ISLE OF WIGHT COUNCIL PTEC Grid Connection Feasibility Study
Final v 7.0 September 2013 ITP/REF – UKP1176
This project has been co-funded by ERDF under the INTERREG IVB NWE programme. The report reflects the author’s views and the Programme Authorities are not liable for any use that may be made of the information contained therein.
Isle of Wight Council
Client contract No. IT Power reference: UKP1176
PTEC Grid Connection Feasibility Study Report September 2013
Contractor: IT Power IT Power St. Brandon’s House 29 Great George Street Bristol, BS1 5QT, UK Tel: +44 117 214 0510 Fax: +44 117 214 0511 E-mail: [email protected] Website: www.itpower.co.uk
Document control File path & name I:\Data\0WorkITP\0Projects\1176 PTEC Grid Study\2 Work Author Keith Jarrett, Sonal Fricker, Joe Hussey Project Manager Joe Hussey Approved Date September 2013 Distribution level Final
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EXECUTIVE SUMMARY The Isle of Wight Council together with its project partners are seeking to exploit the powerful tidal resource offshore of St. Catherine’s Point on the Isle of Wight, for the generation of renewable energy. The objective of the Perpetuus Tidal Energy Centre (PTEC) is to provide a managed test / demonstration facility for tidal energy developers; suitable for the deployment of up to full scale single units and small arrays from prototype to pre- commercial. To provide maximum flexibility to prospective customers, a number of ‘berths’ with varying capacity will be provided. Project construction is anticipated to start in 2015, with operations scheduled for 2016. The project will involve the installation of numerous subsea components such as an export cable(s), an inter-device cable network, a connection hub and cable protection systems. The construction of a terrestrial project substation and associated terrestrial infrastructure will also be necessary, as will the installation of navigational / monitoring / survey equipment. An important part of the project is the connection of PTEC to the Isle of Wight’s electrical grid and this study addresses the feasibility of different cable route options and their associated costs. This study builds on initial work commissioned by the Isle of Wight Council (IWC) in 2011, undertaken by Grontmij which reviewed the potential for connection of embedded generation sources into the existing public electricity supply distribution system, as well as work done for the award of an Agreement for Lease from The Crown Estate. The Grontmij report outlined in some detail the available capacity at substations which the IWC had earmarked for connecting the PTEC project to. It was also vital to have communications with the Distribution Network Operator (DNO) Scottish and Southern Electric Power Distribution (SEPD) to get the most up to date information regarding connection on the Isle of Wight. Through discussions with SEPD System Planning and Future Networks and Policy departments it became evident that since 2011, there has been a considerable amount of embedded generation connected, as well as under consideration for connection and approved for future connection. This has led to a discrepancy between the anticipated ‘available capacity’ at connection sites (in this case the 33kV Tee joint and Ventnor substation) and the actual available capacity at the same site now. SEPD also have concerns regarding the security of the interconnection with the mainland. The IoW is connected to the mainland via three 132kV interconnectors. If one of the interconnectors were to go down, it would be necessary to disconnect PTEC from the grid as the remaining 132kV cables would not be able to take the load. As such, SEPD have stated that an intertrip is necessary between PTEC substation and Wootton Common Substation to facilitate this disconnection if necessary. This would entail installation of a dedicated fibre between Wootton Common and Ventnor. This situation on the IoW is caused by faster than expected growth in renewable energy generation and a lower than expected demand for electricity on the Island. Three potential cable routes were initially identified from the PTEC development site to the grid connection at Ventnor substation. During the course of the study two other routes were identified to be of enough interest to be included within this report, thus making five routes explored in total.
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All routes under consideration have a connection point at the 33kV tee joint at Ventnor 33/11kV substation before the power is further distributed. There is an outdoor 33kV substation and an indoor 11kV substation which share the same site. The Ventnor substation is located in an industrial estate and is mostly penned in by other buildings, as such there is limited space to expand the substation. SEPD’s load flow analysis indicated a reinforcement of the existing 33kV line the project will connect to (circa 15km) will be required. The inclusion of an isolator for the connection has also been included in these considerations, as has the expectation that the majority of the existing line’s towers will need replacing. The upgrade would increase the available capacity by about 50%. The five routes investigated in the study have been identified and costed as follows: Option 1 – Ventnor Haven (£20.1million) Option 2 – West Ventnor (£19.4 million) Option 3 – Niton (£20.0 million) Option 4 – La Falaise Car Park (£20.0 million ) Option 5 – Old Park Road (£19.7 million ) The costs presented above are for comparative purposes only. Only elements associated with the grid connection and offshore export cable were costed as part of this study. Other infrastructure which will not vary with different grid connection routes have been taken from the PTEC development budget. The costs are based on industry standards and figures taken for similar projects, no suppliers of equipment have been consulted over these figures, so they should be used with extreme caution.
All these sites have advantages and disadvantages in terms of ease of installation. The costs are quite similar for all five options. This is because all options require the same offshore infrastructure and upgrades to be undertaken, so the main difference in cost is due to the cost of Horizontal Directional Drilling and the length of the cable routes. The cable options are explained further in Section 8. All but one option require some directional drilling and the adaptation of an existing building or creation of a new one to house the project substation and control room. The cable routes as described are as direct as possible and follow roads as much as possible to minimise excavating potentially unstable or sensitive ground. Any excavation works on roads must reinstate the roads to their original state. This is where a lot of the costs reside in the longer route options. A summary ranking of the cable route options under consideration are presented in the table below.
Next steps to be undertaken in FEED work: Further discussions held with SEPD on the feasibility and costs of the preferred option. Request for a detailed design for the preferred option from SEPD. This would include "route proving", which will require some exploratory excavation (and costs), and the provision of confirmed fault level contributions and harmonic injection capabilities of the equipment that might be installed. Select preferred ICP. Request design of contestable works from the ICP. Harmonic modelling of project.
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Landowners consulted and crossings negotiated. Apply for a Point of Connection (POC) offer from SEPD. Discussions with SSE Future Networks will also continue through the remainder of this work and into the FEED work to see if PTEC can be incorporated into any network management project they may be planning. Further engagement with SSE Future Networks may also help progress the project more effectively with SEPD. In addition, discussions with the following should also be initiated: Wight Salads, to investigate the status, and any potential for PTEC to utilise the spare capacity held by them in relation to the Arreton CHP plant. RWE about East Cowes (140MW) power station status and to investigate the possibility of some sort of capacity sharing arrangement. Cheetah Marine / ITM Power and other potential (large) electricity users in the area to investigate demand and possible storage solutions. Southern Water to investigate the possibility of incorporating the PTEC project substation into the existing compound of their pumping station in West Ventnor and the possible use of their out-fall pipe. SSE and OFGEM to investigate the possibility of amending the application for a like for like replacement of the interconnector(s) for an upgrade of the capacity of the cable(s).
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Table ranking the cable route options under consideration in this study:
Option 1: Option 4: Option 5: Option 2: Option 3: Ventnor Old Park La Falaise West Ventnor Niton Haven Road Car Park Rank Rank Rank Rank Rank Substation location 1 2 5 4 3 Onshore route 3 1 5 4 2 Offshore route 5 4 1 2 3 Foreshore route 5 1 3 4 2 Consenting challenges 3 1 5 4 2 Onshore cost 2 1 5 4 3 Offshore cost 5 3 1 2 4
Overall ranking 4 1 5 3 2
Note: The overall ranking is an average of all considerations and does not reflect the relative importance or difficulty of each consideration.
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ABBREVIATIONS
AFL Agreement for Lease AONB Area of Outstanding Natural Beauty DECC Department of Energy and Climate Change DEFRA Department for Environment, Food and Rural Affairs DNO Distribution Network Operator EU European Union EIA Environmental Impact Assessment EMEC European Marine Energy Centre EMF Electro-Magnetic Field ES Environmental Statement FEED Front End Engineering Design ICP Independent Connections Provider IOW Isle of Wight IWC Isle of Wight Council km Kilometres km2 Kilometres squared kV Kilovolts m Metres m/s Metres per second MCZ Marine Conservation Zone MMO Marine Management Organisation MOD Ministry of Defence MW Megawatt O&M Operation and maintenance PFC Power Factor Correction POC Point of Connection RIB Rigid Inflatable Boats rMCZ Recommended Marine Conservation Zone SAC Special Area of Conservation SCADA Supervisory Control and Data Acquisition PTEC Perpetuus Tidal Energy Centre SEPD Scottish and Southern Energy Power Distribution
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SPA Special Protection Area SSSI Site of Special Scientific Interest TEC Tidal Energy Converter TRL Technology Readiness Level WGS World Geodetic System
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GLOSSARY Acoustic Doppler A current measurement instrument using high frequency acoustic signals current profiler in the water. The current is determined by a Doppler shift from the echo signal from backscatter suspended in the water, assumed to be moving at the same speed as the current.
Agr eement for Lease A contract in which the right to investigate the possibility of developing a wave or tidal energy project for a specific area, for a specific period of time, is granted by the Crown Estate. Appropriate An assessment must be carried out if the project is anticipated to affect Assessment the conservation objectives and integrity of a Natura 2000 site. This is in conjunction with the Conservation of Habitats and Species Regulations 2010.
Array A number of tidal energy converter devices that are positioned in close proximity to one another.
Area of Outstanding An area designated to conserve and enhance the natural beauty of an Natural Beauty area, protecting natural features such as trees, fields and open spaces as well as settlements and working environments that are unique characteristics of the countryside.
Berth Designated location in the test facility for siting tidal energy converter devices.
Busbar distribution conductors common to numerous circuits, usually found in switchgear assemblies and substations
Cable Assembly of fully insulated conductors within overall protective sleeve, generally for installation underground or underwater
Contestable Works Works that can be carried out by an Independent Connections Provider Crown Estate The Crown Estate manages property owned by the monarch and returns revenues to the UK Treasury. The Crown Estate owns almost the entire seabed around the UK.
Department of The UK Government department responsible for sustainable energy and Energy and Climate coordinating the response to climate change. Change
Department for The UK Government department responsible for policy and regulations Environment, Food on the environment, food and rural affairs. and Rural Affairs
Development Site The study area for the PTEC project (grid reference SZ 510 730; Easting 142514, Northing 55719; 50.55N Lat. 1.28W Long.) lies to the south of the Isle of Wight, approximately 2.5km (at the nearest point) off St. Catherine’s Point.
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Device wake Area of disturbed water downstream of a turbine caused by the interaction of the turbine and structure with the flowing water.
Environmental The process that examines the environmental consequences of a Impact Assessment development, in advance of its construction.
Environmental The product of the EIA process that is submitted along with all Statement applications for consents.
Exclusion Zone A zone established by a sanctioned body to prohibit specific activities in a specific geographical area.
Export cable A cable that exports the power generated by a tidal energy converter(s) to the onshore substation.
EMEC A marine energy test and research facility located in Orkney, Scotland.
Front End Basic engineering which follows the conceptual design or feasibility Engineering Design study.
G59/2 Engineering Recommendation applying to embedded generators larger than 5MW.
Groyne Rigid hydraulic structure built from the ocean shore that interrupts water flow and limits the movement of sediment.
Intertidal zone The zone between the mean higher high water and mean lower low water lines.
Landfall site Location where the export cable comes ashore.
Littoral zone The area of sea between the high water mark and the shoreline that is permanently submerged.
Louvre A window blind or shutter with horizontal slats that are angled to admit light and air, but to keep out rain, direct sunshine, and noise.
Marine Conservation An offshore area of conservation protecting nationally important marine Zone wildlife, habitats, geology and geomorphology.
Natura 2000 site The European wide collective name for SACs and SPAs.
Natural England An executive non-departmental public body responsible to the Secretary of State for environment, food and rural affairs.
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Navitus Bay Wind An offshore wind farm, located off the east coast of the Isle of Wight Park with an estimated generating capacity of 1,100MW.
Neap tides Tid es of decreasing height / speed occurring semi-monthly when the Moon is positioned at 90° to the Sun.
Non-contestable Works that must be carried out by the DNO works
Overhead line Arrangement of uninsulated conductors relying upon separation in air for insulation purposes, generally for installation on overhead poles or pylons
Recommended A new type of site classification created by the Marine and Coastal Marine Conservation Access Act 2009. Zone
Recommended A different type of Marine Conservation Zone aimed to protect natural Reference Area conditions and provide information on the reference conditions of the environment and habitats for designated locations.
Revetment Sloping structure placed on banks or cliffs to absorb the energy of incoming water.
Scoping The process which determines of all the potential impacts of a project, and those which are likely to have a significant effect.
Site of Special A conservation designation denoting a protected area in the UK. Scientific Interest
Special Area of An area of conservation designated under the EU Habitats Directive to Conservation protect rare and vulnerable species and habitats.
Special Protection An area of conservation designated under the EU Birds Directive to Area protect rare and vulnerable birds.
Spring tides Tid es of increasing height / speed occurring semi-monthly as a result of a new or full Moon.
Stakeholder A person, group or organization that is affected or can be affected by the proposed development plans.
Substation Installation comprising distribution network switchgear, usually of two voltage levels, interconnected by transformers
Switchgear Assembly of busbars and circuit switching apparatus (usually circuit breakers) with isolation, earthing and measuring facilities
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Transformer Electromagnetic coupling device used to allow transfer of electrical power between distribution networks operating at different voltage levels.
Technology Measure of the maturity of evolving technologies. TRL 9 is Readiness Level representative of a fully matured technology. This is representative of multi-device demonstration of tidal energy converters.
Tee joint Simple mechanical joint to connect a branch conductor into a continuous conductor, forming a three way connection (two in, one out or one in, two out).
Tidal Energy A device that generates electricity from the power of the tides Converter
Wavehub A grid connected offshore facility in South West England for the large scale testing of technologies that generate electricity from the power of the waves. It holds a 25 year lease of 8 sq km of sea bed connected to the grid by 11/33kV subsea cable Yaw Rotation around a vertical axis.
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TABLE OF CONTENTS Executive Summary ...... 2 Abbreviations ...... vi Glossary ...... viii 1 Introduction ...... 15 1.1 Background ...... 15 1.2 The PTEC Project ...... 16 1.3 Scope of Work ...... 17 1.4 Document Structure ...... 17 2 Offshore Electrical Infrastructure ...... 18 3 Isle of Wight Grid and Grid Capacity ...... 19 4 Electrical Network Around Ventnor ...... 21 4.1 Ventnor Substation...... 21 5 Engagement with SEPD ...... 23 5.1 Outcomes from the discussions with SEPD ...... 24 5.2 Further Process of Engagement with SEPD (as part of FEED work) ...... 25 5.3 New Grid Connections with DNOs ...... 26 6 Grid Connection for PTEC ...... 26 7 Project Substation ...... 28 8 Assessment of Cable Routes ...... 30 8.1 Considerations for Offshore Cable Route ...... 30 8.2 The Undercliff and Environmental Designations ...... 31 8.3 Route Option 1 - Ventnor Haven ...... 34 8.4 Option 2 – West Ventnor ...... 45 8.5 Route 3 Option 3 – Niton ...... 49 8.6 Route Option 4 – Old Park Road ...... 52 8.7 Route Option 5 – La Falaise Car Park ...... 55 9 Grid Connection Costs ...... 59 10 Intertripping ...... 65 10.1 Costs of Inter-trip Scheme ...... 65 10.2 Alternatives to Inter-tripping / Fibre link ...... 65 11 Horizontal Directional Drilling (HDD) ...... 66 12 Summary and Next Steps ...... 69
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LIST OF FIGURES Figure 1: Proposed location of the PTEC development ...... 15 Figure 2: Indicative PTEC Project Layout ...... 16 Figure 3: Isle of Wight Electrical Distribution System – Schematic ...... 19 Figure 4: Isle of Wight Electrical Distribution System - Network Map ...... 20 Figure 5: Ventnor Substation ...... 22 Figure 6: Substation Building (Excluding Control Room) of a Similar Size to that Required for PTEC ...... 29 Figure 7: PTEC Substation Options ...... 30 Figure 8: Image Showing On and Offshore Cable Route Option 1 (Substation in Salisbury Gardens) and Interactions with Designations ...... 34 Figure 9: Ventnor Haven and the OceanBlue Quay Building ...... 35 Figure 10: Option 1 Onshore Cable Route for Substation in Salisbury Gardens ...... 36 Figure 11 Option 1 Substation locations...... 37 Figure 12 Salisbury Gardens ...... 38 Figure 13: Salisbury Gardens with Basement Coverings and Ventilation Bricks Highlighted in Red ...... 38 Figure 14: Plans of Salisbury Gardens Showing Basement (Left) and First Floor Elevations (Right) ...... 39 Figure 15 OceanBlue Quay ...... 40 Figure 16: Possible Space Available Adjacent to OceanBlue Quay ...... 41 Figure 17: Eastern Esplanade Car Park ...... 41 Figure 18: Map Showing Location of Possible Project Substation / Control Room in Ventnor Industrial Estate ...... 42 Figure 19: Possible Location of Project Substation / Control Room in Ventnor Industrial Estate ...... 43 Figure 20 Ventnor Haven Cable Run Showing Route from Salisbury Gardens and OceanBlue Quay ...... 44 Figure 21: Image Showing On and Offshore Cable Route Option 2 and Interactions with Designations ...... 45 Figure 22: Southern Water Outfall Pipe ...... 46 Figure 23: Possible Landfall Point via Slipway ...... 46 Figure 24: Option 2 Substation Location ...... 47 Figure 25: Option 2 Onshore Cable Route (Landfall via Slipway) ...... 48 Figure 26: Two Images Showing Footpath Joining Zig Zag Road and Ocean View Road ..... 48 Figure 27: Image Showing On and Offshore Cable Route Option 3 and Interactions with Designations ...... 49
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Figure 28: Onshore Sites at Niton ...... 49 Figure 29: Cable Landfall Point showing Slipway ...... 50 Figure 30: Entrance to Possible Substation Location ...... 50 Figure 31: Niton Onshore Cable Route Option ...... 51 Figure 32: Image Showing On and Offshore Cable Route Option 4 and Interactions with Designations ...... 52 Figure 33: Onshore Sites at Old Park Road ...... 53 Figure 34: Possible Substation Location ...... 53 Figure 35: Old Park Road Onshore Cable Route Option ...... 54 Figure 36: Image Showing On and Offshore Cable Route Option 5 and Interactions with Designations ...... 55 Figure 37: Onshore Route from La Falaise Car Park to Ventnor Substation ...... 56 Figure 38: La Falaise Car Park from The Esplanade ...... 57 Figure 39: La Falaise Car Park from the Western End ...... 57 Figure 40: La Falaise Car Park Showing Possible Location for the Project Substation ...... 58 Figure 41: La Falaise Car Park Onshore Cable Route Option and HDD ...... 58 Figure 42: HDD Riggs ...... 67 Figure 43: Illustration Showing Directional Drilling Procedure ...... 67 Figure 44: HDD in Process ...... 68
LIST OF TABLES Table 1: Possible Locations for Substation and Control Room for Each Option 28 Table 2: Cost Estimation for PTEC Grid Connection Options, Including Offshore Cable 61 Table 3: Base Case vs Worst Case Costs 62 Table 4: Worst Case Cost Estimation for PTEC Grid Connection Options, Including Offshore Cable 63 Table 5: Summary of Cable Route Options 70
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1 INTRODUCTION This report summarises the options for connecting the PTEC project to the existing grid network around Ventnor on the Isle of Wight.
1.1 Background The Perpetuus Tidal Energy Centre (PTEC) is a managed test / demonstration facility for tidal energy developers who have reached a technology readiness level (TRL) of between 6 and 9 (prototype demonstrator to commercial prototype); suitable for the deployment of up to full scale single units and small arrays from prototype to pre-commercial demonstrators. The offshore facility will be a 20MW demonstration site of approximately 5 km2 located approximately 2.5km to the south of St. Catherine’s Point, and will include grid connection via subsea cables as well as navigation aids and monitoring equipment. Figure 1 shows the proposed location.
Figure 1: Proposed location of the PTEC development
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1.2 The PTEC Project The current configuration for PTEC is shown in Figure 2 below and consists of 6 berths totalling 20MW of export capacity. The size and number of berths are currently as follows: • A single 1MW berth suitable for testing individual prototypes. • Three 3MW berths suitable for very large machines or very small arrays. • Two 5MW berths suitable for small arrays. The size, number and layout of these berths will be refined during the FEED stage, which will entail detailed discussions with potential users of the facility.
Figure 2: Indicative PTEC Project Layout © Crown Copyright and/or database rights. Reproduced by permission of the Controller of Her Majesty’s Stationery Office and the UK Hydrographic Office (www.ukho.gov.uk).
The project will consist of the following main subsystems A subsea cable network, including a common connection point or ‘hub’. Five offshore cable routes are currently under consideration as shown in Figure 2. Onshore cable, routed according to the chosen land-fall point. A dedicated project substation and control room Connection to the existing grid Additional offshore infrastructure, such as navigational marking buoys and monitoring equipment These subsystems and different options for them are explored in the sections that follow.
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1.3 Scope of Work The scope of the study covered the following key aspects: Identify potential grid connection points and connection method for the project (Section 6). Consult with SEPD to gather further detailed information as necessary (Section 5). Commission grid connection feasibility studies using the Electricity Networks Association (ENA) process with Southern Electric (Section 5). Provide a comparison of the connection options and cable routes in the form of tabulations, as well as the project risks (Sections 8 and 9). Outline costs of the main components and work involved (Section 12).
For each grid connection option / route considered, analysis of the impact on the following factors was considered, as summarised in Section 6: The steady state loading of the existing distribution network infrastructure, to determine whether the contribution from the PTEC scheme would cause thermal overloading of the existing distribution circuit and equipment, or would remove margin allowed for future load growth. The capability and capacity of the existing primary distribution transformers for handling reverse direction power flow. The effect upon system fault levels due to the contribution from the proposed scheme, to determine whether the existing distribution network infrastructure could withstand the effects of fault conditions. The effect of the embedded generation capacity upon the system voltage profile of the existing distribution network, to determine the necessary modifications to the voltage control regime. All options must be compliant with Engineering Recommendation G59/2-1.
1.4 Document Structure
Section 1: Introduction This section introduces the PTEC project, and summarises the scope of work and layout for the grid feasibility study. Section 2: Offshore Electrical Infrastructure This section summarises the offshore electrical infrastructure that is currently planned for the project. Section 3: Isle of Wight Grid and Grid Capacity This section summarises the electricity grid and available capacity on the Isle of Wight Section 4: Electrical Network around Ventnor This section gives a brief summary of the existing grid network around Ventnor, the likely point of connection to the grid.
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Section 5: Engagement with SSE This section details the process of engagement with SEPD during this work; as well as the continuing process of engagement with SSE during the FEED study, including timescales. Section 6: Grid Connection for PTEC This section details how and where the project will connect to the existing 33kV grid network. Section 7: Project Substation This section summarises the general requirements for a project substation. Specifics for each option are discussed in the relevant section in Section 8. Section 8: Assessment of Cable Routes This section provides details of all 5 cable routes currently under consideration, including offshore. Section 9: Grid Connection Costs This section provides a high-level overview of the costs for each of the options in Section 8. Section 10: Intertripping This section summarises communications with SEPD over requirements for intertripping, as well as a description of intertripping and possible alternatives to SEPD’s current proposal. Section 11: Horizontal Directional Drilling This section provides a brief summary of horizontal directional drilling, including maximum distances achievable and approximate costs. Section 12: Summary and Next Steps This section presents a summary table of the 5 options under consideration, including a ranking system for ease of comparison. It also details the next steps for the grid feasibility study as well as the grid connection work that will be undertaken during the FEED contract.
2 OFFSHORE ELECTRICAL INFRASTRUCTURE The initial concept for the PTEC offshore electrical infrastructure currently consists of the following systems listed below. All offshore equipment will be rated at 11kV; tenants will connect at this voltage. The full subsea infrastructure will be specified during the FEED work, and as such the infrastructure below is subject to change. 6 berth cables ranging in length from 500m to 2km. Each berth cable will be fitted with a set of connectors that the tenant will connect to. A subsea ‘hub’ (watertight junction box) to aggregate the berth cables into a single export cable. The power cores will be terminated onto isolated busbars and fibre optic cables split out and joined. The hub will be passive, having no switchgear, meters or transformers, similar to that deployed at Wavehub. A single (6 core + fibres) 11kV export cable to shore, approximately 6km long. All switch-gear, transformers and metering equipment will be onshore.
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3 ISLE OF WIGHT GRID AND GRID CAPACITY The electricity supply on the Isle of Wight is the responsibility of Scottish and Southern Energy Power Distribution (SEPD), a business of Scottish and Southern Energy, as statutory distribution network operator. SEPD own and operate the 132kV, 33kV and 11kV distribution infrastructure. The Isle of Wight is supplied by three interconnectors with the mainland; each of the three circuits is rated at 124MVA (winter) / 99MVA (summer)1. Power distribution over the Isle of Wight is primarily via 33kV overhead lines (and a small extent of underground cabling in built up areas), connecting ten primary substations, as shown in Figure 3.
Figure 3: Isle of Wight Electrical Distribution System – Schematic Image Source: Grontmij
1Isle Of Wight Renewable Energy Resource Investigation - Review Of Potential For Connection Of Embedded Generation Sources Into Existing Public Electricity Supply Distribution System. Grontmij, March 2011
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Figure 4: Isle of Wight Electrical Distribution System - Network Map Contains Ordnance Survey data © Crown copyright and database right 2012
Embedded generation on the island currently consists of the following generators: East Cowes power station – 140MW gas turbines (peak lopping plant – intermittently operated) Arreton combined heat and power plant – 16MW (primarily for heat requirements of Wight Salads). It is understood that further capacity was installed but this plant has now been decommissioned, but the capacity is still tied to Wight Salads. Gasification plant – 2.3MW Wind turbines – 7MW (none of which have been constructed yet) Landfill gas and biomass - Approximately 1.8MW Solar PV (commercial - excluding domestic schemes) o Approximately 14MW of commercial Solar PV currently operational o Approximately 19 MW of commercial Solar PV currently under construction o A further 14MW currently in planning This gives a total capacity of approximately 214MW that SEPD have visibility of, in addition to domestic solar PV. Island demand typically varies between a minimum of approximately 40MVA and a maximum of approximately 130MVA1. Grontmij estimate the capacity margins of the interconnectors to be approximately 61MVA. However, if one of the interconnectors were to be disconnected, the remaining two would be unable to handle the full on-island generation, particularly in the summer, even before any new projects are installed.
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IT Power have been made aware that at least one of the 132kV subsea interconnector cables from the mainland to Cowes is due to be upgraded. This has recently been approved after 4 years in planning. This upgrade will be for the submarine section of the cable only with no increase in capacity. Work is currently anticipated to start in summer 2014. The existing 132kV submarine cable link dates from 1972, is approximately 5.3km long, and comprises three oil filled three core cables running between Lepe on the mainland and Thorness Bay, west of Gunard, continuing as an underground installation to East Cowes substation and to Wootton Common substation. The proposed replacement cables are to be solid dielectric three core cables, following the same submarine route as the existing cables, and intended to be buried in a 1.5m deep trench excavated into the sea bed. When the upgrade was first tabled over 4 years ago, most of the PV projects were not yet operational, or even in planning in many cases. SEPD have advised that there may be a need for National Grid to assess the impact of this scheme on the transmission network under their ‘Statement of Works’ and ‘Modification Application’ procedure. If an assessment is needed, there will be additional delay while it is completed and the costs will be chargeable. The current interconnectors are already constraining generation on the island before any future developments are considered. Therefore a significant upgrade of the interconnectors is likely to be required imminently, although it is uncertain if this will be necessary for the 20MW of PTEC until detailed design has been carried out by SEPD.
4 ELECTRICAL NETWORK AROUND VENTNOR The distribution network to Ventnor is via two 33kV circuits from Wootton Common and Newport. The 33kV circuit from Wootton Common (to Ventnor No.1 tee joint) has previously been intercepted at Arreton to receive the generation output from the now partly decommissioned Wight Salads combined heat and power plant. This capacity is still tied to Wight Salads however and the fact that the plant has been decommissioned will not have been factored into SEPD’s analysis. The area around Ventnor is supplied radially from the island's main 33kV system, which in its turn is supported by a combination of 132kV interconnection with the mainland and by on-island generation. The town is supplied at 11kV from one main 33/11kV substation and there a number of limited capacity, normally open interconnections with surrounding networks. The town's supplies are judged to be acceptably secure.
4.1 Ventnor Substation Ventnor 33kV substation is an outdoor substation presently configured with four interconnection circuits and two transformer feeder circuits, derived via two tee joints in the vicinity of the substation. There are two 30MVA 33kV / 11kV distribution transformers at Ventnor substation. Both transformers are of vector group Dyn11, and are equipped with on-load tap changers on the 33kV windings, each having a -17% to +6% range1. The star points of the transformers are resistance earthed. The 33kV circuits, with summer circuit ratings and 2014 transformer demands, are1: 1. Arreton 33kV Substation (Tee Joint) Interconnector (Tee Joint) – 25MVA 2. Sandown 33kV Substation Interconnector (Tee Joint) – 25MVA 3. Shanklin 33kV Substation Interconnector (Tee Joint) – 25MVA
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4. Ventnor 11kV Substation Feeder No.1 (Transformer No.1) (Tee Joint) – 10.88MVA (17MVA circuit rating) 5. Ventnor 11kV Substation Feeder No.2 (Transformer No.2) (Tee Joint) – 10.88MVA (17MVA circuit rating) 6. Wootton Common 33kV Substation Interconnector (Tee Joint) – 25MVA
Ventnor 33kV substation is located in a built-up location, to the north of Ventnor Town, at OS reference 456123, 077539 (WGS84 co-ordinates 50.597573,-1.208141). SEPD have stated that there is little prospect for further expansion of the substation site due to the built-up nature of the substation location. There is very limited room for an additional outdoor transformer and associated wiring; and no space within the indoor substation to house additional 11kV or 33kV switch gear (which are very large units).
Figure 5: Ventnor Substation Image Source: Google Earth
Ventnor 11kV substation is an indoor substation adjacent to the 33kV Ventnor substation, with a firm capacity of 30MVA and a 2014 predicted maximum demand of 13.55MVA1. The 11kV switchgear at Ventnor substation is rated at 33.4kA peak making capacity and 13.1kA rms breaking capacity for three phase fault conditions, and is presently subject to three phase fault levels of 19.7kA peak make and 9.0kA rms break1. The corresponding fault level margins are1: Making Capacity 20.3kA peak Breaking Capacity 7.0kA rms
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5 ENGAGEMENT WITH SEPD During the grid connection feasibility study it was vital that IT Power liaised with various departments of the DNO, Scottish and Southern Electric Power Distribution (SEPD), to gain the most accurate picture of the existing Isle of Wight’s electricity supply distribution system. DNO liaison shone a light on areas that helped form the details of the cable route options. The people contacted at SEPD were: Paul Dougal, in charge of IOW System Operations and knowledge of IOW substation equipment etc, SSE Isle of Wight (IOW) Matthew Gordon, System Planning Engineer, SSE Power Distribution (Reading) Richard Hartshorn, Project Developer, SSE Future Networks and Policy (Reading) Brian Shewan, Development Manager, SSE Future Networks and Policy (Reading) Contact was made via the Isle of Wight Council with the SEPD representative on the Isle of Wight, Paul Dougal, for more in depth information regarding the IOW electricity network and substations. Further contact was made with Matthew Gordon in the System Planning department at SEPD Reading and Richard Hartshorn and Brian Shewan in the Future Networks and Policy department . A grid connection feasibility study from SEPD was commissioned using the Electricity Networks Association (ENA) process in early April, The study included analysis of steady- state loadings, voltage issues and reverse power constraints, as well as the latest load and generation situation. The output of this study is the letter from SEPD summarised in Section 6 and presented in full in Appendix A. The outcomes from the various communications with SEPD were captured in the monthly project teleconferences between IT Power, IWC and TBP. These are summarised in the following bullet points, arranged by date of meeting:
20/03/2013 IT Power were introduced to Paul Dougal and Matthew Gordon of SEPD by IWC Matthew Gordon explained the choice between reinforcing the 132kV cables or introduction of intertripping scheme. o 132kV cable reinforcement could be a 4-6 year process in entirety, o The intertrip option is referred as these works are less lengthy and can be coincided with PTEC cable installation. IT Power also learned of active network management plans with SSE Future Networks
22/04/2013 Keith Jarrett held discussions with SSE regarding the intertripping issue Discussion with SSE System Planning indicated that the security of electricity supplies on the island is likely to be jeopardised by a combination of (1) faster than expected growth of generation on the Island and (2) a lower than expected demand growth. SSE proposed intertripping. Costs about £1M as well as annual charges. First budget from SSE Matt Gordon of £1.7M +VAT (£0.8M+VAT for the Ventnor 33kV reinforcement of the overhead cables, and £0.9M for landfall to Ventnor Town cabling).
23/04/2013 IT Power held a meeting with SSE Future Networks.
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SSE had submitted a project to the Low Carbon Networks Fund (LCNF) - Isle of Wight intelligent network switching bid. Similar in principal to the active network management in the Orkneys. o Information from the meeting highlighted the large amount of new generation (approximately 140MW) that SSE System Planning department have been approached about. o Future Networks suggested discussing phased approaches for the connection of PTEC to the grid to see if this would lead to lower connection cost estimates from SSE System Planning department. Disclosure from the system planners that circa 10MW could be connected to Ventnor with very little upgrade work.
24/05/2013 On the 8th May IT Power, TB Partners and IWC conducted a site visit on the Isle of Wight. Keith Jarrett continued cost reduction talks with SEPD. It was decided that a phasing of the project connection is not as practical as it first appears due to the lease arrangements with the Crown Estate and attractiveness to potential tenants. IT Power had follow up talks with Future Networks regarding the LCNF bid. OFGEM announced that Isle of Wight Integrated Network Solutions (WINS) had been shortlisted during the first part of the LCNF bid process.
01/07/2013 SSE Future Networks announced that they will not take their WINS project any further through the LCNF process. o IT Power has been informed that they are “Looking to take Active Network Management to IOW as Business As Usual in conjunction with the other technology being funded by other means.” Further meetings to explore these possibilities with SSE Future Networks scheduled for September.
09/2013 Meeting with SEPD help to clarify intertripping requirements and costs. See Section 6 for further details. o IT Power were informed that Intertripping will be necessary for PTEC, requiring a dedicated fibre. o The lines from Ventnor to Arreton are the ones most in need of upgrading. o A subsea interconnector cable upgrade is already taking place for one 132kV line (not an increase in capacity – just an upgrade of the cable quality) from the mainland to Cowes. It has taken 4yrs to consent.
5.1 Outcomes from the discussions with SEPD Discussions with SSE in May and June focused on the possibilities of reducing the budget costs of £1.7m and the costs and necessity of intertripping (an indicative £1M included in the tables). Within these non-intertripping components, the costs of 33kV reinforcement and of the shore to Ventnor cabling have broadly equal importance.
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The costing of the onshore cable routes, explored in Section 8, and described in Table 2, are principally the costing for excavation and reinstatement, and will be firmed up during the FEED work. The SSE figures provided possibly include a contingency allowance. The outcome of the engagement with SEPD to date has been the gathering of information on available capacity, feasibility of connection and costs for the connection and also the difference in available capacity in 2013 compared to the figures presented in the 2011 Grontmij report.
5.2 Further Process of Engagement with SEPD (as part of FEED work) Following selection of the preferred option and hence completion of this feasibility study, a detailed design study will be commissioned from SEPD as part of the FEED work. This could be done at the same time as an application for a Point of Connection (POC) offer, but there are few time or budgetary savings in combining these elements. Other information SEPD will provide generation forecasts (known and demand). A detailed study, once commissioned, will be completed by SEPD within 3 months from payment. The SEPD design process will involve design of all non-contestable work (see Section 5.3) and identify any local upgrade that is required. This will also highlight if such works require any special consents, such as an EIA, over and above the normal landowners’ permissions and local planning permission. Design of contestable works can also be carried out by SEPD at this point. The detailed design and cost estimate from SEPD will include ‘route proving’, which will require some exploratory excavation (and costs); the provision of confirmed fault level contributions and harmonic injection capability of the equipment that might be installed.
As the proposed installation could emit harmonic currents, SEPD will need to ensure that the connection complies with Engineering Recommendation G5/4 – “Planning levels for voltage distortion and the connection of non-linear equipment to transmission and distribution networks in the United Kingdom”. Details of the project’s harmonic output will have to be provided so that SEPD can complete an assessment of the effect of the project. This will involve measurement of existing levels of harmonic distortion. The assessment will take several weeks to complete and associated costs will be chargeable to PTEC. Note that this study may indicate that the connection suggested by SEPD is not viable without suitable mitigation measures within the project or additional network reinforcement. There may also be a need for National Grid to assess the impact of this scheme on the transmission network under their ‘statement of works’ and ‘modification Application’ procedure. If an assessment is needed, there will be a delay while it is completed and the costs will be chargeable.
Once the design works have been completed, landowners consulted and crossings negotiated, a formal application to SEPD for a POC Offer can be made. SEPD have indicated that an estimated 18 to 24 months minimum should be allowed for this scheme, to provide this connection from acceptance of a formal connection offer, but that the completion time from acceptance of a formal offer could be reduced if detailed design work was carried out in advance of issuing the formal offer (as is planned for PTEC FEED). If 132kV reinforcements are triggered then this timescale will increase considerably.
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5.3 New Grid Connections with DNOs New connection works fall into one of two categories: • Non-contestable works, which the DNO must deliver • Contestable works, which can be delivered by an accredited ICP In general, all new works solely required for a connection can be delivered by an Independent Connections Provider (ICP). Typically, work associated with the POC to the existing network, and any upgrades to the existing network, are non-contestable and must be delivered by the DNO. All other works are contestable and can be delivered by an accredited ICP. Lloyd's Register maintains a list of ICPs who are accredited under the National Electricity Registration Scheme (NERS). This independently maintained list is the best source for finding ICPs who can offer alternative quotations for connections.
ICPs can often offer cost savings from having the work carried out by the DNO itself, due to an element of competition.
Once one or more ICPs have been engaged to provide quotations for the new connection, and they have agreed to respond, they will deal directly with the DNO so that all non- contestable works can be determined. If an ICP is appointed to deliver the connection, they will ask the DNO to adopt the completed works via an Adoption Agreement. This is effectively a warranty for the works that the ICP carries out, covering a period of two years following completion. Beyond this period the DNO becomes solely responsible for the connection assets.
6 GRID CONNECTION FOR PTEC Grid connection will be achieved via a single tee into one of the existing 33kV overhead line circuits serving Ventnor substation that run north from Ventnor to Wootton Common or Newport. The tee will be as close as feasible to the existing Ventnor substation in order to keep the new onshore cables as short as possible (as the existing lines run north from Ventnor substation). The onshore cable will tee into the 33kV tee joint via a compression connection. This is cheaper than making an underground joint. There will also be an air brake isolator installed. This will be of the simple open close type. This will almost certainly be the case regardless of the cable route options as considered in Section 8. This is because Ventnor substation does not have the requisite space for switchgear due to the built up nature of its location. The 33kV transformers in the compound are large enough but the further space required for the other electrical equipment required is not there. This is the only Point of Connection under consideration for all options, and was identified by SEPD and included an analysis of steady-state loadings, voltage issues and reverse power constraints, as well as the latest load and generation situation. A landing near Niton is also under consideration, but as this requires a new dedicated 33kV (onshore) cable / line, it would also still Tee into the existing network as defined above. SSE’s analysis of the load flows under first circuit outage conditions (N-1) has indicated that a reinforcement of the 33kV line (circa 15km) will be needed, and the inclusion of an isolator for the connection of the tidal power station has been included in these considerations, as has the expectation that the majority of the line’s towers will need replacing. This is because the cable will be larger and the towers will need to be able to accommodate this change. The upgrade would increase the available capacity by about 50%. Detailed design by SSE (during the FEED work) will be required to determine the extent and accurate costs for this work.
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SEPD have advised that it is the section of line from Ventnor to Arreton that is most in need of upgrading for the 20MVA to be connected. For this upgrade, there would need to be a line survey carried out, then design work. The design would then go out for tender, then finally construction. SEPD have also advised that an intertrip will be required in the event that one of the 132kV circuits to the mainland is disconnected. Disconnection can occur for electrical or environmental and mechanical reasons, although it is less common for the fault to be electrical. This is due to the rigorous electrical testing of the interconnections as system security is crucial, and the outage of one component should not lead to a cascade of failing equipment causing partial or total blackout. If one of the interconnectors to the mainland were to be disconnected for electrical reasons, the remaining two must be able to handle the full on-island generation, particularly in the summer due to thermal loading and low demand. This is referred to as N-1 conditions (N being the number of interconnectors). The DNO ensures that N-1 situations are electrically survivable, mechanical causes are sorted into three categories: Faults eliminated by auto reclose e.g. a tree branch on the line causes outage, after a short time auto reclose activates and by this time the branch has fallen off and the fault has gone. Group Faults – 4hrs of outage of a circuit (N-1 conditions), during outage work done to repair mechanical faults and system again running. Catastrophic failure – sea storm or landslip causing loss of line (a line is felled, large tree hits power line, etc). The intertrip will require a communication link from the Point of Supply (PTEC substation) to SSE’s Wootton Common Substation, a distance of approximately 17km. SEPD have advised that a dedicated fibre must be used between Wootton Common and Ventnor as radio communications on the Island are problematic and the protection of the 132kV connection to mainland is a valuable and essential asset that the would require the dedicated fibre. Radio communications for intertripping is also not used anywhere else on the Island by SSE, so they are not willing to consider it. See Section 10 for more details on the intertrip scheme.
In 2011 the Isle of Wight Council commissioned Grontmij to produce a report on the potential for embedded generation connection to the existing electricity distribution system; during the engagement with SEPD, this report was used as a reference. During the two years since the Grontmij report, there have been many embedded generation connections made as well as many that are either under consideration or already approved for the future, as summarised in Section 3. This has led to a reduction in the available capacity as quantified in 2011 by Grontmij in their report. Therefore despite indications in the 2011 study that available capacity of the circuits serving Ventnor substation could be as much as 30MW, SEPD have informed IT Power that a maximum potential of around 16MW is available for connection at Ventnor without the need for upgrades. This would reduce the onshore costs (in Table 2) by approximately £700,000. Offshore cable supply costs could also possibly be reduced by between £200,000 and £700,000, as they would not need to be as large.
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7 PROJECT SUBSTATION An onshore substation and control room for the project will be constructed; five locations are currently under consideration, as described in Section 8. All but one of the locations requires a new substation building to be constructed. Option 1 (discussed later) could make use of an existing building to house the project transformer, associated electrical systems and control facilities. The substation / control room may also be split, with the main substation near the landfall point and the control room and developer facilities in the small industrial estate adjacent to the Ventnor 11 / 33kV substation just to the north of Ventnor town, as shown in Section 8.3.3.3. Splitting the building would increase costs and complexity quite considerably, so this is only likely to be a consideration if planning permission at a particular location is likely to be very difficult. The possible configuration / location for substation and control room are summarised in Table 1 for each option under consideration. The location for each building is explored further in section 8.
Table 1: Possible Locations for Substation and Control Room for Each Option Possibility Option of split Substation location Control room location buildings Salisbury Gardens Salisbury Gardens Salisbury Gardens Ventnor Industrial Estate 1 Yes Adjacent to OceanBlue Quay Adjacent to OceanBlue Quay Adjacent to OceanBlue Quay Ventnor Industrial Estate Ventnor Industrial Estate Ventnor Industrial Estate SW Pumping Station SW Pumping Station 2 Yes Council owned field Council owned field SW Pumping Station / field Ventnor Industrial Estate 3 No Niton Landfall Niton Landfall 4 No End of Old Park Road End of Old Park Road La Falaise Car Park La Falaise Car Park 5 Yes La Falaise Car Park Ventnor Industrial Estate Ventnor Industrial Estate Ventnor Industrial Estate
It should be noted that whereas the entire offshore system is rated at 11kV (typical export voltage for tidal turbines), transformation to 33kV as soon as possible after the cables have come ashore is desirable, meaning a substation at the Ventnor Industrial Estate is not ideal. 11kV cables of the rating necessary to transmit the power requirements of PTEC will be very large and difficult to handle onshore. If there is more than one export cable used, the onshore cables may not have sufficient screening to allow them to be installed together in a single trench, meaning multiple trenches in the roads are required.
The substation site will need to be of a suitable size, on level ground with adequate access for incoming and outgoing circuits and for larger vehicles. The location will need to be agreed as part of the design process with SSE.
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Figure 6: Substation Building (Excluding Control Room) of a Similar Size to that Required for PTEC Image Source: Geograph
The substation layout will be finalised during the FEED stage, however it is currently envisaged that it will comprise the following (shown in Figure 7): A chamber where the subsea cables will be terminated and transition jointed into standard three core power cables for onward routing around the substation. A high voltage room which will contain the main circuit breaker, 11kV switchboard, 33kV switchboard and metering equipment. An outdoor transformer compound, with 11/33kV transformer, earthing transformer and possibly a step-down transformer for power conditioning equipment. Power conditioning room, housing any power conditioning equipment required. The nature (straight-capacitance based power factor correction, Statcom etc), extent and rating of this equipment will be decided during FEED. A shared control room, housing a control desk for the PTEC system, as well as control desks and communications interfaces for tenants, allowing operators to monitor and control their offshore equipment from the control room or remotely. This room will also house cabinets for tenants control / SCADA equipment.
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Figure 7: PTEC Substation Options
8 ASSESSMENT OF CABLE ROUTES Five options for the onshore / offshore cable routes are currently under consideration, named according to their landfall sites: Option 1 – Ventnor Haven Option 2 – West Ventnor Option 3 – Niton Option 4 – La Falaise Car Park Option 5 – Old Park Road These are described in more detail in the sections that follow.
8.1 Considerations for Offshore Cable Route The length and challenges of the offshore route impact heavily on the onshore route and final option chosen due to the expense of procuring and installing offshore cables. It is desirable to keep the offshore route as short as possible (which may also allow additional offshore cables to be used), but in some cases the difficulty of negotiating crossings and consent for the onshore route may outweigh the costs of a longer offshore route. A number of the difficulties associated with the offshore route are common to all options; specific considerations for each option are covered in the sections that follow.
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The waters off the southern coast of the Isle of Wight, including St. Catherine’s Point, are designated under the South Wight Maritime SAC due to the presence of the following Annex I habitats, as listed under the EU Habitats Directive (92/43/EEC): Reefs Vegetated sea cliffs of the Atlantic and Baltic coasts Submerged or partially submerged sea caves
The nearshore reefs in and around the littoral zone of the area are distinct due the variety of rock types that form them (chalk, limestone, sandstone, clay/ mudstone and greensand) and the associated communities that they support. The reefs support extensive populations of shellfish and worms which burrow into the soft stone, including burrowing bivalve molluscs such as Pholas dactylus. The underlying chalk substrate is also stable enough that it supports slow growing species of axinellid sponge and soft corals such as Alcyonium digitatum.
The area of large boulders off the coast of Ventnor supports other significant subtidal reef habitats and species such as the burrowing bivalve ‘red nose’ Hiatella arctica. These species are able to bore into the greensand boulders, which although a generally a soft rock, it is often too hard for burrowing piddocks such as P. dactylus and Barnea candida. Instead, the clay exposures and mudstone reefs along the south-east coast provide a good habitat for these species.
The chalk reefs also support kelp forest communities and other species of green and brown algaes. At depths greater than 7m, where light is less able to penetrate the water column, subtidal red algae communities thrive.
The rocky shores west of St Catherine’s Point have large populations of warm temperate littoral species, including the molluscs Patella depressa and Gibbula umbilicalis and the barnacles Balanus perforatus and Chthamalus montagui.
The coastal boulders along the Undercliff have high densities of dog-whelk Nucella lapillus relative to the wider Solent area.
All the offshore sections of the routes considered below will have to cross the SAC at some point. Stakeholder consultation and surveys will help decide if there is a more desirable crossing point in order to minimise impact on habitats. Options 1, 2 and 4 pass closest to the disused explosives dumping ground. All routes are likely to be through chalk, meaning mechanical trenching for cable installation is possible depending on the strength of the rock.
8.2 The Undercliff and Environmental Designations The onshore geology observed across the southern half of the Isle of Wight stems from the Cretaceous era. Around St. Catherine’s Point, a permeable layer of greensand (composed of sandstones, clay sands and chert-rich layers) overlays an impermeable gault formation of stiff, blue clay. Water is unable to permeate through the clay and thus forms planes of weakness between the two rock types, causing instability and erosion. This has a resulted in an extensive landslip zone between St. Catherine’s Point and Bonchurch, one of the biggest in North West Europe and is termed ‘the Undercliff’.
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Ventnor and the Undercliff area is recognised under an Isle of Wight Shoreline Management Plan 22 as Policy Development Zone 4 (PDZ4). Within this plan the issue of coastal erosion, (a serious problem in the PDZ4), is addressed and policy explained. The Ventnor and Undercliff area of coastline was developed heavily over a short period of time during the Victorian age. Because of this and the fragile nature of the cliffs due to coastal erosion (toe erosion in particular) a number of significant defences have been constructed for Ventnor Town and Bonchurch. These defences include groynes and rock armour revetments that allow access along seawalls. To the east and west of Ventnor in less built up areas, the landscape has fewer defences and has a more natural character. Landslides in the Niton and Reeth Bay area have been known to occur and as a result rock armour has been installed to secure the cliffs. Several footpaths in Niton and surrounding area have been closed due to coastal erosion. The UK BAP has identified ‘maritime cliffs and slopes’ as a priority habitat, noted to be of particular importance for the specialised and rich invertebrate fauna that it supports. A number of national priority species associated with the ‘maritime cliffs and slopes’ priority habitat that extends around the coast at St. Catherine’s Point, have been identified. These include one species of reptile, three species of butterfly and moth, eleven other invertebrate species, one species of vascular plant and five species of non-vascular plant. The chalk grassland on the southern coast is home to the Glanville fritillary butterfly (Melitaea cinxia), a UK BAP priority species which is not naturally found elsewhere in the UK. Frequent cliff slippages result in the creation of isolated micro-habitats, putting pressure on colonies via range contraction and threatening the localised extinction of species. The cliffs are one of the longest stretches of naturally-developing soft cliffs on the UK coastline and also include a number of submerged or partially submerged sea caves, formed by an energetic wave climate, which support rare algal species. The Compton Chine to Steephill Cove SSSI (Site of Special Scientific Interest) extends around the coast at St. Catherine’s Point, designated for the national geological and ecological significance of the chalk cliffs and landslips.
Natural England’s reason for the designation of the site is due to the following3 : Vegetated maritime cliffs and slopes Species-rich unimproved chalk grassland Nationally rare plant species An assemblage of nationally scarce plants An outstanding assemblage of nationally rare and scarce invertebrates Exposed and moderately exposed rocky shores (littoral rock) and Nationally important coastal geomorphology
2 Isle of Wight Shoreline Management Plan 2: Main Report – Chapter 4 (Authors IOW Council and Royal HAskoning 2010) 3 Compton Chine To Steephill Cove; Reasons for designating the SSSI (Natural England, 2013) http://www.sssi.naturalengland.org.uk/citation/citation_photo/2000471.pdf
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Around the undercliff ponds near St Catherine’s Point, a diverse reed swamp community occurs, often with abundant bulrush Typha latifolia and the nationally scarce galingale Cyperus longus. The SSSI includes two areas of unimproved chalk grassland, one which is found on the slopes at St Catherine’s Point and the other includes part of the top and face of the steep rear scarp, which characterises the Ventnor Undercliff landslide complex between St Catherine’s Point and Steephill Cove. Species include abundant red fescue and sheep’s fescue Festuca ovina, upright brome Bromus erectus, crested dog’s tail Cynosurus cristatus, false brome Brachypodium sylvaticum, sweet vernalgrass Anthoxanthum odoratum, meadow oat-grass Avenula pratensis and frequentfern-grass Catapodium rigidum. Herbaceous species include mouse-ear hawkweed Hieracium pilosella, wild thyme Thymus praecox, common rock-rose Helianthemum nummularium, squinancywort Asperula cynanchica, bee orchid Ophrys apifera, carline thistle Carlina vulgaris, dwarf thistle Cirsium acaule, small scabious Scabiosa columbaria and burnet-saxifrage Pimpinella saxifraga. Populations of the endangered field cow-wheat Melampyrum arvense and nationally scarce bastardtoadflax Thesium humifusum and Nottingham catchfly Silene nutans are found on the steep scarp. The endangered triangular pygmy-moss Acaulon triquetrum, is found on the southfacing open calcareous grassland at St Catherine’s Point. The site also supports two rare liverworts including the endangered Celphaloziella baumgartneri and the vulnerable blackwort Southbya nigrella, otherwise only known from Portland, grows in a base rich flush at St Catherine’s Point. These bryophytes are at their northernmost European range on the south English coast. Figure 8 shows the location of the SSSI. St. Catherine’s Point and the surrounding area fall within the Isle of Wight’s 191km2 of AONB (Area of Outstanding Natural Beauty). The 34km of coastline from Steephill Cove in Ventnor clockwise to Widdick Chine at Totland has Heritage Coast status. According to the AONB Management Plan for the Isle of Wight, the landscape character of the area surrounding St. Catherine’s Point is Undercliff, defined as ‘dramatic inland vertical craggy cliffs, slumped grasslands, coastal pasture, exotic ornamental planting, Victorian villa and modern suburban housing in highly manicured gardens and unmanaged natural woodland regeneration’. The Island’s AONB Partnership acknowledges support for energy sustainability and the Eco Island initiative, which aims to create a centre of excellence for renewable energy. The Partnership accepts that there should be no reason why renewable energy production cannot be sensitively blended with the conservation and enhancement of the AONB, without compromising the objectives of the AONB designation.
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8.3 Route Option 1 - Ventnor Haven
8.3.1 Summary of Route Option 1 consists of a 6.9km offshore route from the north easterly end of the offshore site, crossing into the SAC to the south of St Lawrence, then running in an east north east direction to Ventnor Town. The landfall point will be just to the east of Ventnor Haven. Substation locations at Salisbury Gardens or adjacent to the OceanBlue Quay building or Ventnor Industrial Estate are all under consideration. The approximately 1km onshore cable route then follows Dudley St, Pier St. High St. Tulse Hill and Grove Rd. up to the existing Ventnor substation, as shown in Figure 10.
Figure 8: Image Showing On and Offshore Cable Route Option 1 (Substation in Salisbury Gardens) and Interactions with Designations Ventnor is built on steep terraces of previous landslips with surrounding villages linked by the A3055 Undercliff Drive. A significant area of the town is built on clay and this suffers from landslip. The cliffs and ground at Ventnor has a reputation for being unstable. This quality has caused utilities problems in the past with slips causing the disruption of pipes and cables. The built up area under consideration for Option 1 is relatively stable (hence the urban development of the area) and it is the eastern and western extremes of Ventnor that still have some movement4 and can affect the other options discussed in this report.
8.3.2 Landfall Point The landfall point for option 1 is currently anticipated to be just to the east of Ventnor Haven, as shown in Figure 10. The subsea 11kV cable would most likely come ashore via a directionally drilled duct or possibly through the sea wall into Eastern Esplanade car park. See section 8.3.3 for further details.
4 http://www.ventnor-iw.co.uk/landscape.html
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The Haven at Ventnor was constructed in 2003 as part of a strategy to promote Ventnor as a working seaside town. The Haven is comprised of two rock arms, the largest extending south and then curving to the south east and the smaller arm extends towards the larger arm. There is a 24m gap between the two arms. Adjacent to the Haven is a southern Water pumping station and a few buildings related to the fishing industry. Cheetah Marine LLP have been contracted by the Isle of Wight council to manage Ventnor Haven and the contract runs until August 2014 (iwight website ref)5.
Figure 9: Ventnor Haven and the OceanBlue Quay Building Image Source: OceanBlue Quay.
When the Haven was first designed, sediment and seaweed accumulation was not predicted to be a problem6, but there has since been a need for dredging works at the Haven to remove the build-up of seaweed, and a sandbar that is created by sediment deposit at the mouth of the Haven. This will affect decision of offshore cable placement as it approaches the landfall area as it is best to avoid parts prone to sediment or seaweed deposit where dredging may be required.
5 http://onthewight.com/2013/01/10/further-concern-expressed-over-ventnor-haven-running- costs/
6 http://www.oceanbluequay.co.uk/haven/view/haven_information/
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Figure 10: Option 1 Onshore Cable Route for Substation in Salisbury Gardens Contains Ordnance Survey data © Crown copyright and database right 2012
8.3.3 Electrical Substation Locations There are several locations for the electrical substation under consideration for Option 1, as follows: Salisbury Gardens Adjacent to OceanBlue Quay Ventnor Industrial Estate
There is also the option to split the substation and control room between two different locations as described in Section 7.
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Figure 11 Option 1 Substation locations Image Adapted from Bing Maps
8.3.3.1 Salisbury Gardens One option is to place a substation within Salisbury Gardens; see Figure 11 and Figure 12. Salisbury Gardens is owned by Isle of Wight Council and is currently occupied by the Isle of Wight Council and Ventnor Town Council. The latter has been granted special purchaser status for the premises by the Council and it is likely that this will result in Ventnor Town Council taking a long term leasehold interest in the building. As a result, PTEC would need to negotiate use of part of the building through the leasing process or, at a later date, negotiate use with Ventnor Town Council. Salisbury Gardens has four floors, starting from a basement to 2nd floor.
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Figure 12 Salisbury Gardens Image Source: Google Earth
Figure 13: Salisbury Gardens with Basement Coverings and Ventilation Bricks Highlighted in Red Image Adapted from Google Earth The basement level of the building could be used to house transformers, switchgear and control equipment. The top of the basement is covered by reinforced concrete. There are ventilation bricks in what appear to be walled up external doorways.
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Street Level Access to Basement for Transformers
Street Level Access to Basement for Transformers
Figure 14: Plans of Salisbury Gardens Showing Basement (Left) and First Floor Elevations (Right) Image Source: Isle of Wight Council
In order to access the basement to insert transformers, the reinforced concrete coverings would have to be removed and replaced with louvres. A flood assessment would have to be carried out as well assessments to ensure the following: Accessibility requirements (24 hour access for utility, loading access for replacing transformer, etc), Ventilation and cooling requirements Sufficient room for spacing of the electrical equipment to manufacturers standards/guidelines, as well as cabling routes.
The building could also house a control room, a developer’s workspace and potentially an information and visitors centre about PTEC, and/or coastal issues. The incoming offshore 11kV cable would be directionally drilled from the car park of Salisbury Gardens to a distance offshore sufficient to avoid the surge zone and potential anchor damage. A cable duct would be installed to take the cable into the building basement. After transformation to 33kV and any power conditioning, the 33kV onshore cable would follow Dudley Road to Pier Street and up to Ventnor substation (as indicated in Figure 10).
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As the building is not listed planning permission and building regulations consent for the modifications is unlikely to pose a significant problem. However, the building is within the Ventnor Conservation Area7. This area is characterised as follows: Close knit residential properties in the town centre which is close to and an extension of the commercial centre. The area is less lively than the commercial centre but still retains an urban feel. The road pattern is tight in form and follows a grid like layout. The character is dependant on the use and activity as much as the appearance of the buildings.
Modifying an existing building for use as substations is seldom cheaper than building a new, purpose designed one, and can in many cases (particularly with older buildings) end up being more expensive. Cooling is often a problem, as is noise, particularly in residential areas and where forced ventilation may be required. Salisbury Gardens only represents an attractive option if planning constraints make a new building in other locations very difficult or when consideration of extensive developer facilities are taken into account.
8.3.3.2 Adjacent to OceanBlue Quay An alternative substation location is adjacent to the OceanBlue Quay.
Figure 15 OceanBlue Quay
7 Section 69 of the Planning (Listed Buildings and Conservation Areas) Act 1990 imposes a duty on local planning authorities to designate as conservation areas any ‘areas of special architectural or historic interest the character or appearance of which it is desirable to preserve or enhance’
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The OceanBlue Quay building is where Cheetah Marine operates from. It could be possible to put the electrical substation to the east of the building. The benefits of this option are that there may not be any need for directional drilling. However, there is limited space for a combined substation and control room at this location – Cheetah Marine have indicated that they intend to use the space directly adjoining their building for a hydrogen refueler system. The building could therefore be split with the main substation adjoining OceanBlue Quay and the control room in Ventnor Industrial estate as described in Section 7.
Figure 16: Possible Space Available Adjacent to OceanBlue Quay
An alternative location for a new combined substation and control building would therefore be in the existing Eastern Esplanade car park to the east of OceanBlue Quay.
Figure 17: Eastern Esplanade Car Park Image Source: Google Earth Consent is likely to be achievable given surrounding usage, although there would be concerns with the stability of the cliffs behind this location. The site is also within the Ventnor Conservation area as described in section 8.3.3.2 above.
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8.3.3.3 Ventnor Industrial Estate Ventnor Industrial Estate which was previously the old railway station, on Old Station Road, adjoins the existing Ventnor 11 / 33kV substation to the north of the town centre. There is a small plot of land near the entrance to the industrial estate owned by the Council (shown in Figure 18 and Figure 19), where the project substation or control room could be built.
Figure 18: Map Showing Location of Possible Project Substation / Control Room in Ventnor Industrial Estate Image Source: Google Earth
As described in Section 7, transformation to 33kV as soon as possible after the cables have come ashore is desirable, to restrict electrical losses and limit handling difficulties with extremely large onshore cables. Therefore Ventnor Industrial Estate is only considered an option for the full substation if consenting or space considerations limit the potential for a substation and control room closer to shore.
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Figure 19: Possible Location of Project Substation / Control Room in Ventnor Industrial Estate
8.3.4 Onshore Cable Route From landfall at the Haven, via the substation at either Salisbury Gardens or adjacent to OceanBlue Quay, the cable will then follow a route up to the existing 33/11kV Ventnor Substation following roads. If the project substation is to be located at Salisbury Gardens the cable will follow Dudley Road west and continue west onto Alexandra Gardens. Coming to a junction, the route will go north uphill to Ventnor substation along Pier Street, the High Street and onto Tulse Hill. At the junction the cable route will turn west onto Grove Road. Where Grove Road terminates, the cable route will either run along Old Station Road or Mitchell Avenue to Point of Connection. This final section will be determined by SEPD. Using the space adjacent to OceanBlue Quay for the substation will mean the route would be the same as above except for the start of the route being via Shore Hill which then proceeds onto Pier Street. This is a distance of approximately 1km8. This will require the cables to be entrenched in the road and will have to abide by the HAUC Specification for the Reinstatement of Opening in Highways9, wherein excavation and reinstatement standards are described. The work
8 800m from Salisbury Gardens, or 950m from OceanBlue Quay 9https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/11042/sroh.pdf “Under section 71 of the New Roads and Street Works Act 1991 (NRSWA) an Undertaker executing street works must when reinstating the street comply with whatever specification may be prescribed for materials to be used and standards of workmanship to be observed. The Undertaker
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would cause disruption for residents and businesses due to the narrow and steep nature of the streets and although there is an option to try and carry out this work as part of the Highways Maintenance PFI, which could reduce costs, the timing of these two works to coincide cannot be guaranteed.
Figure 20 Ventnor Haven Cable Run Showing Route from Salisbury Gardens and OceanBlue Quay Image Adapted from Google Earth
must also ensure that the reinstatement conforms to prescribed performance standards – in the case of an interim reinstatement, until a permanent reinstatement is effected, and, in the case of a permanent reinstatement, for the prescribed period after completion of the reinstatement.”
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8.4 Option 2 – West Ventnor
8.4.1 Summary of Route Option 2 consists of a 6km offshore route similar to that of option 1 (from the north easterly end of the offshore site, crossing into the SAC to the south of St Lawrence, then running in an east north east direction), making landfall near Castle Cove. The 1.2km onshore route then follows Castle Rd., ZigZag Rd and Ocean View Road to the Ventnor Substation.
Figure 21: Image Showing On and Offshore Cable Route Option 2 and Interactions with Designations
8.4.2 Landfall Point The landfall point for this option would be near Castle Cove. Castle Cove is west of Ventnor Bay. The Cove marks the end of a rock armour revetment which protects the extremely vertical cliffs of weak chalk and marls from toe erosion for the next 15-25 years. There are a number of rock armour groynes along the front as well which limits the movement of sediment by interrupting water flow. There is a Southern Water pumping station just to the South of Steephill Road, where the preferred location for the project substation would be (see Section 8.4.3). The pumping station no longer uses the outfall pipe to the sea, as sewage is now pumped to Sandown. If the condition of this pipe is good enough, it could be used as a conduit for the incoming offshore cable. This matter will need to be discussed with Southern Water.
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Figure 22: Southern Water Outfall Pipe Image Source: Flickr If the outfall pipe is not useable, the foreshore crossing could be achieved via the small slipway and track leading to it, shown in Figure 23 and Figure 24. Directional drilling could still be avoided with this option.
Figure 23: Possible Landfall Point via Slipway
8.4.3 Electrical Substation Location There are three options for the location for the electrical substation under consideration for Option 2, as follows: Southern Water Pumping station compound Council owned field Ventnor Industrial Estate
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There is also the option to split the substation and control room between two different locations as described in Section 7. Although as space constraints are unlikely to be such an issue with the first two locations, splitting the building is not considered to be a worthwhile consideration at this point. Figure 24 shows the potential area for the substation development near the foreshore. There is potentially enough space for a new building in the compound of the existing pumping station, avoiding the need for any re-designation of land. This option would have to be negotiated with Southern Water. If this is not possible to negotiate, the adjacent field is owned by Isle of Wight council, so a substation could be located here if a portion of it could be re-designated from its existing recreational use. The site lies just outside the SSSI, AONB and Heritage Coast designations, so consent should be relatively straightforward.
Figure 24: Option 2 Substation Location Image Adapted from Google Earth If negotiations with Southern Water are unsuccessful and re-designation / planning issues associated with the field prove difficult, Ventnor Industrial Estate could also be used as described in Section 8.3.3.3.
8.4.4 Onshore Cable Route From the project substation, the cable run would be routed as per Figure 25. The cable would exit the project substation and via a small unpaved lane join Steephill Road. The
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cable will follow Steephill Road in an easterly direction until it comes to a junction with Castle Road where it continues in a north easterly direction until it meets Zig Zag Road. The cable will follow Zig Zag Road north to a junction with Ocean View Road. Turning east onto Ocean View Road, the cable route then heads east and travels approximately 400m to the Ventnor 33/11kV Substation. This cable route length is approximately 1.6km. The use of a foot path joining Zig Zag Road and Ocean View Road could considerably shorten the route, making it 1km. The possibility of using this footpath would have to be explored with contractors as the size of the cable may make handling it through this very narrow route impracticable
Figure 25: Option 2 Onshore Cable Route (Landfall via Slipway) Contains Ordnance Survey data © Crown copyright and database right 2012
Figure 26: Two Images Showing Footpath Joining Zig Zag Road and Ocean View Road
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8.5 Route 3 Option 3 – Niton
8.5.1 Summary of Route Option 3 has the shortest offshore route (3.5km) running from approximately the middle of the offshore site north to Castle Haven where the cable makes landfall. From there, the 7.2km onshore route would follow Undercliff Drive, Seven Sisters Road, Whiwell Road. and Ocean View Road. to the Ventnor Substation. Niton has a population of approximately 1000 people, and is served by 11kV overhead distribution circuits supplied from Ventnor substation.
Figure 27: Image Showing On and Offshore Cable Route Option 3 and Interactions with Designations
8.5.2 Landfall Point and Electrical Substation Location The area for landfall of the incoming offshore cable is shown in Figure 28. There is a slipway (Figure 29) which the cable will follow to an area on the east side of a building of unknown use (Figure 30). This area could be used to house the project substation.
Figure 28: Onshore Sites at Niton Image Adapted from Google Earth
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Figure 29: Cable Landfall Point showing Slipway Image Source: Google Earth
Figure 30: Entrance to Possible Substation Location Image Source: Google Earth
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As this site is in SSSI, AONB and Heritage Coast designations, it is considered that the project substation could pose consenting difficulties.
Given the length of the onshore cable route, a substation in Ventnor Industrial Estate or a split building is not considered an option.
8.5.3 Onshore Cable Route The 20MWe output of PTEC is rated significantly above the capacity of the existing 11kV overhead lines presently serving Niton, so there is no prospect of connecting the scheme to the existing 11kV overhead distribution network in the vicinity of the village. It would therefore be necessary to construct a new circuit to Ventnor primary substation, via underground cable installed in roads or overhead lines. Overhead lines could be difficult to consent given the AONB and SSSI designations they would traverse. Underground cable has therefore been considered in the costs for this option in Section 9. The cable route from the substation would follow Castlehaven Lane north and then east to a junction with St. Catherine’s Road. The cable route then proceeds in an easterly direction towards a junction with the A3055 Undercliff Drive. The cable would follow Undercliff Drive for approximately 2.5km until it meets a junction with Seven Sisters Road. Proceeding along Seven Sisters Road the cable route then cuts across a field to join Whitwell Road and continue east long it. At a junction with Gill’s Cliff Road, the route follows it northeast to meet Ocean View Road. The route proceeds for a further 600m approximately to Old Station Road where Ventnor 33/11kV substation is located. This is shown in Figure 31.
Figure 31: Niton Onshore Cable Route Option Contains Ordnance Survey data © Crown copyright and database right 2012
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8.6 Route Option 4 – Old Park Road
8.6.1 Summary of Route Option 4 also has a fairly direct offshore route of 3.8km running directly from the offshore site north, just to the east of Binnel Point (west of Woody Bay). The 4.1km onshore cable route would then follow the track and then Old Park Road up to Undercliff Drive and east to Ventnor. This option provides a shorter onshore cable route than option 3 (Niton) and the substation is likely to be easier to consent than in Niton, as it could be located just to the north of the SSSI and AONB designations. This option also provides a significantly shorter offshore cable route than options 1,2 or 5.
Figure 32: Image Showing On and Offshore Cable Route Option 4 and Interactions with Designations
8.6.2 Landfall Point and Electrical Substation Location The possible area of landfall encompasses a large section of the shore at Binnel Bay. Horizontal Directional Drilling is likely to be required under the cliffs and possibly to avoid the SSSI. There are also questions as to where to place the PTEC substation. A large unpaved parking lot at the end of Old Park Road as shown in Figure 34 is currently considered the most likely option.
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Figure 33: Onshore Sites at Old Park Road Image Adapted from Google Earth Given the length of the onshore cable route, a substation in Ventnor Industrial Estate or a split building is not considered an option.
Figure 34: Possible Substation Location Image Source: Google Earth It should be noted that the east end of the area highlighted in Figure 33 consists of derelict infrastructure from the former WWII radar station RAF St Lawrence, located on the site. Consideration would have to be given to his heritage when routing cables or locating the substation.
8.6.3 Onshore Cable Route The onshore cable will proceed to Old Park Road via a small track, where the substation is likely to be located. Then continuing to Spindlers Road, the route would follow Seven Sisters Road before cutting across a field to the join Whitwell Road and continue east long it. At a junction with Gill’s Cliff Road, the route follows it north east to meet Ocean View Road. The route proceeds for a further 600m approximately to Old Station Road where Ventnor 33/11kV substation is located, as show in Figure 35.
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Figure 35: Old Park Road Onshore Cable Route Option Contains Ordnance Survey data © Crown copyright and database right 2012
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8.7 Route Option 5 – La Falaise Car Park
8.7.1 Summary of Route Option 5 consists of a 6.4km offshore route similar to that of option 1 (from the north easterly end of the offshore site, crossing into the SAC to the south of St Lawrence, then running in an east north east direction), making landfall at the Council owned La Falaise car park, just to the west of Ventnor Bay, where the substation would be built. From the car park, the 1km onshore route would join Bath Road. before running into Belgrave Road. Zig Zag Road and following a similar route to that of Option 2, including possible use of the footpath.
Figure 36: Image Showing On and Offshore Cable Route Option 5 and Interactions with Designations
8.7.2 Landfall Point The offshore cable would make landfall at La Falaise Car Park (see Section 8.7.3.1). The offshore cable would be directionally drilled from the car park, under the small cliff, to a distance offshore sufficient to avoid the surge zone and potential anchor damage.
8.7.3 Electrical Substation Location There are two options for the location for the electrical substation under consideration for Option 5, as follows: La Falaise Car Park Ventnor Industrial Estate (see Section 8.3.3.3)
There is also the option to split the substation and control room between the two locations as described in Section 7.
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8.7.3.1 La Falaise Car Park La Falaise translated from French means “The Cliff” in English which is very apt considering its location. The car park is almost on the shore were it not elevated. Directly to the west of the car park is Ventnor Park and The Undercliff. The car park is accessible by the Esplanade and Bath Road, and is shown in Figure 37. The location of the car park makes it quite an appealing option for making landfall for the incoming offshore cable and also has space to build the project substation.
Figure 37: Onshore Route from La Falaise Car Park to Ventnor Substation Image Adapted from Google Earth
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Figure 38: La Falaise Car Park from The Esplanade Image Source: Google Earth There are several areas where the electrical substation could be located within the car park. This depends on whether the substation will be contained all in one installation, or if the substation will be split with transformers, power conditioning and circuit breaker room at the landing point and control building near the Ventnor Substation, as described in Section 7. The preferred location at this point is a partially walled area to the north, around the middle of the site as shown in Figure 40.
Figure 39: La Falaise Car Park from the Western End Image Source: Google Earth It is understood that the car park is owned by the Council and is not very well used. It is right on the sea front making it a very good location for the substation and landfall point. The cliffs above the car park are understood to be very unstable and foot paths running along theses cliffs have been closed because of this. An assessment of the cliff’s stability and a risk assessment for this aspect would have to be undertaken if this option is chosen.
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If stabilisation works are required, this would involve significant additional cost to the project that could easily amount to over £500,000.
Figure 40: La Falaise Car Park Showing Possible Location for the Project Substation Image Source: Google Earth
8.7.4 Onshore Cable Route The onshore cable route would exit from the car park to Bath Road and trail it north to Zig Zag Road via Belgrave Road. Along Zig Zag Road there is a junction to Bellevue Road, which is a short crescent like road, whereupon we find the footpath near the northern most section leading to Ocean View Road that may be useable, as described in section 8.4. Once through to Ocean View Road the route will follow this road a short distance east to turn north onto Old Station Road, where the Ventnor 33/11kV substation is located.
Figure 41: La Falaise Car Park Onshore Cable Route Option and HDD Contains Ordnance Survey data © Crown copyright and database right 2012
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9 GRID CONNECTION COSTS SEPD have provided a preliminary budget for the grid connection of £1.7 million + VAT. This is based on a route from Ventnor Haven to the existing Ventnor 33kV substation. The breakdown is approximately as follows: £0.8 million – For supply of the connection including required reinforcement of the circuit connected to. £0.9 million – For the onshore cabling from the landing point to the grid connection point; this includes supply of the cable and installation. Note that this work is contestable so could be reduced with the use of an independent contractor. The cost includes the supply of the connection, supply and installation of onshore cabling and required reinforcement of the circuit connected to. It does not include the cost of the PTEC substation and control room and the cost of any intertripping scheme required (see section 10 below).
SSE point out that these costs are based on desktop studies and local knowledge only. They do not allow for unknown engineering difficulties with cable routes and assumes consents needed to complete the work will be obtained.
They also highlight that if other formal offers for generation connecting on the Island are accepted then it is likely that there will be a need for further 132kV reinforcement. This would be an apportioned cost between SEPD and PTEC, as described in their standard charging methodology. The cost will be calculated as part of the design works and formal offer. This quote (summarised above) can be found in a letter from SEPD in Appendix A.
Note that these costs are a very high level first assessment and detailed design by SEPD will be required for firm quotations. IT Power believe there is scope for reduction, but the detailed design could also result in an increased cost. It should also be noted that some of this work is contestable so could be reduced with the use of an independent contractor.
The cost of trenching and cable installation as estimated by SEPD seems to be higher than expected but these costs could well be reduced by using contractors on the contestable component of the grid connection. Broadly half of the overall construction cost might be so reduced.
The details of the 33kV connection from the various routing options to the existing 33kV overhead line to Ventnor (to the north of the existing 33/11kV substation) are common to all options and do not present any significant construction, electrical problems or costs. They would probably be executed by SEPD and require the provision of isolators, with the main fault breaking switches being assumed to be located within the PTEC project substation.
IT Power have provided an independent cost estimate for all options, based on previous experience with actual costs and average rates for the sector as well as approximate figures quoted by SEPD. These costs are summarised in Table 2 below.
The costs presented in Table 2 are for comparative purposes only. Only elements associated with the grid connection and offshore export cable have been costed here. Other major infrastructure which will not vary with different grid connection routes (such as berth cables, connector management systems, monitoring systems etc) have been taken from the PTEC development budget.
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The costs are based on industry standards and figures taken for similar projects. No suppliers of equipment have been consulted over these figures, so they should be used with extreme caution. It should also be noted that the costs are based on a single 6 core offshore cable; effectively allowing 2 separate circuits. If additional cables are required to meet developer demands, the cost of the offshore cables would rise considerably, as highlighted in Table 4.
Costs are estimated on the following basis: Offshore cable supply: £600/m estimated cost for a 6 core 11kV custom cable for the export cable. Berth cables are not included.
Offshore cable routes are all to the same point in the offshore site. Vessel Rates: o Cable installation vessel: £750k mob/demob + £150k per day o Rock dump vessel: £200k mob/demob + £60k per day The cable cannot be buried at any point along its length and is instead protected by rock dumping. Horizontal Directional Drilling under cliffs and only long enough to clear the surge zone; through chalk. Onshore cable supply and installation of appropriate 33kV cable in carriageway: £375/m plus setup. Cost includes supply of cable, excavation and reinstatement to match existing surface. Overhead lines are not considered for any option. Project substation for option 1 is in the existing Salisbury Gardens building. Intertripping is required via a dedicated fibre link to Wootton Common substation installed in carriageways. Cost includes supply of fibre, excavation and reinstatement to match existing surface. Project substation and associated equipment as per section 7. Grid connection and upgrades based on budgetary figure from SEPD. No contingency or risk allowance has been included. Table 4 presents a worst case scenario for all options involving the following: Increased onshore cable installation cost Increased HDD cost (and HDD for options 2 and 3) Split substation building options and increased cost for fit out of Salisbury Gardens Increased fibre installation costs intertripping 3 separate 3-core subsea cables plus additional time to install them. An active subsea hub containing switchgear, but no transformer.
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Table 2: Cost Estimation for PTEC Grid Connection Options, Including Offshore Cable Option 1: Option 2: Option 3: Option 4 Option 5: Ventnor Haven West Ventnor Niton Old Park Road La Falaise Car Park Cost Description Cost Description Cost Description Cost Description Cost Description Onshore cable + 800m @ £375/m 1200m @ 375/m 7200m @ 375/m 4100m @ 375/m 1000m @ 375/m £307,750 £457,750 £2,707,750 £1,545,250 £382,750 installation plus set-up plus set-up plus set-up plus set-up plus set-up 500m @ 500m @ 500m @ HDD £711,388 £1,300/m plus - - £711,388 £1,300/m plus £711,388 £1,300/m plus pull-in pull-in pull-in Transformers + Transformers + Transformers + Transformers + Transformers + assoc. protection & assoc. protection & assoc. protection & assoc. protection & assoc. protection & control £170,000. control £170,000. control £170,000. control £170,000. control £170,000. Substation electrical Switchboards, Switchboards, Switchboards, Switchboards, Switchboards, £620,000 £620,000 £620,000 £620,000 £620,000 equipment meters: £140,000 meters: £140,000 meters: £140,000 meters: £140,000 meters: £140,000 Power factor Power factor Power factor Power factor Power factor correction: correction: correction: correction: correction: £150,000 £150,000 £150,000 £150,000 £150,000 Fit above Substation building & equipment into Build and outfit Build and outfit Build and outfit Build and outfit £480,000 £880,000 £880,000 £880,000 £880,000 fit out Salisbury Gardens new building new building new building new building building Grid upgrades + Based on SEPD Based on SEPD Based on SEPD Based on SEPD Based on SEPD £800,000 £800,000 £800,000 £800,000 £800,000 supply of connection figures figures figures figures figures 17km fibre 17km fibre 18.5km fibre 18km fibre 17km fibre Intertripping £1,360,000 £1,360,000 £1,480,000 £1,440,000 £1,360,000 @£80/m @£80/m @£80/m @£80/m @£80/m 6,900m @ 6,000m @ 3,500m @ 3,800m @ 6,400m @ Subsea export cable £4,140,000 £3,600,000 £2,100,000 £2,280,000 £3,840,000 £600/m £600/m £600/m £600/m £600/m 10 days cable 10 days cable 9 days cable 9 days cable 9 days cable install & transit install & transit install & transit install & transit install & transit Subsea cable £2,812,760 6 days rock dump, £2,812,400 6 days rock dump, £2,601,400 5 days rock dump, £2,601,520 5 days rock dump, £2,602,560 5 days rock dump, installation transit & transit & transit & transit & transit & materials materials materials materials materials
Total onshore £4,279,138 £4,117,750 £6,487,750 £5,996,638 £4,754,138 Total offshore export £6,952,760 £6,412,400 £4,701,400 £4,881,520 £6,442,560 cable
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8,000m berth 8,000m berth 8,000m berth 8,000m berth 8,000m berth Berth cables & subsea cable (@£300/m cable (@£300/m cable (@£300/m cable (@£300/m cable (@£300/m £6,350,000 £6,350,000 £6,350,000 £6,350,000 £6,350,000 equipment + install). Hub + + install). Hub + + install). Hub + + install). Hub + + install). Hub + install install install install install Additional offshore £700,000 Buoys, monitoring £700,000 Buoys, monitoring £700,000 Buoys, monitoring £700,000 Buoys, monitoring £700,000 Buoys, monitoring equipment etc etc etc etc etc Detailed engineering £343,000 £343,000 £343,000 £343,000 £343,000 design & procurement Management, Management, Management, Management, Management, Management Costs £1,450,000 insurance, legal £1,450,000 insurance, legal £1,450,000 insurance, legal £1,450,000 insurance, legal £1,450,000 insurance, legal etc etc etc etc etc
Total for Project £20,074,898 £19,373,150 £20,032,150 £19,721,158 £20,039,698
Table 3: Base Case vs Worst Case Costs Option 1: Option 2: Option 3: Option 4 Option 5: Ventnor Haven West Ventnor Niton Old Park Road La Falaise Car Park Base Cost Worst Case Cost Base Cost Worst Case Cost Base Cost Worst Case Cost Base Cost Worst Case Cost Base Cost Worst Case Cost Total onshore £4,279,138 £6,187,638 £4,117,750 £6,337,638 £6,487,750 £8,797,638 £5,996,638 £7,420,138 £4,754,138 £6,082,638 Total offshore export £6,952,760 £9,472,760 £6,412,400 £8,662,400 £4,701,400 £6,201,400 £4,881,520 £6,471,520 £6,442,560 £8,812,560 cable Berth cables & subsea £6,350,000 £7,850,000 £6,350,000 £7,850,000 £6,350,000 £7,850,000 £6,350,000 £7,850,000 £6,350,000 £7,850,000 equipment Additional offshore £700,000 £700,000 £700,000 £700,000 £700,000 £700,000 £700,000 £700,000 £700,000 £700,000 equipment Detailed engineering £343,000 £343,000 £343,000 £343,000 £343,000 £343,000 £343,000 £343,000 £343,000 £343,000 design & procurement Management costs £1,450,000 £1,450,000 £1,450,000 £1,450,000 £1,450,000 £1,450,000 £1,450,000 £1,450,000 £1,450,000 £1,450,000
Total for Project £20,074,898 £26,003,398 £19,373,150 £25,343,038 £20,032,150 £25,342,038 £19,721,158 £24,234,658 £20,039,698 £25,238,198
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Table 4: Worst Case Cost Estimation for PTEC Grid Connection Options, Including Offshore Cable Option 1: Option 2: Option 3: Option 4 Option 5: Ventnor Haven West Ventnor Niton Old Park Road La Falaise Car Park Cost Description Cost Description Cost Description Cost Description Cost Description Onshore cable + 1200m @ £425/m 1800m @ 425/m 7200m @ 425/m 4100m @ 425/m 1600m @ 425/m £516,250 £686,250 £3,066,250 £1,748,750 £431,250 installation plus set-up plus set-up plus set-up plus set-up plus set-up 500m @ 500m @ 500m @ 500m @ 500m @ HDD £811,388 £1,500/m plus £811,388 £1,500/m plus £811,388 £1,500/m plus £811,388 £1,500/m plus £811,388 £1,500/m plus pull-in pull-in pull-in pull-in pull-in Transformers + Transformers + Transformers + Transformers + Transformers + assoc. protection & assoc. protection & assoc. protection & assoc. protection & assoc. protection & control £170,000. control £170,000. control £170,000. control £170,000. control £170,000. Substation electrical Switchboards, Switchboards, Switchboards, Switchboards, Switchboards, £620,000 £620,000 £620,000 £620,000 £620,000 equipment meters: £240,000 meters: £240,000 meters: £240,000 meters: £240,000 meters: £240,000 Power factor Power factor Power factor Power factor Power factor correction: correction: correction: correction: correction: £150,000 £150,000 £150,000 £150,000 £150,000 Fit above Build and outfit 2 Build and outfit 2 Substation building & equipment into new building (split Build and outfit Build and outfit new building (split £1,000,000 £980,000 £880,000 £880,000 £980,000 fit out Salisbury Gardens substation & new building new building substation & building control room) control room) Grid upgrades + Based on SEPD Based on SEPD Based on SEPD Based on SEPD Based on SEPD £1,200,000 figures + £1,200,000 figures + £1,200,000 figures + £1,200,000 figures + £1,200,000 figures + supply of connection contingency contingency contingency contingency contingency 17km fibre 17km fibre 18.5km fibre 18km fibre 17km fibre Intertripping £2,040,000 £2,040,000 £2,220,000 £2,160,000 £2,040,000 @£120/m @£120/m @£120/m @£120/m @£120/m 3 x 6,900m @ 3 x 6,000m @ 3 x 3,500m @ 3 x 3,800m @ 3 x 6,400m @ Subsea export cable £6,210,000 £300/m £5,400,000 £600/m £3,150,000 £600/m £3,420,000 £600/m £5,760,000 £600/m 13 days cable 13 days cable 12 days cable 12 days cable 12 days cable install & transit install & transit install & transit install & transit install & transit Subsea cable 6 days rock dump, 6 days rock dump, 5 days rock dump, 5 days rock dump, 5 days rock dump, installation transit & transit & transit & transit & transit & £3,262,760 materials £3,262,400 materials £3,051,400 materials £3,051,520 materials £3,052,560 materials
Total onshore £6,187,638 £6,337,638 £8,797,638 £7,420,138 £6,082,638
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Total offshore export £9,472,760 £8,662,400 £6,201,400 £6,471,520 £8,812,560 cable 8,000m berth 8,000m berth 8,000m berth 8,000m berth 8,000m berth Berth cables & subsea cable (@£300/m cable (@£300/m cable (@£300/m cable (@£300/m cable (@£300/m £7,850,000 £7,850,000 £7,850,000 £7,850,000 £7,850,000 equipment + install). Active + install). Active + install). Active + install). Active + install). Active hub + install hub + install hub + install hub + install hub + install Additional offshore £700,000 Buoys, monitoring £700,000 Buoys, monitoring £700,000 Buoys, monitoring £700,000 Buoys, monitoring £700,000 Buoys, monitoring equipment etc etc etc etc etc Detailed engineering £343,000 £343,000 £343,000 £343,000 £343,000 design & procurement Management, Management, Management, Management, Management, Management costs £1,450,000 insurance, legal £1,450,000 insurance, legal £1,450,000 insurance, legal £1,450,000 insurance, legal £1,450,000 insurance, legal etc etc etc etc etc
Total for Project £26,003,398 £25,343,038 £25,342,038 £24,234,658 £25,238,198
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10 INTERTRIPPING SEPD have advised that an inter-trip will be required in the event that one of the 132kV circuits to the mainland is disconnected. The inter-trip will require a communication link from the Point of Supply (PTEC substation) to SEPD’s Wootton Common Substation, a distance of approximately 17km. The requirement and specifications for this are still under discussion with SEPD and a number of alternatives are still under consideration. For the time being however, IT Power suggest that PTEC should proceed on the basis that an inter-trip will be required. Inter-trips are required as an automatic control arrangement where generation or demand may be reduced or disconnected following a system fault event to relieve localised network overloads, maintain system stability, manage system voltages and/or ensure quick restoration of the transmission system.
10.1 Costs of Inter-trip Scheme SSE have advised that the inter-trip will require a dedicated fibre from the Point of Supply (PTEC substation) to the Wootton Common Substation, a distance of approximately 17km. Installed costs for fibre links can range between £30 and £80 per metre, depending on the ground conditions (earth, pavement, tarmac) and the level of disruption caused by installation. A budgetary figure of around £1million would be considered prudent for this link. SSE’s costs in connecting the intertrip would be very minor when compared to the cost of installing the fibre and would amount to only a few tens of thousands.
10.2 Alternatives to Inter-tripping / Fibre link
10.2.1 Active Network Management The Active Network Management (ANM) project that SSE are considering for the area (see section 10.2.1.1) would eliminate the need for the inter-trip scheme. There will be some cost associated with the required control equipment for inclusion in the project, but this will be of the order of a hundred thousand pounds. ANM monitors and controls the grid in real time to ensure it remains within its operating constraints. ANM involves a range of software, automation and controls that allow power companies and utilities to use the ‘reserve capacity’ in the grid for new connections. This capacity exists because the grid capacity available for new connections to the electricity grid is generally about half of the installed grid capacity. This is because the grid is planned to operate passively, allocating and relying on a reserve element of grid capacity for grid outages, or other rare and unforeseen occurrences. ANM can create up to two or three times more capacity to host new generation and demand. It can also increase the capacity of the grid when weather cooling effects allow more power to be transferred, particularly through overhead lines.
10.2.1.1 SSE Future Networks SSE Future Networks and Policy team has been set-up within SSE to develop and deliver innovation projects for their network businesses. The team provides an R&D service, identifying opportunities to develop and trial innovative technologies, practices and commercial arrangements on the SSE owned networks.
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The Future Networks team also carries out ‘horizon scanning’ activity to ensure they understand new developments in the industry and learn how others’ work can inform SSE’s own strategy Partnership working is also listed as an important part of the Future Network team’s approach – by collaborating with stakeholders from academia, industry and the public, they help ensure that projects are relevant and provide real benefits to these groups. Most of the Future Network projects are funded through Ofgem mechanisms to incentivise innovation, chiefly the Low Carbon Networks Fund and Innovation Funding Incentive. SSE Future Networks have informed IT Power that their WINS project (Isle of Wight Integrated Network Solution) will no longer be submitted to OFGEM in the final round of bidding for LNCF funding. They have however said they will “take Active Network Management to IOW as Business As Usual in conjunction with the other technology being funded by other means, so steps are being taken to proactively address the issues being faced on the island.” The have also said they are keen to provide input and advice where possible in the FEED stage. A meeting to discuss this point with Future Networks and establish likely timescales and collaboration opportunities will be set up in early September. Until that time, IT Power is proceeding on the basis that the timescales for the PTEC project will not fit with those for an active network management installation on the Isle of Wight. This means that an inter- trip will be required in the event that one of the 132kV circuits to the mainland is disconnected
10.2.2 Alternative Communication Links In certain circumstances other types of communication links can be used for inter-trip schemes, in particular: Carrier channels at high frequencies over the power lines themselves Radio channels at very high or ultra high frequencies
Whether or not a particular communication link is used depends on factors such as the availability of an appropriate communication network, the distance between protection relaying points, the terrain over which the power network is constructed, as well as cost. The cost of using a radio channel would likely be less that at around £100k. IT Power have been advised that inter-tripping is unavoidable, and that a dedicated fibre must be used between Wootton Common and Ventnor as radio communications on the island are problematic and the protection of the 132kV connection to mainland is a valuable and essential asset that the would require the dedicated fibre. Radio communications for intertripping is also not used anywhere else on the island by SSE, so they are not willing to consider it. During detailed design work IT Power will put forward a strong argument to SSE for one of the above alternatives to an expensive fibre link. However, it can in no way be guaranteed that SSE will accept these proposals; so it would be prudent to budget for a dedicated fibre.
11 HORIZONTAL DIRECTIONAL DRILLING (HDD) For short distances to shore or where the topography of the coastline site makes it difficult to achieve a conventional landfall by trenching, Horizontal Directional Drilling (HDD) is frequently employed.
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HDD can be conducted from land, creating a conduit that the cable is passed through. Lengths in excess of 1000 meters (3280 ft) can be achieved when working from shore. The use of HDD virtually eliminates any interruption to the local habitat in the nearshore regions and allows the cable to be buried much deeper than conventional trenching technologies would allow.
Figure 42: HDD Riggs Image Source: Allen Watson Ltd HDD consists of drilling a small diameter pilot hole under directional control along a predetermined path. A ‘pullback’ duct pipe is then connected to a reamer which is then pulled back through the pilot hole. The process is shown in Figure 43 below.
Figure 43: Illustration Showing Directional Drilling Procedure Image source: LMR Drilling The length and duct diameter that can be achieved is dependent on the contractor. Generally only a few hundred meters is necessary to overcome a specific obstacle. For instance the Wavehub duct was 185 meters under the nearby dunes, the cable was then installed across the beach with the use of a cable plough. Therefore whereas there are a
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large number of HDD contractors in the UK, only a specialist few have the capability to achieve drills of more than 1km in length. 2km long ducts of up to 1200mm in diameter have been installed on occasion by specialist contractors. The longest HDD that IT Power is aware of is 3.06km for an oil pipeline in Iran, although distances of over 10km have been achieved using the same technology for oil wells. Costs for HDD are highly dependent on duct diameter and ground conditions, for the case of PTEC, a range of between £1,100 and £1,500 per metre could be expected. This would include the installation of the duct, but excluding cable installation. Therefore whereas the 2.4km drill under the entire SAC zone is feasible, the cost of this would likely exceed £3 million.
Figure 44: HDD in Process Image source: Chiltern Thrust Bore
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12 SUMMARY AND NEXT STEPS A summary of the cable route options under consideration are presented in Table 5 below. They are also roughly ranked according to a number of different categories. The information presented in this report and summarised in this table is considered sufficient to enable a decision on the preferred cable route option to be selected. However, it should be noted that the EIA and FEED work (including detailed design by SEPD) may reveal complications with the preferred option that make it less attractive than one of the others at a later date.
Next steps for the grid connection work that will be undertaken as part of the FEED work are as follows: Further discussions held with SEPD on the feasibility and costs of the preferred option. Request for a detailed design for the preferred option from SEPD. This would include "route proving", which will require some exploratory excavation (and costs), and the provision of confirmed fault level contributions and harmonic injection capabilities of the equipment that might be installed. Select preferred ICP. Request design of contestable works from the ICP. Harmonic modelling of project. Landowners consulted and crossings negotiated, Apply for a Point of Connection (POC) offer from SEPD.
Discussions with SSE Future Networks will also continue through the remainder of this work and into the FEED work to see if PTEC can be incorporated into any network management project they may be planning. Further engagement with SSE Future Networks may also help progress the project more effectively with SEPD. In addition, discussions with the following should also be initiated: Wight Salads, to investigate the status, and any potential for PTEC to utilise the spare capacity held by them in relation to the Arreton CHP plant. RWE about East Cowes (140MW) power station status and to investigate the possibility of some sort of capacity sharing arrangement. Cheetah Marine / ITM Power and other potential (large) electricity users in the area to investigate demand and possible storage solutions. Southern Water to investigate the possibility of incorporating the PTEC project substation into the existing compound of their pumping station in West Ventnor and the possible use of their out-fall pipe. SSE and OFGEM to investigate the possibility of amending the application for a like for like replacement of the interconnector(s) for an upgrade of the capacity of the cable(s).
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Table 5: Summary of Cable Route Options Option 1: Option 2: Option 3: Option 4: Option 5: Ventnor Haven West Ventnor Niton Old Park Road La Falaise Car Park Rank Comments Rank Comments Rank Comments Rank Comments Rank Comments Possible use of existing Possible use of an compound (Southern No obvious location for Site is a Council owned existing building for Water), owned by the SSSI, AONB and Heritage substation. car park. Substation location 1 2 5 4 3 substation and control Council. Council owned Coast Re-designation of land Unstable cliffs above room field adjacent to this required. location. site. Slightly longer route Very long route through Shortest route but Long route partially Very similar length and Onshore route 3 1 than 2 & 3, but less 5 SSSI, AONB and Heritage 4 2 through high-street through SSSI and AONB challenges to option 2 disruption of busy roads Coast SAC. SAC. SAC. Longest offshore Route SAC. SAC. Offshore route 5 4 Proximity to explosives 1 2 3 Proximity to explosives Proximity to explosives Shortest offshore route Short offshore route dump dump dump Possible use of existing outfall pipe from Crossing SSI Crossing SSI Foreshore route 5 HDD under cliffs 1 Southern Water 3 4 2 HDD under cliff HDD not necessary HDD pumping station. No HDD necessary Possible consent for If substation cannot be Long onshore route modification of Salisbury Substation and long Substation would be included in SW through SSSI, AONB and Gardens required. onshore route through installed in a section of Consenting challenges 3 1 compound, consenting 5 4 Heritage Coast. Re- 2 Onshore cable route SSSI, AONB and Heritage car park. More visible could be more difficult designation of land passes directly through Coast than most other options high street than option 3 required for substation Onshore cost 2 £4,279,138 1 £4,117,750 5 £6,487,750 4 £5,996,638 3 £4,754,138 Offshore cost 5 £6,952,760 3 £6,412,400 1 £4,701,400 2 £4,881,520 4 £6,442,560
Overall Ranking 4 1 5 3 2 Note: The overall ranking is an average of all considerations and does not reflect the relative importance or difficulty of each consideration.
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APPENDIX A: SEPD Quote Letter
APPENDIX A: SEPD Quote Letter