Spittal Substation

At SSEN Transmission, we are committed to delivering a robust and transparent consultation process underpinned by inclusion and accessibility. As a stakeholder led business, we understand the importance of involving communities and key stakeholders throughout each stage of our development process.

During this consultation, we are presenting our approach to developing a proposed new substation at Spittal. Our consultation includes technology options, environmental considerations, site selection and maps which aim to give stakeholders and community members a better visual representation of the work on the projects to date.

This period of engagement in the development phase is vital in shaping our proposals and to do this effectively we need to capture feedback from stakeholders, harness local knowledge to identify risks in key areas of the routes and explore potential community benefit opportunities.

Based on the requirements outlined in the ESO’s Pathway to 2030 Holistic Network Design, we have developed proposals to reinforce the onshore corridor between Spittal and Beauly, via Loch Buidhe. To facilitate this connection, and others as part of the wider strategy, new additional 400kV substations and associated infrastructure is also required in these three locations. We are consulting on our preferred sites for the proposed new substation and high-voltage direct current (HVDC) converter station to be located near the existing 275kV substation at Spittal.

A converter station is a site which converts Direct Current (DC) to Alternating Current (AC) or AC to DC. AC is how our houses and businesses use electricity from the grid. High Voltage DC (HVDC) is a well-established technology that allows the efficient transmission of large quantities of electricity across long distances, with much reduced electrical losses compared with AC. It also introduces greater flexibility and resilience in the operation of the network and the management of variable outputs from renewable generation. A converter station needs to connect to a substation or switching station to access the AC network.

We follow formal internal guidance to enable us to consistently and rigorously select sites for new substations, switching stations and converter stations. Each process has a number of key stages, each increasing in detail and definition and bringing technical, environmental and cost considerations together in a way which seeks the best balance in accordance with our Transmission Network Operator’s Licence and the Electricity Act 1989.

This stage seeks to identify an initial preferred substation site from shortlisted options, which minimise where practicable physical, environmental and amenity constraints, are likely to be acceptable to stakeholders and are viable (taking into account engineering and cost requirements). The existing assets form a crucial part of this assessment to reduce the need for additional new infrastructure.

Both the process and our preferred options are then presented to the public and statutory stakeholders for consultation. Comments on our process are critical in ensuring the preferred options are the best to be taken forward to planning. Comments are taken on board and modifications may be made to ensure comments have been accommodated where practicable. These will be presented during further pre-application consultation events to the public and statutory stakeholders.

In order to support the wider connection of both onshore and offshore renewables promoted as part of the UK’s commitment to delivering green energy targets and the transition to a low carbon energy network, SSEN Transmission proposes the establishment of a new 400kV substation near to the existing 275/132kV Spittal substation. The new 400kV substation is needed because the current 275kV network is at capacity and no further renewable energy can be connected without significant reinforcement of the north of Scotland electricity transmission network. This new substation will connect to the existing transmission network at Spittal, allowing existing and proposed renewable generators to transmit electricity to areas of demand on the GB transmission network.

Rather than two separate sites, it is desirable to locate both new installations on a single large site, the advantages of this would be avoidance of longer AC connecting cables and a potentially reduced visual impact from keeping all new infrastructure in one location. The disadvantages are having to find a much larger site which is relatively flat and the potential to sterilise connection routes for the proposed new OHLs. Our site selection process has considered both separate and joint site options. Our preferred combined site would have a footprint of 870m x 340m.

• Proposed new HVDC cable connecting Peterhead from Spittal in case Option 7 will require crossing of existing HVDC cable. However, it has an advantage over the high voltage alternating current (HVAC) OHL circuit connection.
• Option 11 is in proximity with existing 132kV Spittal – Mybster OHLs and existing Spittal substation. Spittal – Mybster OHLs may require to be undergrounded at sections to facilitate entry of new OHL and cable connection at 400kV Spittal substation. Option 12 has advantages with respect to the preferred route corridor for the preferred Spittal to Loch Buidhe to Beauly OHL and to avoid the crossing of existing HVDC cables.

• All options performed equally against these criteria. However from adjacent land use aspects Option 12 has an advantage for potential future expansion possibility.

• Options 7 and 11 performed equally against these criteria due to facilities in proximity.
• Option 12 potentially has fewer underground utilities and less height difference compared to Options 7 and 11.

• Option 7 will require existing forestry removal. This is also an area of potential peatland and so both peatland and forestry drainage will be required.
• Option 11 is in proximity to the A9 trunk road required possible additional stabilization and it is also in proximity to archaeology.
• Option 12 has a low risk flood area, flat ground, is in proximity to an agricultural farming field.

• Option 7 will require major public road improvements.
• Options 11 and 12 performed equally against these criteria being in proximity to public road A9.

• All options performed equally against these criteria. Designations in the area include the Achanarras Quarry SSSI, Caithness Lochs SPA.

• No Groundwater Dependent Terrestrial Ecosystems (GWDTE) have been identified within any of the Options or within 250 m buffer, although there is potential for these to be present and further survey would be required to confirm.

• Option 11 has the highest risk of cultural heritage impact due to close proximity of site to the Magnus Hospital and Church Scheduled Monument.

• Option 7 is highly visible from Achanarras Quarry, a nearby recreational site.
• Option 12 is visible from sections of the A9 and the nearby village Halkirk.
• Option 11 is visible by traffic on the A9.

• Option 7 has high potential for an adverse impact on the local landscape due to the loss of the woodland, a sparse feature of the landscape. Options 11 and 12 have some potential to impact the landscape character.
• Options 7, 11 and 12 would be partially visible from scattered settlements to the north and west of the existing substation. Options 7 and 11 would be highly visible from Achanarras Quarry, and the core path leading to it.

• Options 7 would require the removal of commercial woodland and may affect the recreational value of the Achanarras Quarry SSSI, used by fossil hunters, due to a reduction in visual amenity.

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