Fair Head Tidal (FHT), a development company set up by DP Marine Energy (DPME) and DEME Blue Energy (DBE), proposes to build a tidal energy development of up to 100MW installed capacity off Fair Head in North Antrim in Northern Ireland.
The project received an “Agreement for Lease” (AfL) from The Crown Estate (TCE) on the 10th October 2012. The AfL allows the developer exclusive rights to develop a tidal energy site off Fair Head. The planning application for the project was submitted in February 2017. If, following consultation and environmental impact assessments, the proposal is consented the build programme for phase 1 (four to six turbines depending on turbine capacity) is due to begin in Q2 of 2018 and is planned to be operational by the end of the year, although this will depend heavily on resolving onshore grid connection issues.
The area of development lies within the Rathlin Island and Torr Head Strategic Area 2km east of Fair Head. The site occupies a total area of approximately 4.2km2 and is around 1km off the North Antrim Coast in Northern Ireland.
Grab samples collected by the British Geological survey indicate that the seabed in this area is an extensive rocky outcrop supporting some gravelly sediments, with the majority of the area from Fair Head to Torr Head being shallow course sediment plains. Water depths vary from 25 to 130m with a steep slope being present 50m from the headland. This extends out to 1km and the gradient levels off at a depth of around 120m 4km from the coast line.
Fair Head, Northern Ireland.
Coordinates: 55.231°, -6.107°
The Department of Agriculture, Environment and Rural Affairs (DAERA), Northern Ireland, Marine Strategy and Licensing team issues licences for the construction, extension or operation of generating stations under Article 39 of the Electricity (Northern Ireland) Order 1992.
An Agreement for lease was granted in 2012. In the lead up to the submission of the planning application (February 2017) feasibility studies for onshore grid connections and baseline studies including those associated with Navigational Risk Assessment were undertaken.
It is proposed that the Fair Head Tidal Energy project could be delivered in phases. FHT is considering an initial demonstration array of around 4 – 6 turbines, and with an output of up to 10 MW, which would be connected into the existing electricity grid at Ballycastle. Further phases would complete the proposed 100 MW array of tidal turbines that would be capable of powering some 70,000 homes. The project is still in its consenting phase.
Key Environmental Issues
The key environmental issues associated with the project are those common to the tidal stream industry, including:
- Collision Risk
- Loss of seabed habitat
- EMF impacts
- Barrier to movement
- Vessel disturbance and collision
- Commercial fisheries impacts
Environmental Webpage: http://dpenergy.info/fht/environment
All relevant planning application documents, including EIA docs can be downloaded from the following link: http://dpenergy.info/fht/downloads
The proposal is based on a technology neutral approach. Given the physical constraints and resources of the development site, an envelope has been developed based on a generic design philosophy using horizontal axis tidal turbines with open rotors. The envelope allows for both floating moored and seabed mounted systems which may be surface piercing or non-surface piercing.
Example devices include the Siemens MCT SeaGen S, the Alstom TGL, Voith Hydro and Hammerfest Strom. Currently there is no practical experience for turbine spacing, however analytical models are being produced and preliminary layouts or the array are based on spacing’s of 500m down-stream and 150m across. Rotor diameter will be limited by water depth.
Inter array cables:
Individual turbines will be connected to one or more subsea or surface mounted marshalling units containing both power conditioning equipment and transformers in order to increase the generated voltage to 33kV for transmission without significant losses. It is unlikely that a further step up in voltage to 110kV or 132kV will be necessary. Subsea substations at this scale are still unproven, and consequently the project approach is to utilise surface piercing solutions such as the SeaGen S Mark 2 or floating devices to provide the marshalling points for the farm. The advantage of this approach is that principle connections can be undertaken dry with no requirement for underwater connections or the placement of key electrical equipment on the seabed.
The detailed electrical design is yet to be completed but it is likely that multiple 33kV cables will be used to deliver the 100MW capacity to shore. The Fair Head project is relatively close to the mainland, hence lower voltage cables can be utilised with minimal transmission losses. Additionally there is no requirement for a dedicated high voltage and expensive offshore transformer station. As far as possible, cable routes will avoid traversing areas of very high tidal flow and will be either trenched, pinned or protected by rock dumping or mattresses depending on the seabed characteristics. Installation methods and routing will be defined in more detail as part of the EIA to identify the most appropriate subsea route and landfall location.
The onshore substation location has yet to be defined and will be subject to a detailed assessment of potential landfalls and optimum locations from both an EIA and final grid connection perspective. There is potential for both the Fair Head and Torr Head tidal projects to share a common substation and grid connection point. This has yet to be confirmed and the ultimate size and voltage of the station will depend on this decision. If both projects are brought into a common point ashore it is likely that the substation will need to transform the voltage of the incoming subsea cables to 110kV.
Vessels to be used in construction have not yet been confirmed, however the project description suggests that jack up barges and DP vessels will be required to install the devices.
Baseline Assessment: Fair Head Tidal Array
|Receptor||Study Description||Design and Methods||Results||Status|
|Marine Mammals||Marine mammal surveys.||Two years of boat-based counts and PAM data gathered from a seabed moored C-POD device.||Boat-based counts: During the 24 vessel based surveys, a total of 463 useable transects were run over the study area between July 2013 and June 2015, covering a total on-effort line length of 2,712.6 km. A total of 184 marine mammal and basking shark sightings were made, totalling 350 individual animals. Of these sightings, 138 were made by on-effort Marine Mammal Observers (MMOs), whilst 46 auxiliary sightings were also made. |
The principal species observed at the development site was harbour porpoise, with 113 oneffort sightings totalling 215 individuals. Grey seal, harbour seal, killer whales, and basking sharks were also positively identified (6, 11, 1 and 2 on-effort sightings respectively). In addition, auxiliary observations of common dolphin, bottlenose dolphin and at least one unidentified large whale were made during the survey, while minke whale was confirmed during additional shore-based vantage point seabird monitoring. Absolute density estimates using distance sampling methods could only be produced for harbour porpoise, generating an overall estimate of 0.251 porpoises per km2 (95% Confidence Interval of 0.179 – 0.352 porpoises per km2; data from all 24 surveys aggregated).
The C-POD was deployed for 324 days from June 2014 to June 2015 and recorded 12,795 Detection Positive Minutes (DPMs), defined as a minute containing at least one click train of likely porpoise origin. Results from the C-POD deployment supported the findings from the visual survey that harbour porpoise frequently used the proposed site. However, based on encounter duration they did not appear to spend a very long time in the vicinity of the C-POD device during each visit.
|Fish||Desk based fish study.||This desk-based study examined the species which are present in the AfL area and the associated cable routes.||The study used records of species caught by sea anglers as an indication of species likely to be present at the site. Anglers at Ballycastle, the closest area to the tidal site, listed the following species as being caught: Pollack, Ballan wrasse, flounder, bass, small turbot, dabs, plaice, dogfish, whiting, codling, sea trout, coalfish. |
An overview of the status of elasmobranchs in the area indicated that the following species may be present in the area: basking shark, lesser spotted dogfish, nursehound, porbeagle, spurdog, common skate, blonde ray, thornback ray, spotted ray and cuckoo ray.
The proposed site and cable routes are also probable migration routes for three diadromous species: Atlantic salmon, sea trout and European eel.
|Birds||Ornithological surveys.||A two year programme of boat-based seabird surveys. The survey area encompassed the Agreement for Lease area (AfL, 4.2km2 ) plus a surrounding buffer of up to 4km measured from the AfL perimeter, though in parts the extent of the buffer was clipped by the coast |
The survey design comprised 22 parallel transects spaced 0.5 km apart covering the Survey Area and with a total length of 134 km.
Surveys were scheduled at monthly intervals from July 2013 to June 2015. A total of 24 surveys (with each undertaken in a single day) were undertaken over the period.
|A total of 14 seabird species were commonly recorded. Small numbers of 15 other species of seabird (including divers and seaduck) were recorded occasionally. |
The surveys showed that during the breeding season the Survey Area is regularly used by high numbers of common guillemot and razorbill and moderate numbers of kittiwake, Manx shearwater, gannet and puffin. Common guillemot and kittiwake were also present in moderate to high numbers in the post-breeding season (late summer). Kittiwake, common guillemot and razorbill all breed in moderate to large numbers at colonies on Rathlin Island.
For all the regularly occurring seabird species except kittiwake and razorbill, the mean abundance in the Survey Area was similar in Year 1 and Year 2 during both the breeding/post breeding season and the nonbreeding period. Kittiwake mean abundance was higher in all seasons in Year 2. Razorbill estimates were higher in Year 2 during the breeding season and higher in Year 1 during the post-breeding and non-breeding periods.
Of those species with moderate or high estimated numbers in the Survey Area, common guillemot and razorbill are considered to have high, and puffin moderate vulnerability to tidal devices. Populations of these species are therefore potentially most likely to be adversely affected by the Project.
|Physical Environment, Sediment Transport, Invertebrates||A marine ecology literature review and baseline survey was carried out in order to characterise the intertidal benthic communities in the vicinity of the landfall section of cable route connecting the proposed array site to Ballycastle Bay and Murlough Bay.||An intertidal survey was performed at the proposed Phase 1 export cable landfall site, Ballycastle Bay, by two surveyors during low water spring tides on the 7 th September 2014. |
Intertidal surveys were performed on the section of coastline at Murlough Bay landfall area where the Phase 2 cable route is proposed to come ashore.
Prior to the surveys taking place, an intertidal survey plan was produced including a survey methodology and maps detailing the location of sampling stations. The survey area covered the proposed cable route landfall and at least 500m either side.
|Ballycastle Bay: Ballycastle Bay itself was found to be predominantly sandy, backed by dunes and a golf course. To either end of the beach were rocky areas – to the east, Pans rock, rocky skewers with surge gullies and volcanic platforms, and to the west a harbour with sparsely colonised sea defences, followed by rocky shore area backed by steep vegetated cliffs. |
The sediment shore comprised of moderately sorted fine to medium white sands with very few infaunal organisms recorded. Impoverished sands are a feature of highly mobile sediment in exposed areas and commonly support low species richness and abundance. The exception of this was the sand hopper community living on the seaweed of the strandline.
The rocky shores surrounding the beach at both Pans Rocks and west of the harbour were diverse in habitats due to the topography of these shores which creates an abundance of different niches for marine communities to colonise. The survey location exhibited little tidal movement over the low water period, due to the location of an amphidromic point in the North Channel region which result s in the smallest tidal range in the British Isles.
This small tidal range leads to a compressed littoral zonation of biotopes which manifested itself most obviously on the lower shore/sublittoral fringe where the biotopes found represented a mixture between lower shore, infralittoral and even mid shore communities. Species that are therefore usually separate from each other on other shores with a large tidal range were therefore found in close proximity to each other.
Murlough Bay: Murlough Bay landfall area was found to be predominantly rocky with large boulders and skewers backed by steep vegetated cliffs, and one small sandy bay which comprised moderately sorted medium sands. The area surveyed fell between Fall Point to the north and Ruebane to the south.
Sediment sample analysis revealed a high number of arthropods on the mid to low shore, with the sample dominated by Bathyporeia pelagica. There was also evidence of sand hoppers on the top shore. Impoverished sands are a feature of highly mobile sediment in exposed areas and commonly support low species richness and abundance but this area is afforded some protection and shelter as the bay in recessed in the coastline which could explain the higher number of Amphipods found.
Due to the rocky nature of the majority of the stretch of coastline, the shores create an abundance of different niches for marine communities to exist.
|Physical Environment||A nearshore hydrographic and geophysical survey.||Sea bed habitat mapping included surveys in Ballycastle Bay, in the western part of the cable survey area, and also on the south east side of Fair Head, in the development and Murlough Bay areas. The mapping was carried out using RoxAnn acoustic ground discrimination with ground-truthing undertaken in stages using towed video surveys.||Tidal currents in the Ballycastle Bay area often exceed 3 knots and as a consequence there are few fine sediments on the seafloor. The mapping in Ballycastle Bay showed sea bed at depths shallower than 20 m to be characterised by boulderfields interspersed with sand and cobbles. In deeper water north east of Ballycastle the bed tended to be coarse sand and further east, harder substrates dominated by cobble beds. The coast to the south east of Fair Head is subject to very strong tidal currents. Close inshore is a rubble and boulderfield slope. Into deeper water, rubble predominates before grading into cobbles on coarse sediment further offshore.||Completed|
|Physical Environment, Sediment Transport||A benthic survey of the AFL and cable route corridor area.||A benthic survey campaign was designed and executed in 2014 using high resolution multibeam sonar data to direct sampling of a range of potential habitats. Grab sampling of sedimentary areas and epibenthic towed video allowed identification of infauna and conspicuous epibiota respectively, and provided detailed information on the substrata.||Much of this high energy environment was classified as Annex I bedrock reef and stony reef, which have extensive examples within the Tidal Site and notable examples in both Cable Routes. These areas did not harbour any notable PMF habitats (as sponge and anthozoan assemblages were not in notable densities or diversity, possibly due to sand scour). Circalittoral sands and gravels were identified, but did not form clean sandbanks, and often have a notable cobble component. However, such habitats may be considered as component habitats of the pMCZ habitat “Sublittoral sands”. Mixed sands/gravels and stony reef areas also harboured notable brittlestar beds, particularly within Ballycastle Bay. Brittlestar beds are noted as component habitats in three pMCZ habitats, but their uniqueness and conservation interest is unclear, as similar habitats are found extensively within Northern Ireland’s inshore waters.||Completed|
|Human Dimensions, Fisheries||Desk-based study of species important for commercial fisheries.||Desk-based study of species important for commercial fisheries in the area.||The species identified as occurring in the area and being of importance to commercial fisheries interests include: Brown crab (Cancer pagarus), Velvet crab (Necora puber), Lobster (Homarus gammarus), King scallop (Pecten maximus) and Queen scallop (Aequipecten opercularis).||Completed|