Tidal Power in the UK - Sustainable Development Commission

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Area for birds (see Section 2.2.3), as well as being a Ramsar site for internationally importantwetlands. The SeaGen test site is in the Strangford Narrows, which connects the Lough to theIrish Sea. The area has important subtidal and intertidal rock, sand, mud, and horse musselhabitats as well as wintering waders, breeding terns and seal populations. An EnvironmentalStatement (ES) was initially prepared in June 2005 to support the company’s application forconsent under the Food and Environment Protection Act 1985 (FEPA) and to assist the competentauthority, Northern Ireland’s Environment and Heritage Service (EHS), to fulfil its obligationsunder the Habitats Directive.The ES prepared in 2005 recognised that the novel technology meant that there was someuncertainty about the potential impacts on seals and basking sharks. At maximum turbine speedthe rotor blades would operate at around 12m/s, about a third of the average wind turbinespeed according to the ES. A speed of 10m/s is more likely, which corresponds to around12 revolutions per minute.It was also recognised that the installation and presence of the device will have some visualimpact on the seascape as the part of the structure that is above water will be visible from landand from the ferry crossing from Portaferry. Once installed, the effects will be more significantduring maintenance as a result of increased activity and the cross-arm being raised above thewater level.Outcome and lessonsThe EHS initially granted a FEPA consent for the project in December 2005. However, furtherinvestigations were necessary to fully support the ‘appropriate assessment’ process under theHabitats Directive. This process requires a very high level of confidence that internationallyimportantprotected conservation features will not be negatively affected by development.The EHS granted a further consent for the five-year demonstration in February 2007.The project now has a comprehensive monitoring programme in place for birds, habitats,seals, and basking sharks. The conditions of the consent also give the EHS some options forstopping the operation if significant adverse effects occur, including the ability to require furthermonitoring and assessment, or even early decommissioning. The monitoring can be expected togenerate useful information on the actual environmental impacts of the SeaGen device whichwill have application in future design modifications. It will also help in predicting potentialenvironmental impacts at other sites or from the installation of multiple devices.On the environmental issues, the ES indicated that, early on in the project, there was generalsupport from stakeholders for the development of a new renewable technology but that therewere potential issues around the international designation and impacts on protected species.The delay in the consenting process to fully address concerns under the Habitats Directivesuggests that it might have been possible to avoid or resolve these issues earlier to ensure thatthe strict requirements were met without delaying the project. However, the case study alsoindicates that working in an environmentally sensitive area is a major challenge for a one-offdemonstration project involving a new technology.The testing and monitoring should nonetheless provide valuable information on the operation ofa tidal stream turbine in the marine environment. The actual installation of SeaGen, which wasmost recently scheduled for the summer of 2007, has been further delayed because of a problemwith the jack-up installation vessel but is due to go ahead shortly.44 Tidal Power in the UK Sustainable Development Commission
2.3.3 Summary of environmental impactsThe key environmental impacts from tidal streamdevelopment are those related to:• ecology (habitats and species)• landscape and seascape• noise (airborne and underwater)• seabed, sediments and currents• water qualityImpacts on other users of the marine environment– such as fishing and navigation – will also need tobe considered as part of an environmental impactassessment. In practice, these issues need to beconsidered much earlier at a strategic level and insite selection. The issue of conflicts of use in themarine environment is discussed in Section 2.3,which considers the potential social and economicimpacts of tidal stream development.Environmental impacts at the various stages ofdevelopment will need to be considered, including:• construction• operation and maintenance• decommissioning.At the construction stage, the key impacts willbe related to drilling and piling activities, increasedlevels of noise, and increased activity and pollutionrisk associated with construction boats and activity.Direct effects on the seabed are greatest at thisstage. For tidal stream devices, construction of thedevice itself would usually take place onshore,followed by installation of the device and associatedcabling at sea.At the operation and maintenance stage, thedevice may have effects on water movementsand sediment, as energy is extracted from thetidal flows, and underwater noise and the turbineoperation have the potential to affect ecology, fishand marine mammals.Tidal stream devices, once developed to full scale,can be expected to have a lifetime of around 20 years.At the decommissioning stage, similar effects tothose identified for commissioning can be expected.Further effects at this point may include disturbanceto any new community of marine organisms that hasbecome established on the device.The environmental effects of associated onshoreinfrastructure, in particular power cabling, will alsoneed to be taken into account, and can often bea significant practical issue during consenting (asseparate planning consent must be sought).Ecology (habitats and species)A number of marine species and habitats in UK coastalwaters have the potential to be affected by tidalenergy schemes. These include birds, fish, marinemammals, plankton, and benthic communitieson the seabed. Terrestrial habitats may also beaffected by infrastructure works to accommodatethe landward transmission of electricity.The main issues affecting habitats arise fromchanges to the physical environment – for example,changes in water flow and tidal mixing, waveaction, tidal inundation, patterns of sedimentationand erosion, and disturbance of the seabed byconstruction and cabling. These changes can alterthe character of marine communities, or lead to thedisplacement of species from feeding or breedingareas.Fish and marine mammals may be particularlyaffected by the generation of underwater noise, andthe electromagnetic fields generated by sub-seatransmission cables. Collision risk is another factorthat will need to be considered for each device.Although the risk from turbines turning slowlyunderwater may be low, this risk, and the potentialbehavioural changes of these species, will need tobe assessed with care, and monitoring of installedtest devices will be needed.There are also potentially positive effects fromtidal stream development for nature conservation.A tidal installation may function as a refuge areafor fish populations as a result of reduced fishingpressure from the creation of ‘no-catch’ zones. Thepotential benefits of this will depend on the specificimpacts of a device, the scale of its deployment, andconsideration of decommissioning implications, butthis may offer an opportunity to integrate renewableenergy generation (and a commercial activity) withnature conservation objectives.Landscape and seascapeMany coastal areas have an important amenity andnatural heritage value for communities, visitors, andrecreational users. The placement of a tidal energyscheme in waters close to the shore may have animpact on the landscape and seascape of the area,particularly where the devices are surface-piercingstructures. The level of impact will depend on theSustainable Development Commission Tidal Power in the UK 45
Page 3 and 4: Turning the TideTidal Power in the
Page 13 and 14: Compliance with environmental legis
Page 15 and 16: e publicly-led as a project and pub
Page 17 and 18: Introduction1
Page 19 and 20: 1.2 Our approachThe SDC announced t
Page 21 and 22: 1.3 UK tidal resourceA detailed des
Page 23 and 24: Figure 3UK tidal range resourceHigh
Page 25 and 26: Box 3Quantifying the renewable ener
Page 27 and 28: Tidal rangeThe timing of the tidal
Page 29 and 30: The majority of generation plants i
Page 31 and 32: last few years. However, we remain
Page 33 and 34: comparatively short lifetime of the
Page 35 and 36: are covered in Chapter 4 in relatio
Page 37 and 38: Tidal Stream2
Page 39 and 40: Figure 9Rotor configuration options
Page 41 and 42: Box 4Case study - European Marine E
Page 43 and 44: 2.2.5 Role of nature conservation a
Page 45: This is also a risk issue. At prese
Page 49 and 50: communities at a local and regional
Page 51 and 52: Figure 10 Publicly-funded energy R&
Page 53 and 54: generation a new sub-sea cable to t
Page 55 and 56: wave and tidal devices. The results
Page 57 and 58: is a need to look at the developmen
Page 59 and 60: Tidal Range3
Page 61 and 62: costs. This factor, along with the
Page 63 and 64: Figure 13 Proposed position of the
Page 65 and 66: Figure 14 Artist’s impression of
Page 67 and 68: minutes, resulting in cost increase
Page 69 and 70: isk management plan for the estuary
Page 71 and 72: 4A Severn Barrage
Page 73 and 74: 4.2.1 The Severn EstuaryThe Severn
Page 75 and 76: have a major effect on the surround
Page 77 and 78: Tidal barragesCompatibility between
Page 79 and 80: there will always be some down-time
Page 81 and 82: Figure 19bNeap tide power generatio
Page 83 and 84: Implications for system balancingFr
Page 85 and 86: 4.4 Carbon emissionsThis section as
Page 87 and 88: and processes of the estuary would
Page 89 and 90: Figure 23 Elevation in and around t
Page 91 and 92: 4.6 Environmental impactsBased on t
Page 93 and 94: places the aim of maintaining biodi
Page 95 and 96: Figure 26 Map showing national desi
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Table 7Predicted change in extent o
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Transitional habitatsTransitional h
Page 101 and 102:
year mean peak average (to avoid ex
Page 103 and 104:
well as delays to migration and the
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Table 9Severn Estuary habitat chang
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Directive must be applied. 85 In ef
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Implications and mitigation measure
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4.7.3 Coastal defence and flood pro
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ise with the expectation that as se
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4.7.4 EmploymentA Severn barrage wo
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The potential for wider environment
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have negative economic effects both
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Figure 33 Comparing 25 the cost of
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to find alternative sources of inco
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technologies by deflating the price
Page 127 and 128:
emaining finance raised from the sa
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When given information specifically
Page 131 and 132:
for sustainable development (see Se
Page 133 and 134:
a Severn barrage that lie outside t
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The conservation agencies share thi
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5Conclusions andRecommendations
Page 139 and 140:
for bringing prototype technologies
Page 141 and 142:
use of innovative materials or impr
Page 143 and 144:
upholding the long-term public inte
Page 145 and 146:
estuary, but there is no evidence t
Page 147 and 148:
The Government would need to ensure
Page 149 and 150:
Commission) on whether this could b
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6 References1 The term ‘Governmen
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64 For a discussion of ecosystem se
Page 155:
Glossary of termsBERR Department fo
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