Alyth - Tealing Overhead Line 400kV Upgrade

SSEN Transmission operates, maintains, and improves the high voltage electricity transmission network in the north of Scotland.

Our network extends over a quarter of the UK’s land mass and some of its most challenging terrain. This area has a lot of renewable energy potential such as wind, solar, hydro and marine power.

We work with the National Grid Electricity Systems Operator so that electricity generated in the Highlands and Islands can reach homes and businesses across Britain.

SSEN Transmission is owned 75% by SSE plc and 25% by Ontario Teachers’ Pension Plan.

We are closely regulated by the independent energy regulator, Ofgem, for the work we do constructing, operating, and maintaining the transmission network in the north of Scotland.

The costs of constructing, operating, and maintaining the transmission network are shared between all those using the transmission system, including generation developers and electricity consumers.

Ofgem set how much money we invest, what return we make on this investment and how these costs are recovered from users of the electricity transmission system.

What is Pathway to 2030?

Pathway to 2030 is a series of projects to increase capacity of the transmission network in northern Scotland. It is part of a national effort to upgrade power lines across Great Britain to connect and transport renewable electricity, especially from offshore wind farms.

These projects contribute towards meeting climate goals and renewable targets, ensuring energy security and supporting Scottish and UK Government targets for a just transition to a net zero future.

Why is it needed?

1. Addressing Climate Change: The UK and Scottish Government have ambitious targets to combat climate change and guarantee a secure and reliable supply of energy. The UK is aiming for 50 gigawatts (GW)* of offshore wind-generated electricity by 2030. Our Pathway to 2030 projects have been identified as required to help achieve such targets by delivering the vital infrastructure required. *For background, A GW is a unit of measurement of electrical power. It is equal to one billion watts.
2. Promoting Energy Independence: In 2022, the UK Government set out a strategy to reduce dependence on volatile global gas markets, moving to local, sustainable electricity sources instead. Establishing the necessary infrastructure for this is critical.
3. Planning for future need: Experts with the National Grid Electricity System Operator carry out extensive analysis and research to predict the UK’s future energy needs. This information is then carefully considered to guide infrastructure upgrade decisions.
4. Approved by Ofgem: Britain's independent energy regulator, Ofgem, granted approval for these projects in December 2022 as part of its strategy for accelerated network upgrades.

More information explaining the need for these projects can be found here, for more information on the Government policies that underpin this need and how the need has been identified and assessed please read our information leaflet.

Yes, even though the Pathway to 2030 projects will help meet the UK Government's target of carrying 50GW of offshore wind energy by 2030, the UK Government has also pledged to fully decarbonise the electricity system by 2035. To achieve that target, further infrastructure will be required. The Electricity System Operator, National Grid ESO, is expected to outline these further network infrastructure requirements in early 2024.

SSEN Transmission is responsible for where and how the high voltage transmission network operates in the north of Scotland. However, we don't determine where energy is generated – nor where it is needed.

We have a legal obligation to provide electricity generators access to our network, so that the electricity they generate can be transported across the GB to meet the energy demand of homes and businesses.

The north of Scotland is rich in renewable energy, especially wind, water, and marine sources meaning this region is vital for the UK and Scotland's climate goals. Our area covers a quarter of the UK landmass and will be crucial in the move towards a low carbon future.

Our approach to optioneering (routes for overhead lines or sites for substations) is underpinned by our statutory obligations, as set out in the Electricity Act Schedule 9, to ‘develop and maintain an efficient, coordinated and economical electricity transmission system’. Having regard to the “desirability of preserving the natural beauty, of conserving flora, fauna and geological and physiographical features of special interest and protecting sites, buildings and objects of architectural, historic or archaeological interest; and do what we reasonably can to mitigate any effect which the proposals would have on the natural beauty of the countryside or on any such flora, fauna, features, sites buildings or objects’.

As a result, our optioneering process seeks to balance technical and cost considerations with environmental considerations. To select a proposed option which is economically viable, technically feasible, minimises impacts on important resources or features of the environment and reduces disturbance to those living in it, working in it, visiting it or using it for recreational purposes. The option must also be capable of being granted consent by either the Scottish Government (in the case of overhead line projects) or local planning authorities (in the case of substation projects).

To do this we consider specific topic areas within the environmental, technical and cost categories and assess each in terms of the potential for the option to be constrained. We allocate a Red/Amber/Green (RAG) rating to each topic to highlight where potential issues may be present and use this to help compare the different options. The appraisal seeks to compare the wider implications of each option on those topics (both individually and combined) and reach a reasoned conclusion, on balance across all topics, as to the ‘preferred option’ to take forward.

Any weighting of certain criteria as being of more importance than other criteria would depend on project specific considerations. For example, if a particular technical or environmental constraint has been identified as a priority consideration through stakeholder engagement (or engineering specification) and is unable to be overcome, this will inevitably carry greater weight in the comparison of options which may otherwise contain constraint that can be easily designed out or mitigated.

We follow this comparative approach through stages of refinement. For overhead lines this starts with wider corridors and progress to assessment of routes and alignments. For substations, we start with a long list of sites, which is refined through further assessment to identify one site. Consultation with stakeholders is essential throughout this process so that their views can be taken account of in our considerations prior to progressing to the next stage.

The culmination of this process identifies a ‘proposed option’ that will be taken forward to detailed design, environmental assessment and consent applications.

Consultations began at an early stage of project development, long before any decisions on power line routes or substation locations were made.

Tower locations were not shown because this information is not yet known. Early feedback is crucial, so potential route options were discussed with key stakeholders.

Our goal at this initial stage is to select routes approximately 1km wide that minimise physical or environmental obstacles and disturbances, while also being practical and cost-effective. We presented these routes to the public, statutory and non-statutory organisations to explain our current assessment and thoughts and listen to feedback.

Stakeholder feedback guides our projects from the start. All feedback is considered, and where possible and feasible, adjustments can be made, in which case we will ensure any changes are presented at future consultation events.

Feedback importance: SSEN Transmission values feedback from stakeholders and local communities and considers it throughout the project development process.

Whist community feedback is not our only consideration, we wish to develop all projects sensitively and to reduce impacts on communities as much as possible. Community feedback provides an essential insight into local issues that helps to refine the design, routes, and substation locations.

What we can do: Following consideration of all feedback, we consider what opportunities there are to modify our project's design, route, and substation locations.

What we can't do: We don't decide on the overall need for the Pathway to 2030 projects; that's National Grid ESO’s and Ofgem's role. Therefore, we can't consult on the core necessity of these 2030 plans. Find out more here. 

In November 2020, SSE became the first company to produce a Just Transition Strategy, introducing 20 key principles to ensure fairness as we move away from carbon-heavy activities and embrace climate-friendly changes.

The Pathway to 2030 projects align with these principles, promoting job opportunities, local suppliers, and preserving cultural heritage. Early in project development, SSEN Transmission made sure to engage with communities for feedback and insight.

To read more about our principals click here.

Through our Pathway to 2030 programme, we are investing heavily in the north of Scotland. Bringing benefits to communities through jobs and investment that supports economic development while protecting biodiversity and helping Scotland and the UK meet its net zero ambitions.

We are committed to unlocking Scotland’s renewable energy potential while promoting sustainable economic development in the region. Including careful consideration to the tourism industry, preserving cultural heritage and safeguarding the environment. Socio economic reporting on the contributions the Pathway to 2030 programme make to Scotland's economy accompany each application for planning consent.

Final Pre-Application (PAC) Alignment Consultation Events

We will shortly be hosting a series of public consultation feedback events for each project from 17 February until 6 March 2025. These events conclude the Pre-Application Consultation (PAC) process for the consent application that will be submitted under section 37 of the Electricity Act 1989.  

During the events we will share our Proposed Alignment of the overhead lines, including details on how these were developed. We invite any interested stakeholders to attend these drop-in events, to discuss the plans and share final thoughts, ahead of the consent application later in 2025.

During the events we will share our Proposed Alignment of the overhead lines, including details on how these were developed. We invite any interested stakeholders to attend these drop-in events, to discuss the plans and share final thoughts, ahead of the consent application later in 2025.

Please contact your local Community Liaison Manager if you have any questions about the Reports on Consultation or require any additional information on the consultation events. A full list of venues and dates planned for the events is below:

Environmental Impact Assessment Reports (EIARs) for the Pathway to 2030 projects will be prepared for the chosen options, in line with the relevant legislation.

Once completed, the EIARs will be accessible online via our project website, the Scottish Government’s Energy Consents Unit applications portal, and relevant Local Authority planning portals (depending on the consent being applied for).

Hard copies will also be available to view locally and these will be advertised at the time.

We prioritise environmental protection in our infrastructure projects, strictly adhering to environmental policies and regulations.

We follow a mitigation hierarchy strategy of “avoid, minimise, mitigate and restore” to safeguard local, national and international designated environmentally protected areas.  

We also acknowledge that minimising impacts is not enough on its own, and we have therefore committed to delivering a Biodiversity Net Gain (BNG) on all our projects; as well as compensatory planting for any trees felled during the construction phase, where possible with native species. Where our projects are unable to completely avoid irreplaceable habitats (for example peatland or ancient woodland), we have also introduced a commitment to restore more habitat than we affect.

During our assessments, comprehensive surveys identify potentially affected wildlife, guiding mitigation efforts. For example, bird surveys are ongoing, with winter surveys planned for 2023/24.

We also assess habitats and other species along our routes. Our consultation process to date has highlighted sensitive areas, and we continue to work with environmental experts and seek community feedback to refine our approach.

When planning our overhead line and substation projects, we thoroughly consider environmental, cultural, and built heritage factors in potential locations.

We make use of national archives and data sources as well as gathering data from Local Authorities and detailed site surveys to identify and assess the potential impact on archaeological sites, listed buildings, and other heritage assets.

Environmental Impact Assessment Reports (EIARs) detail these findings and recommend ways to lessen any potential adverse effects. We've received feedback about sensitive archaeological and cultural sites from a range of stakeholders, including local heritage and archaeological groups, all of which our environmental experts have considered.

When planning routes for overhead lines and substations, we consider visual impacts and how this may affect the local scenery, visitor experience and communities.

For each project we develop, we conduct a Landscape and Visual Impact Assessment. This is one element of the Environmental Impact Assessment Reports that forms part of our application to the local authorities and Scottish Government. In this assessment, we consider visual impact from centres of population, popular spots, like walking paths and tourist sites, and where possible reduce any potential negative visual impacts.

When developing overhead lines and substations, we focus on having a minimal noise impact. Detailed noise assessments are conducted as part of our Environmental Impact Assessment, and include current noise levels, potential new noise as a result of our infrastructure, and mitigation measures where required, to ensure noise is within acceptable levels.

In our early project development, we consider flood risks and drainage. We aim to avoid areas prone to flooding and conduct assessments when necessary.

Our team includes a variety of water and flooding experts who help design systems to manage water flow around our sites. Before construction, we will have a plan in place to protect both surface and groundwater and reduce potential impacts.

We have consulted on a Community Benefit Fund for projects until 2026, a first for a transmission operator in Scotland. This fund lets us work directly with local communities to support initiatives in northern Scotland.

We want to give back to the communities hosting our transmission network and to help fund projects that can leave a lasting, positive legacy in those areas.

We're encouraging the UK Government and Ofgem to recognise the crucial role the north of Scotland plays in energy targets in any upcoming guidance, ensuring that community benefits will reflect this significance.

Additionally, our projects will boost the economy, supporting local jobs and businesses. Recent studies show our Pathway to 2030 programme could contribute over £6bn to the UK's economy, support 20,000 jobs across the UK, and benefit Scotland by around £2.5bn, supporting 9,000 jobs.

We value engaging with local communities and residents to gather feedback on our plans. While our projects can cause some uncertainty, we aim to be transparent and start these discussions early. We always welcome and encourage suggestions on improving our approach and work collaboratively with communities as our projects evolve.

We realise the uncertainty created by the optioneering phase of the projects, and this can be difficult for those potentially affected. For this reason we strive to balance the need for certainty with providing sufficient opportunity for people to feed into the optioneering and decision making process.

We would like to reassure stakeholders that we develop, build and operate our infrastructure to meet all health and safety legislation, and guidance set by relevant bodies - including the UK Government, Scottish Government, the Health and Safety Executive and our regulator, Ofgem – including that associated with Electro Magnetic Fields (EMFs).    

In respect of EMFs, we strictly follow the guidance as set by the UK Government, which in turn is informed by international guidance.    

As well as setting exposure limits that protect against known, established effects of EMF; the UK Government’s guidance also includes precautionary measures to protect against possible effects below the exposure limits that have not been established by science.   

In addition to this, the UK Health Security Agency and Department of Health have a remit to review new research in this area and ensure that current guidelines and policies are reflective of that research.    

Furthermore, the UK Government’s latest policy on EMF is set out in National Policy Statement EN-5, (NPS EN-5) which was reissued in November 2023 and came into force on 17 January 2024.  This latest policy is reflective of that review process and in line with the NPS EN-5, the current UK Government guidance, informed by relevant international guidance, is therefore still considered appropriate by the UK Government and their public health experts.  Whilst electricity consenting decisions are devolved to Scottish Ministers and the NPS EN-5 is therefore not all relevant in Scotland, we can confirm compliance with all EMF guidance as set out in the NPS EN-5.  

There have been over four decades of research looking into whether EMF can cause health effects and there are no established effects below the exposure limits.  When we design our overhead lines, substations and cables we do so to ensure they will not exceed those exposure limits, even when operating at 100% capacity, and we also ensure that precautionary measures are also applied to the design where required.  We will provide information on compliance as part of the consenting process, which will be publicly available.   

 In summary, the guidance we follow, which remains subject to ongoing review as required, ensures that safety measures will be applied to our 400kV overhead line infrastructure protecting us all against EMF exposure, keeping our network safe for the public.”

This and further information is available in our EMF Leaflet.

We understand that there are concerns about the potential impact of our proposed developments on properties within the vicinity of SSEN Transmission’s proposed overhead line alignments and substations sites.

These proposals are still under development and are subject to further consultation and design refinement. During this period, we want to work closely with communities and are looking to optimise timescales for decisions on final route alignments and substation location and designs. As the proposed alignments for the overhead lines are determined, and designs of substations are refined, we will engage with property owners, as well as listen to any other concerns there may be.

SSEN Transmission will look to mitigate impacts on residential properties as far as possible and these impacts will be assessed as part of the Environmental Impact Assessments that will accompany our applications for consent. Extensive surveys will be carried out at identified receptors, including selected residential properties so that we are able to model potential impacts on the wider area. .

Concerns in relation to impacts on property are being noted by our team however, as a regulated business, SSEN Transmission is obliged to follow a statutory legal framework under the Electricity Act 1989 and Land Compensation Act 1961. If you are entitled to compensation under the legal framework we will assess any claim on a case-by-case basis under the direction of this legal framework. If this is the case, we will recommend that you engage a professional adviser and SSEN Transmission will generally meet reasonably incurred professional fees in these circumstances. However, for the avoidance of doubt, we should advise that SSEN Transmission will not meet fees incurred in objecting to our proposed developments.

We aim to work cooperatively with stakeholders, including landowners, during the development of the projects.

While we might need to acquire land for substations or rights for overhead lines, our preference is to reach voluntary agreements. Using statutory powers is an absolute last resort.

If we do use them, we'll ensure fair compensation based on established industry standards.

A Notice of Intended Entry is a formal notice given to landowners and occupiers, based on the Electricity Act 1989.

It grants us and our contractors the right to enter land after 14 days to conduct surveys related to our project, including environmental assessments, engineering walkovers, and drone surveys.

It's essential to note that these letters are not linked to compulsory land purchase. If there are any concerns, recipients can contact us using the information provided in the letter.

We have statutory obligations to maintain a minimum ground clearance between conductors and other objects which are included in Regulation 17 of ESQCR 2002. Further guidance of standard clearances for the industry are set out in Energy Networks Association Technical Specification (ENA) TS 43-8.

The minimum clearance from the nearest line conductor to any object which is ordinarily accessible (including permanently mounted ladders and access platforms) or to any surface of a building is 5.3m. This includes temporary structures such as mobile and construction equipment. We provide guidance and information to third parties who intend to develop land near our electricity transmission assets, this includes overhead lines, pylons, substations, and underground cables. Find out more here.

We're looking at using steel lattice towers, averaging 57m in height, for our upcoming Pathway to 2030 400kV overhead line projects.

This is similar to our operational Beauly-Denny line, where 80% of its 600-plus towers are below 57m, ranging from 42m to 65m in height.

The cost of improving the electricity network is covered by GB electricity consumers. It's essential to balance this cost with environmental, technical, and societal factors.

We conduct a Cost Benefit Analysis for our projects, but the cheapest options aren't always chosen. Factors like minimising environmental impact or ensuring technical viability also play an important part in this.

SSEN Transmission's return on investment is determined by Ofgem's regulations, no matter the technology used.

In its assessment of what is required to meet 2030 targets, National Grid ESO concluded there is a need for onshore and offshore projects.

Overhead lines can carry roughly three times more power than subsea cables, making them more efficient and cost effective for energy bill payers.

Technical challenges and constraints limit the use of only offshore solutions. Moreover, onshore reinforcements help support local electricity needs and improve the network’s reliability across northern Scotland.

Where a line exists, it doesn’t necessarily mean that it would be appropriate to build a new one next to it, there are many considerations as to why this may not be possible.

Sometimes, there is no space for new infrastructure due to existing constraints, including proximity to homes. However, in some areas, it is possible to place new lines near the old ones.

These aspects are considered in the optioneering phases of our projects for which we also seek stakeholder views.

The environmental, technical, and operational constraints associated with undergrounding at extra high voltages, particularly 400kV, make the option extremely challenging to deliver in many areas of Scotland.

Some of the challenges that contribute to this position:

1. Technical Limitations: No underground cables for these high voltages (275kV or 400kV) currently exist in our area. Underground cables need specific ground conditions and present challenges in maintenance and power restoration, especially if faults occur.
2. Environmental Impact: Undergrounding can have lasting environmental effects, for example impacts on habitats and hydrology, and the area required for laying cables needs to be clear from significant constructions or vegetation for easy access during construction and repairs.
3. Terrain Concerns: The region's terrain often has slopes that are difficult to install and finding a suitable route for underground cables without challenges is extremely difficult.
4. Infrastructure Needs: For underground cables longer than 1-2km, additional substation infrastructure would be needed, enlarging the project's footprint.
5. Operational needs: Restoring power in the event of a cable fault can take significantly longer than for an overhead line. Faults on overhead electricity lines can typically take a few hours to a few days to repair and are generally easy to locate. Underground cable faults often require extensive works, specialist resource, tools and equipment to locate the fault, followed by significant civils work to expose the damage, replace the damaged section and then it can take up to a month to carry out the repairs. This presents significant risks to security of supply and network reliability. It also impacts on our ability to meet our licence obligations of maintaining an efficient transmission network.
6. Cost: Underground cables at 400kV are estimated to be between 5 and 10 times more expensive than overhead lines, and since these costs are reflected in consumer bills, it's a factor that needs to be considered.

Even if technically feasible, undergrounding over a significant length of or the entirety of a project would be unreasonable as it would be contrary to our licence obligations to be economic and efficient in respect of additional costs to the end consumer and also have additional risk to the electricity transmission network in the event of cable failure and consequent outages.

Given these constraints and our responsibility for an economical and efficient transmission network, overhead lines are our main choice for the onshore ASTI projects. Where there is a clear evidence base to justify undergrounding, this will be carefully considered.

For more detailed information on the undergrounding of cables, click here.

The choice between underground cables and overhead lines is based on the technology used and the power requirements:

1. Technology Type: The Western Isles connection uses High Voltage Direct Current (HVDC) technology, suitable for connecting the Western Isles' power generation. This HVDC technology has low electrical losses and provides better control over the island's network conditions. It requires only two cables for a 1.8GW rating.
2. Power Requirements: The Pathway to 2030 projects, including routes like Spittal-Beauly, requires a 400kV onshore overhead line to transport much more power, 5GW. This setup permits the connection of much more generation. Achieving this rating with HVDC would necessitate at least three subsea cables.
3. Feasibility: Using underground cables for such high ratings isn't viable technically, economically, or environmentally due to the sheer number of cables needed.

While underground cables work for the Western Isles connection, they aren't practical for the larger Pathway to 2030 projects.

While the T-Pylon has been developed for use in England and Wales, it is not currently deemed suitable for our projects in the north of Scotland for several reasons:

1. Weather Impact Our region experiences more severe weather conditions, with increased impact from wind and ice. Using T-Pylons would mean shorter spans between structures, resulting in more structures, thus increasing the visual impact, land occupation, and construction traffic.
2. Material Lifespan: The composite material used for T-Pylon's diamond insulators might only last about 20 years. In contrast, the glass insulators on our lattice steel towers have a life expectancy of 40-50 years.
3. Transport & Delivery: The T-Pylon's large steel sections need a large number of low-loaders for delivery, significantly affecting local traffic. Their design could also force new lines to be closer to major roads, impacting our ability to route away from properties. Lattice steel towers are more compact for transport, minimising traffic disturbance.
4. Design Flexibility: T-Pylons can only turn up to 30° angles, while our lattice steel towers can turn up to 90°. This flexibility helps us avoid communities, viewpoints, and environmentally crucial sites. The limited direction change of T-Pylons would hinder our ability to minimise line impact.
5. Reliability & Repair: T-Pylons support an entire circuit on a single diamond so in the unlikely event of a failure the entire circuit could be lost, whereas lattice steel pylons use a double circuit. Repairs would take significantly longer, delaying power restoration.

Given these factors, we've determined that T-Pylons aren't currently suitable for our projects, as they might result in greater community and environmental impact and increased construction traffic.

We're aware of the impacts from new projects and we are committed to minimising them through thorough environmental assessments.

Our focus includes mitigating effects on biodiversity, water, soil, and traffic disturbances. A Construction Environment Management Plan will be set up, using existing routes to lessen disruptions.

During construction, expected short-term issues may include noise and traffic disruptions. Before starting, we'll have a plan to manage these, including organising deliveries and travel to avoid busy times and sensitive areas.

We'll work closely with community groups and contractors to ensure adherence to mitigation measures. Typically, most project components will take around four years to complete.

All project documents, which include maps of the suggested routes for the overhead lines can be found on our project pages. Contact details of your local Community Liaison Manager are also available.