Sectoral marine plan for offshore wind energy: context report

Explains the background and more recent developments in offshore wind.

6 Updating the Sectoral Marine Plan for Offshore Wind

6.1.1 The UK is the current market leader in offshore wind power, with around 5.8 GW of installed capacity by the end of 2017, all of which consists of conventional fixed-bottom foundation technology located in relatively shallow water depths (<40 m) and near to shore (<30 km). As installed capacity increases and the opportunities in shallow near-shore sites is exhausted, projects will need to be developed further from shore and in deeper water, which will pose greater technical challenges and potentially constrain efforts to reduce costs.

6.1.2 In response to this challenge the industry is considering the potential for deep water offshore wind foundation technology to unlock deep water sites at a competitive cost of energy. Scotland has natural advantages in terms of a combination of high wind speeds and abundant deep water sites.

6.1.3 The potential availability of deep water sites may also assist in addressing potential constraints associated with visual intrusion, commercial fishing and shipping. Deep water sites may also offer fewer potential interactions and impacts associated with seabirds, fish spawning and nursery grounds. Conventional offshore wind technologies rely on fixed foundations and are limited to water depths of less than 40 m. Given the need to avoid unacceptable visual impact this has often led to the siting of offshore wind farms on offshore sandbanks which are also of particular importance to seabirds and marine mammals. By avoiding such areas, deep water wind has the potential to significantly reduce interactions with seabirds and marine mammals.

6.1.4 In addition, some deep water wind technologies avoid the need for noisy installation activity such as percussive piling, which may cause disturbance to marine mammals and fish. Deep water wind technologies may therefore be more environmentally acceptable, particularly when located near to areas of functional importance to marine mammals or fish.

6.1.5 The siting of offshore wind technologies further offshore into deeper waters may offer the potential to reduce impacts and disruption of commercial fishing activity, particularly the smaller vessel inshore fishing fleet operating within 12 nautical miles. The development of deep water wind also provides an opportunity to further develop offshore wind supply chains and to lever existing infrastructure and supply chain capabilities from the offshore oil and gas industry and creating the requisite conditions to position Scotland as a world leader in deep water wind technologies

6.1.6 There now exists the opportunity for Scottish Ministers’ to review the Draft Sectoral Plan for Offshore Wind Energy and undertake a strategic planning process to ensure the spatial strategy is in place to enable the successful development of this sector, to include deep water wind technologies with commercial scale developments potentially coming on line from the mid-2020s onwards.

6.1.7 A range of different technologies have been proposed for floating/deep water offshore wind [24] (Figure 2):

  • Semi-submersible platform: Buoyancy stabilised platform which floats semi-submerged on the surface of the ocean whilst anchored to the seabed with catenary mooring lines
  • Spar-buoy: a cylindrical ballast-stabilised structure which gains its stability from having the centre of gravity lower in the water than the centre of buoyancy
  • Tension leg platform: a semi-submerged buoyant structure, anchored to the seabed with tensioned mooring lines, which provide stability.

6.1.8 These technologies all have different strengths and weaknesses and may be appropriate in different conditions. Over time, further technologies may become available for deployment in deep water.

6.1.9 The Sectoral Plan for Offshore Wind Energy will include areas for both conventional and deep water wind technologies. However, the Plan will be technology neutral with technology preferences determined by the market.

Figure 2: Floating wind foundation typologies [25]

Figure 2: Floating wind foundation typologies

6.1.10 In Scotland, there are extensive deep water locations to the east, north, and west of the country, with more than a 100 GW offshore wind potential located in water depths exceeding 60 m. However there are other sector interests in Scottish waters that will need to be considered as well as environmental ecosystem processes that need to be taken into account when planning sectoral development.

6.1.11 The Sectoral Plan for Offshore Wind Energy will include areas for both conventional and deep water wind technologies. However, the Plan will be technology neutral with technology preferences determined by the market. An initial plan of several GW would help to maintain and develop grid strategy, supply chains and create a climate for potential further exploitation of deep water wind resources in the longer-term.

6.1.12 Marine Scotland has undertaken work to define a number of Areas of Search (AoS) (Figure 3). These AoS will be refined through the development of Regional Locational Guidance ( RLG) to identify Draft Plan Option Areas ( DPOs).

6.1.13 The development of the Sectoral Plan for Offshore Wind Energy will follow the Scottish Government’s sectoral marine planning process (see Figure 4). This will include Strategic Environmental Assessment, Socio-economic Impact Assessment (including Scenario Mapping as required by the Scottish National Marine Plan) and Habitats Regulations Appraisal as part of an overall Sustainability Appraisal together with extensive informal and statutory public consultation set out in Public Participation Statements and reported upon within Consultation Analysis documents.

Figure 3: Areas of Search for future Offshore Wind Development [26]

Figure 3: Areas of Search for future Offshore Wind Development

Figure 4: Sectoral marine planning process [27]

Figure 4: Sectoral marine planning process


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