Western Isles HVDC Link Consultation · In total we maintain about 5,000km of overhead lines and underground cables ... co-ordinated and economical system of ... What is the difference

Western IslesHVDC LinkConsultation

02www.ssen-transmission.co.uk/projects/western-isles

Western Isles HVDC Link Consultation

Who we are

In total we maintain about 5,000km of overhead lines and underground cables – easily enough to stretch across the Atlantic from John O’Groats all the way to Boston in the USA.

Our network crosses some of the UK’s most challenging terrain – including circuits that are buried under the seabed, are located over 750m above sea level and up to 250km long.

The landscape and environment that contribute to the challenges we face also give the area a rich resource for renewable energy generation. There is a high demand to connect from new wind, hydro and marine generators which rely on Scottish and Southern Electricity Networks to provide a physical link between the new sources of power and electricity users. Scottish and Southern Electricity Networks is delivering a major programmeof investment to ensure that the network is ready to meet the needs of our customers in the future.

Our responsibilities

We have a licence for the transmission of electricity in the north of Scotland and we are closely regulated by the energy regulator Ofgem.

Our licence stipulates that we must develop and maintain an efficient, co-ordinated and economical system ofelectricity transmission.

What is the difference betweenTransmission and Distribution?

Electricity Transmission is the transportation of electricity from generating plants to where it is required at centres of demand.

The Electricity Transmission network, or grid, transports electricity at very high voltages through overhead wires, underground cables and subsea cables. The transmission network connects large scale generation, primarily renewables, to central and southern Scotland and the rest of Great Britain. It also helps secure supply by providing reliable connection to the wider network of generation plans.

The Electricity Distribution network is connected into the Transmission network but the voltage is lowered by transformers at electricity substations, and the power is then distributed to homes and businesses through overhead lines or underground cables.

Overview of Transmission projects

We are Scottish and Southern Electricity Networks, operating under licence as Scottish Hydro Electric Transmission Plc for the transmission of electricity in the north of Scotland.

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www.ssen-transmission.co.uk/projects/western-isles


Welcome

Welcome to this statutory pre-application consultation event in relation to Scottish Hydro Electric Transmission plc (SHE Transmission) upcoming plans to submit a Marine Licence application to Scottish Ministers for the subsea element of their proposed Western Isles Connection (the Project) between Arnish and Dundonnell.

The exhibition provides:

Project Need

At present the existing Western Isles system operates with a restricted 132kV connection to the Scottish mainland. The Western Isles possess attractive renewable resources which have been targeted by developers seeking to invest in onshore wind and marine generation projects.

On Lewis and Harris today, a total of 380MW of generation is either connected or contracted to connect in the future. There are further interests from Developers of renewable energy projects in excess of 200MW; a mix of onshore wind, pump storage hydro and solar energy projects.

There is no spare capacity on the existing Western Isles network to connect additional generation. As a consequence, a higher capacity link to the Scottish mainland is proposed to facilitate export into the Great Britain Main Interconnected Transmission System (GB MITS).

SHE Transmission has detailed plans to construct a 158km 600MW HVDC link of which 81km are subsea and 77kmare underground cable between Beauly on the Scottish mainland (located North West of Inverness) and Arnish onthe east coast of the Isle of Lewis via Dundonnell on thewest coast of Scotland.

Image: Example of “Cable float in”

• ProjectNeed

• ProjectOverview

• ProjectTimeline

• SubseaRouteSelection

• SubseaRoutingConsiderations

• LandfallLocations

• TheConsentingProcess

SHE Transmission, as part of a much larger project, is proposing to construct and commission a subsea High Voltage Direct Current (HVDC) Link, which will be approximately 81km in length and with a capacity of 600MW between Arnish and Dundonnell.

Map 1: ProposedWesternIslesConnection

04www.ssen-transmission.co.uk/projects/western-isles


As the HVDC cable leaves land and enters the sea, it will either be routed via ducts that are created using a Horizontal Directional Drill or through a traditionally excavated trench. Once offshore the HVDC cable will be buried.

If the sub sea cable cannot be buried it will be protected by alternative methods, for example High Density Polyethylene (HDPE) duct or rock placement.

In addition to the subsea HVDC cables, the other key elements of the Western Isles HVDC Link include:

• HVDC Converter station at Beauly and associated Civil works

• HVDC Converter station at Arnish and associated Civil works

• AC Substation at Arnish

• 77km of underground land cable from Dundonnell to Beauly

Proposed marine works

The subsea cable installation comprises:• Pre-laysurvey• Boulderclearance• Cabletrenching• Cablelaying• Cableburial• Rockplacement(whererequired)• Concretemattressing (where required)• Armourcable(whererequired)• Postinstallationsurveys

Project Overview

ExistingNetwork

AC Electricity AC ElectricityHVDC Electricity

ExistingNetwork

ConvertorStation &

UndergroundCable

ConvertorStation &

UndergroundCable

SubseaCable

ArnishSub Station

81kmSub Sea

77kmUnderground Cable

BeaulySub Station

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Project Timeline

Nov 17

Submission of report to Marine Scotland to ensure agreement of topics to be included in the supporting environmental information. Statutory consultation undertaken by Marine Scotland as part of this process.

2018

Feb: Receiptofscopingopinionreportfrom Marine Scotland to confirm the requirements fortheEnvironmentalReport.

Mar: Pre-ApplicationConsultationwiththe public on the preferred cable route corridor.

Mar: Consider and reflect on feedback from the consultation on the content of the EnvironmentalReport.

Apr: Submission of Marine Licence application to Marine Scotland and Marine Works applicationstoStornowayPortAuthority.

Apr/May: Statutory Consultation – Marine Scotland will undertake statutory consultation following submission during which representations can be made directly to the relevant authority.

July/Aug: Determination of the Marine Licence and Marine Works applications.

2020

Subject to consents, commencement of construction works.

2023

Completion of construction works.

Sept 17 – Mar 18

PreparationofEnvironmentalReporttosupport the Marine Licence and MarineWorks applications.

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Subsea Route Selection



EnvironmentalSHE Transmission recognise that a major infrastructure project like the Western Isles HVDC Link can impact the environment, therefore careful design and planning is required at every stage. Through careful evaluation, SHE Transmission will deliver effective protection measures within sensitive areas.

AkeyexampleincludeshowtheWesterRossMarineProtectedArea(MPA)willbeprotected.SHETransmissionhasconsideredthephysicaldisturbancetothedesignatedhabitatswithintheMPA,changes in temperature in the immediate vicinity of the cable and effects of smothering communities on the seabed. Given the available information, SHE Transmission intends using cable armouring in this area to minimise the impact on this sensitive marine environment. Additionally, the cable route has been moved slightly tothenorthtoavoidtheShiantBanksMarineProtectedArea(MPA).

EconomicHow the HVDC cable is installed and the route it takes are key factors informing the cost of the Western Isles HVDC Link. A straight-line route theoretically presents the cheapest option; however, the technical challenges and costs of transitioning the cable across multiple seabed and land features would mean that this is not a viable solution.

SHE Transmission’s preferred installation method for HVDC subsea cables is to bury them on the seabed. This method is the most common installation technique and is a proven method for protecting cables. In areas with thin sediment cover, or additional sea bed constraint, alternative means of protecting the cable on the seabed will be necessary. Covering cables with concrete mattressing is possible; however, due to the precise design requirements it is deemed to be relatively expensive, unsuitable for extensive lengths and subsequent maintenance of the cable can be complex. SHE Transmission is also considering placement of rocks to cover the cable. The placement is more economically efficient than installation of concrete mattresses and provides a high degree of protection. The final technique being considered, especially in sensitive marine habitats, is cable armouring where cables will be encased in a polymer casing and laid on the seabed. This option is costly; however, it reduces the requirement for burying, rock placementor laying of concrete mattresses.

SHE Transmission is looking at all options of cable protection along different sections of the cable route. Final decisions will be taken once detailed engineering design studies have been completed.

It is recognised that the sea area through which the proposed cable route passes is considered important for a variety of commercial fisheries activities, including shellfish (e.g. nephrops and scallop) and aquaculture. SHE Transmission is working with the relevant fishing organisations to ensure that possible disruption to fishermen operating in these areas is limited as far as practical.

TechnicalThere is a wide range of technical considerations; from cable size and capacity; connection to existing transmission infrastructure; to the method of installation which inform the routing process, with associated economic and environmental implications.

Technical considerations include cable installation and protection methods, which are more achievable in softer sediment. Avoidance of undulating seabed topography is preferred to minimise the possibility of free spans, where the cable is suspended above the seabed, which can lead to seabed scouring. It is also necessary to take account of the access to existing infrastructure at either end of the cable route.

SHE Transmission have developed the subsea cable route in a manner which balances economic, technical and environmental considerations, a route which is economically viable, technically feasible and capable of being granted consent.

Map 2: Environmental designations along the proposed cable route.

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Defining the route that is best economically, most technically achievable and with the least environmental impacts has been done by considering the constraints associated with each.

To understand these constraints, marine surveys have been undertaken to map the seafloor to provide a detailed understanding of the geology, seabed sediments and the flora and fauna it supports.

This information has been combined with data on other marine factors including fishing, shipping and the suitability of the seabed sediments for cable burial.

The combination of this information enables the development of the preferred subsea cable route.



Subsea Routing Considerations

Route optionsDetermining the most appropriate route for the HVDC cable has involved consideration of several options. Following determination of the most efficient points to connect to the existing transmission infrastructure on Lewis and the Scottish mainland, the focus of our investigation centred on the area between Arnish on Lewis and DundonnellinWesterRoss.

OverallfourroutesbetweenLewisandWesterRosshave been considered during the development process:

1. A northern route connecting Arnish to Dundonnell via Little Loch Broom (proposed option to be taken forward)

2. A southern subsea route connecting Arnish to Dundonnell via Little Loch Broom (discounted due to proximity to ShiantBanksMPA)

3. A route connecting Arnish to Mungasdale via the east of Gruinard Island, thus avoiding Little Loch Broom (discounted due to presence of maerl)

4. A route connecting Arnish with Mungasdale via the west of Gruinard Island, thus avoiding Little Loch Broom (discounted due to the presence of maerl)

5. Straight line route connecting Arnish to Dundonnell via Little Loch Broom.

Sensitivity of ReceptorsReceptorscouldbeconsideredasanyaspectoftheenvironment, both human and non-human which may be impacted upon (positively or negatively).

Completion of a range of technical studies help us to establish what the most sensitive receptors are within the area, the likely impacts they may experience during the installation phases of the project and the extent of these impacts.

Examples of the likely receptors which could be impacted upon include, but are not limited to:

• Seabed habitats and associated organisms• Marine mammals• Commercial fisheries and aquaculture• Shipping and navigation

Impacts on receptors and the most effective means of mitigation have been taken into consideration when selecting the most appropriate route for the subsea cable.

Map 4:ProposedcableroutesMap 3: Bathymetry along the proposed cable route.

Determining Suitability

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Landfall Locations - Dundonnell



Key Considerations and Challenges

The criteria used to identify a possible landfall location were:

• Geology of seabed and coastline

• Proximitytoexistingelectricalinfrastructure

• Suitability of near shore seabed conditions

• Level of any commercial fisheries activities

• Presenceofareasofculturalheritage

• Presenceofecologicalfeatures

• Current use of the landfall location and surrounding areas

• Ease of construction and operation

• Any anticipated licensing obstacles

Dundonnell

The proposed landfall location at Dundonnell has been selected, balancing a range of cost, technical and environmental factors. A key influence in determining this landfall was the proximity to the road network allowing for the cable to be undergrounded along the existing road from Dundonnell to the proposed converter station at Beauly, Inverness-shire.

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Landfall Locations - Lewis



Key Considerations and Challenges

The criteria used to identify a possible landfall location were:

• Geology of seabed and coastline

• Proximitytoexistingelectricalinfrastructure

• Suitability of near shore seabed conditions

• Level of any commercial fisheries activities

• Presenceofareasofculturalheritage

• Presenceofecologicalfeatures

• Current use of the landfall location and surrounding areas

• Ease of construction and operation

• Any anticipated licensing obstacles

Arnish

The proposed landfall location at Arnish has been selected, balancing a range of cost, technical and environmental factors. A key factor in determining this landfall was the proximity to the wider electrical network and the location of the windfarm projects seeking connection to the grid.

SHE Transmission will require a Marine Licence from the Scottish Government as well as a Marine Works Licence from the Stornoway Port Authority.

As part of the licence application procedure, SHE Transmissionis preparing supporting environmental information which willdescribe the characteristics of the project and provide information on the possible environmental effects of the connection and how they will be managed. When completed this information will be available on the projects dedicated webpagewww.ssentransmission.co.uk/projects/western-isles.

The licensing procedures also require SHE Transmission to consult on its proposals. This exhibition forms part of the consultation process.

Scoping of the project has been undertaken with Marine Scotland. This ensures that focused and proportionate environmental information is produced to accompany the application, which addresses the specific requirements and potential effects.

Following advice from Marine Scotland (and consultees), the possible effects of the installation and operation of the subsea cable will be considered along with the possibility for cumulative effects where there is potential for effects to overlap with other marine and coastal developments.

The following topics will be covered as part of the supporting environmental information:• Designatedsites• Benthicecology• Marinemammals• Commercialfisheriesandaquaculture• Shippingandnavigation

Comments made are not representations to the Scottish Ministers. If SHE Transmission plc submits an application for a marine licence to Scottish Ministers, an opportunity will begiven for representations to be made to the Scottish Ministerson the application.

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Information

Information will also be made available via the project web page and social media channels:

Project Website: www.ssen-transmission.co.uk/projects/western-isles

Find us on Facebook: SSEN Community

Follow us on Twitter:@ssencommunity

The Consulting Process

www.ssen-transmission.co.uk/projects western-isles

[email protected]

07825 015 507

Lisa Marchi-GreyScottish and SouthernElectricity Networks,10HendersonRoad,Inverness, IV1 1SN

Community Liaison ManagerLisa Marchi-Grey



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We are keen to receive your views and comments in regards to the following questions:PleasecompleteinBLOCK CAPITALS.(Pleasetickoneboxperquestiononly)

Q5 Do you have comments on the proposed scope of the additional environmental information being prepared to accompany the marine licence application?

Comments

Your comments

Q1 Do you understand the need for the Western Isles HVDC Link project?

Yes No Unsure

Q2 Has the consultation information been clear and easy to understand?

Yes No Unsure

Q3 Do you have any comment on how the subsea cable route and landfall locations have been selected?

Comment

Q4 Do you understand the consenting process that SHE Transmission will follow for the Western Isles HVDC Link?

Yes No Unsure



Please write in any further comments you would like to make aboutthe engagement process as a whole.

Full name

Postcode

Telephone

Email

If you would like to be kept informed of progress on the project please tick this box.

If you would like your comments to remain anonymous please tick this box.

Address

Thank you for taking the time to complete this feedback form.Please hand your completed form in at the event or alternatively by one of the methods below:Post:LisaMarchi-Grey,ScottishandSouthernElectricityNetworks,10HendersonRoad,Inverness,IV11SNEmail: [email protected]

Closing date for feedback is 16:00, Friday 30th March 2018The feedback form and all information provided at the event can also be downloaded from the dedicated website:www.ssen-transmission.co.uk/projects/western-isles

Any information given on the feedback form can be used and published anonymously as part of Scottish and Southern Electricity Networks consultation report. By completing this feedback form you consent to Scottish and Southern Electricity Networks using feedback for this purpose.

Q6 Do you have any other comments that SHE Transmission should consider as it progresses the Western Isles HVDC Link?

Comments

Documents

Western Isles HVDC Link Consultation · In total we maintain about 5,000km of overhead lines and underground cables ... co-ordinated and economical system of ... What is the difference