Annex IV distributes metadata forms (questionnaires) to solicit information from developers involved in environmental monitoring around marine renewable energy project sites around the world. This page provides project descriptions, baseline assessment, post-installation monitoring, and links to available data and reports. Content is updated on an annual basis.

Perpetuus Tidal Energy Centre (PTEC)

Project Site Annex IV

Title: Perpetuus Tidal Energy Centre (PTEC)
Developer:
Country:
Technology Type:
Info Updated:
October 11, 2017
Project Status: 
Planned project
Technology: 
Energy demonstration centre (test site)
Project Scale: 
test site for devices up to 10MW and arrays
Installed Capacity: 
30 MW
Description: 

With the onshore application given local planning consent in summer 2015, the PTEC project at 30MW is now the largest consented tidal stream energy project in England and Wales. It has also secured its future connection to the UK’s electricity grid.

PTEC is operated as a joint venture between a private company, Perpetuus Energy Ltd, and the Isle of Wight Council. It is hoped that the construction of the project will start in 2017, with potential to be generating electricity from late 2018.

A number of tidal turbine manufacturers have already expressed interest in partnering with PTEC to install their turbines. Once operational, PTEC will generate sufficient clean electricity to power more than 15,000 homes with a total expected output of 65,000kWh per year.

PTEC will fill the gap for technology and tidal array developers between testing a prototype device and installing and operating arrays of devices.

The Environmental Impact Assessment (EIA) which formed part of the consent application which PTEC Ltd has been completed and was submitted in the fourth quarter of 2014.

 

A Front End Engineering Design (FEED) study was also completed for PTEC Ltd, by renewable energy specialists IT Power. The FEED study helped PTEC Ltd to decide on a number of design and technology details which was assessed during the EIA process.

Project details:

The development site will provide between 3 to 6 berths for tidal devices to be deployed, with a subsea export cable(s) for each berth to bring the electricity ashore. The subsea export cables will come ashore at Castle Cove to the west of Ventnor on the Isle of Wight. As part of the project, a small substation and control room will be constructed onshore along with associated works.

 

The PTEC development site is proposed to be situated approximately 2.5km south of St Catherine’s Point, Isle of Wight, with the development site being no greater than 5km2 in area. The development site will then be connected to shore by electricity export cables which will come ashore on the south coast of the Isle of Wight.

 

Device suitability:

All kinds of tidal devices can be installed at PTEC.

PTEC will provide facilities for up to 60 tidal devices, with an aggregated maximum capacity of up to 30MW.

 

The 5km2 development site will be segregated into a number of berths (a maximum of 6 berths and a minimum of 3 berths). Each berth will consist of a defined area, leased to a developer in which they will demonstrate their tidal technologies.

 

Berth capacities may vary between 1MW and 10MW (to a total of 30MW) and tidal device capacities may vary from 100kW (0.1MW) to 6MW

 

PTEC will provide developers with grid connection infrastructure via subsea export cables, as well as navigation aids and site monitoring equipment to allow developers to utilise the area to demonstrate their tidal technologies.

 

Consenting Process:

The consenting process, commenced in January 2013 and involved significant consultation. A request for scoping opinion (Scoping Report) was submitted in January 2013 for the PTEC project, at that time known as the Solent Ocean Energy Centre (SOEC), Scoping opinions were received from statutory regulators and representations from a number of other interested parties and agencies. Comments and advice received as responses to the scoping consultation were used to direct the studies and assessments undertaken during the subsequent environmental impact assessment (EIA) and also to identify parties with which ongoing consultation was required.

Any potential environmental and community impacts were closely examined. The Marine Management Organisation gave final consent in April 2016.

PTEC will continue to work closely with the Isle of Wight Council, the Marine Management Organisation, Natural England and other stakeholders to minimise any potential impacts on the environment of the Isle of Wight and its surrounding seas.

 

Export Cable:

6 export cables grouped into 3 bundles of 2 cables each

Various cable landfall locations were considered. The selected landfall location is Castle Cove to the west of Ventnor. Landfall options within the onshore site include:

• Cables trenched/buried, making landfall adjacent to the existing slipway;

• Using an existing 600 mm diameter outfall pipe as a cable duct for some or all of the export cables; or

• Horizontal Directional Drilling (HDD) under the shoreline from a suitable location close to the proposed substation/control room, with cable emerging in the shallow subtidal for connection to the marine export cables.

Process Status: 

In July 2017 it was announced that PTEC would be put on hold amid reports the centre was unable to rival the process of offshore wind in the latest UK Government’s Contracts for Difference (CfD) auction.

 

The UK Government opted not to ring-fence funding for marine energy in this latest allocation round which meant PTEC could not compete on price with more mature renewable energy sectors.

 

The project received all key consents in 2016, and was due for full operations starting from 2020.

 

Perpetuus Tidal Energy Centre (PTEC) is located in United Kingdom.

Baseline Assessment: Perpetuus Tidal Energy Centre (PTEC)

General Description:

The following field surveys were undertaken (or commissioned by) the developer to inform baseline characterisation.

ReceptorStudy Description Design and Methods Results Status
  • Physical Environment

Metocean survey

Vessel-mounted ADCP survey along 6 transect lines over a continuous period of 36 hours and also a static deployment ADCP surveys at 3 locations to measure currents through the water column in vertical slices of 2m.

Tidal propagation is strongly influenced by astronomical tidal effects and is from west to east within the region on a flooding tide; i.e. the flood tide progresses from the Atlantic, through the English Channel into the North Sea, and vice versa on an ebbing tide.

 

The tidal regime within the proposed development site is characterised by current speeds which are generally greater immediately below the water’s surface than those at depth. Mean spring peak and mean neap peak current speeds are typically around 2.5-2.9 m/s and 1.3-1.6 m/s, respectively.

Completed
  • Physical Environment

Geophysical survey

High-resolution swath bathymetric and side-scan sonar survey and sub-bottom profiling.

Within the development site, the shallow geology comprises current-scoured bedrock with boulders and cobbles at the seabed. Within the majority of the subsea export cable corridor, the shallow geology is predominantly bedrock (often with boulders and cobbles) which either outcrops at seabed or is overlain by a thin veneer of mobile surficial sediment cover.

 

In the northern-most parts of the cable corridor, within 1.5km from shore, the shallow sediments comprise gravelly sand and form numerous broadly symmetrical sandwaves with crests predominantly orientated NE-SW, but also are observed cross-cutting with a NW-SE orientation.

Completed
  • Physical Environment

Seabed sediment survey

Drop down video samples at 48 locations across the development site and (the then planned three) cable corridors plus 10 ‘control’ locations at a distance of 1 tidal excursion away.

Grab samples (3 no.) and laboratory particle size analysis.

As the seabed south of the Isle of Wight is an area of relatively strong tidal currents, the seabed comprises mostly bedrock with occasional cobbles and rock boulders and virtually no mobile surficial sediment. Surveys have confirmed that the substrate directly within the development site is dominated by tide-swept bedrock, or bedrock with boulders with some cobbles, with very little finer sediment. These substrates form a solid and relatively stable substrate for biological colonisation in a very dynamic high energy environment.

 

The subsea cable corridor has sediment influenced cobbles along its inshore section; there is a relatively large sediment plain just offshore comprised of coarse disturbed sands with sand waves and ripples as obvious features. Cobbles and boulders on a possible clay bedrock form the substrate for the mid-section of the cable corridor, and towards the development site bedrock and boulder reefs are found on the western edge of the cable corridor, with the eastern edge being lower lying boulders and cobbles.

Completed
  • Sea and Shorebirds

Boat-based bird surveys

The survey area comprised the development site, with a surrounding 4km buffer.

 

A total of 12 surveys (with each undertaken in a single day) were undertaken at approximately monthly intervals over the year. Surveys were only undertaken in conditions of Beaufort scale sea state 4 or below. Days when low sea state conditions (sea state 2 or less) were forecast were selected for surveys, though conditions on the chosen survey day did not always match the forecast.

 

All birds seen were recorded. For each bird record, the species, number in the group, age, plumage, activity, together with information on environmental conditions at the time of each sighting in terms of sea state, swell, wind force and direction, and sun glare intensity.

A total of 12 seabird species were regularly recorded and the results for each of these, together with results for Balearic shearwater, are considered in detail. Small numbers of 12 other species of seabird were recorded only occasionally (less than five occasions), except lesser black-backed gull which was seen on seven occasions.

 

The surveys showed that the Survey Area generally has low importance for seabirds, with all species present in low or very low numbers relative to their population size and to densities recorded elsewhere in their ranges. The range of species and numbers present in the Survey Area was particularly low during the breeding season, reflecting the paucity, and small size, of breeding seabird colonies in the region.

 

Completed
  • Basking Sharks
  • Marine Mammals
N/A

The survey area comprised the development site, with a surrounding 4km buffer.

 

A total of 12 surveys (with each undertaken in a single day) were undertaken at approximately monthly intervals over the year. Surveys were only undertaken in conditions of Beaufort scale sea state 4 or below. Days when low sea state conditions (sea state 2 or less) were forecast were selected for surveys, though conditions on the chosen survey day did not always match the forecast.  Two marine mammal observers were used to provide a varying 360° view during 16 parallel transect lines in suitable weather conditions.

No grey or harbour seal were recorded during the PTEC site specific surveys.

 

A total of six harbour porpoise were sighted on the 10th April 2014 survey, which was the only survey during which harbour porpoise were sighted while on effort. One harbour porpoise was sighted on each of the November and December 2013 surveys while the surveyors were off effort. The low sightings rate further supports the low importance of this area for harbour porpoise.

 

A pod of eight bottlenose dolphin was observed in the PTEC survey area during the August 2013 site specific boat based survey. No further dolphins were observed from September 2013 to July 2014 during the remainder of the site specific surveys.

 

No common dolphin were observed in the PTEC survey area during the site specific boat based surveys from Aug 2013 to July 2014.

 

No Minke whale, long-finned pilot whale or basking shark sightings were made during the sight specific surveys.

Completed
  • Benthos

Video and grab sampling survey

The benthic sampling programme comprised of drop-down video (DDV) surveys and grab sampling where possible.

 

Geophysical survey data identified different acoustic ground types within the study area, this aided the pre-selection of 60 locations for DDV within the offshore site and a further 10 control sites beyond it. Data was successfully collected at 58 sample locations within the offshore site and at all control sites.

 

Only three locations, all at the landward end of the subsea cable corridor, contained substrate suitable for grab sampling (coarse sediment with occasional cobbles); the rest of the sites comprised of rock, boulders and cobble.

 

An intertidal survey of the landfall area at Castle Cove was completed to gain an understanding of the habitats and species present within the intertidal zone.

The DDV survey revealed the development site to contain a consistent coverage of species typical of tide-swept rocky habitats in the circalittoral zone; including rocks covered in dense faunal crusts dominated by the barnacle Balanus crenatus and encrusting and cushion sponges. Some rock surfaces were colonised by a thin, yellow encrusting sponge and a large, white cushion sponge similar to the Elephant’s Ear sponge Pachymatisma johnstonia. The sponges Dercitus (Dercitus) bucklandi and Dysidea fragilis were occasionally seen on the rocks and boulders to the west of the development site. The small, white interwoven network of tubes of Serpulidae worms such as Filograna implexa or Salmacina dysteri were also a conspicuous faunal crust species on the bedrock and boulders. The hydroids, Tubularia indivisa and Nemertesia antennina were occasionally observed, as well as Caridean shrimps.

 

Sponges and the keel worm Spirobranchus were found along the subsea cable corridor, as were the hydroid Tubularia indivisa and the ascidian Dendrodoa grossularia and the gastropod Calliostoma. Red algae such as Delesseria sanguinea and Plocamium cartilagineum dominates the inshore areas of the subsea cable corridor where cushion sponges were also commonly observed.

 

Completed
Reports and Papers

The full ES and associated documents can be accessed from the following link:  https://www.iwight.com/planning/AppDetails3.aspx?frmId=29315

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