The Bowdun Offshore Wind Farm will be built in the E3 leasing zone. This is a 187km2area of seabed located about 44km from Stonehaven in Aberdeenshire .

Thistle Wind Partners (TWP) submitted a bid for the option to lease this area of seabed during the ScotWind leasing round, where Crown Estate Scotland invited offshore wind developers to put forward proposals for wind farm projects around the coasts of Scotland.

In January 2022, Crown Estate Scotland announced that our bid to build a wind farm (later named the Bowdun Offshore Wind Farm after a headland on the Aberdeenshire coast) was successful. We were also awarded a lease option to build the Ayre Offshore Wind Farm off the coast of Orkney.

The Bowdun Offshore Wind Farm is expected to connect to the electricity transmission network in Aberdeenshire to the transmission operators substation in the vicinity of Fetteresso Forest. You can find out more about the onshore infrastructure needed to make out grid connection in the FAQs below.

FAQs - Bowdun's Onshore Connection

The 1GW Bowdun Offshore Wind Farm is at an early stage of development (you can read more in our blog about the milestones coming up this year).

To bring power to shore, we would need to run cables to a landfall point. From here, they would run underground (nothing would be visible above ground at the landfall location), reaching a dedicated TWP substation for converting the offshore voltage (275kV) to the voltage required for the grid (400kV). From that substation, the energy would then pass through another underground cable to the transmission operator’s substation.

The assigned grid connection point for Bowdun is at the proposed transmission operator substation in the vicinity of Fetteresso Forest, and the preferred landfall would be near to Benholm.

We now need to find the best cable route between these locations and consider a substation location. Once this work is done, a proposal will then be presented to the local community (in September 2024, if work progresses as planned).

Here are some questions we have received from the local community about our onshore infrastructure planning. You can submit your questions to  a.needham@twp.scot or post them on our Bowdun Offshore Wind Farm Facebook page.

1. How was this grid connection point decided? Why here?

TWP’s option agreement for leasing the E3 zone (the site of the Bowdun Offshore Wind Farm) provides for a grid connection point onshore, which is allocated by the National Grid Electricity System Operator (NGESO) on behalf of the Uk Government.

The process of deciding these points involves dialogue between developers, transmission operators, and NGESO. This is called the Holistic Network Design Follow-Up Exercise (HND FUE). Some ScotWind developers are in this queue, and some had their grid connections decided in the earlier Holistic Network Design (think of that as HND #1; TWP is  essentially in HND #2). Find out more on the NGESO website.

Our participation in the HND FUE process started in August 2022, sometime after we received the news that our bid for the seabed lease option was successful (granted by Crown Estate Scotland on behalf of the Scottish Government). The HND FUE process will conclude in March 2024, and the results for projects across Great Britain will be announced by NGESO. For our project, we understand that we will be looking at connection options near to Fetteresso Forest.

This news has allowed us to start exploring a landfall site, cable route, and substation location. We have started talking to landowners in the region, investigating the presence of other infrastructure, the environmental impact of different routes, ecological, archaeological and historic sites we should avoid, and weighing the impacts on local communities (and the region) of different design choices.

We will commence non-intrusive walkover surveys from March 2024 to collect data to inform route selection, the project's Environmental Impact Assessment (EIA), and our planning application for the onshore elements of the project.

This is the work we have underway now, and this planning and design process will continue right up to public consultations in late summer.

Network TWP

2. What will the substation look like?

There are several things we need to think about when designing a substation: the location (would it cut into a hillside, for example), local environment, and the types of transformer and electrical components needed. We need to anticipate what kind of components will be available on the market by the time of construction towards the end of the decade.

Our project team will also  consider ways of minimising environmental impacts (through different siting options, landscaping, replanting, etc.) and the wishes of the local community on location, orientation, screening, and design.

All of these factors will dictate the size of the substation when we come to design it. The size of substations varies substantially based on these factors so that using an image of an example substation (say, from previous offshore wind farms) could be very misleading – showing something much larger or smaller.

We do not yet have a design for the TWP substation, as we are looking at different locations near to Fetteresso Forest and we have not conducted the ground investigations or procurement exercise to decide the size of transformers. This exercise would run over a number of years as we explore new technological developments.

We will produce an initial visualisation of the proposed substation once it is ready for public consultation (we anticipate that being from September 2024). After that, the design will evolve further as we integrate feedback from the community and suppliers.

The substation design will also be considered in the Environmental Impact Assessment (EIA) for the project; this report will include a visual impact assessment and measures to reduce or avoid impacts (planting, landscape design, screening using woodland).

3. How loud would the substation be?

Electrical infrastructure does create noise: this is often outside of the range of human hearing; it can be detected as a change in the quality of background noise, or as a humming sound.

The decibel range of the TWP substation will depend on the final design choices of our engineers and will be made public as part of the consultation process. As a general guide, a typical new substation transformer produces about 60 – 80dB of noise (60dB is an ordinary spoken conversation for comparison).

Environmental Health Officers (EHOs) in the local councils are tasked with ensuring that local residents are not affected by noises like these from substations. The rule they apply is that no home should experience excess levels of background noise. It is up to the developer (TWP) to put forward mitigation measures to ensure this does not happen. Potential impacts from noise and vibration will be considered in the Environmental Impact Assessment and levels expected for our substation will be stated. 

4. Are you using pylons?

The cables used for TWP’s Bowdun and Ayre projects will be underground along their entire routes. Once the cables are installed, there will be nothing visible above the ground at the landfall site or along the route (apart from manhole covers for inspection purposes). The substation will be the only visible infrastructure in the landscape, but as noted above, measures will be considered to limit landscape and visual impacts identified by the Environmental Impact Assessment (EIA). 

Project timelines

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