16.6. Methodology to Inform Baseline

16.6.1. Desktop Study

  1. The baseline relevant to major accidents and disasters is based on a summary of the information collected through a detailed desktop review of existing studies and datasets for the following chapters:
  • volume 2, chapter 12: Commercial Fisheries;
  • volume 2, chapter 13: Shipping and Navigation;
  • volume 2, chapter 14: Aviation, Military, Communications;
  • volume 2, chapter 15: Infrastructure and Other Users; and
  • volume 2, chapter 17: Climatic Effects.
  1. The designed in mitigation measures are summarised in Table 16.4   Open ▸ . A detailed overview of the desktop sources is presented in each of the above chapters and relevant technical reports, with a summary being provided in this chapter.

16.6.2. Site-Specific Surveys

  1. No site-specific surveys have been undertaken to inform the EIA for major accidents and disasters. This is because receptor information and data related to the topic can be readily collected through desktop study and consultation with relevant stakeholders, and is currently available due to suitable data throughout the north-east Scotland region.
  2. Whilst no site-specific surveys were undertaken for this chapter, the two 14-day vessel traffic surveys that were completed for shipping and navigation (discussed in volume 2, chapter 13) obtained information on vessel traffic in the vicinity of the Array and has been used to inform the major accidents and disasters chapter.

16.7. Baseline Environment

16.7.1. Overview of Baseline Environment

  1. In line with the IEMA Guidance and the advice provided as part of the Ossian Array Scoping Opinion (IEMA, 2020; MD-LOT, 2023), the baseline environment herein is informed by existing sources of information, in order to identify the hazards of relevance to the Array and inform this major accidents and disasters chapter, rather than collecting survey data (as is typically the case for other EIA receptor topics).
  2. The following sections provide a summary of the baseline environment relevant to major accidents and disasters. It is noted that the study areas for these different baseline topics differ as they relate to different receptors with varying ranges for which impacts must be considered. However, notwithstanding these differences all relevant study areas are appropriate for this assessment.

Unexploded ordnance

  1. This section provides an overview of UXO in proximity to the Array, as described in volume 1, chapter 3.
  2. The possibility exists for UXO originating from World War I or World War II to be encountered during the construction or installation of the Array. Due to the health and safety risks posed by UXO and potential interactions with installed infrastructure and vessel activities, it is necessary for UXO to be surveyed and managed carefully before the construction phase and installation of any offshore infrastructure commences.
  3. If UXOs cannot be avoided or relocated, the preferred method for UXO clearance is the use of a low order technique with a single donor charge of 0.25 kg Net Explosive Quantity (NEQ) for each clearance event. Up to 0.5 kg NEQ clearance shots will be required for neutralisation of residual explosive material at each location, conducted by a specialist contractor in advance of any construction or installation activity. Up to two detonations will be conducted within a 24 hour period, with clearance only taking place during daylight hours. The Applicant has assumed that up to 15 UXOs may require clearance using these low order techniques, such as deflagration, based upon existing knowledge from Seagreen 1 Offshore Wind Farm. Despite this, a risk remains that some clearance events may be required to use high order detonation.
  4. Advice and guidance on UXO clearance within the Array is provided in volume 2, chapter 10.

Commercial fisheries

  1. This section provides an overview of the commercial fisheries in proximity to the Array, as described in volume 2, chapter 12.
  2. Pelagic trawl activity, whereby vessels track shoals of fish and deploy fishing gear to harvest a portion of that migrating shoal, is found to not occur within the Array. No pelagic trawl activity is visible in the commercial fisheries regional study area in 2019 and 2020.
  3. Demersal otter trawls typically target gadoids, other groundfish, plaice Pleuronectes platessa and Nephrops norvegicus (also known as Norway lobster, Dublin Bay prawn, langoustine, and Nephrops). While activity is very limited within the Array it is seen consistently outside the Array, focused on grounds within the Devil’s Hole, which is located approximately 18 km to the east of the Array. The Devil’s Hole is a series of deep trenches that run north to south. Landings are primarily dominated by Nephrops, haddock Melanogrammus aeglefinus and mixed demersal fish species.
  4. Beam trawl activity and demersal seine activity is found to be negligible across the Array with the latter having a notable area of activity to the west of the Array.
  5. Creels or pots, used for the capture of lobster and crab, is predominantly undertaken in inshore areas. As the Array is approximately 80 km south-west of Aberdeen (closest shoreline from the nearest point), it is located in grounds that would typically be beyond the normal operational range of potting vessels.
  6. Dredging activity is indicated to be negligible across the Array, with dredge grounds predominantly located to the west of the Array, further inshore between 6 nm to 12 nm of the coastline.

Shipping and navigation

  1. This section provides an overview of the shipping and navigation activity in proximity to the Array, as described in volume 2, chapter 13.
  2. This chapter provides a description of existing navigational features within a 10 nm buffer around the site boundary. Surveys of this area show that daily vessel numbers are within the range of four to 12 vessels per day during winter and five to 16 vessels per day during summer. The majority of traffic within the 10 nm shipping and navigation study area were observed to be comprised of oil and gas vessels in winter and cargo vessels in summer. Overall, oil and gas and cargo vessels were the most common vessel type, with minimal levels of fishing and recreational vessels.
  3. A total of 11 main commercial routes were identified from 12 months of Automatic Identification System (AIS) data recorded during 2022 within the 10 nm shipping and navigation study area. The busiest of these routes was transited by various oil and gas vessels navigating to and from Aberdeen, with approximately 16 to 17 vessels per week. Routes between the Faroe Islands or Iceland and Rotterdam (ten vessels per week) and Immingham or Rotterdam to Glensanda (two to three vessels per week) were the next busiest. The remaining six routes were each utilised by one vessel or less per week on average).

Aviation, military, and communications

  1. The Array will be situated within the Scottish Flight Information Region (FIR2) in an area of Class G uncontrolled airspace which is established from surface up to Flight Level (FL) 115 (approximately 11,500 ft). Above this Class G Airspace is Class C Controlled Airspace (CAS).
  2. Within Class G and Class C airspace, the following Air Traffic Control (ATC) rules apply:
  • Class G airspace – any aircraft can operate in this area of uncontrolled airspace without any mandatory requirement to be in communication with, or receive a radar service from, any ATC unit. Pilots of aircraft operating under Visual Flight Rules (VFR) in Class G airspace are ultimately responsible for seeing and avoiding other aircraft and obstructions; and
  • Class C airspace – pilots require clearance to enter this airspace and they must comply with ATC instructions. Both Instrument Flight Rules (IFR) and VFR is permitted, and this airspace extends from FL 195 (19,500 ft) to FL 600 (60,000 ft).
  1. An overview of the baseline presented in volume 2, chapter 14 is presented below:
  • Civil aviation: Aberdeen International Airport is located approximately 292°/50 nm north-west of the Array. Radar Line of Sight (RLoS) analysis indicates that the Perwinnes Primary Surveillance Radar (PSR) will detect operational wind turbines at a maximum height of 399 m and Allanshill PSR will detect intermittently, operational wind turbines which are placed within the northern quarter of the Array.
  • Military aviation: the nearest Air Defence Radar (ADR) systems are located at Remote Radar Head (RRH) Buchan in Aberdeenshire (316°/48 nm) and RRH Brizlee Wood in Northumberland (215°/80 nm). ADR systems are used to compile a Recognised Air Picture (RAP) to monitor the airspace in and around the UK to launch a response to any potential airborne threat. Ministry of Defence (MoD) Leuchars Station PSR is located approximately 245°/73 nm from the Array. Leuchars Station is responsible for navigational services to transitory military and civil aircraft operating within a 40 nm radius of the aerodrome, up to 9,500 ft. The Array is adjacent to Low Flying Areas (LFA) and, therefore, military low flying is likely to take place above and around the Array.
  • Helicopter operations: the closest MCA SAR helicopter base to the Array is Inverness Airport, approximately 114 nm north-west of the Array. SAR operations often involve flying at low level. Helicopters supporting offshore oil and gas, in the northern North Sea, use Helicopter Main Route Indicators (HMRI), radiating from Aberdeen International Airport (the main support base) on a hub/spoke radial pattern. These HMRIs lie to the north of the Array; the closest being 4 nm to the north of the north-eastern boundary of the Array on a bearing of 21. The Civil Aviation Authority (CAA) recommend within Civil Aviation Publication (CAP) 764 (CAA, 2016) that there should be no obstacles within 2 nm either side of the centreline of a HMRI, the Array is located outside of the CAA recommended obstacle free distance. Moreover, the CAA also recommend that dependent on radar low level coverage required and the type of radar service required, it may be necessary to maintain a greater buffer than 2 nm.
  • Other radar and communications: the Array is located outside of the Met Office consultation zone, at approximately 95 km from the nearest Met Office radar at Hill of Dudwick, Aberdeenshire.

Offshore energy projects, offshore cables, pipelines, and subsea communications infrastructure

  1. This section provides an overview of the offshore energy projects and offshore cables in proximity to the Array, as described volume 2, chapter 15.
  2. The closest operational offshore wind farm project to the Array is Seagreen 1 Offshore Wind Farm, located approximately 51 km west of the Array. There are several offshore wind farms in the construction phase that, when completed, will be in proximity to the Array. The closest wind farm currently under construction is Seagreen 1A Project which is approximately 66 km west of the Array. Further details about the proximity and stage of other offshore wind farms in proximity to the Array can be found in Table 15.6 of volume 2, chapter 15.
  3. The closest offshore cable is the Eastern Green Link (EGL) 2 cable, currently in planning, located approximately 23.7 km of the Array, along the west side of the Array.
  4. The Firth of Forth supports oil and gas activities with Dundee and Aberdeen ports having deep-water berths and extensive landside project areas to accommodate the significant fabrication and refit projects for North Sea and Norwegian sector operations. There are three active hydrocarbon licence blocks within the site boundary of the Array - Block 27/3, Block 27/9 and Block 27/10. These blocks overlap the north-east of the site boundary of the Array and are all operated by North Sea Natural Resources Ltd (Licence number: P2321).
  5. There are no oil and gas pipelines located within the Array. The closest pipeline, Catcher Gas Export Pipeline, is located approximately 48 km from the Array.
  6. There are no wave and tidal projects, aggregate extraction sites, active disposal sites, or carbon capture, natural gas storage areas, active and disused subsea cables and pipelines identified within the boundary of the Array or within the broad infrastructure and other users study area (see volume 2, chapter 15).

Climatic effects

  1. This section provides an overview of existing environmental baseline of the Array and any LSE1 on and from climate change, as detailed in volume 2, chapter 17, volume 3, appendix 17.1 and volume 3, appendix 17.2.
  2. The baseline consists of various subtidal habitats with the predominant being muddy sand, sand and slightly gravelly sand. These sediments are likely to contain stores of ‘blue carbon’, which is organic carbon that has been captured and stored through biological processes in the coastal and marine environment (Cunningham and Hunt, 2023).
  3. The Array will likely contribute to the abatement of the amount of fossil fuel generation within the UK Grid (i.e. UK Grid carbon intensity). As such, the current baseline with regard to UK Grid-average emission factor for electricity generation, without the Array, is 252.97 kgCO2e/MWh (including well-to-tank but as-generated, i.e. excluding transmission and distribution losses) (Department for Energy Security and Net Zero (DESNZ) and Defra, 2023). Further information is presented in the Greenhouse Gas (GHG) technical report (volume 3, appendix 17.1).
  4. Mean air temperature in the central North Sea (where the Array is located) range from the lows of 1°C in January to 16°C in July, with surface air temperatures exceeding sea surface temperatures during the spring and summer months and falling below sea surface temperatures during the autumn and winter months (Department for Business, Energy and Industrial Strategy (BEIS), 2022). Global air temperatures rose by 0.85°C between 1880 and 2012, and continue to rise (Intergovernmental Panel on Climate Change (IPCC), 2021).
  5. Precipitation rates within the central North Sea follow a seasonal trend with April to June tending to be the driest months, and October to January being wetter. Thunderstorms are infrequent, and snow showers vary from approximately 10 to 12 days in the central North Sea (BEIS, 2022).
  6. Within the climatic effects study area, wind speeds have been recorded up to 31.5 m/s during the 1979 to 2023 period, with winds predominantly from the south-west. Annual mean significant wave height ranges from 1.87 m to 2.05 m, with wave direction predominantly from the north and north-north-east. An easterly storm event occurred within the climatic effects study area during November 2022, with maximum significant wave height of 8.96 m (volume 3, appendix 7.1).
  7. Mean sea level (MSL) is a crucial element of climate change related risks for offshore wind farms, as increased sea level has the potential to both increase water damage and corrosion of components above the water line at time of construction, and/or increase mooring line tension. MSL rise also has the potential to cause increased damage from storm surge. Global MSL rose by 0.2 m between 1901 and 2018, and continues to rise (IPCC, 2021).
  8. Further information is presented in the Climate Change Risk Assessment (CCRA) technical report (volume 3, appendix 17.2).

16.7.2. Future Baseline Scenario

  1. The EIA Regulations require that a “a description of the relevant aspects of the current state of the environment (baseline scenario) and an outline of the likely evolution thereof without implementation of the project as far as natural changes from the baseline scenario can be assessed with reasonable effort, on the basis of the availability of environmental information and scientific knowledge” is included within the Array EIA Report.
  2. If the Array does not come forward, an assessment of the ‘without development’ future baseline conditions has also been carried out and is described within this section.

Commercial fisheries

  1. Commercial fisheries patterns change and fluctuate based on a range of natural and management-controlled factors including:
  • market demand;
  • market prices;
  • stock abundance;
  • fisheries management;
  • environmental management;
  • improved efficiency and gear technology; and
  • sustainability.
  1. Following the withdrawal of the UK from the European Union (EU), the EU have agreed to a Trade and Cooperation Agreement (TCA). The TCA sets out fisheries rights and confirms that from 01 January 2021 and during a transition period until 30 June 2026, the UK and EU vessels will continue to access respective Exclusive Economic Zones (EEZs) (12 nm to 200 nm) to fish. In this period, EU vessels will also be able to fish in specified parts of UK waters between 6 nm and 12 nm.
  2. Over the five-year transition period, 25% of the EU’s fisheries quota in UK waters will be transferred to the UK; 15% in year one, most of this quota has already been transferred and distributed across the four nations of the UK. After the five-year transition there will be annual discussions on fisheries opportunities. Across the commercial fisheries regional study area, where UK fisheries primarily target non-quota shellfish species, it is expected that fleets are unlikely to be impacted by quota transfers. It is possible that UK vessels will seek to exploit additional quota-species opportunities, but vessels would need to access quota holdings.
  3. Market changes have the potential to impact fishing activity in the commercial fisheries local and regional study areas; including the potential reestablishment of the historic ‘small’ haddock fishery. In terms of future baseline scenarios, it is therefore possible, for example, that the UK fleet will more heavily target haddock given the potential return of processing and market for this product.
  4. Further information is presented in volume 2, chapter 12.

Shipping and navigation

  1. For commercial vessels, potential future changes in traffic volumes are complex to predict, noting actual changes will be based on multiple factors including general market trends. Therefore, the Navigational Risk Assessment (NRA) (volume 3, appendix 13.1) has considered two independent scenarios of potential growth in commercial vessel movements of 10% and 20%. It is likely that commercial vessels will deviate to avoid any other future wind farm developments that are under construction or in operation. This is in line with vessel behaviours observed at other UK offshore wind farms including Seagreen 1 Offshore Wind Farm and Neart na Gaoithe Offshore Wind Farm.
  2. It should also be considered that there may be an increase in vessels associated with offshore wind farm construction and operation as further future wind farm developments are developed. Furthermore, fluctuations in oil and gas vessel activity will depend on future development and/or decommissioning, which again is heavily dependent on market conditions and is therefore difficult to predict.
  3. For commercial fishing and recreational vessel activity, there is similar uncertainty associated with long-term predictions given the limited reliable information on future trends upon which any firm assumptions can be made. Therefore, to ensure a conservative approach, 10% and 20% growth scenarios in commercial fishing vessel and recreational vessel movements have also been assumed in the NRA (volume 3, appendix 13.1).
  4. Further information is presented in volume 2, chapter 13.

Aviation, military and communications

  1. The North Sea Transition Authority (NSTA) Oil and Gas Authority (OGA) Annual Report and Accounts 2022-2023 (NSTA, 2023) reported a predicted decline in gas production and usage in following years. Oil and gas operators continue to find it difficult to predict production accurately as older fields mature and their reliability reduces. The Prime Minister’s Office (PMO) and the DESNZ reported during July 2023 that the Prime Minister has committed to future oil and gas licensing rounds with two areas in the North Sea chosen as locations for carbon capture usage and storage clusters. The independent Climate Change Committee predicted around a quarter of the UK’s energy demand will still be met by oil and gas when the UK reaches net zero in 2050, the Government states that it is taking steps to slow the rapid decline in domestic production of oil and gas, which will secure UK domestic energy supply and reduce reliance on hostile states.
  2. At present there is an appraisal well, with permits scheduled to expire in January 2024, to the north-east of the Array. However, as old oil and gas fields are decommissioned it is considered that helicopter use to oil and gas platforms associated with these fields will eventually decline; however, as helicopter support to offshore wind increases it is expected that there may be increased aviation activity as new offshore areas are developed to support net zero targets.
  3. Based on the timings of the development of the Array, the baseline environment for the aviation, military and communications assessment is not expected to change. The present airspace construct or usage, civil and military aviation, above and around the Array is not expected to change significantly.
  4. Further information is presented in volume 2, chapter 14.

Offshore energy projects, offshore cables, pipelines and subsea communications infrastructure

  1. Oil and gas are vital to Scotland and were responsible for nearly 90% of the country’s primary energy in 2015. Although the sector is seen as a critical and integral component to the economy, support for oil and gas programs moving forward will be conditional on the sector’s actions to facilitate sustainable energy transitions for the future (Scottish Government, 2021). Furthermore, a new leasing round called the Innovation and Targeted Oil and Gas (INTOG) leasing round, was opened in August 2022 to deliver a new round of offshore wind leases that aim to help decarbonise the production energy utilised on the oil and gas industry’s platforms and infrastructure in the North Sea (Offshore Wind Scotland, 2023). Further details about the future baseline environment for oil and gas activity in the vicinity of the Array can be found in volume 2, chapter 15.
  2. There is potential for significant growth in offshore wind energy within Scotland, with the Scottish Government setting out plans to increase offshore wind capacity by 11 GW of energy installed by 2030 (Scottish Government, 2023b). Scotland currently has 10.2 GW of projects at various stages of development. The floating wind projects awarded by the ScotWind leasing round and INTOG leasing round are expected to generate approximately 19.3 GW and 5.5 GW, respectively. The total generating capacity of all the awarded floating wind sites is therefore expected to be approximately 24.7 GW (Offshore Wind Scotland, 2023). The Array is one of 13 projects in the ScotWind leasing round based on floating technology (The Crown Estate, 2022). Notably, Morven and Bellrock Offshore Wind Farms will be located 6 km and 9 km from the Array, respectively, if they surpass the pre-planning stage.
  3. The future baseline scenario for offshore cables, carbon capture storage, natural gas storage and underground coal gasification is subject to gradual change as new projects and/or sites are further identified.
  4. Further information is presented in volume 2, chapter 15.

Climatic effects

  1. The future baseline for major accidents and disasters will evolve along a number of factors over the Array lifecycle.
  2. Climate change is predicted to lead to a number of changes including: an increase in peak rainfall intensities; wetter winters and drier warmer summers; and a rise in sea level. It is anticipated that there will be an increased frequency of lightning strikes and wind gusts. Climate change is expected to alter the prevalence of extreme weather conditions which could lead to a disaster during different project phases (e.g. increased wind gusts impacting the construction phase or increased lightning strike frequency increasing risks during the operation and maintenance phase).
  3. The magnitude of changes brought about by climate change is uncertain, but UK climate projections (UK CP18) are available until the end of the 21st century. The anticipated impact of climate change on environmental conditions is considered in volume 2, chapter 17. The effects of climate change on anticipated weather conditions within the construction phase are anticipated to be minimal.
  4. The future baseline GHG emissions for existing land use (seabed) without the Array are expected to remain similar to that of the existing baseline environment. The future baseline for electricity generation that would be displaced by the Array depends broadly on future energy and climate policy in the UK and more specifically, on the demand for operation of the Array compared to other generation sources available. This, in turn, is influenced by commercial factors and National Grid’s needs. Further details can be found in the GHG technical report (volume 3, appendix 17.2).

  1. In the next decade to two decades, within the operating lifetime of the Array, anthropogenic climatic changes are expected to become more apparent. It is expected that sea surface temperatures will continue to increase in the 21st century, with global mean sea surface temperatures predicted to increase by approximately 2.9°C by 2100 under Representative Concentration Pathway (RCP) 8.5[1]. Sea temperatures in Northern Europe (including the North Sea) are predicted to rise at a greater rate than the global average, with temperatures predicted to increase by approximately 3.4°C under RCP8.5 in the same time period. Ocean acidification is anticipated to increase, with a fall in surface pH by 0.4 units by 2100 under RCP8.5 (IPCC, 2021).
  2. Average sea level rise around the UK is expected to increase by 1 m by 2100, though a lesser rise is anticipated in the north of the UK. The east coast of Scotland can expect to see an average sea level rise of approximately 0.5 m to 0.6 m by 2100 (Palmer et al, 2018). The average wave height is predicted to decrease around much of the UK at a factor of about 10% to 20% over the 21st century, with average wave heights in the central North Sea predicted to reduce by 0.5 m. However, owing to variation between different models, confidence in projected sea wave height changes is low (Jaroszweski et al., 2021). Further information has been presented within the climate change risk assessment technical report (volume 3, appendix 17.1).
  3. Further information is presented in volume 2, chapter 17.

16.7.3. Data Limitations

  1. The data sources used in this chapter are based on the existing studies, datasets and limitations presented within the chapters listed in paragraph 14.
  2. The data presented are the most up to date publicly available information which can be obtained from the applicable data sources cited in the relevant chapters. The data are therefore limited by what is available and by what has been made available, at the time of writing the Array EIA Report. It is considered that the data employed in the assessment are robust and sufficient for the purposes of the assessment of effected presented.