Kilroot power station outside Carrickfergus lost out in the all-island market. Photo: Stephen Hamilton-Presseye

Jim Shannon, who is a member of a Westminster committee investigating the security of Northern Ireland’s electricity supply, said that although he did not oppose co-operation with the Republic, the moves to further integrate NI’s electricity market with the Republic’s “always worried me”.

Since 2007, there has been a single electricity market for the island of Ireland.

A new and more integrated all-island market is to launch on 1 October and as part of that process Kilroot power station, one of Northern Ireland’s main generating units, lost out, prompting its owner to announce it would be closed.

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And since 2009 the company which operates the electricity grid in Northern Ireland, the System Operator for Northern Ireland (SONI), has been owned by the Irish government.

Last month the Financial Times reported on the potential for cataclysmic conditions if a no-deal Brexit led to the Republic no longer allowing power to flow north.

The FT said that a Whitehall contingency planning document included plans for the Army to requisition thousands of generators and put them on barges in the Irish Sea in an attempt to prevent power blackouts if power could no longer flow across the border.

Several sources from the energy industry dismissed that as scaremongering and in March the Utility Regulator, Jenny Pyper, told Parliament that “fundamentally, our role as the Utility Regulator means that we will take no chances with security of supply”.

This week the News Letter reported that a source had said that SONI – despite being owned by the Irish government, which opposes direct rule – was privately lobbying the British government to use direct rule powers to approve the huge North-South Interconnector which both SONI and the Utility Regulator say will ensure security of supplies on both sides of the border and cut the cost of electricity.

SONI declined to say whether it had done so.

Mr Shannon expressed concern at the extent of integration which has developed.

He told the News Letter: “I don’t like the idea – it has always worried me, and I think worried the committee, that the power to create energy is in the hands of someone out side of Northern Ireland; that we don’t have the ability to generate all the electricity we need.”

Mr Shannon said he would have preferred to have seen Kilroot “being retained at least for a number of years to enable us to have a long-term strategy in place for where we are going to be in 10 or 15 years”.

He also said it was important that Northern Ireland’s power plants were treated equitably to those in the Republic and that the rules could not be different on either side of the border to ensure that “we have a level playing field” in the all-island market.

The Utility Regulator has declined to clarify whether Kilroot will be given a reprieve after a Dublin power station which lost out during the auction process for the new all-island market was given a reprieve by the Republic’s authorities.

Huntstown Power Plant owner Viridian challenged the decision to neither award it a contract nor allow it to shut and an appeal panel agreed, finding a “serious and significant” error in the process.

The News Letter asked the regulator what it was doing to ensure an equitable situation for Kilroot and to guarantee supply. In a statement, the regulator said that Kilroot’s US owner AES had made a request to close Kilroot and part of Ballylumford and the regulator was “considering information and evidence, including a technical assessment from SONI” and it would make a decision “in due course”.