbines is 107m for Walney 1 and 120m for Walney 2, with a maximum height of 150m from blade tip to sea level. The total area of the development is some 73km2.