Offshore wind energy: draft sectoral marine plan

The Plan aims to identify the most sustainable plan options for the future development of commercial-scale offshore wind energy in Scotland.

3. Impact assessments

Sustainability Appraisal ("SA") has been undertaken on the DPOs, comprising of a Strategic Environmental Assessment ("SEA"), Habitats Regulations Appraisal ("HRA") and Social and Economic Impact Assessment ("SEIA"). The findings are set out in the individual SEA, HRA and SEIA reports and summarised in the overall SA report. These reports are available to view and comment on separately and are outlined below.

In addition, draft Regional Locational Guidance ("RLG") has been prepared for the DPOs, to support further spatial planning and inform project-level site selection and assessment. The draft RLG is also available for review and comment as part of this consultation process.[20]

The assessments have been undertaken in accordance with the European Commission Directive and the Scottish requirements for Strategic Environmental Assessment,[21] the Habitats and Birds Directives[22] and the requirement to consider social and economic factors under the UK Marine and Coastal Access Act 2009, and in accordance with the methodology agreed by the two cross-sectoral Steering Groups (outlined in the Scoping documentation).[23]

The likely significant effects during all phases of offshore wind development, including pre-construction (e.g. unexploded ordnance clearance and survey works), construction, operation and maintenance and decommissioning, have been considered. In order to complete the assessment of potential impacts, a number of underpinning assumptions have been made (these are set out in full in the various assessment reports) but are summarised briefly at section 3.1.

3.1 Underpinning assumptions

The assessment has been undertaken on a technology neutral basis, as it is currently unclear how quickly and to what extent deep water technologies will become cost competitive and, therefore, what the balance of deployed technologies may be. Whilst the precise nature of technology and construction method(s) etc. have implications for the scale and nature of potential impacts, it is not appropriate to make detailed assumptions about these within the assessments. The draft Plan identifies DPOs located in a range of water depths, but does not direct what type of technology or technologies should be deployed within the individual DPOs. Full details on the range of technologies and methods assessed were set out in the Scoping Context Report.[24]

The impacts of individual DPOs have been assessed using a realistic maximum deployment scenario for each DPO, which equates to a proportion of the overall area of the DPO. This proportion varies according to the size and conditions of the DPO and has been derived from known constraints on development, early indications as to likely developer interest and established infrastructure to support development during the plan timescale.

Development within DPOs should not exceed the parameters assessed in the Sustainability Appraisal, e.g. meaning that operational development(s) within a DPO should not exceed the maximum realistic development scenario for that DPO (as outlined in Table 1 below and Appendix C of the SEA). The regional scenarios presented have been used in the assessment to provide an indication of potential impacts, however, these regional scenarios will not be used to constrain potential levels of operational development within DPOs.

In addition, the impacts have been assessed at regional and national levels using a range of overall deployment scenarios (3, 5 and 10 GW at a national level). This range of development scenarios has been used within the SEA, HRA and SEIA to assess a wide range of impacts and reflect the inherent uncertainty in carrying out strategic assessments and the possible scales of development within each DPO, regionally and nationally. These figures are outlined in Table 1.

A recent review of the density of offshore wind turbine layouts of recent European offshore wind projects, indicated average deployment densities of between 4-6.5 MW/ km2,[25] and, therefore, an average deployment density of 5 MW/ km2 has been assumed in the assessment. When this average deployment density is applied, it is estimated that approximately 2,000 km2 of seabed would need to be operationally developed to deliver up to 10 GW of generating capacity.

Implications of development scenarios for the first cycle of ScotWind Leasing

The development scenarios outlined in the Sustainability Appraisal equate to the operational development of approx. 2,000 km2 of seabed to deliver up to 10 GW of generating capacity.

It is recognised, however, that due to the nature of the leasing and development processes and likely attrition rates,[26] Crown Estate Scotland will need to offer Option Agreements for an area of greater than 2,000 km2 to be likely to enable the operational development of up to 10 GW of generating capacity.

Making an area of up to 8,600 km2 of seabed available for Option Agreements via the first cycle of ScotWind Leasing could, therefore, support the development of projects capable of delivering up to 10 GW of total generating capacity.[27]

It should be noted, however, that the total generating capacity installed in leased areas of seabed arising from option agreements awarded in the first cycle of ScotWind Leasing should not exceed 10 GW and the parameters of any proposed developments within a DPO should not exceed the maximum realistic development scenario assessed for that DPO in the Sustainability Appraisal.

Figure 7 Implications of development scenarios for the first cycle of ScotWind Leasing

Table 1 Summary of maximum realistic development scenarios (DPO, regional and national levels)

Region DPO Total DPO Area (km²) Realistic maximum development scenario for DPO (GW) Realistic development as percentage of total DPO Area Regional Low Scenario (GW) Regional Medium Scenario (GW) Regional High Scenario (GW)
East E1 3816 3 16%
E2 1287 2 31%
E3 474 1 42%
Sub-total 5577 6 1 2 3
North East NE1 776 2 52%
NE2 464 1 43%
  NE3 339 1 59%
  NE4 440 1 45%
  NE5 496 1 40%
  NE6 699 2 57%
  NE7 1027 3 58%
NE8 401 1 50%
Sub-total 4641 12 1.5 3 4.5
North N1 1163 2 34%
N2 560 2 71%
  N3 1106 2 36%
N4 200 1 100%
Sub-total 3030 7 1 2 3
West W1 1107 2 36%
Sub-total 1107 2 0.5 1 2
South West SW1 292 1 68%
Sub-total 292 1 0.3 0.6 1
Total: 14646 28 4.3 8.6 13.5
Scaled back to national scenarios (GW): 3 5 10

3.2 Strategic Environmental Assessment ("SEA")

SEA is intended to increase the consideration of environmental issues during decision-making related to strategic documents such as plans, programmes and strategies. For the draft Plan, it has been used to test and comment on the selection of DPOs from a strategic perspective and to identify potential strategic environmental constraints, in order to steer future development. The process is applicable to strategic and, to some extent, regional issues.

As a result, the SEA findings have led to broad recommendations for the draft Plan as a whole. The findings can also, where appropriate, be used as a starting point for further, detailed, data collection and environmental assessment – either to support strategic level review or for project-level assessment. A summary of the key findings for each DPO are set out in section 4.

The SEA is available here:

3.3 Habitats Regulations Appraisal ("HRA")

It was identified at the pre-screening stage that HRA would be required, as the possibility of likely significant effects on European site(s) from the Plan could not be excluded (either as a result of development within a DPO in isolation or in-combination with other plans or projects). Details of the HRA screening process are included in the Sectoral Marine Plan for Offshore Wind Energy: Strategic Habitat Regulations Appraisal Pre-Screening Report.[28]

The HRA has included consideration of impacts on Special Areas of Conservation ("SAC"), candidate and possible SAC ("cSAC and pSAC"), Special Protected Areas ("SPA"), proposed SPA ("pSPA"), Sites of Community Importance ("SCI") and Ramsar sites (listed under the Ramsar Convention on Wetlands of International Importance). HRA has been undertaken for all DPO within the Plan and has resulted in the implementation of plan-level mitigation measures to avoid potential adverse impacts on site integrity, as well as recommendations for project-level mitigation measures. A summary of the key findings for each DPO are set out in section 4.

The HRA is available here:

3.4 Socio-Economic Impact Assessment ("SEIA")

The SEIA has considered the potential negative and positive social and economic impacts of the Plan on a range of sectors. Due to uncertainties regarding the potential scale of development within any DPO, regionally or nationally, assessment has been undertaken for a range of deployment scenarios (ranging from low-medium-high), which have been compared to the do nothing approach. The SEIA has also been undertaken on a worst case scenario basis, given the uncertainty around development and technology types at a plan level. More detailed project-level assessment will be required accordingly.

The SEIA identified that DPOs are most likely to have negative impacts on the commercial fisheries, commercial shipping, tourism and recreation sectors. The SEIA also identified that development may also have impacts for other sectors (such as the defence and aviation sectors). The SEIA therefore identified a range of possible project-level mitigation measures, such as; 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. Positive impacts in relation to Gross Value Added and employment, including social impacts, were also assessed in the SEIA. A summary of the key findings for each DPO are set out in section 4.

The SEIA is available here:

3.5 Sustainability Appraisal ("SA")

SA is a tool to undertake cross-sectoral assessment of the impacts of plans, in order to promote sustainable development and has been an integral part of the every stage of the planning process. The SA has contributed to the Scottish Ministers' decision-making process and the SA report provides an overview of the conclusions of the component reports (i.e. SEA, HRA and SEIA).

The SA is available here:

3.6 Consultation Analysis Report ("CAR")

Extensive stakeholder consultation has been undertaken throughout the planning process to support and identification of DPOs and the development of the draft Plan. During June to July 2018, a consultation exercise on the Scoping Areas of Search and supporting screening and scoping reports was undertaken and the feedback used to further refine the O&C Model and identification of revised AoS. Further stakeholder engagement was undertaken post-scoping to support the identification of DPOs. The CAR provides a summary of the feedback received during the scoping and post-scoping periods. A further report, detailing the outcome of this consultation exercise, will be published with the final Plan.

The CAR is available here:

3.7 Supporting partial impact assessments

Draft partial Islands Communities Impact and Equalities Impact Assessments have been prepared, to consider how the draft Plan may impact on island communities and equalities considerations These partial assessments are available to view as separate documents and views are sought on whether these partial assessments have identified all potential impacts.

These partial impact assessments are to view available here:



Back to top