3. EFFECTS ON CLIMATE

3.1.                  STUDY AREA

The Effects on Climate study area includes the Project, all carbon emitting activities within the site, relevant carbon emitting activities beyond the site boundary that contribute to the total carbon footprint of the site area (e.g. production of construction materials) and energy generation from alternative sources.

Effects on Climate is a wide-ranging topic in terms of potential sources, both originating at the Project and from much further afield and is not limited to the geographic extent of the Project.

3.2.                  BASELINE

3.2.1.             METHODOLOGY TO INFORM BASELINE

The baseline conditions for the Effects on Climate assessment are informed by the total background emissions of GHGs from all sources, i.e. all UK and Scottish GHG emissions, as provided by national statistics. In addition, baseline environmental characteristics for the Project with specific reference to GHG emissions are provided for the existing situation and in the future, assuming the Project is not constructed. 

3.2.2.             National GHG emissions

As of May 2022, the UK is the world’s fifteenth largest emitter of carbon dioxide equivalent[3] (CO2e), with the total UK emissions for 2020 (last reported year) being 406 million tonnes (Mt) CO2e (BEIS, 2022a). Provisional figures have been released for 2021, with the total UK emissions for 2021 being 424.5 Mt CO2e (BEIS, 2022b).

The UK has in place carbon budgets for five-year periods up to 2037, as shown in Table 2-2. Whilst budgets have not yet been set beyond 2037, there is a legal requirement for the UK to reach net zero emissions by 2050, as set in the Climate Change Act 2008 and for Scotland to reach net zero emissions by 2045 as set in the Climate Change Scotland Act 2009 (as amended by the Climate Change (Emissions Reduction Targets) (Scotland) Act 2019).

The UK emitted 0.270 kgCO2e for each kWh of energy generated in 2020 (last reported year, long-run marginal figure) (BEIS, 2021). This emission factor has been projected by BEIS up until 2100. The emissions factor is projected to decrease significantly over the next 10 years, due to lower carbon forms of energy generation coming online and older, higher carbon forms of energy generation (i.e. fossil fuels) being phased out. The emissions factor is projected to be 0.156 kgCO2e/kWh in 2028 (first partially operating year of the Project). The emissions factor continues to decrease until 2049 when the emissions factor is 0.006 kgCO2e/kWh. It is then projected to remain at this low level of residual emissions until 2100.

3.2.3.             Regional GHG emissions

The total GHG emissions for Scotland for 2020 (the last reported year) were 40.0 MtCO2e (Scottish Government, 2022a).

Scotland has a legislated target to achieve net zero by 2045. To help the delivery of this long-term target, Scotland’s climate change legislation also includes annual targets for every year until 2045 (see also Table 2-3). This includes a target of a 71.2%[4] reduction in GHG emissions from the 1990 baseline emissions by 2028 (first partially operating year of the Project). This percentage reduction increases by 1.5% each year until reaching a 90% reduction in 1990 baseline emissions by 2040. It then increases by 2% each year until reaching a 100% reduction in GHG emissions by 2045, i.e. net zero.

In 2020, 61.8% of Scotland’s electricity generation came from renewable energy sources with a total of 12.1 GW of installed capacity across the country, largely from onshore wind and hydroelectric power (Scottish Government, 2022b).

Scotland has already reached its target of having an electricity grid intensity below 50 gCO2e/kWh, with a grid intensity of 41.4 gCO2e/kWh reached in 2019. The Scottish Government anticipates that grid intensity will remain at or below 50 gCO2e/kWh in the future, with the increased penetration of renewable sources and no planned expansion of fossil fuel power generation.

3.2.4.             Site specific baseline GHG emissions

Currently the onshore Proposed Development (Onshore EIA Report; Introduction, volume 2, Figure 5.1) is in agricultural use and spans three large fields that are primarily used for growing crops. The current agricultural use of the land within the site has minor levels of associated GHG emissions. Baseline GHG emissions are dependent on soil and vegetation types And present and fuel use for the operation of agricultural vehicles and machinery. As the current onshore GHG emissions are unknown, it is assumed that baseline emissions are zero to apply a worst-case scenario.

The offshore Proposed Development (Offshore EIA Report; Introduction, volume 1, chapter 1, Figure 1.1) is partially located in an area designated as a Marine Protected Area (MPA) to the south and north. It also contains shipping lanes and is used by commercial fisheries. The vessels range from smaller fishing and recreational vessels up to large military vessels, tankers and cargo vessels. Whilst there are GHG emissions associated with the vessels that use the shipping routes through the offshore site, these have not been possible to be quantified with any certainty due to the vast array of vessel types that travel through the offshore Proposed Development and issues with calculating the distances and fuel consumption for each journey travelled.

The total current baseline emissions are unknown but are considered to be negligible when compared to the construction GHG emissions resulting from the Project. Therefore, for the purposes of the assessment, a conservative GHG emissions baseline of zero is applied, which represents a robust worst-case approach.

3.2.5.             Future baseline scenario

If the Project is not constructed, the current agricultural use of the onshore Proposed Development would likely continue. Offshore, the MPA is considered likely to continue in its current state unless any other development comes forward that may impact it. The vessel movements that currently occur within the offshore Proposed Development will continue along the current routes that exist, taking into account any changes caused by the construction of the Seagreen Wind Farm to the north. A robust, conservative approach estimates that total vessel traffic will grow by 20% by 2050 (Offshore EIA Report, volume 2, chapter 13, Section 13.7.2). 

As mentioned in section 3.2.2 the emissions factor for UK energy generation is projected to continuously decrease until 2049 when it reaches 0.006 kgCO2e/kWh. This rate of decrease is based on a variety of factors and is altered every year based on changes in policy, current energy generation capacity, economics and planned projects. The projection would remain similar in future years, without the Project, and would only be materially impacted by large scale changes in government policy, geopolitical events or economic issues.

3.3.                  ASSESSMENT METHODOLOGY

The potential impacts of GHG emissions are very specific in terms of receptors and impacts because:

• There is only one receptor, the atmosphere, which is non-site-specific;
• There is only one direct impact, global warming, which is also non-site-specific; and
• All units of CO2e can be considered to have the same impact no matter where they are emitted.

Therefore, assessment of the effects of the Project on climate is limited to quantification of the magnitude of GHG emissions, from individual sources and in total, and comparisons of these to the baseline. Different GHGs have different global warming potentials, and to account for this they will be reported throughout this assessment as their CO2e value. 

3.3.1.             GUIDANCE

The assessment has been undertaken in accordance with the following guidance:

• IEMA (2022) Environmental Impact Assessment Guide to: Assessing Greenhouse Gas Emissions and Evaluating their Significance; and
• PAS 2080: Carbon Management in Infrastructure.

3.3.2.             IMPACTS TO BE ASSESSED

Table 3-1 presents the elements included in the Effects on Climate assessment, including their data sources.

Table 3-1 – Elements Included in the Assessment

Table 3-2 presents the elements not included in the assessment, and the justification for their exclusion. The elements excluded are not anticipated to materially affect the outcomes resulting from this assessment. This is in line with a proportionate approach which considers that where expected GHG emissions are less than 1% of total GHG emissions they can be excluded from assessment, provided that the combined exclusions are not more than a maximum of 5% of total GHG emissions, in accordance with IEMA guidance.

Table 3-2 – Elements Not Included in Assessment

3.3.2.1.            GHG Emissions Resulting from the Loss of Blue Carbon

The Scoping Opinion (MS-LOT, 2022) and advice from Marine Scotland Science (MSS) as part of the scoping process requested that the Applicant undertake an evaluation of the potential loss of carbon sequestered into marine sediments within the footprint of the offshore Proposed Development. 

The surficial sediments (i.e. top 10 cm of sediment) of the mapped extended Scottish Exclusive Economic Zone (EEZ), an area of approximately 554,755 km2, holds an estimated 1,515 ± 252 Megatonnes (Mt) of carbon. The majority of this carbon is in the form of calcium carbonate (CaCO3), with an estimated 1,294 ± 161 Mt of inorganic carbon being held within the surficial sediments (Smeaton et al., 2020).  A significantly lower quantity of carbon in these surface sediments is stored in the organic form, with an estimated 221 ± 92 Mt of organic carbon currently held within the top 10 cm of sediment within Scotland’s mapped extended EEZ (Smeaton et al., 2020).

One of the challenges in assessing blue carbon is the lack of agreed or consistently applied terminology, and the differences in timescales when discussing carbon sequestration (Burrows et al., 2017). For example, for fine grained sediments the relative proportion of inorganic carbon and organic carbon in these sediments varies greatly, depending on the rate at which organic carbon is remineralised and recycled as carbon dioxide or buried within the sediment, and the rate at which carbonate containing phytoplankton are deposited as detritus (Burrows et al., 2017). The offshore Proposed Development is located across a wide range of different seabed types including areas of hard substrate including rock, areas of boulders and cobbles. Where sediment is present the composition of sediment ranges from sandy gravel to muddy sand, with 36% of samples taken as part of site-specific surveys classified as slightly gravelly sand (see Benthic Subtidal and Intertidal Ecology Technical Report in the offshore EIA, volume 3, appendix 8.1). Therefore, given the range of habitat types and uncertainty in organic content, it makes undertaking a meaningful assessment challenging, particularly given that the specific locations and nature of construction activities will not be known until post consent following detailed design work. Whilst an assessment for blue carbon loss could be undertaken for a worst case scenario by considering the carbon levels in sediments within the offshore Proposed Development array area and in the offshore Proposed Development offshore export cable corridor, despite the associated uncertainty around carbon levels in sediments, the locations for offshore components and installation methods are highly relevant for carrying out a meaningful assessment because of the sediment types impacted.

It should however be noted that survey samples taken within the offshore Proposed Development benthic and subtidal study area (see figure 3.5 in volume 3, appendix 8.1) were tested for Total Organic Carbon (TOC) as the amount of carbon found in a sediment sample is often used as a non-specific indicator of water quality (rather than for the purpose of evaluating carbon sequestration). Levels of TOC were low (<1%) across all samples, except for one sample which was still <5%, which may indicate that the offshore Proposed Development site is not particularly important for carbon sequestration. Further detail is provided in the Benthic Subtidal and Intertidal Ecology Technical Report (Offshore EIA Report, volume 3, appendix 8.1). 

The maximum area of the offshore Proposed Development site is 1,178.1km2 within which all offshore Proposed Development infrastructure will be located. This constitutes a very small proportion (less than 0.2%) of the Scottish EEZ, that are used in Smeaton et al. (2020) to calculate the availability of carbon in Scottish Waters. Furthermore, the actual area which may be impacted by construction activities which may result in the disturbance of sediment and the release of carbon into the water column is significantly smaller (approximately 114 km2; see Benthic and Subtidal Ecology chapter in volume 2, chapter 8). Therefore, set in the context of the wider marine environment, the offshore Proposed Development has limited potential for the release of sediment containing carbon in into the marine environment. 

The physical processes chapter (volume 2, chapter 7) has assessed the potential for the increase in suspended sediment concentrations (SSC) and sediment deposition as a result of the offshore Proposed Development. It is considered that the impact of increased suspended sediment levels and associated sedimentation is predicted to be of local spatial extent, short term duration, intermittent and of high reversibility. Following suspension of material, it is predicted that a significant amount of sediment will be redeposited within the boundary of the offshore Proposed Development in close proximity to the release site, with further redistribution of sediment occurring during proceeding tides, retaining sediment within the area it originated from. No significant effects were concluded in EIA terms. The chapter also considers the potential alteration to hydrodynamics i.e. waves, tides and sediment transport which may result in indirect release of sequestrated carbon but similarly the effects were assessed as either negligible or negligible to minor and not significant in EIA terms.

An evaluation of blue carbon and possible effects in carbon has been undertaken including the consideration of:

• Uncertainty around carbon levels in sediments and the lack of information available on the level of carbon stored within sediments within the footprint of the offshore Proposed Development and the potential significant variability across the offshore Proposed Development site;
• The relatively small footprint and local scale of impacts of the offshore Proposed Development when set in the broader marine environment and therefore limited potential for significant release of carbon from sediments;
• Uncertainty at pre-application stage on the detailed design of the offshore Proposed Development including locations and final installation methods and therefore which sediment types may be disturbed during construction, which is highly relevant for a meaningful assessment; and
• Non-significant effects in EIA terms of SSC and deposition and alterations to hydrodynamics, with significant volumes of sediment being redeposited within the offshore Proposed Development boundary and retained within the spatial area.

Based upon the above, it is considered the contribution from release of carbon from marine sediments is negligible and hence has not been further considered in the Effect on Climate assessment. There is no indication that the sediments within the offshore site boundary are of particular importance for carbon storage (and to the contrary TOC analysis indicates carbon levels are low), the disturbance of sediment is of local scale, temporary and of short duration with much of the disturbed sediment being redistributed and retained in the local area. 

3.3.3.             CALCULATING CONSTRUCTION GHG EMISSIONS

This section applies to the construction phase of both the onshore Proposed Development and offshore Proposed Development of the Project unless otherwise stated.

The data for the assessment has been provided by the Applicant and is up to date for this stage of the design. As the Applicant follows the Project Design Envelope (PDE) approach for both the offshore EIA (see volume 1, chapter 3) and onshore EIA (see volume 1, chapter 5), it should be noted that several options exist for various elements of the design (e.g. total number and size of wind turbines). The PDE approach applies a ‘maximum design scenario’ that considers a realistic range of Project parameters (or scenarios). The PDE describes a range of parameters that apply to a Project technology design scenario (e.g. largest wind turbine option).

Where there are several design options, the elements chosen in this assessment are those that are likely to create a reasonable worst-case scenario (i.e. lead to the highest quantity of GHG emissions) for the Project. This is to ensure that the assessment considers the greatest magnitude of impact as a result of constructing the Project, and that the final design option would not exceed the impacts that have been assessed.

A quantification of construction phase GHG emissions has been calculated using the Atkins’ Carbon Knowledgebase tool, which contains a detailed library of calculation formulae and over 1,000 emissions factors from authoritative sources such as the Inventory of Carbon and Energy (ICE, versions 1.6(a), 2.0 and 3.0) (Circular Ecology, 2022), the Department for Environment, Food and Rural Affairs (Defra) Greenhouse Gas Reporting Conversion Factors (Defra, 2022), and the EMEP/CORINAIR Emission Inventory Guidebook (EMEP/EEA, 2019). The tool calculates the construction phase emissions in accordance with PAS 2080: Carbon Management in Infrastructure, the international standard for assessing carbon emissions throughout a project’s lifecycle.

For the onshore Proposed Development, worst case assumptions over the material quantities have been made. This information will become available at the detailed design stage of the Project. It has been assumed that materials will be transported 100 km to the site. This is a robust and conservative assumption based on the likelihood that the majority of materials will be sourced from within the UK.

Several components of the offshore Proposed Development do not have a detailed design at this stage. Where it has not been possible to identify the material composition of Project components, conservative assumptions have been made. This includes basing wind turbine material volumes on the Vestas V164 9.5MW wind turbine, one of the largest wind turbines that exists in the market (Vestas, 2022). Assumptions regarding the construction phase GHG emissions are listed in Section 3.3.6.

It is not determined where the wind turbine elements will be produced or sourced from. Given the size and scale of the wind turbines, it is likely that all or some of the wind turbine elements will be produced outside of the UK. Due to its distance from the site, Asia was chosen as the worst case as the source for the wind turbine components. It is assumed that all elements are manufactured close to the coast and shipped directly to the offshore site.

As mentioned in section 3.2.4 there are several shipping routes running through or close to the offshore Proposed Development array area (see Offshore EIA Report, volume 2, chapter 13). To avoid collisions during the construction and operation and maintenance phase, these routes will be diverted. As part of the Navigational Risk Assessment (NRA) for the Offshore EIA Report (volume 3, appendix 13.1), vessel surveys were undertaken and new shipping routes have been determined and the length of diversion from the original routes have been calculated. The data from the January 2021 & June 2020 surveys have been extrapolated to provide an estimate of the GHG emissions resulting from the diversions. The August 2022 survey data were not used in the calculations but a review showed that the information from the surveys was similar and should not make a material difference to the outcome of the assessment.  A decarbonisation rate has also been applied to these vessels since the sector is required to reach net zero by 2050[5]. This rate applies a steady, yearly decrease in GHG emissions from vessels.  

3.3.4.             CALCULATING OPERATION AND MAINTENANCE GHG EMISSIONS

The operation and maintenance phase of the Project has three key areas:

• Operational electricity production;
• Operational electricity, water, and material consumption; and
• Maintenance and repair.

The Project has a maximum generating capacity of 4.1 GW of electricity. However, due to a variety of factors, the Project will not operate at maximum generating capacity for the majority of the time. This is called the ‘Load Factor’ of the Project. The load factor for the Project is estimated to be 40.22% (RenewableUK, undated). This is considered to be the worst-case scenario as the efficiency of wind turbines has increased over time and is likely to continue to do so. The GHG emissions saved by the generation of renewable electricity has been calculated using the anticipated marginal emissions factor for 1kWh of national grid electricity generation for each operating year as projected by BEIS (BEIS, 2021). The factor for 2028 (first partially operating year of the Project) is calculated to be 0.156 kgCO2e/kWh decreasing to 0.063 kgCO2e/kWh in 2033 (first full operating year of the Project). This value decreases year-on-year until 2050 as the sources of energy generation across the country change.

Losses of energy from the transmission and distribution of the energy generated have not been calculated. This is due to the level of uncertainty and lack of data that exists for calculating such losses so far into the future. Additionally, such loses are not incurred solely due to the Project but also from the transmission and distribution across the National Grid to where the energy is required at that point in time and therefore would not provide a fair comparison of the carbon savings that the Project would provide.

The Project will consume electricity, water and materials during the operation and maintenance phase to maintain vital equipment, provide back-up emergency power, and support personnel operating on both offshore and onshore elements. The following elements of the design have known or estimated consumption values during the operation and maintenance phase:

• Wind turbine lubricants and emergency back-up fuel; and
• Offshore substation emergency back-up fuel.

The level of maintenance and repair that the onshore Proposed Development would require is unknown at this stage of the design. Due to the lack of certainty about the level of repair and maintenance required, the material emissions associated with this aspect have been scoped out of this assessment.

The level of maintenance and repair for the offshore Proposed Development has been extrapolated from data of the maintenance and repair of Beatrice and Greater Gabbard offshore wind farms, the latter of which has been operating for 10 years. From this data, the likely replacement of major components for the wind turbines (except for blades), all cables and offshore substation platforms has been estimated. The data has also been used to determine the number, type and trip frequency of vessels that will be used during this phase. A conservative estimate of 1% of all wind turbine blades requiring replacement over the 35-year lifespan of the Project has been applied.

The number of maintenance vessels and their respective trips has been calculated by the design team and modelled on the worst-case assumption that all these vessels will require diesel fuel to operate, but with a decarbonisation rate applied year on year as noted above in section 3.3.3.

It should be noted that the load factor for the production of electricity from the wind turbines (based on industry research) does include a maintenance and repair factor when being calculated. 

A quantification of operation and maintenance GHG emissions has been calculated using the Atkins’ Carbon Knowledgebase tool, as described above in section 3.3.3.

3.3.5.             Significance Assessment

The method of assessment of whether the calculated GHG emissions from the Project will have a significant effect on climate has been determined in accordance with IEMA’s 2022 guidance. There is no legal limit for GHG emissions for any one development. The guidance suggests that the level of significance should be related to how a project contributes to reducing GHG emissions relative to a comparable baseline consistent with a trajectory towards net zero by 2050, as stated in section 6.2 of the guidance: “The crux of significance…is not whether a project emits GHG emissions, nor even the magnitude of GHG emissions alone, but whether it contributes to reducing GHG emissions relative to a comparable baseline consistent with a trajectory towards net zero by 2050.”

The IEMA 2022 guidance document notes that practitioners need to consider whether project GHG emissions are aligned to achieving net zero by 2050, using the science based 1.5°C trajectory.  Where this is not the case, then the effects are judged to be moderate adverse or major adverse, and thus can be classed as a significant effect. Projects that are compatible with the trajectory can have their effects classed as minor adverse, or where the project achieves GHG emission mitigation that goes beyond the trajectory, negligible. In both cases, the effects are not considered to be significant. Projects that result in GHG emissions being avoided or removed from the atmosphere can be considered to have a significant beneficial effect.

The percentage contribution of the Project to the national carbon budget has been determined in accordance with IEMA 2022 guidance on significance. Although the IEMA guidance suggests that for context, it would be good practice to consider a project’s GHG emissions in relation to sector-based targets, there are currently no sector budgets for electricity generation or any other sector, provided by the UK Climate Change Committee, the body responsible for developing the UK and devolved administrations’ carbon budgets. Sector-based targets have therefore not been considered in accordance with current UK legislation.

3.3.6.             Limitations and Assumptions

The key limitation of the Effect on Climate assessment is the information available within the Project Design Envelope to enable estimations of GHG emissions at the time of the assessment. This has required assumptions to be made, and some industry standard data to be used as a proxy. The following assumptions have been made during the carbon assessment:

• Carbon factors are drawn from the Inventory of Carbon and Energy (ICE versions 2.0 and 3.0);
• The Project will start construction in 2025 and finish by Q4 2032;
• The first partial operation of the Project will commence in 2028, with the Project becoming fully operational in Q1 2033;
• The Project will be operational for 35 years;
• There will be a maximum of 239 wind turbines with an individual generating capacity of up to 18 MW. This wind turbine option is considered the worst-case scenario based on all the possible wind turbine options considered in the Offshore EIA Report. There would be no material change in the assessment outcome if another wind turbine option was used as part of the Effect on Climate assessment;
• The material composition and component weights of the wind turbines are referenced from the Vestas V164 9.5 MW offshore wind turbine (Vestas, 2022) and Smoucha et al. (2016);
• All wind turbine components are assumed to be manufactured in Asia under a worst-case scenario, and transported to the site via sea routes;
• The Project will have up to ten Offshore Substation Platforms/Offshore converter station platforms, eight weigh 2,500 tonnes each and 2 weighing up to 10,000 tonnes each;
• The load factor for the Project is assumed to be 40.22%. This is the current industry average for offshore wind (RenewableUK, undated)[6]. This is considered conservative and likely to increase in future due to inclusion of actual site wind data measurements, improvements in wind turbine technology and associated operation and maintenance activities that are included in the load factor. Hence the load factor for the Project is likely to be higher once the Project is operating;
• Data has been extrapolated from shipping surveys undertaken as part of the Navigational Risk Assessment for the offshore Proposed Development (volume 3, appendix 13.1) to inform part of the assessment. Surveys were undertaken in June 2020, January 2021 and August 2022. The June 2020 and January 2021 survey data were considered for the assessment. Survey data from August 2022 indicated that the August 2022 findings are not significantly different to those obtained in the previous survey;
• GHG emissions from shipping will decrease at a steady rate year-on-year until reaching net zero in 2050 due to the anticipated decarbonisation of shipping vessels in line with the UK government’s net zero legislation (UK Chamber of Shipping, undated);
• It is assumed as a worst case that all fuel used in vessels operating at the site will be diesel in the offshore Proposed Development’s first year of construction, and a year on year decarbonisation rate has been applied to these vessels as required to reach the UK Government’s net zero by 2050; and
• It is assumed that no wind turbine nacelle or tower components will need to be replaced during the operation and maintenance phase of the Project. A conservative estimate of 1% of all wind turbine blades requiring replacement over the 35-year lifespan of the Project has been applied.