Who we are We are Scottish and Southern Electricity Networks, operating under license as Scottish Hydro Electric Transmission plc (SHE Transmission) for the transmission of electricity in the north of Scotland. What is the difference between Transmission and Distribution? Electricity Transmission is the transportation of electricity from generating plants to where it is required at centres of demand. The Electricity Transmission network, or grid, transports electricity at very high voltages through overhead lines, underground cables and subsea cables. The transmission network connects large scale generation, primarily renewables, to central and southern Scotland and the rest of Great Britain. It also helps secure supply by providing reliable connection to the wider network of generation plans. The Electricity Distribution network is connected into the Transmission network but the voltage is lowered by transformers at electricity substations, and the power is then distributed to homes and businesses through overhead lines or underground cables. In total we maintain about 5,000km of overhead lines and underground cables easily enough to stretch across the Atlantic from John O Groats all the way to Boston in the USA. Overview of Transmission projects Our network crosses some of the UK s most challenging terrain including circuits that are buried under the seabed, are located over 750m above sea level and up to 250km long. The landscape and environment that contribute to the challenges we face also give the area a rich resource for renewable energy generation. There is a high demand to connect from new wind, hydro and marine generators which rely on Scottish and Southern Electricity Networks to provide a physical link between the new sources of power and electricity users. Scottish and Southern Electricity Networks is delivering a major programme of investment to ensure that the network is ready to meet the needs of our customers in the future. Our responsibilities We have a licence for the transmission of electricity in the north of Scotland and we are closely regulated by the energy regulator Ofgem. Our licence stipulates that we must develop and maintain an efficient, co-ordinated and economical system of electricity transmission.
Existing network in Orkney There is currently no transmission infrastructure on the Orkney Islands. The electricity network on Orkney is connected via two distribution subsea cables between Rackwick Bay on Hoy, and Murkle Bay near Thurso. These cables were installed in 1982 and 1998 with a total import/ export capacity of 40MW. Demand on the islands varies between 7MW in summer and 46MW in winter. The current connected embedded generation in Orkney exceeds the capacity of the existing 33kV cables and no further generation can connect to the system at this time. Why reinforcement is required At present, the current level of contracted generation between National Grid (the System Operator) and developers is for a minimum of 220MW of new generation by 2022. To connect this level of generation, a transmission connection is needed between Orkney and the Scottish mainland. An alternative and innovative approach The current regulatory framework requires capacity to be allocated in chronological order based on respective developers contracted position. To proceed with a transmission connection first requires regulatory approval from Ofgem, which in turn requires those contracted developers to demonstrate commitment to their projects. Due to a number of factors over recent years, such as changes in government policy or the readiness of renewable energy projects across Orkney to progress, it has not been possible to proceed with the transmission connection proposal to date. To try and overcome this impasse and help Orkney realise its vast renewables potential, we are considering an alternative approach to allocate the necessary volume of capacity that is required to underpin the case for the proposed 220MW connection. This approach would see capacity allocated on a ready to connect basis, whereby those developers who are ready to commit to their projects would be allocated capacity. This innovative approach, the first of its kind in GB, would first require approval from the energy regulator, Ofgem. An initial consultation on the principles of the proposed alternative approach took place in February and March 2018, with a follow up consultation planned for the summer.
Our proposed solution Orkney to Mainland Scotland Transmission Connection In order to provide a transmission connection that will facilitate the connection of renewable generation, a marine cable linking Mainland Orkney and Mainland Scotland will be required. The new link would provide an additional 220MW of capacity. The main elements of this projects are as follows: A new substation at Finstown; An underground cable linking Finstown substation to a cable landing site west of Stromness; A marine cable linking Mainland Orkney and Caithness; A new cable route between the Dounreay marine cable landing point and the new substation at Dounreay; and Construction of a new substation at Dounreay. Public Consultation took place in November 2017 regarding the above elements, further consultation will take place in Summer 2018. Orkney Infrastructure Project To facilitate the connection of new renewable generation across Orkney will require the construction of new transmission infrastructure. To provide the most efficient and economical solution for the network we are proposing to connect renewable generators to a central point within the Orkney mainland at our proposed main substation location at Finstown. This will maximise the opportunity for generators across Orkney to connect to the transmission network. The System Operator has accepted several transmission owner construction offers, to connect various renewable generation developments. To unlock the renewable potential inherent in the Orkney Islands, this infrastructure project would need to be undertaken. The aim of the project is to design, construct and install 132kV Transmission infrastructure which will enable access to the electricity network for new generation. The main components of the project are: Construction and installation of 132kV trident wood pole overhead lines and 132kV cables; Installation of 132kV subsea cables; Construction and installation of 132kV substation switchgear at each developer s substation and Finstown substation; and 2 Switching Stations. At a previous Public Consultation in February 2017, SSEN presented initial proposals for potential routes from Orkney to the Scottish mainland and connections within Orkney. Following that Consultation SSEN reviewed the feedback provided and began working on potential routes to connect the new generation on Orkney. The routes being considered are to connect the 132kV infrastructure at the generation developments to Finstown substation. The process for selecting a preferred route is based on identifying as direct a route as possible ensuring it is technically feasible and economic whilst minimizing impacts on the environment. The purpose of this Consultation is to present our proposal for preferred routes from the contracted generation sites to Finstown substation. We welcome the opportunity to listen to your views on all the route options presented as this will aid in the next stage of design. A second Consultation will take place in late summer 2018, our design will be further refined and we will confirm the type of infrastructure to be installed based on further technical and environmental analysis and the feedback considered through this consultation. Following the Consultation in late summer we will begin to prepare our consent applications to the Scottish Government, Orkney Island Council and Marine Scotland as required.
The Routeing Process SHE Transmission s approach to identifying where a new overhead power line is to be located follows the four stages illustrated below. This project is currently at Stage 3 - Route Selection. Each stage in the process is iterative, increasing in detail and resolution to find the best Stage 1 Routeing Strategy Approx Width balance of economic, technical and environmental considerations. This staged process leads to the eventual identification of a proposed alignment to be taken to consent application stage. Corridor Selection 2 km Stage 2 The objective of Stage 3 is to identify a preferred route within the preferred corridor for further appraisal and consultation. Routes are typically between 500m to 1km wide, Stage 3 Route Selection 1 km although they may be narrower / wider in specific locations in response to certain constraints. Stage 4 Alignment Selection 20 m During Stage 3 the engineering, land and environmental teams systematically evaluate a variety of route options. The preferred route is the option considered to present the best opportunity to achieve an economically viable, technically feasible and environmentally Consent Application acceptable alignment for consent application.
Route Selection The selection of potential routes brings together work by three main disciplines: Engineering Team - who identify engineering constraints and where overhead lines and cables can be installed from a construction and operational perspective; Environmental Team who identify key constraints (aspects) along the routes which the new infrastructure could impact upon; and Land Team - who engage with landowners to identify key land use constraints. Identifying Key Environmental Aspects Key environmental aspects are identified through a mixture of desktop assessment and site surveys. Work undertaken to date on the route options has included detailed mapping of all potential corridors and routes and identification of environmental aspects which could constrain the proposed development both physically and in terms of gaining consent. In addition, a suite of environmental surveys has been undertaken to provide additional baseline information, these covered: Landscape and visual walkover survey by landscape architects; Cultural heritage walkover survey by archaeologists; Bird surveys including for wildfowl, raptors, breeding birds and wintering birds; Habitat survey; Otter survey; and Peat survey. The key environmental aspects that have informed the land routeing process include: Views from residential properties; Special Protected Areas (SPA), for birds; Special Areas of Conservation (SAC), for habitat; Sites of Special Scientific Interest (SSSI); Local Nature Conservation Sites; National Scenic Areas; World Heritage Sites; Scheduled Monuments; Listed Buildings; and Peat Here are the key environmental aspects relating to each section of the proposed routes: Considerations in identifying a route - North Section Finstown to Ellibister: Views from residential properties including those at Settiscarth and Harray. Passes over SPA and SSSI and an RSPB reserve. Large numbers of bird flights have been recorded along sections of the route including red throated diver, hen harrier and short eared owl. Sensitive habitats including wet and dry heaths and fens. Views from scheduled monuments including the Knowes of Trotty. Setting of the world heritage sites. Ellibister to Rendall: Views from residential property around Tingwall and along the route. Setting of scheduled monuments including Tingwall broch. Sensitive habitats including wet heath. Ellibister to Costa Head: Views from residential properties evenly distributed along the A966. SPA and SSSI to the west. Large numbers of bird flights have been recorded along sections of the route including red throated diver, great black-backed gull and great skua. Sensitive habitats including wet and dry heaths, fens and blanket bog. Setting of scheduled monuments. Considerations in identifying a route - South Section Finstown to St Mary s (FS): Views from residential properties particularly around Heddle, Scapa, properties along the A961 and east of St Mary s. SPA and SSSI to the south. Setting of the world heritage site and scheduled monuments. St Mary s to South Ronaldsay (SS): Views from residential properties and the presence of an overhead line in the wider landscape on Burray and South Ronaldsay. Bird species associated with the proposed Scapa Flow SPA including great northern, red and black throated diver. Hesta Head to South Ronaldsay (HS): Views from residential properties and the A961. Sensitive habitats including wet heath and marsh. South Ronaldsay to Hoxa Head (SH): Views from residential properties including those around St Margaret s Hope. Sensitive areas including Local Nature Conservation Sites. Rinnigill to Melsetter (RM): Views from Melsetter House and other residential properties along the B9047. Setting of listed buildings and the garden and designed landscape at Melsetter House. Passes through the edge of SPA, SAC and SSSI and large numbers of bird flights including great skua have been recorded. Sensitive habitats including wet and dry heaths, fens and blanket bog. Flotta (F): Views from residential properties and potential for direct and setting impacts on scheduled monuments.
The Preferred Routes - North Section The maps presented show the route option we have considered within the scope of SHE Transmission s currently contracted connection agreements, based on the environmental and engineering assessments carried out. We believe this route, represents the best balance between economic, technical efficiency, constructability and environmental impact. Key considerations are presented below. Finstown to Ellibister (FE) The preferred route is selected to avoid the steeply sloping area to the north of Finstown as it is more difficult to construct a power line on this terrain. The preferred route is also less visible from Finstown. Challenges of the preferred route include passing through an SPA and SSSI, and potential setting impacts on the World Heritage Site and the Knowes of Trotty Scheduled Monument. Ellibister to Rendall (ER) The preferred route is selected as the most direct route between the potential Westray South substation and the Ellibister switching station. Ellibister to Costa Head (EC) The preferred route is selected to avoid direct impacts on designated sites including SPA and SSSI and a RSPB reserve. It is west of most residential properties and reduces the potential for visual impacts on views east from residential properties to the coast.
The Preferred Routes - South Section Finstown to St Mary s (FS) The preferred route is selected as the most direct option and offers a potential alignment avoiding SSSI and SPA and RSPB reserves. Behind St Mary s the route stays higher on the hill to reduce visibility from residential properties in views south towards the coast. St Mary s to South Ronaldsay (SS) The preferred option is a subsea cable between the Mainland and Burray with an overhead line connecting to a switching station on South Ronaldsay. A subsea cable route to the east between the Mainland and Newark Bay is not preferred as this would have to pass over an oil pipeline and communications cables. Hesta Head to South Ronaldsay (HS) The preferred route is selected as the most direct option between the proposed Hesta Head wind farm and a switching station to be located on South Ronaldsay. No alternative was identified. South Ronaldsay to Hoxa Head (SH) The preferred route is selected as the most direct option between a switching station on South Ronaldsay and a proposed subsea cable landfall at Hoxa Head. No alternative was identified. Rinnigill to Melsetter (RM) The preferred route is selected as the most direct option between the proposed subsea cable landfall at Rinnigill and the proposed Brims tidal development. No alternative was identified. Hoxa Head to Rinnigill (HR) The preferred route is a subsea cable connecting Flotta to Rinnigill and Hoxa Head with an overland route on Flotta. On Flotta only one route is identified between subsea cable landfalls at the east and west ends of Flotta. A subsea cable to the south of Flotta is not preferred due to areas of bedrock, strong currents and crossing of the Flotta discharge pipeline.
Marine Once potential land routes have been identified, the selection of potential subsea routes between landing points is driven by the Marine Consenting & Environment Team who carry out desktop assessments and marine surveys to identify: The shape of the seabed; Types of seabed sediment and its depth; Types of species living on the seabed; Protected habitats; Wrecks or debris; MV Strill Explorer, Marine Survey Vessel Existing subsea infrastructure (e.g. pipelines and other cables); Key marine activities (e.g. fishing, anchorages and shipping). This information is used to assess constraints and inform the preferred submarine cable routes and installation methods. Footprint and wreckage in Scapa Flow, from one of the recovered vessels from the German Fleet. Maerl Identifying Key Environmental Aspects The key environmental aspects that have informed the cable routeing process include: Marine Special Protected Areas (SPA); Maritime Scheduled Ancient Monuments War Graves and the remaining wrecks of the German High Seas Fleet; Sensitive marine habitats e.g. Maerl and Horse mussel beds; Existing infrastructure oil pipelines and communications cables; and Marine conditions strong currents and bedrock. HVDC cable bundle ducted over a Horse Mussel bed
Proposed Technology A new substation will be required at each new renewable generation development to facilitate a connection to the new 132kV circuits. These substations will be located in proximity to the new renewable developments and are shown on the overall plan. The equipment at these substations will all be contained within buildings which are designed to look like agricultural sheds. Overhead Line The proposed overhead lines will consist of double Trident wood pole with a steel crossarm, back stays and 3 vertical insulators. The lines will be a single circuit construction made up of three wires (conductors) in a flat formation with an under running non-metallic wire referred to as an All Dielectric Self Supporting cable (ADSS). This carries fibreoptics to allow the circuits to be protected by providing communication between substations. The new overhead line will operate at 132kV. The average height is anticipated to be 14m although depending on the lie of the land to terrain, the height may vary between 14m and 17m. The substation locations have been selected after an appraisal of a range of factors including; ecology, drainage, flood risk, ground conditions, access constraints, connectivity to services, visual amenity and security. Each Renewable Generator is responsible for securing the necessary planning consents for their associated substations. Example - Ardmore Substation, Isle of Skye Example of existing Trident Poles, Isle of Skye Comparison drawing of proposed 132kV Trident Pole against scale of existing 33kV Infrastructure on Orkney Switching Station A switching station is like a substation without transformers and is required where 2 or more overhead line circuits meet and either allows the flow of power to be switched between different circuits or allows one or more circuits to be disconnected. There are 2 proposed switching stations on the project where a T connection is required for a developer onto the main circuit. One station is required near Ellibister, north of Finstown, the other on South Ronaldsay, to the south of St Margaret s Hope. We have identified a search area for these on the maps (green circles) within the preferred routes to avoid the need for additional overhead lines. A site selection process will be undertaken, once our preferred OHL route has been agreed, to identify the best location based on constructability, technical, cost and environmental grounds. There are a few different technical options for these stations which we are currently considering and will consult on at a later date.
Proposed Technology Land Cables Underground cables are referred to as land cables to distinguish from the subsea cable sections. A number of land cable options may be required at points along the route for example at the entrance into substations, where a line passes through environmentally sensitive areas or where it passes through more built up areas. Land cables would generally use an open cut method to install and would be laid 1.2m deep to the top of cable. A construction corridor of around 50m width would be established which will be returned to normal use after installation. Longer cable routes, over 1km, may employ the use of link boxes which will be in the form of buried pits with lids for maintenance access. Cables would terminate at either a substation or onto an Overhead Line terminal structure. Subsea Cables 132kV cable trench being installed to connect Aberdeen Offshore Wind Farm These cables are typically laid on the seabed and subsequently buried in the seabed sediment. This type of cable will be used to connect the islands - between the Orkney Mainland and South Ronaldsay and from South Ronaldsay to Hoy. These cables are specially designed to withstand subsea conditions. The subsea routeing around Orkney is particularly challenging with regards to existing infrastructure and wreckage on the seabed i.e. wrecks, moorings, pipelines etc. There are also other challenges posed by strong currents and extensive bedrock. The cable will be buried in the sea bed or, where this is not possible, surface protection will be used to ensure the safety of other sea users. When laying cables we must adhere to the following: There is a presumption against surface lay of cables without subsequent burial in the marine spatial plan; cables must not pose a risk to other legitimate users of the sea; and cables should be routed around any wrecks or protected / sensitive areas.
Potential future developments We are aware of a number of renewable projects that are seeking to connect to the distribution network owned and operated by Scottish Hydro Electric Power Distribution plc (SHEPD). SHEPD have indicated that these projects are located in-and-around the islands of Eday, Stronsay and Hoy (as illustrated in the geographic on the right). When we have further clarity on these projects we will review and amend our proposed Orkney Infrastructure Project proposals accordingly. Further information in this regard will be provided at our next round of consultation events in Quarter 3, 2018. Project Timeline The key stages of the project development process, and the opportunities for interested parties to provide feedback on the project are as follows Q2 2018 Public Consultation on routing of Orkney Infrastructure Project Public Consultation on Orkney to Dounraey Marine link, proposed cable route and Finstown Substation. Q4 2018 Q1 2019 Section 37 Planning Application for overhead line Switching Station Planning Application Finstown Substation planning application Marine consent applications 2022 Q2 Commissioning Q4 Energisation Q3 2018 Report on Consultation Public Consultation on alignment of Orkney Infrastructure Project Q3 2020 Commence Construction