Beauly to Blackhillock to New Deer to Peterhead 400kV OHL

This project, along with several other major projects planned in the north of Scotland, is part of a major upgrade of the electricity transmission network across Great Britain that has been independently assessed by the ESO as required to meet UK and Scottish Government climate change and energy security targets. More specifically, these projects are needed to deliver UK and Scottish Government 2030 renewable targets and follows the publication in April 2022 of the UK Government’s British Energy Security Strategy (BESS).

The BESS set out the UK Government’s plans to secure the country’s future energy independence by reducing dependence on, and price exposure to, volatile global wholesale gas markets. This will be achieved by accelerating the deployment of homegrown and affordable low carbon electricity generation, together with developing the electricity network infrastructure required to connect and transport this power. The BESS included an increased ambition for offshore wind of 50GW by 2030, up from the previous target of 40GW.

To enable connection of that 50GW of offshore wind by 2030 target, the ESO, working in

collaboration with the three GB Transmission Owners (of which SSEN Transmission is one), developed what is known as the ‘Holistic Network Design’ (the HND). Published in July 2022, it sets out the onshore and offshore electricity transmission infrastructure required across GB to deliver this UK Government target with a “Required in Service Date” of 2030.

In December 2022, the energy regulator, Ofgem, approved the need for these projects as part of its Accelerated StrategicTransmission Investment (ASTI) framework decision.

Our 2030 reinforcements are also key to enable the connection of the first phase of the ScotWind leasing round, which will connect 11GW of ScotWind’s total ambition of 28GW.

The requirement for an onshore connection from Beauly to Peterhead vi Blackhillock and New Deer is confirmed within the Holistic Network Design and Ofgem’s ASTI framework, and forms part of a portfolio of SSEN Transmission projects to deliver these requirements we call the 'Pathway to 2030'.

The new overhead line (OHL) can follow the existing lines in some areas where other constraints allow, and the route options demonstrate sections where this may be feasible in parts. Since the existing line was developed in the 1950s/60s there have been changes to environmental and consenting requirements that mean routeing the new OHL entirely adjacent to the existing OHL would be difficult to consent.  

There are several new offshore cables being proposed as part of the Pathway to 2030 scheme. The decision to exclude subsea cables from our corridor assessment was driven by wider network requirements. National Grid’s Pathway to 2030 Holistic Network Design (HND) study concluded that an onshore connection was required to strengthen the network in parallel with planned offshore solutions, which excluded the option of exclusively using subsea cable to provide the required connection.  

There are several reasons why overhead lines are required alongside subsea cables. This includes the capacity that different technologies can enable, with 400kV overhead line double circuits capable of carrying around 5GW of electrical power when compared to up to 2GW for subsea cables, meaning multiple subsea cables would need to be developed, procured and delivered simultaneously to deliver the same capacity uplift.  

Furthermore, onshore reinforcements present opportunities to accommodate onshore electricity generation and demand connections, including the support of local and community decarbonisation ambitions. It will also enhance the resilience and security of supply of local electricity networks across the north of Scotland.  

Finally, cost is clearly an important consideration, particularly given the cost of investing in the electricity transmission network is ultimately recovered by electricity bill payers across GB and that is one of the key factors in the ESO’s assessment of the proposed network reinforcements. The cost of HVDC subsea links and the associated HVDC Converter Stations that are required at each point these links connect to the onshore AC network are significantly higher than 400kV onshore reinforcements to deliver the same capacity uplift. 

These projects are steered by the National Grid ESO, and we are currently investigating options for an overhead line (OHL). Should there be a requirement to use underground cable (UGC) for a specific section of the route then this will be investigated.  
 
OHL is currently favoured for the majority of the route for several reasons, including the following:    
 
• The cost is 4-6 times higher for cabling and as a regulated business we must provide best value for customers  
• Operation and maintenance – it is easier to identify and address faults for an OHL. OHL also provides greater flexibility to upgrade based on future network requirements.  
• Land-use – UGC would require construction land width of approx. 50 m along the entire length which once reinstated, land use restrictions may apply to this width to avoid risk of cable damage. Land use beneath OHL can generally return to previous use, although the operational corridor must remain free of trees.  
• Community impact (visual and noise) – OHL generally have a greater visual and noise impact than UGC however, long distance UGC would require additional equipment above ground to maintain stability of the network or to convert power from DC to AC.  
• Environment (land take) – the impacts to sensitive habitats and soils & geology associated with 50 m construction width for UGC would be substantial. OHL impacts are limited to tower footings, which can often be micro-sited to avoid sensitive habitats. Although impacts associated with access tracks also need to be considered. 
 
Specifically relating to this scheme, the following points are important to note: 
 
•           No 275kV or 400kV underground cable on the SSEN Transmission network, only 132kV and HVDC 
•           Due to the voltage and capacity of the proposed circuits it could lead to more infrastructure required: 
•           Reactive compensation compounds  
•           Substation like compounds to stabilise the network 
•           Could be a frequent as every 10-15km of UGC 
•           Suitable compound locations may drive the cable route 
•           Joint bays, testing locations and cable sealing end compounds will be required 
•           Longer construction timescales 
•           Wider construction corridor creating potential for greater impact 

We recognise that in the development of our projects, there may be an impact on land and property interests.

In terms of entitlement to compensation, this is governed by law under the Electricity Act 1989. Compensation will be considered on an individual basis in accordance with current legislation.

Throughout our project development, we welcome feedback on our proposals and are committed to working with stakeholders to ensure that the impacts of our developments are mitigated as far as possible.

Throughout the ongoing development of this project, we remain fully committed to work constructively with all stakeholders, including landowners and we remain at the early stages of development where no decisions about potential substation locations or overhead line routes have been taken.

Where there may be a requirement for us to purchase land for our infrastructure, every attempt will be made to reach agreement on a voluntary basis and it is only as an absolute last resort, when all other options have been exhausted, that we would consider using our statutory Compulsory Purchase Order powers.

In the event that Compulsory Purchase Orders are used, we can confirm that appropriate levels of compensation will be agreed in line with established industry practices.

We are obliged to develop our network in a coordinated, economic and efficient manner to ensure the GB energy consumer receives value for money, as the cost of investing in the electricity transmission network is ultimately paid for by GB electricity consumers.

The key factors that we must consider when we develop new transmission infrastructure are; environment and people, cost and technical, and a balance must be sought between all three.

As part of the development of all our projects, a Cost Benefit Analysis is carried out to help demonstrate the economic viability of the project. However, this does not necessarily mean that the lowest cost options are put forward for development. Avoiding significant effects on people or the environment or ensuring the most technically viable solutions are taken forward will often outweigh costs when it comes to determining optimum solutions for the location of our infrastructure.

Some consultation feedback received suggested overhead line solutions are being progressed solely on financial grounds, or that they are more profitable to us, however this is not the case. As a regulated business, the rate of return on investment, or rate of profit, we can make is set by Ofgem as part of its regulatory framework, regardless of the technology employed.

Therefore, the higher the value of the investment made, the higher the value added to the Regulatory Asset Value (RAV), and the higher profit in absolute terms we make. Given underground cabling is significantly more expensive than overhead lines, the return on investment would translate to a higher profit figure than would be achieved from overhead infrastructure.

As a responsible developer, we take our environmental responsibilities very seriously and follow a mitigation hierarchy of ‘avoid, minimise, mitigate and restore’. We are committed to deliver 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. Robust policies are also in place to manage and mitigate any impacts on irreplaceable habitats, like peatland and ancient woodland.

As part of the process of identifying potential route options, we considered all of the environmental designations in the search area, including those connected with species and habitats such as Special Protection Areas (SPAs), Special Areas of Conservation (SACs), Sites of Special Scientific Interest (SSSIs) and Ramsar (wetland) sites, in addition to nationally or locally designated sites such as RSPB reserves and local nature reserves. We have identified route options that seek to avoid or minimise interaction with these protected areas as much as possible.

A large number of surveys will be conducted as the project develops so that all wildlife, including plants, birds and protected species (both terrestrial and aquatic) which may be potentially affected are identified and appropriate action can be taken in line with our mitigation hierarchy of ‘avoid, minimise, mitigate and restore’.

Where there is potential for impact, these surveys will help up to identify appropriate mitigation to minimise impact. Breeding bird surveys will commence in 2023 and will carry on into 2024. Further surveys of wintering species will be undertaken through winter 2023/4. We will also be surveying other species at various locations along the route. We will be undertaking habitat appraisals and ecological walkovers of potential routes.

All of this work will feed into a detailed Environmental Impact Assessment of the proposed development, which will be required to support the application for consent to the Scottish Government, and which we aim to submit in late 2024.

During the current consultation process, we have been made aware of a number of areas of sensitivity for various species along our potential route options. We are sharing this information with our environmental consultants who will undertake all species and habitat surveys and assessment on our behalf.

We welcome further similar feedback from local communities that we can incorporate into our assessments.  

SSEN Transmission is responsible for maintaining and investing in the electricity transmission network in the north of Scotland and our network extends over a quarter of the UK’s land mass, crossing some of its most challenging terrain.
Our operating area is home to vast renewable energy resources, and this is being harnessed by wind, hydro and marine generation. Working closely with National Grid Electricity System Operator (the 'ESO'), we enable electricity generators to connect to the transmission system, allowing the electricity generated by them to be transported to areas of demand across the country.

Following a minority stake sale which completed in November 2022, SSEN Transmission is now owned 75% by SSE plc and 25% by Ontario Teachers’ Pension Plan Board.

SSE plc sold its UK domestic electricity and gas retail business, along with domestic energy services to OVO Energy in January 2020 and no longer manages these customer accounts.

It’s the highest voltage electricity network in the UK – the ‘motorway network’ of the energy world. It transmits large quantities of electricity over long distances via wires carried on a system of mainly metal towers (pylons) and large substations. Transmission voltages in Scotland are 132kV, 275kV and 400kV. Larger generation schemes usually connect to the Transmission system.

The lower voltage parts of the system are called distribution networks. In Scotland, these local networks operate below 132kV whereas in England the distribution network includes 132kV. 

As a stakeholder-led business, throughout the life of our projects, we aim to work positively with local communities and keep people informed about what we are doing. This is particularly important when we are developing new projects, we want to understand what local people think about our plans.

We always endeavour to take the time to discuss our proposals with local community councils and the wider affected community and to carry out engagement throughout each of the development stages, listening to feedback before finalising project plans. The feedback we receive is vital to help us develop proposals that reflect the views of a variety of stakeholder.

To find out more about a project, visit our project web pages which can be searched by location or area. Each project has a dedicated Community Liaison Manager that you can contact. You can find their contact details in the individual project pages, where you can also sign up to project updates.

Search projects