4. Site Selection and Consideration of Alternatives

4.1. Introduction and Overview

  1. This chapter of the Array Environmental Impact Assessment (EIA) Report discusses the site selection and alternatives which have been considered by the Applicant during the design of the Ossian Array (hereafter referred to as the “Array”), prior to award during the ScotWind Leasing Round in January 2022 through to design freeze of the Project Design Envelope (PDE) to inform the EIA. Further detailed design will be undertaken post-consent.
  2. The Marine Works (Environmental Impact Assessment) Regulations 2007 and Electricity Works (Environmental Impact Assessment) (Scotland) Regulations 2017 (hereafter referred to as the EIA Regulations) makes provisions for the consideration of alternatives. Schedule 3 of The Marine Works (Environmental Impact Assessment) Regulations 2007 state that the following information must be included in the Array EIA Report: “2. A description of the reasonable alternatives (for example in terms of project design, technology, location, size and scale) studied by the applicant, which are relevant to the proposed project, the regulated activity and their specific characteristics, and an indication of the main reasons for selecting the chosen option, including a comparison of the environmental effects” (HM Government, 2007;). Schedule 4, paragraph 2, of the Electricity Works (Environmental Impact Assessment) (Scotland) Regulations 2017 makes similar provisions (HM Government, 2017). This chapter considers this requirement of Schedule 3 and Schedule 4, respectively, and sets out the reasonable alternatives considered by the Applicant, and the process followed in defining the chosen option for the Array. Further detail on relevant legislation, planning policy and guidance is included in volume 1, chapter 2.

4.2. Project Objectives

  1. The site selection and consideration of alternatives process has been informed by the overarching objectives of Ossian. Details of these objectives are provided in Table 4.1   Open ▸ .

 

Table 4.1:
Ossian Objectives

Table 4.1: Ossian Objectives

 

4.3. Assessing the “Do Nothing” Scenario

  1. This section considers the “do nothing” scenario in the context of the objectives of Ossian set out in section 4.2 above. The “do nothing” scenario outlines the changes which would occur to the baseline environment (if any) if development of Ossian was not progressed.
  2. As per the EIA Regulations, each technical topic (volume 2, chapters 7 to 20) has undertaken an assessment of the future baseline under the ‘do nothing’ scenario.
  3. One of the key objectives for Ossian which will not be achieved under the “do nothing” scenario, is the contribution towards clean, renewable energy, climate change targets and the statutory requirement to achieve net zero carbon emissions by 2045 (Scotland) and 2050 (UK) (see paragraph 11). As per the objectives set out in Table 4.1   Open ▸ , the Array will provide low carbon electricity for the consumer, and allow for deployment, at scale, of floating offshore wind in Scottish waters which is essential in accelerating Scotland’s and the UK’s path to net zero and ensuring UK energy supply security.
  4. It is estimated that global warming caused by human activities has reached approximately 1ºC above pre-industrial levels and it is likely that this will continue to increase without a significant and rapid decline in carbon emissions across all sectors (IPCC, 2018; IPCC, 2023).
  5. The Sixth Intergovernmental Panel on Climate Change (IPCC) Synthesis Report published in 2023 notes that there is an urgent need for action to mitigate and reduce the probability of the most catastrophic events that could result from anthropogenic climate change which are forecast to have extremely adverse effects on human populations across the globe (IPCC, 2023).
  6. The Sixth IPCC Synthesis Report also noted that a rise in global temperatures above 1.5°C could cause irreversible climate change, the potential for widespread loss of life and severe damage to livelihoods. However, it is recognised that global temperatures are now set to exceed 1.5°C by 2030 and it is becoming more likely that they will exceed 2°C after 2030 (IPCC, 2023). Therefore, if there is any delay in reducing carbon emissions now, the challenges faced in the future will be significantly more difficult to address.
  7. Within the UK, there are a number of legal instruments which set out obligations and commitments with regard to climate change, including:
  • International: the Paris Agreement (2015), led by the United Nations Framework Convention on Climate Change and adopted at the United Nations Conference of the Parties 21 (COP21) in Paris, France in December 2015;
  • UK: Climate Change Act 2008 (as amended); and
  • Scotland: Climate Change (Scotland) Act 2009 (as amended).
  1. Within these legal instruments, commitments to become carbon neutral (i.e. reach “net zero”) are set out. Internationally, the aim is to achieve net zero by 2050. The UK is also aiming to reach this target by 2050, with Scotland aiming for net zero by 2045. Interim targets are set out within the legislation listed above. The Climate Change Committee (CCC) provides advice to the UK Government on emissions targets, and reports to Parliament regarding progress made in reduction of greenhouse gas (GHG) emissions. The CCC produces carbon budgets for the UK which present a progressive limitation on the total quantity of GHG emissions to be emitted over a five-year period. However, the Institute for Government states that “the UK is … not on track to meet its fourth (2023-27) and fifth (2028-32)” carbon budgets (Institute for Government, 2020).
  2. Scottish and UK waters are facing increases in sea temperatures due to long-term global increase in temperature and regional variations in the Atlantic Ocean (Moffat et al., 2020). Sea surface temperatures in all Scottish Marine Regions have increased between 1893 and 2018, with increase in sea surface temperatures between 0.05 and 0.07°C per decade for each region (Moffat et al., 2020). When compared to a shorter period from 1981 to 2010, the rate of increase in surface sea temperature for each region was higher, ranging from between 0.2 and 0.4°C per decade (Moffat et al., 2020).
  3. Although sea levels change globally and locally in the short term due to tides and storm surges, global climate change is leading to sea level rise (Moffat et al., 2020; NOAA, 2022). Since 1880, global mean sea level has risen 21 cm to 24 cm due to melt water from glaciers and ice sheets, and thermal expansion of sea water (NOAA, 2022). In 2022, global mean sea level was 10.12 cm above 1993 levels, which was recorded as the highest annual average in the satellite record (1993-2022). The rate of global mean sea level rise is increasing; between 2006 and 2015, global mean sea level rise was recorded as 3.6 mm per year, which was 2.5 times higher than the average rate of 1.4 mm per year throughout the majority of the 20th century (NOAA, 2022). It is expected that global mean sea level will continue to rise with a predicted increase by 2100 of 0.2 m to 0.8 m for the 1.5°C global warming scenario and 0.3 m to 1.00 m for the 2°C global warming scenario, relative to 1986 to 2005 levels, as projected by the IPCC (2023). Rises in global mean sea level are likely to impact coastal ecosystems such as wetlands, mangroves, sea grasses and salt marshes. These ecosystems may be able to shift shoreward as sea levels increase, however, coastal developments (e.g. sea walls, buildings, agriculture) may prevent this from occurring (IPCC, 2023). Coastal and low lying areas are particularly at risk from submergence, salinisation, flooding and erosion, which has a wide range of impacts on human health, biodiversity, freshwater availability, fisheries and other ecosystem services (IPCC, 2023).
  4. Research has shown that climate change is already impacting fish species in Scottish and UK waters with changes in distribution, timing of life history events, and effects on body size already recorded and investigated (Wright et al., 2020). Increased occurrence of species more commonly found in warmer waters has been observed, alongside the reduction in occurrence of cold water species, indicating shifts in distribution due to sea temperature change (Wright et al., 2020). A study by Townhill et al. (2023) which reviewed projected changes in distribution of 49 commercial fish and shellfish species due to climate change in UK waters showed that UK waters would likely become more suitable for species such as European seabass Dicentrarchus labrax, sardine Sardina pilchardus and anchovy Engraulis encrasicolus, and less suitable for species including Atlantic cod Gadus morhua and saithe Pollachius virens. In addition, the frequency of occasional visitors to UK waters, such as blue-fin tuna Thunnus thynnus, has increased in recent years which is likely linked to increase in sea temperature and expansion of prey species range (Wright et al., 2020). Some fish species have also been recorded to spawn earlier; four out of seven sole Solea solea stocks from across the UK were found to spawn at a rate of 1.5 weeks earlier per decade since 1970 (Wright et al., 2020). Further research indicates that sole are likely to continue spawning earlier based on the 2°C global warming scenario (Lacroix et al., 2018). Climate change is also thought to be linked to decreases in body size of fish with one study by Baudron et al. (2014) showing that six out of eight commercial fish species examined from the North Sea over a 40 year period had an average decline in body size of 16%. During this time period, water temperature increased by 1°C to 2°C (Baudron et al., 2014). Ultimately, the impacts of climate change will lead to changes in marine ecosystems which will affect the productivity and economic sustainability of commercial fisheries, and food security (Stewart and Wentworth, 2019).
  5. Similar to fish species, marine mammals have also shown distribution shifts, thought to be linked to climate change. It is considered that the northern extent of species is moving northward, evidenced by trends in strandings data from north-west UK waters (OSPAR III Region North) which showed that the proportion of warm water adapted species such as short-beaked common dolphin Delphinus delphis and striped dolphin Stenella coeruleoalba has increased over time, while the proportion of cold water adapted species such as Atlantic white-sided dolphin Lagenorhynchus acutus and white-beaked dolphin L. albirostris has decreased in the same region (Martin et al., 2023). This same significant trend was also observed in north-east UK waters (OSPAR II North) however it was not as acute as north-west UK waters, (Martin et al., 2023). Distribution shifts of marine mammals are also thought to be related to changes in distribution of prey species which are more acutely impacted by factors such as sea temperature as discussed in paragraph 14. Changes in harbour porpoise Phocoena phocoena distribution in the North Sea have been observed over the past 20 years which are linked to changes in distribution of sandeel Ammodytes spp. Changes in sea temperature has impacted the timing of phytoplankton blooms and peaks in copepod abundance which feed upon phytoplankton. Key timings in the lifecycle of sandeel rely on copepod production; changes in the peaks of copepod abundance means that sandeel lifecycles no longer correlate as effectively and recruitment (i.e. the process of small, young fish transitioning to larger, older fish (Camp et al., 2020)) has declined. This is thought to be a key driver in the observed distribution shifts of harbour porpoise (Martin et al., 2023). Increases in sea temperature, reduction in prey availability and reduction in habitat availability are likely to have severe impacts upon marine mammal species, particularly those species which are already threatened or those with a limited habitat range (Kebke et al., 2022).
  6. Climate change is considered one of three key threats to UK seabirds (Pearce-Higgins, 2021). Seabird populations can be impacted directly and indirectly by climate change. Environmental changes, such as occurrence of storm events causing occasional high mortality of seabirds in breeding and wintering areas, and sea level increases causing breeding failure due to water inundation of low lying nests, are examples of direct impacts to seabirds. These direct impacts are likely to increase due to climate change, both in terms of frequency and intensity (Daunt and Mitchell, 2013). Indirect impacts such as changes in prey abundance, distribution and quality, can also impact seabird abundance and distribution. A study by Johnston et al. (2013) indicated that under a high climate change scenario by 2080, the number of internationally important breeding seabirds around the UK are projected to decline by more than 50%, with 40% of species projected to be Red-listed due to climate change.
  7. Also linked to climate change is the process of ocean acidification. Ocean acidification is the process by which carbon dioxide in the atmosphere produced by human activities, is absorbed in the ocean which causes a decrease in pH of oceanic waters (Moffat et al., 2020; NOAA, 2020). Although the absorption of carbon dioxide from the atmosphere in oceanic waters is a natural process, increases in carbon dioxide in the atmosphere through human activities also increases the amount of carbon dioxide absorbed by oceanic waters which is driving ocean acidification and has implications on the flora and fauna which inhabit this environment (NOAA, 2020). Ocean acidification impacts many species of marine life, particularly those species which form hard shells and skeletons such as shellfish and corals which can be decalcified or dissolved by decreased pH levels (IPCC, 2018). Fish species are also impacted by ocean acidification through changes in behaviour and reduction in growth, fitness and survivability (Smithsonian Institution, 2018; Fabry et al., 2008). As well as impacts to individual species, ocean acidification can affect whole ecosystems through disruption of food webs and changes in community structure (Doney et al., 2020). As a result, ecosystem services such as commercial fisheries, aquaculture and shoreline protection are at risk from ocean acidification (Doney et al., 2020).
  8. It is clear that rapid decarbonisation is required to tackle the climate emergency and cost-of-living crisis through reduction of the UK and Scotland’s reliance on fossil fuels. The Array is located within the E1 Plan Option (PO) Area identified in the Sectoral Marine Plan (SMP) as suitable for generating several GW of energy from offshore wind (Scottish Government, 2020). The Applicant’s expertise in developing offshore wind in Scottish waters, and accelerated delivery schedule of key consents for the Array (SSER, CIP and Marubeni, 2021b) allow for deployment, at scale, of floating offshore wind in Scottish waters which is essential in accelerating Scotland’s and the UK’s path to net zero, and achieving Scotland’s ambitions for 11 GW offshore wind connected to the grid by 2030 as set out in the SMP (Scottish Government, 2020).
  9. Table 4.2   Open ▸ summarises the outcomes under the ‘do nothing’ scenario. It is clear that the development of the Array will make a substantial contribution towards the UK’s and Scotland’s climate change targets and the commitments towards reaching net zero. Without the development of the Array, these targets and commitments will be more difficult to achieve.

 

Table 4.2:
Consideration of the Do Nothing Scenario in the Context of Ossian Objectives

Table 4.2: Consideration of the Do Nothing Scenario in the Context of Ossian Objectives