Moyle Return Cables Project
Cross BorderOperationalGB500 MW1 kV53 km2016
Also known as:Moyle Interconnector, Moyle Interconnector Cable, Moyle Returns Cable Project, Moyle Cable Returns Project, NESO TEC PRO-001292-2, Moyle Return Cables Project, Moyle Return Conductor Cables
Status:Operational
Capacity:500 MW
Project Company:
Moyle Interconnector Limited
Type:cross border
Expected Life:30 years
Website:www.mutual-energy.com
Moyle Returns (the cable replacement context for the Moyle Interconnector) concerns works associated with the Moyle HVDC link between Scotland and Northern Ireland. The underlying Moyle Interconnector is a dual‑monopole LCC HVDC scheme with engineering capacity of 500 MW (2 × 250 MW monopoles), nominal dc voltage 250 kV and...
Supply Chain (3)
Project Timeline (17)
~Oct 2017System TestingStale
In an April 2013 letter to the Utility Regulator, Moyle Interconnector Limited outlined its long‑term repair plan for the Moyle interconnector by laying new low‑voltage submarine cables to replace the existing return conductors. The company stated that, assuming timely planning and environmental consents and favourable factory availability, commissioning of the new cables could be achieved as early as autumn 2016, with a more prudent base case of commissioning in autumn 2017. This projected commissioning milestone relates to completion of testing and commissioning activities for the replacement return‑cable system, restoring the interconnector’s long‑term reliability and full capacity.
2017System RestorationStale
In planning documents for the Moyle Returns cable replacement, Moyle Interconnector Limited indicated that, subject to timely consents and manufacturing availability, commissioning of the new low-voltage return cables was expected with full delivery of the EPC contract before the end of 2017, restoring the Moyle Interconnector to full 500MW operational capability.
2016Commercial Operations Full Power
The Moyle Return Cables Project was completed in 2016, restoring the Moyle Interconnector to its full 500 MW capacity between Auchencrosh (Scotland) and Ballycronan More (Northern Ireland). The project replaced the original return conductor cables. The north cable was laid in August 2015 and commissioned in early 2016; the south cable was laid in October 2015 with jointing completed during a planned outage in summer 2016. The project was delivered by Mutual Energy, owner and operator of the Moyle Interconnector.
26 Sept 2015Onshore Construction Start
Onshore cable construction for the Moyle Return Cables Project transition joint commenced in both Scotland and Northern Ireland, including excavation of a small pit with a flat surface required for the jointing works. An outage on the existing cable was arranged over the weekend of 26–27 September 2015 to enable these onshore works, during which the pit was successfully excavated.
4 Aug 2015Cable Installation Start
Installation of the Moyle Return North cable between Northern Ireland (Portmuck South near Larne) and Scotland (Currarie Port near Ballantrae) started on 4 August 2015, using the cable-laying vessel Nexans Skagerrak to surface lay the undersea conductor parallel to the existing Moyle interconnector route, and continued until 13 August 2015.
18 Feb 2015Cable Supplier Selected
By February 2015 Moyle Interconnector Limited had awarded a contract to Nexans Norway A.S. for the design, manufacture, testing, supply, installation, jointing and commissioning of replacement subsea metallic return conductors for the Moyle Interconnector. Nexans, the original manufacturer of the Moyle HVDC cables, was selected without a full competitive tender on the basis of its unique technical capability and existing qualified technology, with Moyle’s February 2015 correspondence to regulators confirming that Nexans would provide and install the replacement low-voltage cables needed to restore the interconnector’s long‑term reliability and full capacity.
13 Feb 2015Fid Financial Close
By mid‑February 2015, Moyle Interconnector Limited reached investment commitment and awarded a contract to Nexans Norway AS for the Moyle Returns project, covering the design, manufacture, testing, supply, installation, jointing and commissioning of replacement subsea metallic return conductors to restore the interconnector’s full capacity and long‑term reliability. The confidential contract price was noted as significantly below the earlier £60 million estimate, with the project to be funded largely from Moyle’s reserves and capacity auction revenues, supplemented by CAIRt use‑of‑system charges, while delivering substantial forecast consumer benefits from lower wholesale electricity prices and improved security of supply.
2015Cable Installation Complete
In 2015, Moyle Interconnector Limited completed the Moyle Returns Cable Project by installing two new low-voltage metallic return conductor cables between the existing HVDC converter stations at Ballycronan More in Island Magee, County Antrim, and Auchencrosh in Ayrshire. Laid close to the original north and south integrated return conductor cables along a route optimised using bathymetric, seismic and ROV seabed surveys, these additional land and submarine cables restored the Moyle Interconnector to its full 500MW operational capacity after previous insulation-related faults had reduced it to half capacity.
2015Planning Consent Awarded
Authority: Department of the Environment, Northern Ireland Marine Division and Marine Scotland Licensing Operations Team · Licence: Marine Construction Licence for installation of two metallic return conductors in the Northern Ireland inshore region and Marine Cable Installation Works licence in Scottish waters
Moyle Interconnector Limited obtained marine consents required for the Moyle Return Cables Project, including a Marine Construction Licence for installation of two separate metallic return conductors in the Northern Ireland inshore region and a Marine Cable Installation Works licence for the Scottish marine region. These licences, issued by the Department of the Environment, Northern Ireland Marine Division and Marine Scotland Licensing Operations Team, set conditions such as preparation of a Cable Burial Assessment Plan and effectively authorise the replacement return cable installation to proceed.
26 Jun 2014Procurement Notice
On 26 June 2014 Moyle Interconnector Limited issued a contract notice to procure a Technical Framework Consultant for Offshore Cable Installation for the Moyle Return Cable Replacement project. The framework, valued at GBP 2–3 million, sought experienced personnel to support and supervise the main EPC contractor for all offshore and inshore site preparation, cable laying, burial, surveys, and compliance with health, safety, environmental and consenting requirements along the new return cable route between Northern Ireland and Scotland.