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5.3.5 Electricity generation

a.    Extent of activity

i.   Within the site

No fossil fuel power stations exist within the cSAC.

ii.  Outside the site

No fossil fuel power stations exist directly adjacent Cardigan Bay.

b.    Mechanism for effect on the feature

The development and running of fossil fuelled power stations could influence the Cardigan Bay environment in a variety of ways.

  • Pollution through emissions and from plant operations. See ‘Pollution’.

  • Changes to local environmental parameters e.g. use sea as cooling waters. See ‘Habitat Impacts’ and ‘Natural factors’.

c.    Management Response

i.   Rationale

New fossil fuelled power stations may be proposed adjacent to Cardigan Bay in the future, though the likelihood of this is believed very small. Any new power station development would be assessed both as a plan or project and under the EIA Regulations.

ii.  Type of Response

F1 : The activity constitutes a plan or project.

iii.  Actions

  • If development proposals arise which may affect the SAC, ensure appropriate assessments take place which properly address the SAC interests.

5.3.5.2    Nuclear

a.    Extent of activity

i.   Within the site

No nuclear fuel power stations exist within the cSAC.

ii.  Outside the site

To the north of the SAC the former nuclear plant at Trawsfynydd in Snowdonia has been closed for many years. On Anglesea there is the Wylfa nuclear power station, which has been closed recently due to a fault. At the northern end of the Irish sea the Sellafield nuclear reprocessing plant is currently operational.

b.    Mechanism for effect on the feature

The development and running of nuclear power stations could influence the Cardigan Bay environment in a variety of ways.

  • Pollution through emissions and from plant operations. See ‘Pollution’, page 56.

  • Changes to local environmental parameters e.g. use sea as cooling waters. See ‘Habitat Impacts’ and ‘Natural factors’.

c.    Management Response

i.   Rationale

The Trawsfynydd plant, when operational, was relatively self contained both in terms of cooling waters and emissions. Discharges were largely into an adjacent lake though some did enter the sea via a discharge into the Afon Prysor. The plant has now been closed for some time and there has been no fuel on site for over three years. The plant is not therefore thought to require further management consideration at present though this may change in the event of any future decommissioning.

Figure 18. The distribution of the radionuclide Caesium 137 around the UK in 1973.

Figure 18.  The distribution of the radionuclide Caesium 137 around the UK in 1973.

Reproduced from the UK digital marine atlas courtesy of CEFAS.

Sellafield reprocessing plant has disposed of radioactive effluent into the sea for some time. Dispersing levels of radionuclides (such as Caesium-137) from the site are measurable down the Irish Sea (see Figure 16). Emissions have been more tightly regulated in recent years though concerns have been expressed from as far away as Scandinavia as a result of recorded plutonium levels attributed to the Sellafield plant. Emissions from Sellafield may need to be reviewed in the future if the THORP reprocessing plant comes on line. The levels of radionuclides taken up by bottlenose dolphins, and their significance to the dolphins health, is unknown. However, research has shown that harbour porpoise stranded on Irish Sea shores possess higher levels of Caesium 137 than other areas around the UK.

Whilst new nuclear fuelled power stations may be proposed adjacent to Cardigan Bay in the future, the likelihood of this is believed very small. Such a development would require consideration under the procedures for a ‘plan or project’.

ii.  Type of Response

F1 : The activity constitutes a plan or project.

iii.  Actions

  • If development proposals arise which may affect the SAC, ensure appropriate assessments take place which properly address the SAC interests.

5.3.5.3    Alternative (Offshore energy structures)

This section covers the construction and operation of structures seaward of low water mark, for generating electricity from wind, wave or tidal power. Other types of operation (e.g. oil/gas exploitation) are dealt with elsewhere.

a.   Extent of the activity

A variety of structures such as wind and current turbines typically make use of wind, wave and tidal movement. There are presently no such structures either within the SAC or elsewhere in Cardigan Bay. However, alternative energy sources are being promoted by the UK government as part of its commitment to reduce CO2 emissions and reach a target of 10% of electricity supply being met from renewable sources. There have been preliminary expressions of interest by developers in placing offshore wind turbines at various sites in Cardigan Bay, but as yet, no formal proposals.

Little is known by the authors of this management plan about the suitability or otherwise of the SAC or its vicinity for these structures, but this is clearly a developing area which may become more significant in the near future. In addition to environmental and landscape/seascape considerations, the constraints on development are principally suitable environmental conditions, transport of the structures to the site and costs of connection to the national grid.

b.   Mechanisms for effects on the feature

The types of structures may vary enormously - single turbines or “farms” of many tens or hundreds of turbines, placed anywhere from just offshore or in waters up to 20 m deep, although 5-10 metres is more likely. The Sarnau of Cardigan Bay are likely to attract interest as potential siting grounds due to their shallow depth and distance offshore. Tidal structures usually make use of areas with high rates of tidal flow such as narrows, headlands and estuaries. Wave power generators require a good sea swell. Structures may be floating, self supporting or anchored in the seabed.

Therefore, although the type of effects would vary greatly according to individual circumstances, it is possible to make some general conclusions.

Construction/placement of structures and associated cabling

i.   Noise

From vessels and construction equipment. See ‘Noise’.

ii.  Water quality

The construction/placement activities are likely to cause short term, localised changes in turbidity and sediment loads in the water column. This may affect the dolphins by directly causing them to avoid the area, or if persisting over longer periods, through effects on their habitat.

iii.  Pollution

Contamination of water and/or sediments by chemicals used on or within the structures (e.g. grouting, antifouling coatings). See ‘Pollution’.

Operation/maintenance

i.   Vessels

Depending on the maintenance requirements, there may be significant increases in vessel traffic, servicing the offshore structures. See ‘Shipping’.

ii.  Noise

Any structures with moving parts (e.g. wind or tide-driven turbines, wave-riding buoys) are liable to generate noise, which may interfere with the dolphins’ communication, navigation and prey location. See ‘Noise’.

iii.  Seabed effects

The presence of structures on or anchored to the seabed may cause changes to the local sedimentology/geomorphology, e.g. causing scouring or deposition. This may cause changes to the benthos and hence might affect dolphin prey availability. It is also important to note that very little is known about why this area appears to be attractive to bottlenose dolphins - it may be related to the quality or morphology of the seabed. See ‘Habitat Impacts’.

iv.  Pollution

Contamination of water by chemicals used on the structures (e.g. antifouling coatings). Increased risk of ship collisions resulting in accidental release of cargo. See ‘Pollution’.

Further information sources.

An assessment of the environmental effects of offshore wind farms can be found in, ‘METOC. 1999. An assessment of the environmental effects of offshore windfarms. Report to the Energy Technology Support Unit. Report No. 920.’ This report identifies several areas requiring further work, including:

  • Full characterisation of the noise and vibration generated by offshore wind farms.

  • Further study of the effect of noise and vibration on the biological environment.

  • Assessment of the effects of wind farms on sediment transport and wave climate.

c.    Management response

i.   Rationale

This type of operation would require a number of statutory consents if occurring with the Cardigan Bay cSAC (see also section 5.3.4 relating to cables and pipelines):

  • A consent under section 34 of the 1949 Coast Protection Act 1949 (works likely to interfere with navigation). The responsible authority is DETR Ports Division.

  • A licence under section 5 of the Food and Environment Protection Act 1985 (deposit of articles on the seabed). The responsible authority is the National Assembly for Wales, although the licencing system is operated on behalf of the NAW by MAFF.

  • A consent under section 36 of the Electricity Act 1989 (if more than 50 megawatts will be generated). The responsible authority is the Department of Trade and Industry.

  • Planning permission under Town & Country planning legislation may also be required for associated onshore developments.

  • In addition, a lease from the Crown Estate, as owners of the seabed, would be required.The construction of offshore windfarms would clearly constitute a plan or project, and therefore the consents above would not be issued until the operation had been subject to the steps set out in Regulation 48 of the Habitats Regulations. Many schemes would also be subject to Environmental Impact Assessment.

ii.  Type of response

F1 : The activity is considered to constitute a plan or project for the purposes of the Habitats Directive. Therefore the impact on the SAC of each proposed development should be assessed on its individual characteristics.

iii.  Actions, including links to other policies/plans/initiatives

  • If development proposals arise which may affect the SAC, ensure appropriate assessments take place and address the SAC interests.

  • Monitor the development of UK government policy/strategy with respect to the development of offshore alternative energy generation, and ensure that the SAC is appropriately considered in the development of such a policy, e.g. in any consultation exercises.

  • RAs (or one of them) to write to government seeking information on their latest policy position.

  • Promote research by DTI/Industry into the potential impacts on marine mammals (including bottlenose dolphins) of underwater noise and vibration arising from offshore windfarms and other ‘at sea’ alternative energy structures.