Scottish Government makes a somewhat specious ‘claim‘ to the Robin Rigg Off Shore Wind Farm (60X3Mw turbines) in the Solway Firth, but, Robin Rigg was constructed,and is maintained from a base in England, near Workington, where it ‘lands’ its power to the grid.
Scotland, currently, has NO offshore wind generated supply.
The current L&C/investment/construction trajectory indicates *NO* Scottish Offshore generation till 2016/2017.
The Summer of 2013 has seen off shore wind farms commissioned in Germany, Denmark,England,and Belgium, consequently NTA can offer, via this page,visual presentations of all stages of offshore wind farm construction.
Ultimately this page will offer a library of videos of all aspects of construction,both above and below sea-level, to inform on the extent, and environmental impact of such projects.
This page may offer images of off shore wind farms, but NTA feels its own Tiree visualisation page offers all the imagery of an offshore wind farm that is required.
The visual contrast, to be put in its full visual perspective, is that the proposed Tiree Array will be 5Km offshore Tiree. The videos below are from off shore wind farms located more than 28 km off shore.
Scotland is the only European country proposing offshore wind farms be located as close as 5km to the proximate community.
*NOTE*;- Currently 3 proposed Scottish off shore windfarms are in Marine Scotland’s Licence and Consent process. Consent does not imply investment. All developers, under their leases with Crown Estates, have a further 12 months,post consent, to decide to invest or not. Hence 2016/17 estimate for generation.
So how do we get to this if the proposed Tiree Array is consented ?
Lets build an offshore wind farm, or as they are bizarrely called, an Array !!
The above video is of the construction of the Ormonde(Barrow) Offshore Wind Farm which NTA visited as a guest of SPR in Sept 2011. Of interest is the closing sequence showing the windfarm at night. This confirms NTA’s perspective, at the time, that the Array looked like an oil refinery at night. SPR predictably disputed NTA’s perspective, but this video gives credibility to NTA night time visualisations of the proposed Tiree Array
This is a such huge, and varied subject that it merits a separate page. This is currently in gestation to be published shortly.
The turbine foundation decision is pivotal any development of the proposed Tiree Array,and SPR arriving at a ” a technical solution that is fit for purpose in dealing with the physical characteristics of this site “( SPR update 7th Dec 2012)
TRANSMISSION AND DISTRIBUTION:-
In offshore wind farms a network of inter-array inter Array undersea cables link the turbines to substations, and in turn to an HVDC converter(offshore or onshore). This transforms AC to DC for the most efficient transmission to a mainland connection point, into the Grid, for onward transmission and distribution.
Thornton Bank(Belgium) 54X6Mw turbines. 28km offshore. Commissioned Sep 2013.
This video shows a substation being put on site. The proposed Tiree Array will have 4-6 substations if developed. A substation must not be confused with a HVDC converter.
Nordsee Ost and Meerwind: substation (35KM offshore Heligoland).
This Helwin 1 (546 MW) HVDC link to the German mainland.
Borkum-West: 45Km off shore (Currently 80X5Mw ). End 2013 hoped-for commissioning.
The video below is the installation of DolWin Alpa, this windfarm’s offshore HVDC converter station. At 800MW it is bigger than the Helwin1 (above) and weighs 16,000ton/62 meters long/42 meters width/approximately 95 meters in height . This is smaller than each of the HVDC stations for the proposed Tiree Array.
Site Preparation:- Dredging ,Trenching,and Cabling:-
The unseen aspect of construction, with significant marine environmental issues.
This will be addressed in greater detail in the separate foundation page.
If Gravity Foundation are used then extensive site leveling will be required. This requires dredging with with conventional trailer hopper suction dredgers, or on a rocky seabed by cutter suction dredgers. This will be addressed in greater detail in the separate foundation page.
Dredging may also be required in preparation for cable trenching.
Cables have to be buried by trenching ( SPR Scoping Request Aug 2010 p 14) . [Note, it is now proposed to bury Tiree’s Gunna Sound Grid cable connection, to avoid a continuum of the significant Tiree Grid power-outs of 2013(2 months), and 2011-12(5 months)] .
The proposed Tiree Array will require the displacement of approx 3-5 Million Tons of seabed sand and rock. This has serious environmental implications.
Cabling is ‘ploughed-in’. Conventional seabed ploughing, like agricultural ploughing, prefers soft, level terrain, none of which apply to the proposed Tiree Array. It will require rock cutting ploughs for inter array/export cable trenching and laying. Irrespective, one of the major difficulties that would be encountered would be the severity of the topography of the seabed.
This animation illustrates the operation on a flat sandy seabed !!
Operation and Maintenance(O&M)
As with cable trench ploughing, offshore wind farm O&M much prefers ‘level’ conditions. The offshore wind farm O&M industry is currently struggling to operate in wave heights in excess of 2m. This poses a significant problem to develop the proposed Tiree Array.