ecological significance of electromagnetic fields generated by the offshore wind industry ewec,...
TRANSCRIPT
Ecological Significance of Electromagnetic Fields Generated by
the Offshore Wind Industry
EWEC, Athens
2nd March 2006
Ian Gloyne-Phillips, CMACS Ltd;
Andrew Gill, Cranfield University; Yi Huang, Liverpool University
EWEC March 2006
Overview of Presentation
• Electromagnetic Field (EMF) generation
EWEC March 2006
Overview of Presentation
• Electromagnetic Field (EMF) generation
• Why EMF is an environmental concern
EWEC March 2006
Overview of Presentation
• Electromagnetic Field (EMF) generation
• Why EMF is an environmental concern
• What we are doing to address this issue
EWEC March 2006
EMF Generation
Typical Submarine Power Cable
EWEC March 2006
Electric Field (E field)
Magnetic Field (B field)
Induced Electrical Field
(iE field)
the E field will be retained within industry-standard cables
the B field is detectable outside the cable...
...and induces a second electric field outside the cable
Electromagnetic Field (EM field)
EMF Generation
EWEC March 2006
Why is EMF a concern?
EWEC March 2006
Because certain marine organisms may be able to
detect electromagnetic fields from submarine power cables
or offshore substations
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EMF Detection by Marine Organisms
• Electric field sensitivity
• specialised electroreceptors (elasmobranchs)
EWEC March 2006
EMF Detection by Marine Organisms
• Electric field sensitivity
• detection of voltage gradients (jawless fish and some bony fish)
EWEC March 2006
EMF Detection by Marine Organisms
• Magnetic field sensitivity
• induced electric field detection
(elasmobranchs and some bony fish)
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EMF Detection by Marine Organisms
• Magnetic field sensitivity
• magnetite based detection
(e.g. salmonids, Cetacea, Chelonia)
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Evidence of EMF detection
• Experimental studies
• adult behaviour, egg/larval development
• Observational evidence
• sharks biting cables
• apparent reactions to power cables
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Potential Impacts of EMF
• Affect orientation
• Disruption of migrations
• Attraction/repulsion of animals
• Egg/larval development impacts
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Potential Impacts of EMF
• Particular concern for elasmobranchs
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Potential Impacts of EMF
BUT it is uncertain:
1. if 50 Hz fields of a magnitude produced by submarine power cables are detected
2. if so, whether there is any adverse impact
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…EMF is an issue for the offshore renewables industry because as a potential environmental impact it is a matter of concern to environmental regulators…
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…and can therefore affect the consenting of offshore developments…
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So What are We Doing?
• Improving understanding– EMF modelling– Experimental studies with animals
• Field measurements of EMF
• Monitoring existing offshore wind farms
• Planning comprehensive research
• Negotiating with regulators
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Example Model Scenario(current density)
Cable x-section (internal) Cable x-section (external)
Sea bed
20m
1m
Cable x-section (internal) Cable x-section (external)
Sea bed
20m
1m
internal E field induced E field
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Key Outputs of Modelling
• Magnetic fields up to 1.6 µT (micro Tesla)NB the geomagnetic field is c. 50 µT
EWEC March 2006
Key Outputs of Modelling
• Magnetic fields up to 1.6 µT (micro Tesla)– cf the geomagnetic field (c. 50 µT)
• iE fields of tens of µV/m (micro Volts/m)– Modelled range 2.5 – 91 µV/m
EWEC March 2006
Key Outputs of Modelling
• Magnetic fields up to 1.6 µT (micro Tesla)– cf the geomagnetic field (c. 50 µT)
• iE fields of tens of µV/m (micro Volts/m)– modelled range 2.5 – 91 µV/m– within the range which may be attractive to
sharks, skates and rays (elasmobranchs)
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Experimental Studies
S a l t b r i d g e e l e c t r o d e
E l e c t r i c c i r c u i t
S a l t b r i d g e e l e c t r o d e
E l e c t r i c c i r c u i t
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Field Measurements of EMF
• Portable E and B field probes
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Field Measurements of EMF
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50 60 70 80
distance from start (m)
EM
F (
uV
/m)
import/export cables
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Field Measurements of EMF
• Field measurements have supported modelling results
EWEC March 2006 Photo courtesy Npower Renewables
Monitoring Wind Farms
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Monitoring Wind Farms
• Fishing surveys
• results of current programmes are unclear in terms of EMF
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Future Investigations
• Further laboratory work
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Future Investigations
• Further laboratory work
• Mesocosm study– control EMF and track fish within a large
experimental enclosure
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Future Investigations
• Further laboratory work
• Mesocosm study
• Large scale tracking study
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The Consultant’s Dilemma
…there are grounds for concern but a lack of good evidence and developers want certainty
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How we can proceed now
• Get some answers– requires industry and regulator support
EWEC March 2006
How we can proceed now
• Get some answers– requires industry and regulator support
• Adaptive management– pragmatic progression of developments
EWEC March 2006
How we can proceed now
• Get some answers– requires industry and regulator support
• Adaptive management– pragmatic progression of developments
• React to knowledge as we gain it
