The Perpetuus Tidal Energy Centre (PTEC) is operated as a joint venture between a private company, Perpetuus Energy Ltd, and the Isle of Wight Council. PTEC is a proposed tidal energy demonstration facility with a planned electrical generation capacity of 30MW. 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 centre will be suitable for the deployment of up to full-scale single units and small arrays of tidal devices from prototype to pre-commercial demonstrators. The centre comprises an onshore site with substation/control room building and a development site for the deployment of devices, with the two sites being connected by a subsea cable corridor along which the power cables pass.
A number of tidal turbine manufacturers have expressed interest in partnering with PTEC to install their turbines. The PTEC facility will provide tenants with grid connection infrastructure via subsea export cables as well as navigation aids to allow developers to utilise the area to demonstrate their tidal technology. Tenants will provide the tidal energy devices and foundation/support structure.
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.
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 lease 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.
The consenting process commenced in January 2013 and involved significant consultation. 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 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.
Any potential environmental and community impacts were closely examined. The Environmental Impact Assessment (EIA) which formed part of the consent application which PTEC Ltd is complete and 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 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).
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.
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.
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.
In The Crown Estate published a notice with the intent to extend the Isle of Wight’s option for the Perpetuus Tidal Energy Centre project off the south coast of the Isle of Wight. The extension will extend the date under the Isle of Wight’s agreement for lease, by which they may call for a lease of the site, from 15 November 2018 to 19 April 2021.
At the time of writing there has been no further progression of the PTEC project.
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.
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
Environmental website: http://perpetuustidal.com/ptec-2/ptec-and-the-local-environment/