OES-Environmental 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)

Description

Perpetuus Tidal Energy Centre (PTEC) Limited is an independent company working with The European Marine Energy Centre (EMEC) in Orkney, together with world leading turbine operators, to deliver tidal stream energy in the next four years. PTEC intends to construct a 30MW commercial demonstration facility for tidal stream projects, located off the south coast of the Isle of Wight. It will be a state-of-the-art development with the potential to generate enough clean electricity to power over 20,000 Isle of Wight homes per year.

PTEC aims to support and speed up the process of developing tidal technologies to full commercialisation, by providing a pre-consented facility to allow tidal developers to take the step from testing individual tidal devices to installing and optimising the performance, operation and maintenance of small arrays of tidal devices, on a long-term, commercial basis, in ‘real world’ conditions. PTEC will be a world’s first of its kind within a globally significant market and provide an opportunity to commercially operate tidal arrays and examine their interaction with the marine environment, all whilst generating zero emission energy, and providing employment, skills, educational opportunities and investment to the Isle of Wight. 

Device suitability: PTEC will be suitable for the installation of a wide range of tidal devices. 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 six berths and a minimum of three 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.

Export Cable: The development site will provide between three to six berths for tidal devices to be deployed, with a subsea export cable(s) for each berth to bring the electricity ashore. Six export cables are planned to be grouped into three bundles of two cables each. The subsea export cables will come ashore at Castle Cove to the west of Ventnor on the Isle of Wight, which was selected as the location that will cause the least environmental impact. As part of the project, a small substation and control room will be constructed onshore along with associated works. Cable 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. 

Consenting Process (2013-2016): In 2012 The Crown Estate entered into an agreement for lease for the Perpetuus Tidal Energy Centre.  The consenting process, which commenced in January 2013, was rigorous and involved significant consultation. Any potential environmental and community impacts were closely examined. A Scoping Report was submitted in January 2013 for the PTEC project, previously called 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. A Front End Engineering Design (FEED) study was  completed for PTEC, by renewable energy specialists IT Power. The FEED study helped PTEC to decide on a number of design and technology details which was assessed during the EIA process. The EIA was submitted in the fourth quarter of 2014. 

The onshore application received local planning consent in 2015. The centre received consent from the Marine Management Organisation (MMO) in April 2016 for up to 30 MW total installed generation capacity for a maximum period of twenty-five years (maximum of twenty years’ operation per tenant and up to five years for pre-construction, re-powering and decommissioning works).
 

Location

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.

Licensing Information

The approach of PTEC was to obtain site-wide consents (Marine Licence and Section 36) that covered a range of development scenarios and included the range and flexibility to attract a wide spectrum of developers and devices. This is in contrast to the licencing approach at the European Marine Energy Centre (EMEC), whereby individual developers are responsible for obtaining their own Marine Licences and Section 36 licences.

Therefore, there was the need to develop an envelope of development scenarios and establish workable limits on potential impacts. A programme of developer consultation was undertaken to carry out a review of existing device types and understand the range of device types that could be deployed at PTEC. The review also allowed the identification of realistic worst case parameters which were used to define the project envelope. This flexibility was deemed as crucial to allow PTEC to adapt to future improvements as part of ongoing efforts to maximise industry viability.

Project Progress

The project received all key consents in 2016 and was due to begin full operations south of the island from 2020. Following a change in government policy in 2016, however, the project was temporarily put on hold. Since this time, the project team together with the wider industry has lobbied government for a fair revenue support mechanism to be reinstated, which would enable the tidal stream sector to mature in the same way as wind and solar. Following an extensive period of industry collaboration and positive developments in reducing the cost of energy, PTEC restarted its development programme in October 2020, backed by partnership with EMEC.

PTEC is in the process of engaging world leading turbine operators for deployment. In May 2021, PTEC signed a pivotal agreement with Orbital Marine Power, Ltd. (Orbital), developers of the world’s most powerful tidal turbine, the Orbital O2, to bring the Isle of Wight a step closer to producing tidal energy. PTEC has gained offshore consents to place tidal turbines in the sea off the south coast of the Isle of Wight, and Orbital is the first company to sign up, with an initial target deployment of up to 15MW by the end of 2025.

In August 2021, an application for planning permission was submitted to the Isle of Wight Council for the onshore elements of the PTEC development. This application follows up onto previous planning approvals for a substantially very similar development on the site, which have expired. In December 2021, planning permission was granted for the onshore elements of the project, i.e., the substation construction within the Southern Water Services compound to the west of Ventnor. 

In December 2022, PTEC entered it’s 20-year seabed lease from the Crown Estate. This has now enabled the project to move into its final stages of development before construction can commence.

In January 2023, PTEC transitioned to a Build-Own-Operate model and private offtake with large energy users and is preparing for the next round of the Contracts for Difference (CfD) scheme which helps support low-carbon electricity generation. The project is anticipated to be completed in 2025.
 

Key Environmental Issues

The following potential impacts were considered in the Environmental Statement:

  • Marine water and sediment quality: the disturbance and re-suspension of sediments and their associated contaminants, as well as from accidental releases and spills of polluting substances across the life of the project;
  • Seabirds: disturbance, accidental contamination, displacement and collision risk with tidal devices;
  • Benthic and intertidal ecology: impacts related to habitat loss and disturbance due to construction and repowering activities;
  • Marine mammals: effects of underwater noise, collision with vessels and devices and indirect impacts from depletion of their food resource; and
  • Fish and shellfish: underwater noise during installation (particularly drilling of foundations).

As shown a number of potential interactions were identified that could potentially arise from the proposed project, however, none of these were anticipated to have a likely significant effect on receptors within the receiving environment.

The following mitigation measures were identified during the environmental assessment:

  • Best practice vessel speed limits and protocols with contingency plans and specialist facilities to deal with incidents;
  • PTEC to keep up to date with any advances in the understanding and management of collision risk to diving birds and take reasonable actions to reduce risk where this can be shown to be practical and worthwhile;
  • The potential adverse effects of lighting on birds will be taken into consideration in the design and final choice of necessary lighting;
  • Routing cables to avoid key reef features identified in pre-construction surveys, using appropriate cable protection to avoid the cable moving around on the seabed, and surface laying of the cables where possible to reduce the need for drilling, blasting or jetting a cable trench;
  • The Environmental Management Plan will include mitigation to reduce the risk of spreading Sargassum muticum;
  • Application of best-practice techniques including appropriate vessel maintenance as outlined in the International Convention for the Prevention of Pollution from Ships (MarPOL);
  • Embedded mitigation measures that have the potential to reduce electromagnetic field (EMF) emissions

A brief description of planned post-consent monitoring is provided in the Environmental Statement. No monitoring of birds or marine mammals is proposed. The numbers of both groups of receptors are now known to be very low at the offshore site, making the collection of sufficient data to allow meaningful analysis and monitoring extremely problematic. It is anticipated that potential environmental monitoring at the offshore site may focus on two key areas; benthic ecology and physical processes, as detailed further below.

 

Papers, Reports, Research Studies

The full Environmental Statement and associated documents can be accessed from the MMO’s Public register of marine licence applications and decisions (case reference MLA/2014/00563/2). 

Baseline Assessment: Perpetuus Tidal Energy Centre (PTEC)

Receptor Study 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.
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. 		Complete
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.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. 		Complete
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. 		Complete
Marine Mammals 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. 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 sightings were made during the sight specific surveys. 		Complete
Fish 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. 		No basking shark sightings during the sight specific surveys. Complete
Birds Boat-based surveys The survey area comprised the development site, with a surrounding 4km buffer. 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. 		Complete
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.

Post-Installation Monitoring: Perpetuus Tidal Energy Centre (PTEC)

Stressor Receptor Study Description Design and Methods Results Status
Habitat Change Invertebrates Monitoring to determine the degree of effect, the efficacy of mitigation, and the recoverability of benthic and intertidal habitats. Ecological monitoring will focus on the benthic ecology along the subsea cable corridor, particularly within the South Wight Maritime Special Area of Conservation (SAC). Some monitoring within the development site may also be appropriate. If trenching at the landfall is undertaken, then intertidal monitoring will also be undertaken.

Remote methods (e.g. regular drop video monitoring) are proposed as much as possible to minimise health and safety risks, while maximising potential data collection possible. 		Planned
Changes in Flow Physical Environment Potential effects of tidal arrays upon tidal resource. A number of Acoustic Doppler Current Profiling (ADCP) surveys may be undertaken within the development site.

Over time, data on tidal resources may be able to be related to data collected on benthic ecology, with tidal stream being better understood as an influence on benthic ecology within the development site. 		Planned