Marine Mammals and Tidal Turbines: Understanding true collision risk - - PowerPoint PPT Presentation

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Marine Mammals and Tidal Turbines: Understanding true collision risk - - PowerPoint PPT Presentation

Jun 08, 2023 305 likes •519 views

Marine Mammals and Tidal Turbines: Understanding true collision risk Carol Sparling, Mike Lonergan, Beth Mackey, Cormac Booth, Gordon Hastie, Doug Gillespie, Jamie MacAulay Thursday 1 st May EIMR Stornoway SeaGen, Strangford Lough, Northern

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Marine Mammals and Tidal Turbines: Understanding true collision risk

Carol Sparling, Mike Lonergan, Beth Mackey, Cormac Booth, Gordon Hastie, Doug Gillespie, Jamie MacAulay Thursday 1st May EIMR Stornoway

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SeaGen, Strangford Lough, Northern Ireland DeltaStream, Tidal Energy Ltd, Ramsey Sound

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SeaGen, Strangford Lough, Northern Ireland

  • Installed and commissioned in 2008
  • Generates at currents >1m/s;
  • Rotors diameter 16m ;
  • Rotates at a maximum speed of 14RPM;
  • Maximum tip speed is 12m/s;
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SeaGen, Strangford Lough, Northern Ireland

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Step 1: Conclusions of EMP: no significant impacts on marine mammals as a result of installation or operation of the turbine

AS LONG AS MITIGATION IN PLACE

Step 2: reassess risk of collision after 5 years of operation Step 3: carry out a Habitats Regulation Assessment

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Step 2: reassess risk of collision after 5 years

  • f operation

What is the close range encounter rate between seals and the turbine? Data sources:

  • Super SeaKing Sonar
  • Gemini Multibeam Sonar
  • Seal telemetry study
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Super SeaKing ‘mitigation’ scanning sonars Since August 2009

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Gemini Multibeam deployment May-July 2011

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/232963/OESEA2_SMRU_tracki ng_marine_mammals_around_renewable_devices.pdf

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Seal telemetry study March-July 2010

12 tagged harbour seals: rate of close transit

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10 20 30 40 50 60

  • 25
  • 20
  • 15
  • 10
  • 5

usage (%) depth (m)

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Encounter rates -

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Taking most precautionary encounter rates and collision probability, Non uniform depth distribution, 50% avoidance Estimated collision risk = 1 seal per month in summer 0.3 seals per month in winter

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How much can the population sustain?

Population now appears to be increasing Calculated PBR is 3.6 seals HRA ‘allows’ a 3 month trial over the summer

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  • Four Gemini multibeam sonars mounted on the cross beam

(to maximise vertical coverage of rotors).

  • Data on passage rates in the presence of an operating turbine (compare

these with previously estimated –refine collision risk

  • Evidence for evasion/avoidance???

70m 40m Side view Plan view

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Tidal Energy Ltd’s DeltaStream unit being deployed in Ramsey Sound

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Passive acoustic monitoring:

3D Hydrophone array: detection and localisation (tracking) of echolocating cetaceans around the device

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Active acoustic monitoring:

MULTIBEAM SONAR

Side view Plan view

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Dr Carol Sparling Principal Scientist

T: +44 (0) 1334 479100 M: +44 (0) 785 634 942 E: ces@smrumarine.com