Offshore wind energy - draft updated Sectoral Marine Plan 2025: consultation

Assessment Summary Findings

In order to understand the sustainability of the draft updated SMP-OWE, a sustainability appraisal for the draft updated SMP-OWE has been undertaken. This comprises various assessments of impact, outlined in the Plan Development Process section.

Assessment of plan level impacts has been undertaken in a broad and strategic manner, proportionate to the national-scale of the draft updated SMP-OWE. The assessments have been informed by the best available evidence at the time of assessment (September – December 2024) and are underpinned by a range of assumptions where information remains unknown. Project specific assessment of impacts that are undertaken as part of the licensing and consenting processes are expected to provide a greater level of detail.

Summaries of the key underpinning assumptions and key outcomes of plan level assessments can be found below.

It is expected that these plan level assessment findings will be considered in the licensing and consenting decision making process alongside the more detailed project specific assessments. Although there is no statutory relationship between plan level and project specific assessments, the plan level assessments can help set the framework for the more detailed project specific assessment of impact. By addressing potential impacts at a higher, more strategic level, plan level assessment can help streamline the assessment process of individual projects that will then focus on project specific details. Together, plan and project level assessment provide a comprehensive approach to understanding potential impacts of offshore wind development.

Underpinning Assumptions

The draft updated Plan is underpinned by a range of assumptions as part of the appraisal through the SEA, HRA AAIR, SEIA and NCMPA assessment. Together, these assessments have considered at a strategic level the social, economic and environmental effects at of development within the OAs covered by the draft updated SMP-OWE, as well as assessing the potential effects on protected sites and features. The assessments considered the most recent and up-to-date information available at the time of preparation (September – December 2024). This has provided a reasonable degree of certainty on the level of development to be progressed under the draft updated Plan (i.e. capacity). However, it is recognised that project level assessments will benefit from greater detail and certainty regarding project details.

To address uncertainty within the assessments, a precautionary approach has been taken, in line with the UK Withdrawal from the European Union (Continuity) (Scotland) Act 2021. Assumptions have been made to identify the potential impacts of the draft updated Plan in line with the required precautionary approach.

The underpinning assumptions are set out in full in each of the assessment reports and are summarised briefly below.

• Assessment period – The impacts were assessed over a 50-year period, from 2025 to 2074. The likely significant effects during all phases of offshore wind development, including pre-construction (e.g. unexploded ordnance clearance (UXO) and survey works), construction, operation and maintenance and decommissioning, have been considered. This period ensured that the assessments covered the likely period of construction of projects (expected from the mid-2020s to the 2030s) and for a period of at least 30 years thereafter. It was assumed it is possible that sites may be repowered, and impacts could continue after 25 years rather than decommissioned. Lease periods are 60 years for ScotWind projects, 50 years for TOG and 25 years for IN projects; and have been assessed for the 50-year period for consistency across the assessments.
• Timing of development - The timing of possible development within individual OAs or T&D projects is uncertain. Recognising uncertainty in timings and where this may occur, it has been assumed that multiple developments may happen at once in any given region (West, North, Shetland, North East, East). More detailed assumptions on the timing of development are provided in the SEIA^[5].
• Technology – Available information on technology and project details as of September 2024, when the assessments were undertaken, was used to inform the assessments. Where assumptions were required due to lack of project details (e.g. turbine size, blade tip/airgap, floating or fixed, footprint, construction methods), the SEA, HRA AAIR and NCMPA assessment took a worst-case scenario applied against each of the relevant receptors or interest features. The SEIA took technology choice into consideration where this may affect socio-economic impacts. There also may be impacts of technological advances that take place over time with respect to wind energy developments and any future upgrading of wind generating technologies in established areas.
• Spatial Footprint - Information on the area of the individual OAs was used and assumed to be a fixed maximum across the SEIA, SEA, HRA AAIR and NCMPA assessment. The total spatial footprint, of all OAs within the plan, is assumed to be 9,569 km² and the lower scenario assumed a 30% reduction in spatial footprint. Given the spatial footprint of the OAs cannot be exceeded, the higher scenario assumes there will be an increase in capacity through technology adjustments operating within the same area.
• Density – Where applicable for the assessments the intended installed capacity and overall spatial area covered by each OA has been used to determine the capacity density of each OA. It was assumed that there would be potential to microsite and spatially plan array development at a project level to minimise impacts within OAs with a capacity density less than 3.0 MW/km². Where relevant, the proportion of the OA occupied by offshore wind array was calculated by assuming a final turbine density of 5 MW/km².
• Capacity - For the draft updated SMP-OWE, a consistent set of scenarios for capacity (lower, central, higher) have been applied to consider benefits/risks and identify sensitivities. The central scenario of 37.4 GW is representative of the intended installed capacity and has been based on ScotWind Lease Option Agreements and INTOG EAs with CES and further updated in September 2024 where developers have publicly declared changes in capacities. It also includes a total of 1 GW generating capacity for T&D sites across Scottish waters. The lower scenario is 26.2 GW (-30%) and the higher scenario is 48.7 GW (+30%). A +30% figure was selected to reflect existing knowledge of project increases, with –30% chosen to reflect potential attrition.

Assumptions – Test and Demonstration Projects

Assessment of T&D projects has been at a high level in terms of location, as these projects have not been spatially defined. For the purpose of assessment, it is assumed that these sites are more likely to be located “inshore” as opposed to “offshore.” This is a precautionary approach, as impacts (e.g. visual impacts) would likely be greater if sites were inshore. The draft updated SMP-OWE however does not exclude the development of T&D projects offshore. It is assumed that due to their temporary nature, infrastructure should be removed once testing and demonstration operations have been completed.

Assumptions - Storage, Construction and Maintenance of Devices

At the time of assessment there is limited spatial data available for storage, construction and maintenance of devices proposals and, therefore, it is assumed that storage areas are likely to occupy several locations near the Scottish coast close to ports and key manufacturing hubs, and in sheltered waters.

Assumptions - Cables

Assessment of the potential impacts associated with the intra-array cabling and possible offshore substation connections has been included in the draft updated SMP-OWE assessment process, as it is assumed that these would be located within the OA boundary under consideration.

Key Outcomes of Plan Level Assessments

The Sustainability Appraisal (SA) Report summarises the key outcomes of the individual detailed reports (SEA ER, SEIA, HRA AAIR, and NCMPA assessment) that contributed to the assessment of the draft updated Plan to achieve sustainable development objectives. The SA Report outlines the approach taken by each assessment and highlights the key impacts (positive and negative) of the draft updated Plan on environmental, social and economic receptors. It presents the overall findings from the full assessments of the draft updated Plan and summarises the results of the above assessments to ensure compliance with relevant legislative requirements and adhere to best practice. The following provides a summary of the key effects identified on the environment, economy and other marine users and people, population and health and the main conclusions and next steps. Individual assessment summaries are provided in Annex C.

Key Environmental and Socio-Economic Effects Identified and Conclusions

The key potentially significant environmental effects identified include:

• Loss and/or damage of protected habitats;
• Effects on marine mammals and bird species, including potential mortality/injury, displacement or barrier effects;
• Effects on landscape and coastal character and also on visual receptors;
• Effects on navigational safety;
• Effects on historic environment features and their settings (W1 and N4 only);
• Effects on population and human health arising from noise, vibration, light and shadow flicker effects (N4 only);
• Effects on soil and water quality receptors as a result of changes in the hydrodynamic and sediment regime (N4 only); and
• Potential benefits in supporting the decarbonisation of the energy sector and the establishment of a secure energy supply in the UK are also identified.

Areas of key concern, and the issues most likely to constrain development from an environmental viewpoint, are the collision or displacement risk of birds, navigational risk and potential significant effects on landscapes and seascapes for developments located within 30 km of inhabited shoreline.

The SEIA identifies potential impacts (both positive and negative) on the economy, other marine industries and users and knock-on social effects on impacted communities.

Based on the assumptions applied, the plan level SEIA has calculated positive impacts relating to increased spend along the offshore wind supply chain estimated at £22,000 million to £28,000 million, supporting an estimated maximum 18,000 to 22,000 direct jobs in any one year.

Potential negative economic effects were quantified for commercial fisheries, power interconnectors and transmission lines, recreational boating, commercial shipping, telecom cables, tourism and water sports. It was not possible to quantify the potential negative economic impacts on sectors such as aquaculture; aviation; carbon capture, utilisation, and storage (CCUS); energy generation; military activities; oil and gas; and ports and harbours and so impacts to these sectors were assessed qualitatively. Implementation of the draft updated Plan has an estimated potential cost impact (relating to increased operating costs of other marine sectors) of £78 -111 million, and a potential negative economic impact (relating to loss of revenue of other marine sectors) of £100 million.

Positive impacts on people, population and health identified include job creation, access to higher-skilled roles, and training proposals. Communities may see long-term positive impacts on facilities and possible flood risk reduction as a result of increased spend and re-development in certain areas. Negative impacts associated with service demand increases, visual impacts and increased noise levels may also be experienced.

The following provides a summary of key conclusions. Detailed results, including recommended plan level and project level mitigations, are set out in the comprehensive assessment reports themselves.

The assessments recommend a range of plan level and project level mitigation measures. These can go some way to avoid and minimise negative effects of the draft updated Plan and promote beneficial effects.

The SEA results indicate that at a national scale, the draft updated Plan will have significant effects on the environment. The majority of adverse effects, however will not have a cumulative effect at a national scale beyond that identified at the individual site or regional level. The exception to this is the potential for moderate to major adverse effects on both resident and migratory bird populations due to collision or displacement. More specific detail in relation to impacts on protected sites is set out in the NCMPA assessment and HRA AAIR.

In addition, the development of the OAs at a national scale has the potential to have significant beneficial cumulative effects in terms of supporting a diverse and decarbonised energy sector and also contributing to a secure energy supply.

The NCMPA assessment concluded that draft updated Plan activities have the potential to significantly hinder the achievement of the conservation objectives of East of Gannet and Montrose Fields NCMPA and Norwegian Boundary Sediment Plain NCMPA. This is because it is considered unlikely or not possible to avoid the protected features of these NCMPAs. It sets out recommended project level mitigation measures that should be applied as far as possible to reduce impact. It is expected that development in TOG9 and TOG11 would be supported by a project specific NCMPA assessment to provide a more detailed assessment of impact.

The HRA AAIR concluded that, even with the provision of mitigation, several impact pathways remained for bird features in relation to the draft updated Plan alone and in-combination with other plans and projects. An AEOI is therefore concluded in the HRA AAIR. Key to this is the risk of effects on protected bird features from collision and displacement impacts. The next steps in the HRA process have been outlined under the section on the Development of the Final Plan.

Individual assessment summaries are provided in Annex C.