Offshore windfarms - monitoring impacts on the commercial fishing industry: good practice guidance
Good practice guidance for offshore wind developers on how to monitor the impacts of offshore wind farms on the commercial fishing industry. This includes how to identify appropriate monitoring datasets, develop monitoring methodologies and to identify the best means of disseminating outputs.
Appendix F Overview of owf types
F.1 Fixed offshore wind
Fixed offshore wind turbines have foundations which are fixed to the seabed, supporting the main body of the infrastructure. Fixed turbines are usually deployed in water depths between 50 m – 70 m (Jiang, 2021). The type of foundation used is influenced by the seabed type and the water depth (Bhattacharya, 2019). The deepest installed fixed wind turbine in Scotland is a Seagreen turbine at 58.7 m (Seagreen, 2023). There are different types of offshore wind turbine foundation, which include monopiles, gravity bases or jackets/tripods (OWIC, 2021) (Figure 7‑8).
The commercial fisheries impact assessments of certain projects using fixed wind turbines highlight that displacement to fishers will be temporary and activities will be able to recommence within the area (Scottish Government, 2022b). It is assumed that certain changes may be required to the fishing gear being used and the skipper’s perception of safety of the vessel to prevent impacts such as collision or snagging (Scottish Government 2022; West of Orkney, 2023).
F.2 Floating offshore wind
Floating offshore wind turbines are generally used in deeper water, typically over 60 m due to the technical and financial constraints associated with building fixed turbines at these depths. Floating turbines have a buoyant structure and are held in place with mooring lines. There are various types of floating turbines, such as spar, semi-submersible/barge, and tension leg platform (OWIC, 2021).
The typical length of anchor chains can exceed 1000 m; therefore, floating turbines require a larger spatial footprint compared to fixed-bottom turbines. Due to the mooring line spread it is anticipated that, during the operational lifetime of a floating project, fishing activities could be limited between floating installations.
Figure 7‑9 Floating turbine foundation types (Edwards et al., 2023).
F.3 References
Bhattacharya, S., 2019. Design of foundations for offshore wind turbines. John Wiley & Sons.
Edwards, E. C., Holcombe, A., Brown, S., Ransley, E., & 1others. 2023. Evolution of floating offshore wind platforms: A review of at-sea devices. Renewable and Sustainable Energy Reviews. DOI: 10.1016/J.RSER.2023.113416.Jiang, Z., 2021. Installation of offshore wind turbines: A technical review. Renewable and Sustainable Energy Reviews, 139, p.110576.
Offshore Wind Industry Council (OWIC). 2021. Pathways to Growth – Offshore wind in the UK. Available at: OWIC website [Accessed January 2024]
Scottish Government. 2022b. Scottish Sea Fisheries Statistics 2021. Available at: Scottish Government website [Accessed January 2024]
SeagreenWind Energy. 2023. Scotland's largest offshore wind farm is now operational. Available at: Available at: Vattenfal website
West of Orkney. 2023. West of Orkney Windfarm Offshore EIA Report Volume 1, Chapter 14 - Commercial Fisheries. Available at: Marine Scotland website
Contact
Email: ScotMER@gov.scot