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Wave Dragon and the environment 

Wave Dragon is a clean power generation technology even compared to other renewables:

  • Very low visibility; Wave Dragon can be compared to a moored ship and will have a maximum height above mean sea level of 7 meters
  • Modest "footprint" on seabed from anchor block and the power cable duct
  • No noise
  • No risk of spill; all hydraulic oils have been replaced with water hydraulics, no toxic antifouling is used

Potential environmental impacts and mitigating measures

Below are listed construction, operating and decommissioning activities associated with the Wave Dragon technology. For each activity potential environmental impacts are stated as well as the associated mitigation measures.

Various studies and guides for offshore wind farms have been used in compiling this list for a Wave Dragon farm.

Construction

Activities

Potential impacts

Mitigation measures

Subsea cables

Temporarily affect the nature of sub tidal habitats in the cable duct. Comparable to effects known from e.g. offshore wind projects.

Identification of important habitats for fisheries, benthos etc. and avoiding laying cables in these areas.

 

Damage to archaeology sites.

Identify potential sites and avoid these.

Onshore cables

Temporarily affect the nature of shore habitats. Comparable to effects known from e.g. onshore wind.

Identification of important habitat or scenic places and avoid going onshore at these locations.

Installation of
mooring system

Temporarily affect the nature of sub tidal habitats. Effects are known from mooring of ships.

Identification of important habitats for fisheries, benthos etc. and avoiding deployment of mooring blocks in these areas.

Construction of
Wave Dragon

Wave Dragon will not be constructed on site but towed to the site from the dry dock where it is constructed.

A separate EIA will be made if a purpose build dry-dock is established. Sensitive areas will be avoided and the area re-established after use.

Vessels traffic
during installation

Installation of the mooring arrangement and deployment of the Wave Dragon units will cause an increased amount of traffic. Can affect sea birds
• Moulting
• Breeding
• Resting
Comparable to the effect known from existing vessel traffic.

Installation will be carried out with respect to the breeding, resting and moulting periods of sea birds species.

Operation and Maintenance

Activities

Potential impacts

Mitigation measures

Physical presence of
moored structures
at sea

 

 

 

 

 

 

 

Will have some impact on landscape and be visible.

The colour and design of the Wave Dragon structure will – to the extend possible with regard to marking requirements and to the operation of the Wave Dragon - be adjusted to minimise visual impact. Compared to wind turbines the visual impact will be low.

Effects on sea birds in periods of breeding, moulting and resting.

Due to the non-motional nature of the Wave Dragon negative effects are not likely. Impacts are studied in the present prototype project situated in a RAMSAR and EU bird protection area.

Positive effects on fish resources
• Will create a fishery exclusion zones
• Artificial reef effect will attract fish

No mitigating measures needed. See below.

Negative effect on fisheries.

Locations have to be chosen with respect to commercial and recreational fisheries.

Effects on mammals;both the back side of the arms, mooring buoys, the ramp and horizontal trash rag covering the reservoir will attract resting seals

Design will be adapted to the optimal solution for the seals.

Effect on navigation: Will affect the navigational use by commercial ships, fishing vessels and recreational boating.

Standard marking of the structures and the area: lights, colours, radar reflection. Wave Dragon farms will be located out of traffic zones.

Reduce marine debris and spill of oil from ships washed on shore. A substantial part of this debris will end in the reservoir.

No environmental mitigating measures needed.

Changes in the hydro physical regime due to extraction of energy from the waves may cause:
• Impact on coastal processes as erosion and sediment transport.
• Changes in the marine habitats
• Reduced recreational value, i.e. regarding surfing due to smaller waves.

Wave Dragon farms will extract energy from waves and to some extend changes the hydrodynamics behind a farm. Wave heights are initially estimated to be between 37 % to 22 % lower 1 km behind a Wave Dragon farm. Effect will be subject to generic and site specific hydrodynamic studies and the results from these will act as guidance in the site selection process.

Presence of
subsea cables
in seabed

Electromagnetism.

The subsea cables will be buried in the sea bed.

Operation of
the turbines

 

 

 

Fish and mammals will to some extend travel with the overtopping sea water into the reservoir. This may cause physical damages on fish and mammals from passage through hydro turbines.
Impact level: Permanent – low.

Establishing of a trash rag covering the total reservoir preventing fish and mammal access to the reservoir and turbine system (as known from traditional hydro power stations). Fish smaller than the openings in the trash rag will pass through the operating turbines. A turbine with a slow turning (300 rpm) propeller has been chosen.

Increased level of noise and vibrations may affects mammals dependent on sound for navigation.

Noise and vibration impact level will be low. If necessary measures to dampen these effects will be taken.

 

Areas with abundance of cetaceans will be avoided.

Leaking of hydraulic fluids.

Water hydraulic has been chosen to eliminate any possibility for leaks of oil to sea water. No other potential polluting fluids etc. onboard.

Presence of
mooring
arrangements

 

 

Mooring blocks on sea bed will locally affect the nature of sub tidal habitats

Identification of important habitats for fisheries, benthos etc. and avoiding deployment of mooring blocks in these areas.

Mooring chains moving on the seabed may damage the nature of sub tidal habitats

Design mooring arrangement in a way that chains are kept free of the sea bed.

Mooring arrangement – blocks, chains and buoys – may have an artificial reef effect with locally increased wildlife in quantity and diversity.

No mitigating measures needed.

Overhead-lines
and substations
onshore

Can reduce the aesthetic value of the landscape.

Landscape and visual assessment to identify route and location of infrastructure.

Maintenance

 

Offshore installations and machinery require regular maintenance. Wave Dragon is modularly built and components as turbines will be replaced on a regular basis for maintenance onshore. This will generate vessel traffic.

Maintenance will be carried out with highest possible respect to the breeding, resting and moulting period of sea birds species.

Maintenance on mooring arrangements, marking equipment and the Wave Dragon structure will be performed on site. This will generate vessel traffic.

Maintenance will be carried out with highest possible respect to the breeding, resting and moulting period of sea birds species.

Anti fouling

There will be emission from any toxic antifouling.

Toxic antifouling is not used, as the weight from fouling is not a problem. A non-toxic silicone based slippery coating is tested in the turbine system (turbine outlet) in the present prototype project.

Decommissioning

Activities

Potential impacts

Mitigation measures

Removal and
decommissioning
of WEC from site

No impact near the deployment site.

The structure will be towed to an appropriate site for re-cycling and decommissioning. Wave Dragon is designed and constructed in a way to ease recycling.

Removal of
mooring
arrangements

Will temporarily affect the nature of sub tidal habitats.

Available low impact techniques will be used.

Removal of
subsea cables

Will temporarily affect the nature of sub tidal habitats.

Available low impact techniques will be used.