4.4. Site Selection Process

20. The approach taken with regard to site selection and the definition and refinement of the Array involved the following steps:

• stage 1: Identification of SMP Option Areas and ScotWind Leasing Round;
• stage 2: SMP Option Areas: site assessment and selection of preferred plan option area;
• stage 3: ScotWind Leasing Award and Array site boundary;
• stage 4: Array and PDE - EIA Scoping; and
• stage 5: Array and PDE – EIA and Application.

21. These stages are discussed in sections 4.4.1 to 4.4.5. The Proposed offshore export cable corridor(s) and Proposed onshore transmission infrastructure for Ossian do not form part of this Application due to the ongoing coordination of the offshore grid network and landfall points through the National Grid Holistic Network Design Follow Up Exercise (HNDFUE). Details of these are provided in section 4.5.

4.4.1. Stage 1 – Identification of SMP Option Areas and ScotWind Leasing Round

                        Overview – ScotWind Leasing Round and the SMP

22. In November 2017, Crown Estate Scotland (CES) announced its intention to launch a leasing round for commercial scale offshore wind energy projects within Scottish waters (Scottish Government, 2020a). The SMP for Offshore Wind Energy provided the spatial framework for this leasing round through identification of which areas of seabed could be available for leasing by CES. The development of the SMP for Offshore Wind Energy began in 2018, with Draft Plan Options (DPOs) published in early 2019 which considered the environmental, social and economic information to identify areas best suited for further offshore wind farm development. A plan-level Strategic Environmental Assessment (SEA) and Habitats Regulations Assessment were undertaken to consider offshore wind farm development within the DPOs.
23. The first ScotWind Leasing Round was subsequently launched by CES in June 2020. In the ScotWind Leasing Round, developers were able to apply for the rights to build offshore wind farms in Scottish waters within specified lease areas initially based upon the DPOs as per the SMP and subject to gaining the required consents ( Figure 4.1   Open ▸ ). The final PO Areas were published in October 2020.
24. In November 2020, the Applicant announced that they were in the process of preparing bids for PO Areas offered as part of the ScotWind Leasing Round (SSER, 2020).
25. Based on the lease areas put forward as part of the ScotWind Leasing Round, it was expected that up to 10 GW of new generating capacity would be built over the following ten years[1]. The application window for registered applicants opened in January 2021 and closed in July 2021, with Option to Lease Agreements offered in January 2022.

                        SMP – identification and development of Plan Option Areas

26. The SMP for Offshore Wind Energy was published by the Scottish Government in October 2020. The SMP outlines a spatial strategy for commercial scale offshore wind development in Scotland and provides a strategic framework for the ScotWind Leasing Round (Scottish Government, 2020a) through the identification of 15 final PO Areas across four regions (West (W), North (N), North East (NE) and East (E)) for renewable energy generation.
27. An iterative process was followed to develop these final PO Areas. Firstly, initial Areas of Search (AoS) were identified and subsequently refined through two iterations of Opportunity and Constraint Analysis.
28. The first iteration of Opportunity and Constraints Analysis, published as part of the AoS Scoping Report in 2018, built upon work undertaken by Marine Directorate – Science Evidence, Data and Digital (MD-SEDD; formerly Marine Scotland Science (MSS)) in 2011, and draft Regional Locational Guidance for potential deep water floating offshore wind test sites in 2014 (Scottish Government, 2018). The aim of this first iteration was to develop broad AoS which could be viable for offshore wind development and serve as a starting point in the development of PO Areas (Scottish Government, 2018). Broad AoS were identified using multi-criteria analysis which brought together multiple geospatial data layers depicting opportunity (e.g. average wind speed, existing grid connections) and constraint (e.g. commercial fishing activity, shipping activity, environmental sensitivities) into spatial analysis software which combined these geospatial data layers in to one map. Each spatial dataset was standardised in terms of resolution (grid cell size), spatial extent and classifications (high, medium or low level of constraint), and then given a “weight” value to determine the influence the data will have in the resulting output. The resulting map showed areas around Scotland where there was both available wind resource and lower levels of spatial constraint. Following this, spatial datasets showing where no development should occur (e.g. in areas where there is existing oil and gas infrastructure) were combined to produce a separate ‘exclusion’ dataset which was used to remove areas from the multi-criteria analysis output.
29. This process resulted in the production of a map showing broad AoS, showing varying degrees of constraint with higher levels of constraint typically located closer to shore and lower levels of constraint typically located further offshore. From this map, six broad AoS were identified. A refinement process was then carried out which considered the spatial extent of single issue activities which included individual species fishing activity, combined shipping routes and marine nature protection designations. This resulted in 24 distinct AoS within the six broad AoS identified which were taken forward into the planning process of the SMP (Scottish Government, 2018).
30. The second iteration of Opportunity and Constraints Analysis took in to account specific spatial issues and feedback raised at sectoral engagement workshops held in spring 2018 to further refine the AoS. The draft SMP is technology neutral, therefore, no commercial or technology specific information fed into this refinement process (Scottish Government, 2020a).
31. In June and July 2018, Scottish Ministers consulted on the screening and scoping stages of the SMP. Following this, a third iteration of Opportunity and Constraints Analysis was undertaken to consider stakeholder responses received during Scoping consultation. Certain AoS were either removed or refined to avoid or incorporate certain areas of Scottish waters. Areas of seabed which were proposed by stakeholders via the Scoping consultation were also considered. Although a number of the areas proposed by stakeholders overlapped with existing AoS, some overlapped with areas with higher levels of constraint and some areas proposed were completely new areas. Following the review of this information, a number of areas were identified to move forward in the plan process, including some additional areas where there was significant stakeholder interest but also increased constraint (Scottish Government, 2020a).
32. Following the third iteration of Opportunity and Constraints Analysis, 22 revised AoS were brought forward to the SMP Project Board and Project Steering Groups for consideration and comment. Scottish Ministers then reviewed these, resulting in the selection of 17 revised AoS as DPOs (Scottish Government, 2020a).
33. The DPOs were subject to a Sustainability Appraisal process, comprising a Strategic Environmental Assessment (SEA), Habitats Regulations Appraisal (HRA) and Social and Economic Impact Assessment (SEIA), which examined cross-sectoral impacts of the DPOs to support sustainable development of renewable energy generation in Scottish waters. The Sustainability Appraisal was undertaken on a technology neutral basis, and the impacts of individual DPOs were assessed using a realistic maximum deployment scenario (in GW) for each DPO, equating to a proportion of the overall area of the DPO. The potential impacts were assessed at regional and national levels and used a range of deployment scenarios in order to assess a wide range of impacts.
34. The SEA provided broad recommendations on the DPOs from a strategic perspective and identified potential strategic environmental constraints to steer future development. The SEIA considered the adverse and beneficial socio-economic impacts of the SMP on a range of sectors. Whilst it concluded that the DPOs were likely to have an adverse impact on commercial fisheries, commercial shipping, tourism and recreation sectors, as well as other sectors such as defence and aviation, possible project level mitigation measures were identified, including “adherence to Maritime and Coastguard Agency guidance regarding shipping lanes, spatial planning within DPOs to avoid areas of higher fishing activity, maintaining access to recreational fishing grounds within arrays or reduction in turbine sizes to minimise landscape, seascape and visual impacts” (Scottish Government, 2020a). The SMP also took in to account the findings of draft partial Islands Communities Impact and Equalities Impact Assessments, however, no additional impacts for consideration were identified from the comments received on these draft partial assessments (Scottish Government, 2020a).
35. The HRA was undertaken as it was identified that the possibility of likely significant effects on European site(s) from the SMP could not be excluded, either due to development within an individual DPO or in combination with other plans or projects (Scottish Government, 2020a). The HRA considered Special Areas of Conservation (SACs), candidate and possible SAC (cSACs and pSACs), Special Protected Areas (SPAs), proposed SPA (pSPAs), Sites of Community Importance (SCIs) and Ramsar sites (listed under the Ramsar Convention on Wetlands of International Importance), to identify sites where there is a potential for likely significant effects. A total of 468 European/Ramsar sites were identified within a 100 km screening buffer around the DPOs. An Appropriate Assessment was undertaken to determine whether there would be an adverse effect on integrity (AEOI) on any of the sites with reference to their conservation objectives (Scottish Government, 2019). It was concluded that development of offshore wind farm projects at DPOs E3, NE2, NE3, NE4, and NE5 could lead to an AEOI due to in-combination effects with other wind farm projects. The possibility that an AEOI from in-combination effects could also occur with other wind farm projects (including those already consented within the Moray region) if development at NE6 were to occur was also noted due to the increased risk to Kittiwake as a qualifying feature of the Troup, Pennan and Lion’s Heads SPA, however, this would be dependent upon NE4 and NE5 also being developed (Scottish Government, 2019). The findings of the HRA have advised plan level and project level mitigation measures to avoid potential adverse impacts on site integrity. Plan level mitigation included classification of E3, NE2, NE3, NE4, NE5 and NE6 as being subject to high levels of ornithological constraint and development of these DPOs could only progress if sufficient scientific evidence could be provided to reduce the risk to an acceptable level (unless it can be determined that there are imperative reasons of overriding public interest that require development to proceed). In addition, project level mitigation for DPOs E1 and E2 was put forward, noting that regional level surveys should be carried out to address knowledge gaps regarding potential impacts arising from development of these DPOs (Scottish Government, 2020a; Scottish Government, 2019). 
36. Statutory consultation was held between 18 December 2019 and 25 March 2020 to seek feedback on the DPOs. A Consultation Analysis Report was produced to inform the Scottish Ministers’ decision on which DPOs to progress (Scottish Government, 2020b), following which, the SMP was published which identified the refined, final PO Areas (Scottish Government, 2020a). Of the 17 DPOs, 15 final PO Areas were identified ( Figure 4.1   Open ▸ ).
37. Within the SMP, it was noted that depending upon the final PO Areas developed, there was potential for regional cumulative impacts on bird populations, benthic habitats, cetaceans, navigational safety, seascape/landscape and commercial fisheries across the four regions. The SMP provides several mitigation measures regarding potential impacts at various scales (Scottish Government, 2020a).
38. The SMP was developed in accordance with the aims of the National Marine Plan (NMP) (Scottish Government, 2015) and sits alongside the Scottish Offshore Wind Energy Policy Statement (OWEPS) (Scottish Government, 2020c) to build a framework towards Scotland’s sustainable green recovery.
39. It should be noted that the SMP is subject to an iterative review process to ensure that the SMP and its underpinning assessments are informed by the most up-to-date scientific research and understanding, the spatial/regional context of the SMP (i.e. level of construction, operational and other activity within the region) and the potential transboundary impacts are reflected accurately, and the prevailing market conditions, technological advancements and regulatory environment are reflected in the SMP, including grid connections and connections to coastal infrastructure. To support this iterative review process, requests for new evidence which could impact the implementation of the SMP and resulting development will be submitted to key stakeholder representatives, who form part of the Sectoral Evidence Group, on at least an annual basis. The iterative review of the SMP is expected to take place every two years following adoption (Scottish Government, 2020a). At the time of writing, the iterative review process is currently ongoing, therefore, the information provided within this chapter is based upon the SMP published by the Scottish Government in 2020 (Scottish Government, 2020a).
40. The final PO Areas of the SMP and the identified strategic constraints were given due consideration as part of the Applicant’s preliminary SMP PO Area site assessment and down selection process. Whilst the identification of SMP PO Areas does not pre-determine the decision-making process, it aims to identify sustainable options for commercial scale offshore wind energy and provides a spatial strategy to inform the seabed leasing process (Scottish Government, 2020a).
41. Whilst the SMP does not specify the type of technology for PO Areas, it aims to identify opportunities for offshore wind development within PO Areas in a range of water depths, where deeper water wind technologies such as floating wind turbines could be investigated. This has influenced the consideration of alternative technology options as part of the development of the Array.

Figure 4.1: Sectoral Marine Plan Option Areas

4.4.2. Stage 2 – SMP Option Areas: Site Assessment and Selection of Preferred Plan Option Areas

                        Joint Venture site identification and selection

42. The Applicant completed a site assessment to understand risk and constraints of all 15 of the final PO Areas included in the ScotWind Leasing Round. This process was supported by Renewables Consulting Group (RCG) to down select sites to bid for as part of the ScotWind Leasing Round, as set out in the Scotland Offshore Wind Development: Site Identification and Selection Report. Constraints mapping underpinned the preliminary site assessment of the 15 PO Areas which was divided into phases comprising of:

• Phase 1 – initial site identification including technical and environmental constraints mapping and initial LCoE modelling at a DPO level focusing on potential floating sites; and
• Phase 2(A-C) – site refinement and down selection, included further technical and environmental constraints mapping to determine the most preferential boundaries for project sites.

43. The assessment considered alternative technology options at a preliminary level, with a specific focus on floating foundations whilst also considering sites suitable for fixed and ‘hybrid’ solutions.

                        Phase 1

44. A constraints screening exercise was undertaken, involving the mapping of wind resource, environmental and engineering constraints in GIS to identify potential development areas, resulting in 27 potential development areas being identified. Following identification of these 27 potential development areas, a red-amber-green (RAG) scoring system was used to assess and score key risks for each area.
45. The draft revised AoS were published in early 2019 as part of the SMP process. RCG undertook a detailed analysis of the 22 draft revised AoS to understand initial characteristics, environmental and engineering constraints, development potential, and risks present at each. No AoS were excluded at this stage (RCG, 2020).

                        Phase 2A: assessment of Draft Plan Options (floating)

46. Phase 2A was based upon the 17 DPOs published as part of the SMP process. In phase 2A, a RAG assessment was undertaken which built upon the high-level RAG assessment conducted in Phase 1. Each constraint or topic was assigned a RAG rating in accordance with defined assessment criteria and based on consenting risk, the requirement for non-standard technology and mitigations, and foreseeable design and construction challenges (RCG, 2020). This phase allowed for initial identification of sites which may be more suitable for floating technologies due to water depths. The RAG assessment found that all DPOs could be considered ‘good’ areas from an environmental and consenting point of view, however, it was considered that there may be engineering and commercial challenges for DPOs in the North (N) and West (W) regions due to the anticipated seabed and metocean conditions and the proximity to potential grid network connection locations. In addition, DPOs NE2-NE5 were identified as less suitable due to the potential for cumulative impacts (RCG, 2020). The LCoE Assessment found that the East (E) region sites were more favourable, with DPOs E1 East (E1E), E3, and E1 West (E1W) ranking within the top four DPOs based on LCoE (RCG, 2020).

                        Phase 2B: initial site identification and first selection of preferred site boundaries

47. Sites were identified within each DPO with consideration given to a number of principles to guide defining site boundaries, including capacity considerations, bathymetry considerations, avoidance of overlap with environmental designations and other environmental and human constraints and users of the sea, as far as practicable, and minimum distance to shore and port infrastructure (RCG, 2020).
48. For each site, RCG presented a site summary (including information covering site boundary and area, indicative capacity and primary foundation type (i.e. fixed or floating foundations, or a hybrid solution based on water depth)). Water depth was a key consideration in determining the most suitable foundation type with approximately 70 m considered the upper limit of installation of fixed foundations when considering the commercial and technical feasibility. Beyond this depth it was considered that there was significant technical risk to deployment of fixed solutions. Monopiles and gravity-based solutions were discounted from further consideration due to fabrication limitations and high volumes of material required for deployment in deep water, respectively. Jacket foundations were considered most suitable for deep water deployment; however, these were discounted following engagement with transportation and installation contractors who noted that there was significant technical risk in installing jackets onto pin piles in depths around 70 m. Therefore, where average depths exceeded 70 m within an identified project area, floating foundations were identified as the preferred solution. Other site conditions taken into account in developing appropriate site boundaries included ground conditions, bathymetry and metocean, human constraints (including shipping and navigation, commercial fisheries, seascape and visual, aviation and military, unexploded ordnance (UXO), oil and gas blocks and infrastructure, cables and pipelines and other wind energy projects), environmental constraints (including ornithology, marine mammals, benthic ecology and archaeology and cultural heritage), potential for expansion, grid connection points, and export cable route options. This informed the down selection process and resulted in 15 sites across 12 DPOs being taken forward to the next phase.

                        Phase 2C: LCoE analysis, site refinement and second down selection

49. The second down selection aimed to identify the sites to be taken forward in to the ScotWind Leasing Round. The Applicant selected a total of eight sites to be taken forward to the next stage based upon environmental constraints and technical feasibility, and LCoE analysis as described above, and consisted of six fixed foundation (those with an average depth of less than 70 m) and two floating foundation sites (those with an average depth in exceedance of 70 m).

                        ScotWind Leasing Round: final selection of sites for bid

50. Following review of the DPOs and selected sites further work was undertaken by the Applicant to narrow their site selection further using the guidelines set out in the CES ScotWind Leasing documents (CES, 2021). Four sites were identified within three DPOs which included the E1 DPO. Two specific sites were defined within the E1 DPO taking in to account a detailed environmental constraints analysis within the wider E1 DPO Area.
51. As discussed in paragraph 23, the ScotWind Leasing Round was launched in June 2020 and the final PO Areas available for application were released in October 2020. At this stage, the Applicant proceeded to bid for one of these specified sites within the E1 PO Area, referred to as ‘E1 East’. ( Figure 4.2   Open ▸ ). The sections that follow (paragraphs 52 to 80) detail the constraints analysis for the E1 PO Area and the project concept put forward as part of the Applicant’s ScotWind Leasing Round bid.

Figure 4.2: E1 East Site Boundary Located Within the E1 PO Area

4.4.3. Stage 3 – ScotWind Leasing Award and Array Site Boundary

                        Overview of constraints analysis

52. The Applicant undertook a detailed review of a number of parameters and constraints within the E1 PO Area (SSER, Marubeni and CIP, 2021b) including:

• water depth and distance to shore;
• wind speed and metocean conditions;
• offshore geotechnical conditions;
• offshore environmental designations (existing and proposed) including SPAs, Ramsar sites, Sites of Special Scientific Interest (SSSIs), SACs and Nature Conservation Marine Protected Areas (NCMPAs);
• ornithology;
• offshore habitats;
• benthic ecology, including epifauna and infauna;
• fish and shellfish ecology;
• marine mammals including cetaceans and seals;
• shipping and navigation
• commercial fishing activity;
• seascape and landscape;
• archaeology and cultural heritage;
• aviation and radar, including civil and military aspects;
• existing infrastructure and oil and gas leases;
• energy generation;
• emergency services, including search and rescue (SAR) operations; and
• cables and pipelines.

53. Baseline data from Berwick Bank and Seagreen 1 (formerly known as Seagreen Alpha and Seagreen Bravo) Offshore Wind Farm projects, and Seagreen 1A Project including metocean, climatic and ornithology baseline data, were considered in the assessment process.
54. According to the SMP, the key environmental constraints within the East Region are:

• risks to bird species (including collision risk, displacement and impacts to birds on migratory pathways);
• potential impacts to marine mammal receptors;
• potential impacts to benthic habitat and species;
• potential impacts to migratory fish species;
• potential cost impacts and navigational risk through diversion of key commercial shipping routes; and
• potential impacts on commercial fishing (Scottish Government, 2020a).

55. Specifically within the E1 PO Area, key environmental concerns included minor[2] socio-economic impacts to commercial shipping, commercial fishing, power interconnector sectors, and Ministry of Defence (MOD) radar interference, as well as impacts to ecological receptors (Scottish Government, 2020a).
56. With regard to mitigation of impacts, the SMP noted that the socio-economic impacts to commercial shipping, fishing and power interconnector sectors would need to be considered at a project level, and consultation with the MOD would be required regarding radar interference. It was recommended that impacts to fish spawning would also have to be considered and mitigated at a project level. Due to the concerns of potential in-combination impacts on bird populations, the SMP noted that regional survey effort and consultation would be required.
57. To further understand the potential constraints associated with the E1 PO Area, the Applicant carried out several studies and analyses to inform the bid for the ScotWind Leasing Round.

                        Metocean conditions, wind climate and wind yield

58. Desk based analysis was undertaken to understand the metocean conditions within the E1 PO Area. The Applicant also assessed the wind and climatic conditions within the E1 PO Area to understand site suitability and project feasibility (SSER, Marubeni and CIP, 2021b).
59. The metocean climate conditions within the E1 PO Area were characterised through two long term modelled metocean datasets (ERA5 and MOW) and validated against metocean data collected from wave buoys deployed at the Seagreen 1 Offshore Wind Farm and Seageen 1A Project (SSER, Marubeni and CIP, 2021b). The ERA5 regional model provided over 40 years of hourly metocean and atmospheric data, and a model produced by meteorology and oceanology specialists MetOcean Works (MOW) which provided 41 years of wave, current and water level data specific to the E1 East site boundary. The validation exercise between these models and the collected data from metocean sensors (wave, currents, etc) deployed at the Seagreen 1 and Berwick Bank Offshore Wind Farm projects showed that the ERA5 data demonstrated good agreement with normal metocean conditions and could be used to inform the PDE. The Applicant used the MOW model to characterise extreme metocean conditions within the E1 East site boundary. The analysis of the validated data showed that the metocean conditions were not expected to vary across the E1 PO Area, therefore, this did not influence site boundary refinement. Although it was identified that the metocean climate was harsher within the E1 PO Area in comparison to other areas which have been subject of offshore wind development, the Applicant considered that the foundation design, installation modelling, and operations modelling based on site-specific conditions have demonstrated the feasibility of designing, constructing, and operating a floating offshore wind farm within the E1 PO Area (SSER, Marubeni and CIP, 2021b). The Applicant also has experience of challenging metocean conditions at their Seagreen 1 and Dogger Bank B Offshore Wind Farm projects which have comparable extreme wave and climate conditions to the E1 PO Area, therefore, their knowledge and ability to overcome these challenges provided a good opportunity to develop within the E1 PO Area (SSER, Marubeni and CIP, 2021b).
60. The Applicant characterised the wind climate conditions within the E1 PO Area using a long term bespoke model produced by MOW, and data from two FLiDAR buoys located in the centre of the Seagreen 1 and Berwick Bank Offshore Wind Farm project sites which measured wind speed and direction at heights between 30 m and 300 m mean sea level (MSL) (SSER, Marubeni and CIP, 2021b). The review of this data provided the Applicant with confidence and robust insight into the wind resource at the E1 East site boundary and allowed the Applicant to make informed decisions regarding layout design and optimal array alignment reflective of the wind directional distribution and wind turbine suitability. In addition, the FLiDAR data provided an understanding of the wind climate across the full rotor diameter, which provided an appreciation of site characteristics and determination of wind turbine suitability.
61. The Applicant assessed site suitability of the E1 PO Area against the International Electrotechnical Commission (IEC) 61400-1 standard and the wind conditions dataset described in paragraph 60. It was found that all climatic and extreme wind parameters were within the IEC 61400-1 criteria for a Class IC Wind Turbine Generator except for the mean wind speed which was recorded as 11.37 m/s. This mean wind speed exceeds the IEC Class I value of 10.0 m/s, however, this was not expected to have implications on wind turbine suitability or project feasibility[3].

                        Geotechnical conditions

62. The Applicant commissioned Atkins to carry out a desktop geological and foundations feasibility assessment of the E1 PO Area (Atkins, 2020). This study found that water depths within the E1 PO Area ranged from 60 m to 154 m lowest astronomical tide (LAT), with an average water depth of 73 m LAT. It was concluded that these water depths were suitable for the siting of a floating offshore wind farm but was also shallow enough to accommodate limited fixed bottom foundations. These locations were considered suitable to accommodate Offshore Substation Platforms (OSPs) (Atkins, 2020). (SSER, Marubeni and CIP, 2021b).
63. The Quaternary geology of the E1 PO Area was found to comprise the Marr Bank Formation characterised by sands and pebbles, the Forth Formation characterised by sands, clays and gravels, and the Coal Pit Formation characterised by sands, pebbles and over consolidated clays (Atkins, 2020; SSER, Marubeni and CIP, 2021b). Based on the understanding of the geotechnical conditions at this stage optionality was retained at this stage for a range anchor systems or cables. The site was considered to be suitable for development utilising a range of potential technologies. The Applicant also undertook further work to reprocess, repurpose and interpret historical oil and gas seismic data which improved understanding of geohazards within the E1 PO Area (SSER, Marubeni and CIP, 2021b).

                        Environmental constraints

64. The E1 PO Area is primarily comprised of sandy sediments and does not overlap with any SACs or NCMPAs designated for benthic habitats or species. Although the SMP notes that Ross worm Sabellaria spinulosa (which form Annex I reefs) and ocean quahog Arctica islandica (a Priority Marine Feature (PMF) and listed as a threatened or declining species under the OSPAR Convention) have been recorded within the East region, there is generally limited diversity in the benthic species present in the East region. Therefore, benthic features did not appear to pose a significant constraint within the E1 PO Area (SSER, Marubeni and CIP, 2021b).
65. A spawning analysis study, carried out by Brown and May Marine Ltd (Brown and May Marine Ltd., 2021), indicated that the E1 PO Area overlaps spawning grounds for several fish species. The Applicant’s involvement in several research projects considering the footprint of floating wind turbines will further guide decisions on anchoring solutions and placement of infrastructure on the seabed. Considering these factors, the Applicant determined that potential impacts on fish species were limited and did not impact project feasibility or site suitability within the E1 PO Area (SSER, Marubeni and CIP, 2021b).
66. Marine mammal species are known to be present within the E1 PO Area, either seasonally or year-round. Occasional or seasonal marine mammal species are known or suspected to be present within E1 PO Area in lower densities (SSER, Marubeni and CIP, 2021b). The Applicant noted that mitigation measures with regard to the floating technologies implemented would be further investigated following award to ensure that impacts to marine mammals were reduced as far as practicable (SSER, Marubeni and CIP, 2021b).
67. The E1 PO Area is situated in an area of relatively low seabird density and away from seabird hotspots in the East region during both breeding and non-breeding seasons. The E1 PO Area is located within the foraging range of SPAs for limited key East region species, and its distance from shore further reduces ornithology constraints. Within the SMP, it was noted that the E1 PO Area would be subject to plan-level ornithological mitigation measures (see paragraph 35) which required Regional Digital Aerial Surveys (DAS). The Applicant commissioned both site-specific and regional DAS surveys prior to the conclusion of the ScotWind Leasing Round and the successful award of the development rights to the E1 East area to the Applicant. Regional DAS surveys were carried out for a period of 18 months in agreement with Marine Directorate – Licensing and Operations Team (MD-LOT) and the data has been provided to the Offshore Wind Directorate to inform the iterative review process for the SMP. Site-specific DAS surveys commenced prior to award to help inform a robust consent application as quickly as possible.
68. The E1 PO Area does not overlap with any existing or proposed designated sites, therefore, this had no impact on site suitability or project viability. The E1 PO Area is located 40 km from the Firth of Forth Banks Complex NCMPA (designated for ocean quahog aggregations, offshore subtidal sands and gravels, shelf banks and mounds and moraines) and 115 km north-east of the Berwickshire and North Northumberland Coast SAC (designated for grey seal), therefore, any interaction between the E1 PO Area and designated sites is considered to be negligible.
69. Due to the key environmental, shipping, fishing and aviation constraints identified in the SMP, the Applicant also commissioned several studies pre-ScotWind Leasing Round award to gain an early understanding of the potential risks to human receptors within the E1 PO Area and to inform the site boundary, as follows:

• a shipping activity and constraints study, carried out by Anatec Ltd (Anatec Ltd., 2021);
• a fishing intensity and spawning analysis study, carried out by Brown and May Marine Ltd (Brown and May Marine Ltd., 2021); and
• an aviation and military activity study, carried out by Coleman Aviation.

70. The findings of these studies have been given due consideration as part of the optimisation and refinement of the E1 PO Area to develop the E1 East site boundary.
71. Anatec undertook an assessment of Automatic Identification System (AIS) data to identify risk of impacts to vessel transit routes. The study concluded that the western half of the E1 PO Area was of greater risk to shipping, whereas the eastern half of the E1 PO Area was identified as having low to medium risk to shipping (Anatec Ltd., 2021).
72. As part of the optimisation of the E1 East site boundary, Brown and May Marine Ltd. were commissioned to undertake a desk based review of the commercial fishing activity within the E1 PO Area. Commercial fishing activity within the E1 PO Area was concluded to be negligible to very low fishing activity in the western section, increasing to low to moderate activity towards the eastern boundary of the E1 PO Area. In terms of commercial fishing constraints, consideration has been given to the areas identified by the Scottish Fishermen’s Federation (SFF) and Scottish White Fish Producers Association (SWFPA) as preferred for development ( Figure 4.3   Open ▸ ) and as a result the site boundary overlaps with three of these areas. The E1 East site boundary was therefore selected to reduce interaction with commercial fishing activity and reduce the risk of any exclusion from key fishing grounds.
73. The E1 PO Area is situated in relatively complex airspace within range of both Air Traffic Control (ATC) and military air defence aviation radars. It is also in close proximity to Helicopter Main Routes (HMRs) used for transiting between Aberdeen Airport and North Sea oil and gas installations. The E1 PO Area falls within the radii of action of numerous UK SAR helicopters, the closest of which is located at Inverness Airport.
74. The Applicant also undertook a desktop study of other infrastructure in the area, including oil and gas, cables and pipelines and energy generation (SSER, Marubeni and CIP, 2021b). The E1 PO Area overlaps the Eastern Green Link (EGL) 2 High Voltage Direct Current (HVDC) bootstrap (Peterhead to Teesside) to the west as well as several currently licenced oil and gas blocks (SSER, Marubeni and CIP, 2021b).
75. Taking these receptors into consideration allowed the Applicant to determine the preferred areas for the development of an offshore wind farm within the E1 PO Area.

Figure 4.3   Open ▸ : Scottish Fishermen’s Federation (SFF) Preferred Areas in the Vicinity of the E1 East Site Boundary (Scottish Government, 2023)

                        Project concept

76. The constraints analysis detailed above also led to the selection of the Preferred Project Concept (PPC) put forward by the Applicant at the bid stage of the ScotWind Leasing Round. The PPC was a floating offshore wind farm located within the E1 PO Area with a proposed capacity of 2.6 GW (SSER, Marubeni and CIP, 2021b). Preliminary wind turbine selection and foundation types were put forward as part of the ScotWind Leasing Round bid for the E1 PO Area, the parameters of which are described below.
77. Water depth was considered a key driver for the selection of floating technology as the preferred solution for wind turbine generators. Use of fixed foundation solutions for the wind turbines was excluded within the PCC based on the difficulties in installing fixed wind turbines in water depths greater than 70 m. Due to the limited areas of shallow depth that could accommodate fixed foundations the Applicant aimed to deploy a floating foundation solution across the entire site. A floating solution across the site supports streamlined engineering and technical approaches, is more efficient from a cost perspective and helps to ensure eligibility for a single and more competitive floating CfD pot.
78. Floating wind turbine foundations were considered suitable for deployment across the entirety of the depth ranges noted across the full E1 East site boundary. It was considered that a semi-submersible concept was most appropriate, based on the seabed (see paragraph 63) and metocean conditions (SSER, Marubeni and CIP, 2021b). Semi-submersible floating foundations are more stable in high sea states and are the most suitable concept for shallower ports (like those that are found along the Scottish coastline) (SSER, Marubeni and CIP, 2021c). They are also more resilient in severe metocean conditions. Therefore, it was indicated that floating semi-submersible substructures would be suitable with wind turbines even under extreme conditions (SSER, Marubeni and CIP, 2021b). A range of mooring and anchoring systems could be employed within the E1 East site boundary with mooring system most likely to consist of chains or synthetic line, and various anchoring options dependant on seabed conditions (SSER, Marubeni and CIP, 2021c).
79. The preferred site boundary and indicative offshore layout of the PPC took into account areas of optimum water depth for use of floating foundation concepts, whilst also providing suitable buffers to ecological, offshore ornithology, and commercial fishing constraints in the north-west (SSER, Marubeni and CIP, 2021c).
80. The base case for OSPs assumed that they would be installed on fixed foundations which would be located in the shallower areas of the site to address the complexities in having multiple dynamic inter-array and interconnector cables converging at a floating OSP. High numbers of dynamic inter-array and interconnector cables converging at floating OSPs can present technical difficulties to the cables due to movement of the OSPs which can increase cable wear, reduce operational life and has implications on accessing platforms during construction and O&M. However, the potential for floating OSPs was retained within the PDE for Scoping to account for any technological developments that reduced this complexity. It was anticipated that High Voltage Alternating Current (HVAC)/HVDC OSPs would be utilised, and unmanned OSPs would be considered. Unmanned OSPs have shown significant reduction in weight per megawatt through removal of living quarters, helideck, and sewage system, and ultimately results in lower costs for UK electricity consumers (SSER, Marubeni and CIP, 2021c) which aligns with Ossian’s objectives outlined in Table 4.1   Open ▸ . Dynamic inter-array cables were proposed at this stage to connect wind turbines to each other and to the OSPs (SSER, Marubeni and CIP, 2021c).
81. In January 2022, the Applicant was awarded an Option to Lease Agreement for the E1 East site boundary. This area was derived following the aforementioned constraints assessments which balanced technology, consenting and commercial feasibility factors. At this stage, a degree of flexibility was maintained for the site design to be moulded towards the optimum configuration once detailed site work, such as geotechnical surveys and ornithological studies, have been completed.
82. In August 2022, the Applicant announced that the E1 East floating offshore wind farm was to be renamed ‘Ossian’; the site boundary remained unchanged.

4.4.4. Stage 4 – Array and Project Design Envelope for EIA Scoping

83. Following award of the Option to Lease Agreement, the Applicant developed the PDE for the Array EIA Scoping Report. The PDE built upon the PPC put forward within the ScotWind Leasing Round bid (see section 4.4.2, paragraphs 76 to 80).
84. In developing the PDE, several options and parameters were evaluated with respect to the floating wind turbines and their mooring and anchoring systems, OSPs, inter-array cables, interconnector cables and scour and cable protection. The options considered and the process followed in defining the PDE for Scoping is discussed in this section.
85. To define the PDE for Scoping, the Applicant’s engineering teams built upon the PPC developed at the bid stage, and undertook further studies and analyses to refine project parameters. Due to previous site condition assessments, the PDE parameters were based upon deployment of floating turbine technology and fixed bottom OSPs due to the depth range across the Array. In addition, the results of site-specific surveys informed the PDE for Scoping. These studies included the following:

• deployment of metocean buoys and FliDAR buoys within the Array in August 2022;
• DAS across the Array plus an 8 km buffer collecting ornithological and marine mammal data. This was undertaken between February 2021 and February 2023;
• geophysical survey undertaken across the Array between March and July 2022; and
• benthic surveys undertaken across the Array between March and July 2022.

86. Compared to the initial PPC defined at the bid stage (see section 4.4.2, paragraphs 76 to 80), further studies resulted in an increase in capacity from 2.6 GW to 3.6 GW. Site-specific geophysical surveys conducted across the Array provided greater detail on the site bathymetry and seabed conditions which indicated that there was a greater area of favourable ground conditions for turbine installation that could support an increased capacity. This information was provided to MD-LOT as part of the Call for Evidence to inform the SMP iterative review process. In addition, the number of wind turbines also increased (from 145 to 240). This was a direct result of the increased potential capacity of the Array, allowing more wind turbines to be installed to meet this increased capacity and to maximise the energy generated within the Array. The inclusion of the potential option for larger wind turbines also resulted in increased upper blade tip height, rotor diameter and hub height in comparison to the PPC to ensure that Ossian could take advantage of any future technological developments and efficiencies. The number of OSPs increased from three to six to accommodate the increased capacity.
87. In November 2022, the Applicant engaged with statutory consultees prior to submission of the Array EIA Scoping Report and Array HRA Likely Significant Effects (LSE2) Screening Report to provide a project update and the initial conclusions drawn for key biological and human topics, and to seek feedback and agreement on impacts to be scoped in and out of the topic assessments. Statutory consultees engaged at these pre-Scoping Workshops included MD-LOT, MD-SEDD, NatureScot, Royal Society for the Protection of Birds (RSPB), Maritime and Coastguard Agency (MCA), Northern Lighthouse Board (NLB), SFF, SWFPA and North and East Coast Regional Inshore Fisheries Group (NECRIFG).
88. The Applicant presented the draft EIA Scoping PDE, with the main PDE parameters presented at these pre-Scoping Workshops as follows:

• floating offshore wind farm with up to 3.6 GW capacity;
• installation of up to 240 wind turbines with floating foundations;
• maximum blade tip height of 375 m above LAT;
• maximum rotor diameter of 330 m above LAT;
• maximum hub height of 210 m above LAT;
• consideration of a range of mooring systems; and
• installation of up to six OSPs with fixed foundations (base case) or floating foundations (potential option).

89. The updated PDE parameters were presented during the pre-Scoping workshops with stakeholders. No concerns were raised by any of the statutory consultees with regard to the PDE for EIA Scoping during the pre-Scoping Workshops or within the finalised meeting minutes. Representatives from the SWFPA shared support for the increased total capacity, noting that it would be better for commercial fisheries if the greatest output can be generated from the smallest footprint.
90. Following the pre-Scoping Workshops, further refinement of the EIA Scoping PDE was undertaken. Revised parameters presented in the Array EIA Scoping Report were as follows:

• increase in maximum number of wind turbines: up to 270 wind turbines proposed;
• increase in maximum upper blade tip height: up to 399 m above LAT;
• increase in maximum hub height: up to 224 m above LAT; and
• increase in maximum rotor diameter: up to 350 m.

91. Table 4.3   Open ▸ presented the evolution of key PDE parameters from the initial PPC to what was presented within the Array EIA Scoping Report.

Table 4.3: Evolution of Key PDE Parameters from ScotWind Bid Phase PPC to Array EIA Scoping Report

92. These updated wind turbine parameters accounted for the current commercially available technology and anticipated available technology during the latter stages of construction.
93. The Array EIA Scoping Report and Array HRA LSE2 Screening Report were submitted by the Applicant to the Scottish Ministers in March 2023 (Ossian OWFL, 2023).

4.4.5. Stage 5 – Array and Project Design Envelope for Environmental Impact Assessment

94. Following submission of the Array EIA Scoping Report in March 2023, the Applicant refined the PDE to identify sufficient detail to undertake a robust EIA. The key refinements made to the PDE from the Array EIA Scoping Report to this Array EIA Report are summarised in Table 4.4   Open ▸ and have been informed by early engineering works and consultation with stakeholders. In addition to stakeholder consultation, the Applicant held internal workshops to develop and inform the EIA PDE with representatives from the engineering and consenting teams to ensure proportionate and realistic parameters have been set whilst considering environmental, consenting and engineering constraints.

Table 4.4: Overview of PDE Refinements for the Array

                        Anchoring solutions

95. Limited geotechnical investigations, comprising Cone Penetration Tests (CPTs), vibrocores and borehole sampling, were conducted within the Array to provide a greater understanding of subsurface geological conditions. A preliminary review of this data was undertaken to down select the most appropriate anchor solutions across the Array. Based on this preliminary data, multiple anchor solutions were identified and incorporated within the PDE. A reasonable worst case scenario of piling at all wind turbine locations was retained within the PDE for EIA. However, other anchoring solutions, including a 65% driven pile and 35% DEA solution, which have the potential to reduce subsea noise emissions during installation have been considered. Full details of all anchoring solutions considered as part of the PDE for EIA are provided in volume 1, chapter 3.

                        Wind turbine layout development

96. Based on the geotechnical data collected to date, and greater certainty over feasible anchor solutions to support a greater project capacity, layouts were developed to maximise the efficiency of the turbine array whilst taking into account environmental receptors. Layouts were developed to align with the requirements set out within key shipping and navigation guidance documents including Marine Guidance Note (MGN) 654 (MCA, 2021). Layout development has included at least one line of orientation to comply with SAR requirements (MCA, 2021). The maximum adverse layout was also developed and included within the PDE for the Array EIA Report which incorporates a packed perimeter with internal grid and aims to increase the energy generation within the Array by reducing wake loss.

                        Minimum blade tip clearance

97. Within the Array EIA Scoping Report (Ossian OWFL, 2023), the Applicant committed to identifying an appropriate air gap to reduce and mitigate collision mortality of seabird species that may forage in the vicinity of the Array. Development of floating wind turbine foundations is still in relative infancy when compared to fixed bottom sites, therefore, there remains uncertainty over the limitations of floating foundations to support larger wind turbine towers. Due to the horizontal and vertical movements resulting from the pitch of floating foundations increases in minimum blade tip clearance can result in increased stress on the tower, and greater wear on the turbine generator within the nacelle. The full implications of this on offshore wind turbines is not fully understood due to reliance on experience from smaller demonstrator sites with limited deployment periods. However, increased turbine heights could result in reduced operational lifespans of wind turbine generators and require additional design elements to stiffen the tower and floating foundation and associated mooring and anchors therefore impacting the technical and commercial feasibility of Ossian.
98. A precautionary comparison of collision mortality based on preliminary collision risk modelling, was undertaken to understand the point of diminishing returns. The minimum blade tip clearance has been set at 36 m (above LAT) to balance the reduction in collision mortality whilst remaining cognisant of the potential limitations of floating foundations and the uncertainty around feasibility of deployment of wind turbines with larger towers. At 36 m (above LAT) the greatest reduction in collision mortality is achieved with the smallest increase in minimum blade clearance.