OUR ELECTRICITY BUSINESS

Mutual Energy owns and operates the Moyle Interconnector which links the electricity transmission systems of Northern Ireland and Scotland through submarine cables running between converter stations in Islandmagee, Country Antrim and Auchencrosh in Ayrshire.

As well as moving significant volumes of electricity between Northern Ireland and Great Britain, it provides key ancillary services to the operators of the two connected electricity grids.

The High Voltage Direct Current (HVDC) connection is made up of two 250MW cables that can operate in either direction, providing a total connection of 500MW between the all-Ireland Single Electricity Market (SEM) and the GB market. Initially commissioned in 2001 and entering commercial operation in 2002, it ended the isolation of Northern Ireland from the much larger electricity systems of Great Britain and continental Europe, enhancing the security of electricity supply in Northern Ireland and reducing the costs of running the electricity system.

The introduction of the all-island Single Electricity Market (SEM) in 2007 saw these benefits extended to consumers across the island of Ireland. When the new Integrated Single Electricity market (I-SEM) went live on 1st October 2018, the SEM and GB markets became even more closely linked, and evidence suggests that Moyle is now being used much more efficiently to benefit consumers in both markets.

In 2023, the interconnector’s control system underwent a significant renovation, and the Control System Upgrade Project (CSUP) successfully future-proofed the interconnector for years to come. The CSUP means that Moyle can continue to provide reliable support to both NI and GB electricity grids, providing security of supply, enabling renewable generation, and delivering economic benefits to NI consumers.

TRADING ACROSS THE MOYLE INTERCONNECTOR

The SEM and GB wholesale electricity markets are “coupled”, meaning the physical interconnector flows are determined by the relative prices in the two connected markets. Moyle interconnector capacity is solely available for allocation in two coupled intraday auctions between the SEM and GB. Market participants in the SEM may access these auctions via SEMOpx, while GB market parties can access them via either the EPEX SPOT or Nord Pool power exchanges. More information on these coupled intraday auctions can be found on the SEMOpx website.

MOYLE CAPACITY

While Moyle is technically able to transport 500MW between the two markets, due to constraints on the transmission networks at either end of the interconnector, the commercial capacity of the interconnector is lower than this.

Further documentation detailing the rules underpinning capacity calculation and FTR allocation and compensation can be found on the Publication’s Page