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Offshore Structures: Electric Cables

Answer

In the last 30 years, there has been a total of 1340km of sub-sea electricity transmission cables laid in the waters surrounding the UK.

This comprises 702km of licenced sub-sea offshore transmission cables1 that connect offshore wind farms in UK territorial sea and surrounding Renewable Energy Zone (REZ)2 to shore, and 638km of interconnector cables, consisting of links from the UK mainland to France, the Netherlands, Northern Ireland, the Republic of Ireland and the Isle of Man.

Lengths provided are for sub-sea sections of cables only, and do not include onshore components that link to relevant grid connection points.

Table of licenced offshore transmission projects

Licenced offshore wind farm transmission assets	Sub-sea cable length (km)	Year licence granted	Sea
Robin Rigg East and West	25.2	2011	Irish Sea
Sheringham Shoal	44	2013	North Sea
Barrow	26.6	2011	Irish Sea
Greater Gabbard	152.5	2013	North Sea
Gunfleet Sands 1 and 2	9.3	2011	North Sea
Ormonde	43	2012	Irish Sea
Wallney 1	45.3	2011	Irish Sea
Wallney 2	43.7	2012	Irish Sea
Lincs	96	2014	North Sea
London Array	216	2013	North Sea

Total Cable length

702

Table of interconnectors

Interconnector	Sub-sea cable length (km)3	Laying year(s)	Connection points	Sea
IFA	45	19864	GB – Folkestone, Kent FR - Calais	English Channel
Moyle	53	20015	N.I - Nr Belfast, Scotland - near Stranraer	Irish Sea
BritNed	250	2009 to 20106	GB - Isle of Grain, Netherlands - Maasvlakte	North Sea
East West	186	2009 to 20127	GB - Deeside, north Wales, Ireland - Woodland, County Meath	Irish Sea
Isle of Man	104	20008	Bispham, Blackpool to Douglas, Isle of Man	Irish Sea

Total Cable length

638

[1] Source – Ofgem. Offshore transmission is defined as all electric lines of 132 kilovolts or more which are built for the purpose of conveying electricity generated by an offshore generating station. The km length figure does not include ‘inter array’ cables that connect individual wind turbines to the nearby sub-station.

2 The REZ is an area of the sea, beyond the UK’s territorial sea, which may be exploited for energy production. A map of the REZ may be obtained from the UK Hydrographic Office - https://www.ukho.gov.uk/ProductsandServices/Services/Documents/Renewable_Energy_Web%20Page_Jan06_v2.pdf . A map of the ten offshore transmission projects tendered to date, as well as the five projects currently in Ofgem’s competitive tender process, can be found on Ofgem’s website - https://www.ofgem.gov.uk/electricity/transmission-networks/offshore-transmission/offshore-transmission-tenders

3 Length provided refers to the distance between landing points and does not take into account cable configurations of the interconnectors.

4[1] Refers to the year IFA was commissioned. Source: National Grid - http://faculty.london.edu/mottaviani/IFA.pdf

5 Source: Mutual Energy - http://www.mutual-energy.com/The_Moyle_Interconnector/History_and_Development_of_the_Interconnector.php

6 Source: BritNed - http://www.britned.com/BritNed/About%20Us/Construction

7 Source: ABB - http://www05.abb.com/global/scot/scot221.nsf/veritydisplay/4d580b5e493d268dc1257c00003e44dc/$file/Overview%20of%20the%20500MW%20EirGrid%20East-West.pdf

8 Source: AWJ Marine - http://www.awjmarine.co.uk/fishery-liaison/isle-of-man-interconnector/

Secondary information

Type

Written question

Reference

216069

Session

2014-15

Subjects

Electric cables Offshore structures

Contains statistics

Yes

Link

View this Written question on www.parliament.uk