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TRANSCRIPT
COMBINED IMPACTS OF TIDAL STREAM
ENERGY ARRAYS
FINAL VERSION
29/09/15
Gemma Keenan and Frank Fortune (Royal HaskoningDHV)
CONTENTS
Contents ................................................................................................................ 3
1. Introduction ....................................................................................................... 2
1.1 Background ................................................................................................... 2
2. Potential Combined Array Level Impacts ................................................................ 5
2.1 Physical processes .......................................................................................... 5
2.2 Marine mammals ............................................................................................ 6
2.3 Ornithology ................................................................................................. 13
2.4 Fish ............................................................................................................ 14
2.5 Benthic ecology ............................................................................................ 17
2.6 Shipping and navigation ................................................................................ 17
2.6.7 Commercial fishing .................................................................................... 23
3 Conclusions ....................................................................................................... 24
4 References ........................................................................................................ 25
This project has been co-funded by ERDF under the INTERREG IVB NWE programme. The report
reflects the author’s views and the Programme Authorities are not liable for any use that may be
made of the information contained therein.
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1. INTRODUCTION
1.1 BACKGROUND
This report provides a review of the potential impacts associated with the deployment of
arrays of tidal stream energy devices, scaling up impact predictions based on data
collected for single device installations. This is done through a review of the
Environmental Statement (ES) documents for planned tidal arrays, as well as a review of
any available literature in relation to predicting array level effects. At the time of writing
no tidal arrays have been deployed and therefore there are no available field data in
relation to array level impacts.
There are currently a small number of planned tidal array projects, some of which have
been consented. This report focusses on European projects, with key tidal array
Environmental Impact Assessment (EIA) examples from the UK discussed further in
Section 2. These represent an important opportunity for the industry and regulators to
develop further understanding of the potential impacts of an array through strategic
monitoring.
1.2 CURRENT STATUS
Table 1 provides a list of key individual tidal devices that have been installed for varying
periods of time.
TABLE 1: EXAMPLES OF TIDAL ENERGY DEPLOYMENTS IN EUROPE
Company Device
Technology
Location Capacity
(MW)
Andritz Hydro Hammerfest HS1000 Fall of Warness, European
Marine Energy Centre
(EMEC)
Single
1MW
device
Alstom DeepGen Fall of Warness, EMEC Single
1MW
device
Marine Current Turbines
(now owned by Atlantis)
SeaGen S Strangford Lough, Northern
Ireland
Single
1.2MW
device
Minesto Deep Green Strangford Lough, Northern
Ireland
Single
0.5MW
device
OpenHydro Open Centre Fall of Warness, EMEC Single
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TABLE 1: EXAMPLES OF TIDAL ENERGY DEPLOYMENTS IN EUROPE
Company Device
Technology
Location Capacity
(MW)
Turbine (OCT) 0.25MW
device
Scotrenewables Tidal Power
Ltd
SR250 Fall of Warness, EMEC Single
0.25MW
device
Voith Hydro Ocean Current
Technologies
Hy Tide Fall of Warness, EMEC Single
1MW
device
Sustainable Marine Energy
(SME)
Plat-O Yarmouth, Isle of Wight Single
0.1MW
device
Nova Innovation Ltd Nova 30 Bluemull Sound, North Yell,
Shetland
Single
0.03MW
device
Nautricity CorMaT Sound of Islay, and
Falls of Warness, EMEC
Single
0.5MW
device
EDF/ OpenHydro OCT Paimpol-Bréhat, Brittany
France
4 x 2MW
devices
Andritz Hydro Hammerfest HS300 Kvalsund, Norway Single
0.3MW
device
Sabella D10 Ushant island, France. Single
1MW
device
1.3 PLANNED PROJECTS – SCALING UP TO ARRAYS
The following tidal arrays have been consented in the UK, but are not yet installed:
Scottish Power Renewables (SPR) Sound of Islay Tidal Demonstration Array
(10MW);
Atlantis Resource Ltd (ARL) MeyGen Phase 1 Tidal Array (36MW, on the condition of
installing Phase 1a (6MW) and undertaking environmental monitoring before full
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build out of the remaining Phase 1 capacity); and
Marine Current Turbines (MCT, now owned by ARL) Skerries Tidal Stream Array
(10MW).
In 2010, the Crown Estate (TCE) undertook the Pentland Firth and Orkney Waters (PFOW)
leasing round, aimed at the development of tidal arrays of 100MW to 400MW. However,
the ambitious scale of the projects invited through that leasing round did not match the
level of technology readiness within the tidal sector. It became apparent that a leap from
single devices or prototypes, to full scale commercial arrays, carried very high project
risk, particularly in the PFOW, which is an extreme environment to undertake installation,
operation and maintenance for any marine project.
In addition, Perpetuus Tidal Energy Centre (PTEC) Ltd, secured a lease for a 30MW
demonstration site to the south of the Isle of Wight in 2012. This project is in the consent
determination phase at the time of writing.
In 2014, TCE undertook another leasing round and agreed the following tidal stream lease areas, each with the potential to deliver an array of 10MW or greater:
EMEC - Stronsay Firth;
MCT (ARL) - the Mull of Galloway;
EMEC working with the Islay Energy Trust - Islay;
Wave Hub - North Devon;
MCT (ARL) - Portland Bill, Dorset;
MCT (ARL) - Strangford Lough (in addition to the existing SeaGen device in
Strangford Lough);
Menter Môn - West Anglesey, north Wales; and
Minesto - Holyhead Deep, north Wales.
These projects have yet to submit applications for consent, although some have been
through the scoping phase of EIA at the time of writing.
At the time of writing, in September 2015, a further leasing round for projects under 3MW
has been announced by TCE, which will open for bids from the 21/09/2015.
OpenHydro was selected in 2014 by EDF to install a 14MW array of OpenHydro’s OCT
device in Raz Blanchard in Normandy, France. Installation is planned for 2018.
Tidal Sails has a 4MW demonstration project in the Sami community of Kvalsund,
Northern Norway. The project has consent from the Norwegian Water Resources and
Energy Directorate (NVE), and a power purchase agreement with Hammerfest Energi,
Norway.
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2. POTENTIAL COMBINED ARRAY LEVEL IMPACTS
This section provides a desk based review of potential impacts from tidal arrays, based on
lessons learned from the impacts assessed for a number of tidal array project consent
applications. Available technical studies are also considered, as is the variation in
receptor sensitivity at different sites and associated variations in the significance of
impacts.
2.1 PHYSICAL PROCESSES Robins et al. (2014) provides modelling of sedimentary processes off north west Wales for
theoretic arrays of 10, 50, 100 and 300MW. The results show that arrays of 10 to 50 MW
in this location reduce velocities locally by only a few percent, and reduce bed shear
stress and bed load transport by only slightly more. Suspended load transport is relatively
unchanged, since arrays induce locally increased turbidity. These changes are small
compared to the range of predicted natural variability. The modelling shows arrays of
more than 50 MW may significantly affect sedimentary processes locally. Further afield
(e.g. 10 km from the modelled array location), it is unlikely that the impact of energy
extraction on bed shear stress will exceed natural levels of variability. Sedimentary
processes are highly site specific, based on waves, tides, sediment type, and morphology
and so should be assessed on device and site specific basis.
The PTEC EIA (Royal HaskoningDHV, 2014) considered a wide range of tidal device types.
To help define which devices represent the worst case scenario in respect of the physical
process environment, a series of wake assessments were undertaken for both individual
tidal devices and arrays of tidal devices up to 10MW arrays, based on the indicative
spacing rules defined in the Project Description. The modelling determined that the
greatest wake effect from an individual device (of the device types and parameters
included in the PTEC Rochdale Envelope) will be generated by a seabed mounted twin
rotor tower device type e.g. SeaGen S, with 24m diameter rotors and hub heights 20m off
the seabed (although it was noted that the envelope of wake effects from all
representative technology types was narrow). The greatest 10MW array scale wake
effects were also found to arise from an array of the device type with the greatest wake
(i.e. seabed mounted twin rotor device type e.g. SeaGen S). Other array scenarios were
shown to have either:
(i) the same capacity but different device types (and hence will cause lower array
scale wake effects);
(ii) lower capacity, with fewer tidal devices of the same type and rating (and hence
will cause lower array scale wake effects); or
(iii) the same capacity, with more tidal devices of lower ratings and smaller diameters
(and hence will cause lower array scale wake effects).
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2.2 MARINE MAMMALS Potential impacts on marine mammals are defined in a number of sources including Faber
Maunsell & Metoc (2007); Aquatera (2012); and Thompson et al. (2013). These outline
the following key impacts, which are discussed further in this section:
Collision risk (vessels and devices);
Underwater noise;
Entanglement with device moorings (if applicable);
Electromagnetic fields (EMF); and
Barrier effects/ habitat exclusion, including disturbance at haul out sites.
In addition, the following potential impacts may cause indirect impacts on marine
mammals. The primary impacts are discussed in other sections of this report:
Increased turbidity - which links primarily to potential changes in physical
processes (discussed previously)
Water quality – dependent primarily on risk of accidental contamination which can
link to shipping and navigation assessments (discussed further below) and potential
changes to physical processes (discussed previously)
Changes to prey resource – dependent on changes to fish and/or benthic ecology,
described below.
There are significant knowledge gaps in relation to how individual marine mammals may
respond to the potential impacts described above and what the population level
consequences may be. This is coupled, in some cases, with uncertainty in the baseline
characteristics as well as understanding of how marine mammals use tidal environments.
There are currently a number of strategic studies underway, for example in relation to
understanding how seals use highly tidal areas and how seals respond to the operational
noise of a tidal turbine.
EIAs are undertaken on the basis of the best available guidance and information, which is
progressing rapidly. This section provides a review of current information in relation to the
key potential impacts listed above.
2.2.1 COLLISION RISK
Uncertainty regarding the potential for marine mammal collision risk is potentially a key
constraint for tidal developments, where the location has high densities of marine
mammals or has unstable populations, vulnerable to potential loss of animals from death
or injury.
There is limited actual understanding of how marine mammals will interact with
operational turbines (single devices or an array) and what the consequence will be for an
individual if a collision occurs (i.e. what is the likelihood of injury, or death).
Telemetry data collected during three years of monitoring for the SeaGen device in
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Strangford Lough, Northern Ireland indicated some local avoidance of the device. Tagged
seals continued to transit past SeaGen but transited further away from the centre of
Strangford Narrows (where SeaGen is located) than they had during the baseline (pre-
installation) period. However individual seal behaviour variability among tagged seals
was high. During the same period, passive acoustic monitoring indicated that harbour
porpoise also continued to transit past SeaGen, moving between Strangford Lough and
the Irish Sea. (Marine Current Turbines, 2011)
Carcass studies during the SeaGen Environmental Monitoring Programme (EMP) showed
the device was highly unlikely to have been the cause of any marine mammal fatalities.
(Marine Current Turbines, 2011).
Similarly it should also be noted that there is no evidence to date of any interaction
between any marine mammal species and the turbines at the European Marine Energy
Centre (EMEC) since the first turbine was deployed in 2006 (EMEC, 2014).
Consent conditions for SeaGen required shutdown of the device if a marine mammal came
within 30m in order to minimise the risk of a fatal collision as part of an adaptive
management strategy. This level of mitigation is unviable in the commercialisation of tidal
arrays and better understanding of actual, rather than hypothesised, marine mammal
interactions is required. The consent conditions for SeaGen were altered in 2014 to allow
operation without the shutdown requirement for marine mammals, however, the
operation of the device has been constrained since then.
As mentioned previously, studies are underway (Thompson, 2013) to monitor the
behaviour of seals in a tidal stream in the presence of artificial operational noise, based on
available operational noise data. It is important to understand whether devices produce
sufficient noise to instigate an avoidance response or whether changes to the sound
characteristics of the device or use of Acoustic Deterrent Devices (ADD) may be required
to minimise collision risk.
Ambient noise levels in tidal areas are generally high, with natural sources including water
flow and turbulence as well as movement of substrata, such as boulders and cobbles. As
a result marine mammals in these areas may have some existing habituation to noise
levels which are beyond the thresholds of predicted avoidance used in conservative noise
modelling.
As available information and guidance on collision risk for marine mammals has
developed, Environmental Statements have used a range of approaches to assess collision
risk, including collision risk modelling. A number of models have been used, including
models created by the Scottish Association of Marine Science (SAMS) and models derived
from the Band model used in ornithology collision risk modelling for wind farms.
In 2015, guidance from Scottish Natural Heritage (Band, 2015) was produced in relation
to using the following models:
“Collision Risk Model” (CRM) based on the Band model used for bird collision with
wind farms; and
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“Encounter Rate Model” (ERM) based on the work by the Scottish Association for
Marine Science (SAMS) (Wilson et al., 2007).
In the EMEC environmental appraisal (EMEC, 2014), Band noted that, for small animals,
the ERM is likely to over-estimate encounter rate, as it does not take account of the
geometry of the blade and under-estimates the likelihood that a small animal moving
downstream may pass between blades, making use of the pitch of the blade to allow free
passage. While this may apply to smaller diving bird species; it is less likely to apply to
much larger marine mammal species.
Band also noted that for large animals like marine mammals, an encounter with more
than one successive blade is quite possible. As the ERM calculates the encounter rate
with individual blades, rather than with the turbine as a whole, it counts such events as
multiple encounters, which may be hard to interpret. In contrast, the CRM counts such
events as a single no-avoidance collision. This is an issue particularly for basking shark
and minke whale, because of their body length (EMEC, 2014).
Band suggested a modified CRM approach for annular devices, such as the OpenHydro
OCT (EMEC, 2014). Annular devices have a ring of blades, surrounding an open central
core. The open core is typically sufficiently large to allow clear passage through for small
animals. The approach to collision estimation is to take into account the area of the open
core as a proportion of the overall device cross-sectional area, though allowing for the
body-width of the animal to clear the annulus, either within the open core or outside the
turbine (EMEC, 2014).
Each model provides a predicted impact for a single rotor, based on the project/ device
specific parameters fed in to the model. For a device with multiple rotors and/or an array
of multiple devices, the total collision risk is scaled up by direct multiplication from the
risk for a single rotor. There is insufficient understanding of collision risk to be able to
incorporate layout into the modelling scenarios. However, using the ERM described above
to compare the collision risk for a greater number of smaller devices against the risk
associated with fewer, larger devices with the same overall swept area, the results
indicate that collision risk may potentially be slightly greater for a higher number of
smaller devices. This indication is based on comparison of the ERM for the following
examples:
5 x open rotors of 20m diameter
o Swept area = 5 x 314.159 = 1570.8
20 x open rotors of 10m diameter
o Swept area = 20 x 78.540 = 1570.8
with all other applicable parameters equal
The majority of device technologies in development have axial flow rotors, either open
(unshrouded) rotors or ducted (shrouded) rotors and these are captured by the CRM, ERM
or modified ERM modelling approaches described above. However, there are a number of
devices that fall outside these characteristics, some examples of which are provided in
Figure 1, below.
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Image source: www.keplerenergy.co.uk
Image source: http://tidalsails.com Image source: http://minesto.com
FIGURE 1: EXAMPLE DEVICE TYPES THAT DO NOT FIT WITHIN TYPICAL COLLISION RISK
MODELLING (LEFT – RIGHT: KEPLER ENERGY, TIDAL SAILS, MINESTO)
There is no available information or guidance on modelling the collision risk for devices
that do not have axial flow rotors. The PTEC ES considers a wide range of device types,
however, it was agreed with the MMO and their advisors that, given the low numbers of
marine mammals at that site, it was appropriate to discuss the collision risk qualitatively
rather than providing quantitative modelling. That assessment considers the maximum
swept areas and tip speeds and provides discussion of all device types as it is not possible
to define which would represent the worst case scenario for collision risk.
2.2.2 UNDERWATER NOISE
There are limited available data for operational tidal devices, with all available data to
date being for single devices and in many cases for devices on a smaller scale than those
proposed for scaling up to arrays. Noise output is not likely to be directly affected by the
size of a device, for example larger devices may have different characteristics in terms of
generators and rotor blades and so it can be difficult to scale up the predicted noise levels
from one device capacity to another. However the best available data is used in EIAs and
underwater noise monitoring may be a condition of consent to account for uncertainty in
the assessments.
In the Kyle Rhea ES (SeaGeneration (Kyle Rhea) Ltd, 2012) Subacoustech provided
calculations on scaling up to a 2MW device, based on the increase in noise output that
was measured in relation to the 1.2MW device in Strangford Lough (operational noise
data collected by Kongsberg (Needham, 2010)) compared with the operational noise of
the 350kW SeaFlow device (Parvin et al., 2005). However, this study is specific to the
MCT device and dependent on having collected previous operational data. Other
developers are also collecting underwater noise data, for example, during deployments at
EMEC.
The MeyGen ES (Xodus Group, 2012) states that an array of 36 Atlantis or Hammerfest
Strøm turbines of 2.4MW produces higher noise emissions than an array of 86 turbines of
1MW. Noise modelling by Kongsberg is provided in the MeyGen ES for two phases of array
deployments including:
12 x 2.4MW devices; and
36 x 2.4MW devices.
Figure 2 (source: Xodus, 2012; Kongsberg, 2012) provides the predicted Sound Pressure
Levels (SPL) for arrays of 12 and 36 devices of 2.4MW capacity. Kongsberg (2012) states
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that an array of 36 devices may reach SPLs of 166dB re 1 μPa and an array of 12 devices
may reach 163dB re 1 μPa. This is an increase of 11dB and 8dB, respectively, over that
generated by the operation of a single 2.4MW device. Maximum background noise levels
in the area were measured at 139 dB re 1 μPa.
FIGURE 2: PREDICTED SOUND PRESSURE LEVELS FOR MEYGEN BASED ON ARRAYS OF 12
(LEFT) AND 36 (RIGHT) 2.4MW DEVICES (SOURCE: XODUS GROUP, 2012)
The predicted impacts on marine mammals are dependent on the noise characteristics of
each tidal turbine and the hearing sensitivities of each marine mammal species/ group.
The noise propagation is also highly dependent on the environmental characteristics of
each development site (e.g. substrate type and depth).
Table 2 provides an example of the impact ranges when scaling up to arrays, showing the
predicted ranges for strong avoidance behaviour (90dBht) for 12 or 36 devices, from the
MeyGen ES (Xodus Group, 2012).
TABLE 2: PREDICTED STRONG AVOIDANCE RANGES FOR MARINE MAMMALS IN THE
MEYGEN ES
Marine mammal group 12 x 2.4MW Range (m) 36 x 2.4MW Range (m)
Pinnipeds 8 38
Odontocetes 63 98
Mysticetes 266 588
2.2.3 ENTANGLEMENT
Benjamins et al. (2014) provides a review of the risk of entanglement with tidal device
mooring lines for different marine mammal groups. It is not currently possible to quantify
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the risk of entanglement and there are limited EIAs that have been undertaken for
floating or moored buoyant devices at the time of writing. The PTEC ES provides an
assessment for a wide range of devices including floating structures with catenary
mooring (slack to allow the support structure to stay on the surface with the change in
tides) or tension mooring (taught where the device is buoyant but submerged). The
assessment considers the maximum area taken up by the anchor spread of moored
devices and the maximum possible area taken up by an array, based on spacing rules
defined in the project description. The PTEC site is in an area of low density for marine
mammal species and therefore the risk was deemed to be negligible.
As discussed in the preceding Section 2.2.1 and 2.2.2 of this report, there is uncertainty
regarding the extent of avoidance behaviour likely to be instigated by the presence/ noise
of a tidal turbine and as some anchor spreads may extend to approximately 200m there
may be risks of entanglement beyond the range of avoidance. Benjamins et al. (2014)
state that moorings typically consist of large cables that are likely to be detectable at
considerable distances (tens of metres) for echolocating odontocete cetaceans, and are
likely to be far more detectable than nylon or monofilament fishing gears.
Risk of entanglement for an array may vary depending on whether mooring lines are
shared between multiple devices in the same array, or whether individual devices each
have their own independent mooring system. A number of device technologies e.g.
Scotrenewables and Sustainable Marine Energy (SME) devices are likely to share anchors
but have individual mooring lines, allowing each device to be removed for maintenance if
required. It is uncertain whether layout will affect potential entanglement risk, for
example whether the risk could be greater with a row or network of joined devices (most
likely perpendicular to the water flow and predominant marine mammal movement
direction) or with multiple separate devices with space in between but a larger overall
array area. The risk of entanglement is likely to be greater where an array is in a narrow
channel or inlet due to confined space. Not enough information is currently known on the
risk of entanglement with tidal device moorings to understand what space is required for
safe transit by marine mammals, however, this is likely to vary according to multiple
factors, including current speed and directionality, device/mooring type, and species
characteristics (e.g. size, detection capabilities and swimming speed).
Benjamins et al. (2014) compares the qualitative risk of entanglement with mooring lines
for different marine mammal groups. Small dolphins (e.g. common and bottlenose
dolphin), porpoise and pinnipeds (i.e. harbour seal and grey seal) are deemed to
generally have the lowest level of risk for most mooring types with moderate risk for
certain types of mooring line e.g. those containing nylon. The lower risk is a result of
their body size and flexibility, as well as their feeding mode, and ability to detect mooring
lines.
2.2.4 ELECTROMAGNETIC FIELDS (EMF)
The potential impacts from Electromagnetic Fields (EMF) for tidal arrays may be
comparable with offshore wind farms once tidal arrays scale up to a similar level of
generation. To date there is no evidence of significant effects due to EMF for offshore
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wind farms. Modelled and measured data from ten offshore wind farms, summarised in
Figure 3, shows magnetic field ranges and distances. It can be seen that EMF are highly
localised. There is no available EMF data for single tidal turbine devices.
FIGURE 3: AC MAGNETIC FIELD PROFILES ACROSS THE SURFACE OF THE SEABED FOR 10
SUBMARINE CABLE SYSTEMS FOR 10 OFFSHORE WIND FARMS (SOURCE: NORMANDEAU
ET AL., 2011).
There may be potential for marine mammals to exhibit behavioural changes, including
displacement due to the presence of electromagnetic fields (EMF) around subsea cables
(Gill et al. 2005). There is currently limited information on this effect but it is widely
believed that marine mammals use the geomagnetic field of the earth to navigate during
long distance migrations (Kirschvink et al. 1986; Klinowska 1985).
Although it is assumed that harbour porpoise are capable of detecting small differences in
magnetic field strength, this is unproven and is based on circumstantial information.
There is also presently no evidence to suggest that existing subsea cables have influenced
cetacean movements. Harbour porpoise move in and out of the Baltic Sea, with several
crossings over operating subsea high voltage direct current cables in the Skagerrak and
western Baltic Sea without any apparent effect on their migration pattern.
2.2.5 BARRIER EFFECTS/ HABITAT EXCLUSION/ HAUL OUT DISTURBANCE
The potential for barrier and exclusion effects are highly site specific. Barrier effects may
apply if the site is confined and represents an important transit route between important
areas, e.g. haul out sites and feeding grounds or a larger scale migratory route. Exclusion
effects may apply if the site is in, or close to, an important area e.g. feeding ground or
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haul out site.
The physical presence of turbines, noise (underwater and airborne in the case of haul out
site disturbance), and increased human activity may cause displacement or barriers.
Very little is known about this potential impact and it is likely that with sufficient
motivation (e.g. feeding or reproduction) marine mammals will habituate to the presence
of an array. Data collected during the Environmental Monitoring Programme (EMP) for the
single SeaGen turbine in Strangford Lough (Marine Current Turbines, 2011) has shown
that harbour porpoise (monitored through the use of MMOs and Passive Acoustic
Monitoring (PAM)) continued to use the tidal narrows as did harbour and grey seals
(monitored by MMOs and active sonar around the device). This was in keeping with the
predictions of the EIA (MCT, 2005) which predicted strong avoidance to 9m for harbour
porpoise and 1m for harbour seal, and mild avoidance at 108m for harbour porpoise and
15m for harbour seal. Kongsberg (2010) provides operational noise measurements for the
SeaGen device, as well as background noise and ferry noise, which are all below the levels
at which strong avoidance by marine mammals would be expected (with background
noise around the mouth of the lough, around 1-3km south of the SeaGen device providing
the highest noise measurements).
The potential for marine mammals to continue to transit through or around a tidal array
should be considered in relation to potential collision risk, along with the potential for
mitigation in terms of active discouragement or displacement of marine mammals as
mitigation (e.g. using Acoustic Deterrent Device (ADD)), in order to minimise collision
risk. Deployment of ADD would have to be carefully planned and monitored, so as to not
limit access to important areas (e.g. for feeding and reproduction) as a result of barrier
effects if it is uncertain that marine mammals will find an alternative resource in the
surrounding area.
Array spacing and layout may alter the potential for marine mammals to pass through an
array, however, not enough is known about this potential impact to determine what would
represent the best layout to mitigate such effects. There is insufficient information on the
impacts of individual tidal devices, as well as of tidal arrays, to understand what space is
required for transit by marine mammals within and/or around arrays and therefore the
potential for barrier effects. It is likely to be highly site specific, with variation dependent
on multiple factors, including current speed and directionality, device type, and species
characteristics (e.g. size, detection capabilities, swimming speed, site specific behaviour).
As discussed previously, motivation/habituation may greatly alter the nature, extent and
significance of impacts, compared with hypothetical assessment (e.g. underwater noise
modelling). The monitoring of operational tidal arrays in areas of high usage by marine
mammals will be highly valuable, providing better understanding of true nature of
potential barrier effects.
2.3 ORNITHOLOGY The key impact on birds which is of relevance in relation to scaling up to tidal arrays is
collision risk. Other impacts on birds relate to disturbance from vessels and increased
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activity which will be temporary although of increased duration with increasing array size.
As discussed in the marine mammals section, disturbance effects are likely to be highly
device/array specific as well as site specific. Tidal devices/arrays may also cause indirect
impacts as a result of changes to prey resource (which are discussed below in relation to
fish and benthic impacts).
2.3.1 COLLISION RISK
The moving rotors of tidal devices pose a theoretical risk to some diving bird species. To
date, there is no evidence of a bird collision with a tidal turbine.
The potential significance of collision risk will be dependent on the presence of diving birds
which dive to sufficient depth to encounter the rotors of the tidal device. This is therefore
also device and site specific, depending on the device parameters and water depth.
There is also uncertainty as to whether animals of relatively small size such as diving
seabirds would be struck by a rotor blade or would be swept past by hydrodynamic flow
and, if a collision were to occur, it is also unknown whether the force would be sufficient
to cause injury or death (Wilson et al., 2007).
For developments where collision risk may be relevant, collision risk modelling has been
undertaken in order to provide a conservative impact assessment. A further area of
uncertainty in relation to collision risk modelling is the likely avoidance rates for diving
birds whilst underwater. The PTEC ES (Royal HaskoningDHV, 2014) considers avoidance
rates of 95%, 98% and 99% in line with previous advice received by the authors from
Scottish Natural Heritage and JNCC, with respect to tidal array projects in Scotland,
acknowledging that there is no available data in relation to underwater avoidance rates.
The PTEC ES (Royal HaskoningDHV, 2014) states these avoidance values reflect the
general view of many biologists working in the field that the actual number of harmful
collisions will be substantially lower than the predicted number of encounters (Robbins, et
al, 2014).
Given the high levels of uncertainty in relation to the potential collision risk for diving
birds, it is not possible to determine if altered array configuration could have a potential
effect on the overall impact significance.
2.4 FISH Tidal energy developments may result in the follow key impacts on fish ecology:
Collision risk with operational tidal turbines;
Underwater noise impacts;
EMF;
Exclusion/ barrier effects; and
Habitat loss as a result of the seabed footprint – discussed in Benthic ecology
section.
2.4.1 COLLISION RISK
Further to the uncertainty discussed previously in relation to marine mammal and bird
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collision risk, there is additional uncertainty in relation to fish collision risk modelling due
to a lack of understanding of the baseline environment, particularly in terms of fish
density estimates in the marine environment.
Most assessments are therefore done on a qualitative basis, however, as with birds, there
is also little understanding regarding whether fish will pass around or through a tidal
device and if a collision occurs what the consequence on the individual and population will
be.
Direct observational research of interactions between fish and tidal devices is limited but
provides the best available insight into any potential risks or behavioural changes
associated with the presence of turbines (Copping et al., 2014).
Viehman, 2012 provides a study of fish behaviour around a barge-mounted tidal turbine
in Maine, U.S, using acoustic cameras either side of the turbine. The camera data showed
fish to regularly approach the area containing the barge and turbine, interactions were
highest when the turbine was stationary and during these periods fish commonly entered
the turbine. The study recorded no incidences of dead or dying fish to the lee side of the
turbine.
Fish passage through another barge-mounted turbine was examined on the Mississippi
River by introducing two size classes of fish outfitted with radiofrequency and balloon tags
directly into the turbine. The fish were retrieved downstream and assessed for mortality
and injury immediately after retrieval, held and re-examined after 48 hours. Survival for
the small (115 to 235 mm length) and large (388 to 710 mm length) fish was greater
than 99% after 48 hours (Normandeau Associates, 2009).
Video footage at the face of the pile mounted open-centred ducted turbine at EMEC in
Scotland recorded fish, primarily pollock, visiting the lee side of the turbine to graze on
the vegetation attached to the structure. This occurred at times when tidal currents were
lower than the cut in speed of the turbine. As currents increased and the turbine began to
rotate the fish appeared to disperse. To date the video data has not recorded any fish
passing through the turbine when it is rotating and therefore no observations relating to
fish strike mortality have been made (Polagye et al., 2011).
Laboratory and flume experiments have also been undertaken by researchers, with fish
directed towards rotating turbine blades, with limited potential for avoidance. This
allowed assessment of injury, survival rates and behavioural changes as a result of
passage through such an aggressive turbine. Alden Laboratory (U.S) experiments found
only small numbers of fish passed through the turbine-swept area; the majority of fish
swam upstream and/or were swept around the turbine. For those fish passing directly
through the turbines, all trials produced survival rates greater than 98%, with these rates
similar between the experimental and control groups. Conte laboratory (U.S) recorded no
injuries to fish passing through the turbine or around it, and again, no significant
differences between survival and control mortalities were observed (Jacobson et al.,
2013).
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Given the high variability of factors affecting fish collision risk (e.g. fish parameters and
behaviour, site depth, tidal flows, and device parameters), it is not possible at this stage
to determine whether scaling up to tidal arrays and array configuration could significantly
alter the potential collision risk.
2.4.2 UNDERWATER NOISE
The potential changes in source level and propagated sound pressure levels associated
with tidal devices and arrays is discussed previously in the marine mammals section.
Disturbance impact ranges for fish during the operation of tidal arrays are highly localised,
with strong avoidance ranges generally around 10m or less (Royal HaskoningDHV, 2014,
SeaGeneration (Kyle Rhea) Ltd, 2012, Tidal Ventures, 2014). The MeyGen ES (Xodus
Group, 2012) states that hearing specialists (e.g. herring) could be expected to show
strong avoidance up to 18m from the tidal array, whereas hearing generalists would need
to be less than 1m from the source of the noise to exhibit a behavioural response.
These ranges are less than the likely spacing between tidal devices in an array and
therefore no additive weighted (in relation to the receptor hearing capability) received
level effects are likely. The impacts of the array are therefore likely to be the direct
displacement, locally, around each device.
2.4.3 EMF
As with marine mammals, the potential impacts from EMF for tidal arrays is likely to be
comparable with offshore wind farms once tidal arrays scale up to this level.
A range of marine species including elasmobranchs, salmon, trout and eel, have adapted
to detect naturally occurring electric and magnetic fields in order to locate prey, avoid
predation and navigate. While it is recognised that potential pathways for interactions
between EMF emitted from subsea cables and fish and shellfish exist, there is no
conclusive evidence to date of the nature of these interactions or whether they have
positive or negative effects on species. Studies to date have shown EMF to both repel and
attract individuals of different species under different conditions; consequently it is not
currently possible to infer the nature, nor significance, of these observed responses (Gill
et al., 2010, Marine Scotland, 2015)
2.4.3 EXCLUSION/ BARRIER EFFECTS
As with marine mammals, the potential for barrier and exclusion effects are highly site
specific. Barrier effects may apply if the site is confined and/or represents an important
route for migratory fish. However there remains significant uncertainty in the routes taken
by migratory fish whilst at sea.
Exclusion effects may apply if the site is in, or close to an important area, e.g. spawning
or nursery area where impacts such as noise may affect the success of the population. As
discussed previously the impacts of noise are highly localised for fish and the impact of an
array is likely to be localised around each device. This extent of the predicted array level
impacts can then be considered in the context of the surrounding area e.g. available
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habitat or space for transiting through or around the array.
2.5 BENTHIC ECOLOGY The key relevant impact on benthic ecology, when considering the potential effects of
scaling up from a single device to a tidal array, is habitat loss or disturbance. Indirect
impacts may also occur as a result of changes to physical processes (discussed
previously), but these are anticipated as being far less significant.
2.5.1 HABITAT LOSS/ DISTURBANCE
Habitat loss and disturbance is highly dependent on the device type to be installed. For
arrays of seabed mounted devices, the footprint on the seabed will be a direct
multiplication of the device parameters for a single device and the number of devices.
This can then be considered in the context of the available relevant habitat.
Some device types have established areas of efficiency in the number of rotors/generators
on each support structure and foundations/moorings. For example, MCT’s SeaGen and
Tidal Energy Ltd’s Delta Stream, mount two or three large rotors on a single foundation.
Similarly, platform structures, such as Tidal Stream’s Triton can hold multiple small rotors
on a single structure and foundation.
A number of device types can share components of the foundation structure or moorings
between individual devices within an array. In particular, floating or buoyant technologies
may share anchors between devices to minimise footprint and infrastructure. In a similar
way, transverse axis devices, such as those developed by Kepler Energy and Ocean
Renewable Power Company, can be deployed as a linear array or ‘fence’, with the
potential to share support structure and foundations between devices within the fence.
An indicative array layout is usually provided in the ES for tidal arrays, with some
parameters defined e.g. maximum and minimum spacing, in order to provide a
meaningful assessment. This flexibility allows the final array layout to be provided based
on detailed site investigation, generally undertaken post-consent. This may include micro-
siting the array around species of conservation importance where necessary.
2.6 SHIPPING AND NAVIGATION Constraints in relation to navigational risk associated with the deployment of a tidal array
depend on the importance of the site as a shipping route and the potential for an
alternative route around the proposed array. This section provides a review of key
available impact assessments for a number of tidal array sites with discussion of lessons
learned in relation to shipping and navigation.
2.6.1 KYLE RHEA TIDAL STREAM ARRAY
The Marine Current Turbines (MCT) Kyle Rhea Tidal Stream Array Environmental
Statement (SeaGeneration (Kyle Rhea) Ltd, 2012) showed that shipping and navigation
was one of the key constraints for the project. The project proposed an array of four
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SeaGen S devices with a surface piercing tower of up to 18m above Lowest Astronomical
Tide (LAT) in a narrow tidal strait (approximately 600m wide). The ES provided an
indicative layout for assessment which was highly constrained by resource (optimum
towards the centre of the channel) and space for navigation (requiring the array to be as
far to the western side of the channel as possible).
Consultation with key stakeholders confirmed that the strait was a commonly used
through route for a variety of sea users and that alternative routes passing around the
Isle of Skye which would add considerable time and cost as well as additional risk of
encountering extreme weather conditions. Figure 4 shows the summer survey tracks for
existing traffic as part of the baseline characterisation confirming the high use of the site.
FIGURE 4 SUMMER 2010 SURVEY DATA (20 DAYS) IN GENERAL AREA OF KYLE RHEA
(SOURCE: SEAGENERATION (KYLE RHEA) LTD, 2012)
The Navigation Risk Assessment (Appendix 17.1 of SeaGeneration (Kyle Rhea) LTD, 2012)
determined that without mitigation the risk of collision was potentially unacceptable. The
following mitigation measures were proposed with the aim of bringing the impacts to an
acceptable level:
The Project will be depicted on Admiralty Charts produced by United Kingdom
Hydrographic Office (UKHO) with an associated note on the available underwater
clearance;
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Information about the devices will be distributed, e.g. liaison with local harbours,
clubs and associations; Coastguard Maritime Safety Information broadcasts;
Notices to Mariners; inclusion in Clyde Cruising Club Sailing Directions and other
almanacs, etc.;
Marking and lighting of the Project will be decided by Northern Lighthouse Board
once they have reviewed the NRA and consulted on the appropriate scheme to
ensure devices are conspicuous and / or to mark a safe passage. The existing
leading light will need to be altered; and
Fendering of towers (if practical) - a bumper surrounding the device to absorb the
kinetic energy of a vessel in the event of a collision, could potentially mitigate the
impact if a small vessel collided with a device. This would be effective only in a
glancing collision with the device.
The project is currently on hold due to grid connection issues and consent determination
was not fully processed.
2.6.2 SKERRIES TIDAL STREAM ARRAY
The MCT Skerries Tidal Stream Array project proposes an array of the same device
technology (SeaGen S) as proposed for Kyle Rhea, but located in open water. The ES
provides minimum and maximum spacing parameters along with two indicative layouts,
one with the array in one row, with relatively close spacing, the other in two rows, taking
up a larger area overall, but with more spacing between the devices (Figure 5). The
shipping and navigation assessment assumes a larger overall array area represents the
worst case scenario for assessment.
Site characterisation surveys showed the key shipping route is further offshore than the
planned array. This means that navigation and space to manoeuvre is not constrained or
confined, unlike Kyle Rhea (Section 2.6.1) where navigation is within an already
constrained and relatively narrow strait.
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FIGURE 5 INDICATIVE ARRAY LAYOUTS IN THE MCT SKERRIES ES (SOURCE:
SEAGENERATION (WALES) LTD, 2011)
The assessment concludes that the devices should be avoidable, with traffic able to pass
through or around the array. The assessment indicated that all identified risks are
classified As Low As Reasonably Practicable (ALARP) or better.
2.6.3 TORR HEAD TIDAL ARRAY
As with the Skerries Tidal Array (Section 2.6.2) the Torr Head ES provides an indicative
layout of an array, with the devices located in a relatively open coast location. The array
includes up to 100 fully submerged devices with 8m clearance above LAT.
The assessment concludes that all impacts are tolerable or broadly acceptable, with the
exception of fishing interaction with subsea equipment (discussed further in the
commercial fisheries section below).
The Torr Head tidal array proposal is in the consent determination phase at the time of
writing.
2.6.4 MEYGEN PHASE 1 TIDAL ARRAY
The MeyGen ES states that due to the minimum surface clearance of 8m below LAT for
their proposed devices, and given the shallow draught of most local vessels; the risk of
collision is minimal. A collision would therefore only be possible given a combination of
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low tide and extreme wave conditions, a set of conditions during which local vessels are
unlikely to be out at sea.
Transiting of larger vessels through the development site is relatively low, however, any
vessels constrained by their draught will have to re-route to the south of the array, which
has reduced sea room (see Figure 6), or via the Outer Sound. This will lead to increased
encounters with other vessels and therefore increased collision risk but the overall change
from the baseline risk levels is assessed as low (Xodus Group, 2012).
MeyGen has received consent to deploy a first phase on four devices. This was restricted,
primarily due to uncertainties in relation to marine mammal impacts. Shipping risk will be
significantly reduced compared with the assessment of 100 devices.
FIGURE 6: MEYGEN INDICATIVE LAYOUT
2.6.4 SOUND OF ISLAY TIDAL ARRAY
The Sound of Islay Tidal Array is located in a narrow channel (approximately 1km width).
The sound provides a direct route for traffic and is preferential to the increased distance,
cost, travel time and risk of inclement weather encountered if travelling around Islay.
The Navigation Safety Risk Assessment concluded that the potential impacts are tolerable
with monitoring (Scottish Power Renewables, 2010). Key factors in this acceptable level
of risk were the available space to manoeuvre within the Sound of Islay, the general
absence of difficult tidal eddies and other navigation hazards, as well as the use of fully
submerged tidal technology, with substantial clearance above rotors to allow passage of
vessels.
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2.6.5 PERPETUUS TIDAL ENERGY CENTRE (PTEC)
The PTEC ES (Royal HaskoningDHV,2014) includes a range of options for the potential
tidal devices that may be deployed. The minimum and maximum likely device spacing is
used in the impact assessment and to consider the maximum overall space the array
could take up within the wider redline boundary as well as the potential space to navigate
through arrays. The PTEC site will provide berths for different developers and therefore
within berth and between berth spacing was considered.
The site could include surface piercing or fully submerged devices with clearance from a
minimum of 3m above LAT to much deeper/ increased clearance. The devices (submerged
or surface piercing) could include an anchor spread and/or may also move around on their
anchors or foundations.
Site characterisation for PTEC, through consultation and data collection, including
commissioned surveys, showed that the study area has relatively high levels of vessel
traffic, with the majority passing around development site. A particular constraint is the
use of the site by recreational yachting, in particular the attraction of the Round the
Island Race (RIR) which attracts yachting competitors internationally and is of high socio-
economic value to the Isle of Wight.
The Navigation Risk Assessment concludes that the impacts predicted are broadly
acceptable. However, a commitment is made to providing array layout and navigation
information to the MMO prior to the deployment of any devices. This will allow
confirmation of how well any particular layout and navigation risk fits within the impacts
assessed in the ES, as well as providing any information on device/array specific
mitigation and residual risk.
The PTEC proposal is in the consent determination phase at the time of writing.
2.6.6 SHIPPING AND NAVIGATION SUMMARY
The review of various ESs for tidal arrays shows that shipping and navigation impacts
vary, particularly in relation to the following key factors:
Site characteristics (e.g. open sea or narrow channel, shallow or deep water);
Alternative route options;
Existing levels and types of traffic; and
Device type characteristics (e.g. submerged or surface piercing and extent of
surface clearance).
Minimising the impacts on shipping and navigation falls primarily at the site selection and
device selection (e.g. feasibility) stage of the project. For example, if the site is narrow,
with high levels of existing traffic, and limited alternative options, a submerged device
technology with sufficient clearance (based on the latest available guidance) may be
advisable.
The potential impacts on different users may also differ, for example depending on the
size of the vessels, powered or non-powered, likely skill of the skippers (e.g. recreational
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or professional). Recreational vessel users, in particular, yachts may be additionally
affected due to largely being under sail and therefore have less manoeuvrability on a
small scale and involve amateur skippers who may have more potential to misjudge the
situation.
The detailed layout of each of the tidal array examples discussed in this section will be
defined post consent. This is likely to be on the basis of additional site investigation in
terms of seabed/ geological characterisation and tidal resource characterisation. In
addition, some flexibility in the array layout post-consent may also allow some micro-
siting of devices in an array to incorporate mitigation for shipping impacts.
Lessons learned from offshore wind farms are also likely to be valuable, particularly when
tidal array sizes increase. For example arrangement of devices in straight lines and with
sufficient spacing to allow navigation through the array may reduce the impact.
2.6.7 COMMERCIAL FISHING Impacts on commercial fishing are related to shipping and navigation impacts affecting
the potential to use and access to fishing areas, as well as any impacts on fish and
benthic ecology, discussed previously. In addition, a key potential hazard of tidal arrays in
relation to commercial fishing is that of potential snagging or entanglement hazard
through the deployment of fishing gear. The consequence could be serious if the snagged
/ entangled gear causes the vessel to capsize. This significant of these impacts will be
highly dependent on the level of use of the development site for fishing, as well as the
type of fishing activity.
There is no available information at present as to whether the potential snagging risk may
vary with device technology.
Spacing of devices within an array may be sufficient to allow vessels to move through the
array (see Section 2.6.6), but may be insufficient for the safe deployment and recovery of
fishing gear. This is particularly the case in highly tidal environments where a vessel may
drift considerable distances whilst gear is deployed or being recovered. Array layouts
with minimum spacing and therefore taking up a smaller area overall may be preferable in
some areas, however, this would be assessed on a site specific basis, and will be highly
dependent on the types of fishing gear used and the presence of available alternative
fishing areas nearby.
The PTEC proposal includes a number of potential berths, suitable for various developers,
and so there will be between three and six arrays within the site. The spacing between
arrays is likely to be greater than the spacing between devices of a single array. PTEC has
committed to ongoing discussions with fishermen, to include discussing the potential for
fishermen to continue to use the site.
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3 CONCLUSIONS
Due to the evolving nature of the tidal industry there is still uncertainty regarding the
nature and significance of the potential impacts of single tidal turbines and consequently
for tidal arrays. For this reason conservative approaches are taken through any tidal
array EIA to carefully assess the combined impacts.
This report reviews available literature and ES documents to demonstrate that the
potential impacts of any tidal array are uncertain, highly site specific and also technology
specific. The deployment of tidal arrays which are currently in planning or consented
(generally around 10MW or less) will provide an excellent opportunity for ecological and
physical monitoring, as well as providing data on actual commercial fisheries, socio-
economic, shipping, and recreational impacts. The lessons learned can be taken forward
in the further commercialisation of the tidal industry and the deployment of arrays in the
order of 100MW or greater.
The layout of an array is likely to be defined, primarily, by ground conditions, water depth
and tidal resource. This will usually be informed by detailed site investigation works, post-
consent and therefore EIAs generally assess an indicative layout with a range of spacing
parameters. Where there is sufficient physical space as well as other suitable conditions,
there may be an opportunity for micro-siting to minimise and mitigate risks and impacts.
This approach would be applied using a balanced approach to appraisal and prioritisation,
considering the key constraints of each site, particularly if receptors have conflicting
mitigation requirements. Not enough is currently known about the potential combined
impacts of arrays to fully understand the effect (if any) that micro-siting the array layout
could have on receptors.
Strategic industry level monitoring is underway to improve understanding of key issues, in
particular in relation to marine mammal collision risk, including activity around tidal
devices and behavioural response of seals to artificial operational noise of tidal devices.
Monitoring to verify key assumptions made during the impact assessments for various
receptors, once tidal arrays are deployed and operational, will be valuable in better
understanding the true impacts and the differences associated with differing device
technologies and site variations.
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4 REFERENCES
Aquatera (2012). A review of the potential impacts of wave and tidal energy development
on Scotland’s marine environment. Report to Marine Scotland.
Band, W.T.2015. Assessing collision risk between tidal turbines and marine wildlife (draft).
Scottish Scottish Natural Heritage Guidance Note Series.
Benjamins, S., Harnois, V., Smith, H.C.M., Johanning, L., Greenhill, L., Carter, C. and
Wilson, B. 2014. Understanding the potential for marine megafauna entanglement risk
from renewable marine energy developments. Scottish Natural Heritage Commissioned
Report No. 791.
Copping, A., Battey, H., Brown-Saracino, J., Massaua, M. & Smith, C. (2014) Courtney
Smith b An international assessment of the environmental effects of marine energy
development Ocean & Coastal Management 99 (2014) 3-13
EMEC (2014) Fall of Warness Test Site: Environmental Appraisal. August 2014.
Gill, A.B., Gloyne-Phillips, I., Neal, K.J. & Kimber, J.A. (2005). The potential effects of
electromagnetic fields generated by sub-sea power cables associated with offshore wind
farm developments on electrically and magnetically sensitive marine organisms – a
review. Report to Collaborative Offshore Wind Research into the Environment (COWRIE)
group, Crown Estates.
Gill A.B., Huang Y., Glyne-Phillips I., Metcalfe J., Quayle V., Spencer J., and V Wearmouth
(2009) COWRIE 2.0 Electromagnetic Fields (EMF) Phase 2: EMF-sensitive fish response to
EM emissions from sub-sea electricity cables of the type used by the offshore renewable
energy industry. COWRIE-EMF-1-106. Collaborative Offshore Wind Research into the
Environment Ltd. UK
Jacobson, P., Amaral, S., Castro-Santos, T., Giza, D., Haro, A., Hecker, G., McMahon,
B.,Perkins, N., Pioppi, N., 2013. Effects of Hydrokinetic Turbines on Fish: Desktop and
Laboratory Flume Studies. Electric Power Research Institute.
Kirschvink, J. L., A. E. Dizon, and J. A. Westphal (1986). Evidence from strandings for
geomagnetic sensitivity in Cetaceans, J. Exp. Biol. 120, 1–24.
Klinowska, M. 1985. Cetacean live stranding sites related to geomagnetic topography.
Aquatic Mammals (1):27-32.
Kongsberg (2010). Operational Underwater Noise, SeaGen Unit. For Marine Current
Turbines Ltd
Marine Current Turbines (2005). Strangford Lough Marine Current Turbine Environmental
Statement.
26
26
Marine Current Turbines, 2011. SeaGen Environmental Monitoring Programme; Final
Report. Available at: http://seageneration.co.uk/files/SeaGen-Environmental-Monitoring-
Programme-Final-Report.pdf
Marine Scotland. (2015). Effects of magnetic fields on the behaviour of eels and salmon.
Available at: http://blogs.scotland.gov.uk/coastal-monitoring/2015/09/10/effects-of-
magnetic-fields-on-the-behaviour-of-eels-and-salmon/
Maunsell & Metoc (2007). Wave and Tidal Strategic Environmental Assessment. Available
at: http://www.gov.scot/Publications/2007/03/seawave
Needham K. (2010). Operational Underwater Noise, SeaGen, Strangford Lough –
Technical Report – Measurement. Kongsberg Report for Marine Current Turbines Ltd.
Report Ref: 449-PR-0001-B, March 2010.
Normandeau Associates, Inc, 2009. An Estimation of Survival and Injury of Fish Passed
Through the Hydro Green Energy Hydrokinetic System, and a Characterization of Fish
Entrainment Potential at the Mississippi Lock and Dam No. 2 Hydroelectric Projects.
Normandeau Associates, Inc., Westmoreland, New Hampshire.
Parvin S J, Workman R, Bourke P and Nedwell J R. (2005). Assessment of Tidal Current
Turbine Noise at the Lynmouth site and predicted impact of underwater noise at
Strangford Lough. Subacoustech Report No. 628R0104, June 2005.
Polagye, B., Van Cleve, F.B., Copping, A., Kirkendall, K. (Eds.), 2011. Environmental
Effects of Tidal Energy Development: Proceedings of a Scientific Workshop, March 22e25,
2010, National Marine Fisheries Service. National Oceanic and Atmospheric
Administration, Portland, Oregon.
Robbins, P. E., Neil, S. P., Lewis, M, J. (2014). Impact of tidal-stream arrays in relation to
the natural variability of sedimentary processes.
Robbins, A., Thaxter, C., Cook, A.,Furness, R,. Daunt, F,. and Masden, E. (2014). A
review of marine bird diving behaviour: assessing underwater collision risk with tidal
turbines. Presentation to Environmental Impacts of Marine Renewables (EIMR)
conference.
Royal HaskoningDHV (2014). Perpetuus Tidal Energy Centre (PTEC) Environmental Impact
Assessment
Scottish Power Renewables (2010) Sound of Islay Tidal Array Environmental Statement
SeaGeneration (Kyle Rhea) Ltd, 2012. Kyle Rhea Tidal Stream Array Environmental
Statement
SeaGeneration (Wales) Ltd, 2011. Skerries Tidal Stream Array Environmental Statement
Thompson, D., Hall, A., Lonergan, M., McConnell, B. and Northridge, S. (2013). Current
state of knowledge of effects of offshore renewable energy generation devices on marine
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27
mammals & research requirements. Sea Mammal Research Unit report to Scottish
Government (currently in draft). Available at: http://www.smru.st-
and.ac.uk/documents/1321.pdf
Thompson. (2013). Understanding how marine renewable device operations influences
fine scale habitat use and behaviour of marine vertebrates. Presentation to 2013
SUPERGEN UCMER Assembly. Available at: http://www.supergen-
marine.org.uk/drupal/files/events/assembly_2013_presentations/environmental/Thompso
n_RESPONSE_2013.pdf
Tidal Ventures (2014) Torr Head Tidal Energy Array Environmental Statement. Available
at: http://www.tidalventures.com/contact.html#downloads
Viehman, H.A., 2012. Fish in a Tidally Dynamic Region in Maine: Hydroacoustic
Assessments in Relation to Tidal Power Development. The University of Maine, Orono,
Maine. Master’s thesis.
Wilson, B., Batty, R.S., Daunt, F. & Carter, C. (2007). Collision risks between marine
renewable energy devices and mammals, fish and diving birds. Report to the Scottish
Executive. Scottish Association for Marine Science, Oban, Scotland, PA37 1QA.
Xodus Group (2012) MeyGen Tidal Energy Project – Phase 1 Environmental Statement.
Available at: http://www.meygen.com/the-company/reports-and-documents/