Offshore wind energy - draft updated Sectoral Marine Plan: strategic environmental assessment

Overview

The SEA aims to ensure that decision-making and consultation on the draft updated Plan are informed by relevant environmental information. It identifies the likely significant environmental impacts of the draft updated Plan and proposes reasonable alternatives. It provides a high-level assessment of potential environmental effects that are likely to result from the development of offshore wind OAs and T&D projects that comprise the draft updated Plan. The SEA identifies the individual and overall (cumulative) effects of the draft updated Plan on various SEA topics that have been scoped into the assessment. The assessment also considers the effects of development on a series of key statements (SEA objectives). These objectives reflect the scope of the assessment as well as the environmental protection objectives from relevant legislation.

The development of the draft updated Plan has been an iterative process that has considered reasonable alternatives at each of the three stages of the assessment. This includes: reviewing the potential environmental effects associated with a range of alternative offshore wind and transmission technologies; applying the potential environmental effects identified in the first stage to the individual OAs within each region, as these different areas themselves constitute reasonable alternatives; and determining the potential cumulative environmental effects associated with differing scales of development (lower, central and higher development scenarios) in multiple alternative OAs at a regional and national level, and also in-combination with other plans and projects.

The SEA assessed each OA against several impact pathways that were scoped into the assessment. Based on the assessment, the key potentially significant environmental effects that arise from the implementation of the draft updated Plan 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 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);
• Effects on historic environment features and their settings (W1 and N4 only); and
• Potential benefits in supporting the decarbonisation of the energy sector and the establishment of a secure energy supply in the UK.

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 shorelines.

Regional cumulative effects include potential for adverse effects on protected habitats, migratory and resident bird populations, marine mammals, and navigation. At a national scale, all of the OAs are individually recognised as having potentially significant (i.e. above minor) adverse effects. The majority of effects, however, will not have a cumulative effect at a national scale beyond that identified in the individual site or regional assessments. 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. 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 SEA also identifies mitigation measures that are required to avoid or minimise any significant adverse effects and highlights opportunities for enhancements of beneficial effects. Both plan and project level mitigation measures that have been identified and may be implemented are detailed in the SEA ER.

Recognising the uncertainty that still remains about the precise design, technology, method and/or timescale for the development projects, comprehensive project level assessment will still be required for these developments against these specific details and the baseline environment at that location.

Please note this document is available as a PDF only from the above supporting documents section.