Ecological impact assessments - the case for offshore windfarm proposals

Orsted Power (UK) Ltd are responsible for the development, construction and operation of offshore windfarms across Europe. Hornsea Project Three has been proposed in the North Sea, off the North Norfolk Coast, with the potential to be generating up to 2,400 MW of electricity, the average daily needs of approximately 2 million UK homes.  

Developers  responsible for the Hornsea Three project, were required to undertake a subtidal benthic ecology characterisation study, comprised of both desk-based assessment and designated site surveys, of the proposed Hornsea Three site and surrounding area within the zone of potential impact, as requested by the UK’s relevant statutory consultees for projects of this nature. Data gathered from the Hornsea Three site were compared with data from the southern North Sea, to provide a basis for evaluating the importance of habitats and species as ‘valued ecological receptors’ for consideration in future impact assessments, as there was very limited baseline ecology data available for the study area.  Users therefore needed access to as much data as possible on the benthic environment of the comparative control North Sea area, in order to draw valid conclusions from their study of the proposed development area.     

EMODnet Seabed Habitats broadscale predicitve mapping via (EUSeaMap 2016) including habitat data and associated environmental variables were available offering full coverage for both the Hornsea Three benthic ecology study site and across the wider southern North Sea, allowing for good comparison between study areas. This information fed into the Ecological Impact Assessment, alongside datasets from other providers which were more limited in their coverage, meaning that EUSeaMap 2016 was able to fill in gaps in other existing data. The application has since been accepted by the Planning Inspectorate, with consent decision being expected in 2020. 

The EUSeaMap 2016 was also used in the nearshore biotope mapping review, identifying habitats and biotopes within the Hornsea Three cable corridor, covering the entire nearshore area.  Boundaries between biotopes were drawn using bathymetry and broad-scale habitat mapping products.    

Thanks to EMODnet Seabed Habitats, assessors were able to characterise the benthic ecological resources in the zone of potential impact, providing up-to-date evidence to the consultation and highlighting the significance of impacts of the maximum design scenario.

Kite surfer near a UK offshore wind farm © Orsted Hornsea Project Three (UK) Ltd., 2018