The visual impact of a Pelamis machine or wave farm is driven by the need to balance safety of marine traffic with the aesthetic effects on the coast and seascape.
Pelamis Machines at Sea
Image to scale. Figures reference: Scottish Health Survey, 2008
Each Pelamis machine is 180m long, with a tube diameter of approximately 4m. When installed offshore, around 60% of the machine sits below the surface of the water. In total, approximately 1.68m of the machine is visible above the sea surface.
Being semi-submerged means that Pelamis machines have a low profile.
As Pelamis machines extract the maximum wave energy in depths above 50m, wave energy farms will be located at least several miles offshore, further reducing the visibility to any coastal viewers.
The photograph to the right shows the Pelamis prototype machine installed at the European Marine Energy Centre in Orkney. It was taken from the top of Black Craig cliffs which stand just over 100m high, with the machine about 2 nautical miles from shore.
The sensible siting of Pelamis wave farm sites is an important part of site development activities, factoring in navigational sensitivities and use of the area by other sea users.
Like any structure in the sea, Pelamis machines need to be marked and lit to ensure visibility to marine traffic. The current painting, lighting and marking scheme is defined by the National Lighthouse Board of Scotland to ensure each Pelamis machine in a wave farm is visible in all conditions, at all times of day, and in all sea conditions.
Safety recommendations integrated into our design include painting each machine in a red and yellow colour scheme to maximise visibility at sea, radar reflectors and lighting each machine for identification in the dark. Two lights are installed on each machine, visible at a specific distance (currently 2 nautical miles), and flash at a certain frequency to ensure passing vessels can identify machines at night. Future wave farms of Pelamis machines will be marked and lit at the boundaries with cardinal markers.
Pelamis machines will be lit to ensure visibility at night. Image courtesy of E.ON UK and ScottishPower Renewables.
Cables coming ashore will be buried and a small substation will step up power for onward export to the grid. The substation will be designed and built in line with normal planning regulations and will incorporate design mitigation to reduce visual and landscape impacts where required.