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The turbines are of a height not used in Orkney before (almost 150m to blade tip) and we've been asked many times at the public engagement events why they have to be so big - other frequently asked questions include whether overhead lines will be used, how much the project is going to cost and how would the turbines be taken to site - including how we get them to Faray! This blog post covers some of those key questions.
Why such tall turbines?
By installing taller turbines, it means we need fewer of them.
Taller wind turbines with larger rotor blades dramatically increase the amount of power that can be generated. For every unit increase in blade length, power generation can be increased to the power of three.
Taller turbines mean that we wouldn’t have to install a huge number of turbines in order to generate the level of power that we’re aiming for and would make the project more viable in the current subsidy free environment. There is a possibility that we could be allocated a remote island wind CfD (Contracts for Difference – a type of subsidy) but taller turbines are still needed to be able to compete for that as guaranteed export prices fall.
The final proposed turbine dimensions will be arrived at through an iterative design process taking into account the findings of all of the impact assessments and to ensure that the site is financially viable.
The image above shows how the Quanterness project could look from Gorseness.
How will this connect to the grid?
SSEN will undertake a study to determine a solution to connect to the grid, with cost being one of the considerations in this. The Council will have some say in how the projects connect to the new grid however not of the overall new grid infrastructure.
The likely connection points would be:
Hoy – to be established. Likely via a substation on Hoy and then to the Finstown substation.
Faray – to be established. Likely via a substation on Faray and then to Stronsay or direct to Finstown substation.
Quanterness – the Kirkwall Power Station or the Finstown substation– there will be a small project substation located on site as well.
The power generated is likely to be exported to the Scottish Mainland, although some could be used locally depending on the final design on the new connection for Orkney.
Will overhead lines be used?
On site underground cabling will be used. For the reasons above we can’t commit to overhead lines not being used elsewhere - any planning application to install overhead lines would go to Scottish Ministers as per the Electricity Act.
How much will it cost to build the project?
A rough rule of thumb is that it costs about £1 million per MW to build a wind farm. So Quanterness may cost around £30 million to build. It is likely that the Council would seek to borrow as much as possible and minimise the amount of capital that goes towards this.
Developing a project of the scale under consideration will costs several hundreds of thousands of pounds - we estimate about £300k per project in consultancy and survey fees, then planning application fees of £125k per project (which can be viewed as an internal cost to the Council). The exact value will depend on individual site complexities.
How will you get kit on site and how expensive will this be?
We’ll be carrying out studies which would work out the best route to site given the size of the components. That would include discussions with Roads Services and other stakeholders.
It’s likely that the components would be delivered to Hatston for Quanterness and then be transported along the main Kirkwall to Stromness road. For Hoy components would be dlivered to Lyness. Detailed Construction Traffic Management and Pier Management Plans would be developed which would aim to minimise disturbance to other road/pier users and safely control deliveries.
Faray is of course much more of a challenge because there isn’t already a large pier on the island. However, a pier won’t necessarily be required - other methods might be possible such as barges or landing craft. Detailed studies will help inform any solutions therefore the exact cost is not yet known. We will keep an eye on all of the costs as they become more certain and feed them into the financial model.
If the projects get planning permission, when will they be built?
The earliest that the sites could be in operation is 2024 due to reliance on a new interconnector. The construction of the sites could start one to two years before this, depending on when the applications are determined.
How will the turbines be managed/ who will run the wind farm?
The Council has committed to developing the wind farm projects to the planning permission stage. We are investigating the most appropriate way of taking the projects into the operational phase.