Surfers Against Sewage Wave Hub & Wave Farm Policy Document

SAS believe that climate change poses a major threat to recreational water users, the marine environment, and the planet as a whole. SAS agrees with the majority of the scientific community that action needs to be taken now to combat climate change.

Predicted increases in rain intensity are expected to increase the frequency at which storm sewer overflows operate, resulting in a decrease of coastal water quality in many areas. Widespread flooding is also likely to result in the mobilisation of land based pollution into the marine environment. Sea level rise will alter the shoreline (and consequently surf breaks) in many ways. This may result in some breaks being lost.

Wave power concept and technology

Areas such as the South West peninsular and the West Coast of Scotland have a huge wave energy resource, with mean annual wave powers of around 20 - 40 kW per metre of wave crest just a few miles offshore.

If some of this power could be harnessed and converted to electricity, it would represent a clean and safe source of renewable energy. This would help to reduce CO2 emissions and therefore help combat climate change, and avoid further investment in hazardous and polluting technologies such as nuclear power.

It is envisaged that this can be achieved by wave energy devices, deployed in arrays (i.e. a wave farm). At present, there are many different types of wave energy device in development.

Impact of the wave hub on surf

The first of these projects is the pre-commercial test site 12 miles off the coast of North Cornwall. SAS were invited, along with the British Surfing Association, as stakeholders throughout the consultation process and are part of a Marine Renewables Working Group. SAS pushed to make sure that the views of surfers were represented. This was done by ensuring that comprehensive modelling was carried out into the possible impacts of the proposed wave hub on surfing waves inshore. In all likelihood, this would not have been done had SAS not been involved.

To date, SAS have been involved in two separate projects modelling the possible effects of the wave hub on the surf climate and have given information for a third. Over the last two years, we have introduced the issue to our members and the wider public through the watersports related press and mainstream media, to generate interest and debate on such projects. We have consulted heavily with and sought advice from experts in all aspects of wave energy, oceanography and nearshore coastal dynamics. From this process, SAS are satisfied that the effect of the proposed wave hub on the surf will be minimal and will not affect its recreational value. All further comments have been made on the basis of these consultations.

Modelling results

Initial modelling was carried out by the University of Exeter. This has since been peer reviewed and published in the journal Ocean Engineering. The main results are as follows:

• Using a realistic energy absorption scenario, the average reduction in significant wave height at the shore is 1cm or less.
• The maximum reduction in significant wave height at the shore (again using a realistic energy absorption scenario) is 4cm.
• Average and maximum percentage reductions in significant wave height under this scenario are 0.31% and 2.3% respectively.
• If a higher energy absorption scenario is assumed (representing an optimistic target for developers in the future), the average and maximum reduction in significant wave height is 2cm and 13cm respectively.
• The effect on wave period is negligible.
• The study concludes by saying 'There is little cause for concern that effects introduced by the Wave Hub will be felt by shoreline users of the sea.'

The main results of the modelling carried out by Halcrow on behalf of the South West of England Regional Development Agency are as follows:

• Worst case scenario is a reduction in the height of waves at the coast by a maximum of 13%.
• A more likely scenario (considering the devices which are to be installed) is a maximum wave height reduction of up to 5%.
• The farm will have a greater effect on shorter period waves than longer period waves (swell).
• The effect on wave period is negligible.
• The hydrodynamic modelling suggests that the effect on sediment transport will be undetectable against the background variation.
• Some types of devices are predicted to have a larger effect on wave height than others.

SAS believe that any slight reduction in wave height (i.e. 5% maximum) will be unnoticeable by surfers. Wave period and bathymetry are also key factors in determining the quality of a surfable wave in addition to wave height. Both studies state that the effect on wave period will be negligible and the Halcrow report suggests that sediment transport (and therefore bathymetry) will not be altered to any significant degree.

Given these facts, the overall effect on surf quality under these conditions is predicted to be extremely slight at most and undetectable by surfers.

SAS believe the occasional reduction in wave height of up to a maximum of 13% along a small section of the coast, as a worst case scenario, should not result in a substantial reduction in surf quality. A height reduction of this scale occurring occasionally is viewed by SAS to be within acceptable limits, given the nature of the project and what it is trying to achieve (i.e. combating climate change and the problems associated with it).

After analysis of all the information available, including the model outputs (which need to be taken in context of what they are trying to show), and after consultation with experts on the matter, SAS believe that, as a result of the wave hub project, no surf breaks will be destroyed or suffer a consistent reduction in surf quality on a scale that would be detectable by surfers. Any noticeable effect is likely to be very marginal and occasional.

In conclusion, SAS are supportive of the wave hub project for the following reasons:

• SAS believe that under the vast majority of conditions, there will be no noticeable effect on surf quality.
• Any noticeable effects are likely to be very marginal and occasional.
• Wave energy is clean and renewable and therefore can help in combating climate change.

Future of wave farms

SAS believe that wave farms have the potential to reduce CO2 emissions thus combat climate change and are therefore a benefit to recreational water users, the marine environment, and the planet as a whole.

Some locations are going to be more suitable for the siting of wave farms than others. Clearly, SAS would be very concerned about any proposed plan that resulted in a significant noticeable reduction in surf quality in its lee or reduced the amenity resource for any other watersport. For this reason, whilst backing the technology, SAS will look at each proposal on a case-by-case basis before deciding whether to support or oppose the plans.

Any group that oppose all wave farms in principle, irrespective of their effect on the surf, run the risk of not having their views properly considered when opposing plans for a poorly placed wave farm that would adversely affect surf. SAS do not wish to put themselves in this position.

The proposed Wave Hub itself cannot be upgraded to take an increasing number of wave energy devices, due to the capacity of the cable that links the hub to the shore. Uncontrolled proliferation of devices is therefore not technically possible without replacement of the 12 mile cable. In addition to this, other marine sectors such as shipping and fishing restrict the area that can be used for marine renewables. Any new development will have to go through the normal planning process, including a comprehensive assessment of the impact on surf. SAS will consider any new proposal on this site on the basis of these assessments.

What has become clear from the EIA process and additional investigation is that different wave energy devices are likely to have significantly differing effects on the waves that pass through them. It is expected that large arrays of some devices could potentially have a bigger impact on the nearshore surf conditions than others. It may be the case in the future that SAS oppose some devices in certain locations in favour of different devices, due to their impact on surf quality. SAS will continue to look into this as the technology develops.

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