Surging electricity demand prompted national grid operator EirGrid to call on emergency power plants to boost supplies twice this summer, the State company confirmed at the weekend.
EirGrid built four temporary emergency generators in 2023, meant to bridge gaps if there is a risk that electricity supplies will not meet demand. It had not deployed them until this year.
The company called on one of the four emergency units, a plant on Dublin’s North Wall, in June – the first time it was forced to use the backstop to shore up electricity supplies, the company confirmed at the weekend.
It had already confirmed that a shutdown of renewable power during last Wednesday’s eclipse forced it to call on another emergency plant in Tarbert, Co Kerry, for more than an hour.
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EirGrid said it used the North Wall unit for a period on June 24th “to manage generation adequacy” when asked whether it had been forced to use emergency power before the eclipse.
That confirmation followed the news that Wednesday’s eclipse had shut down the solar power plants on which the Republic has been relying recently for large quantities of electricity.
There was little or no wind power available at the time, while three large power stations had shut down for routine maintenance, meaning the grid operator had to deploy the Tarbert facility.
The loss of solar power, combined with higher-than-expected demand and a squeeze on imports from Britain, prompted the Single Electricity Market Operator to issue a “margin warning” on Wednesday evening.
That signalled that the buffer between likely electricity supplies and expected demand was tighter than ideal. It did not indicate that a power cut was imminent.
All electricity systems are meant to supply power as it is needed and hold sufficient supplies in reserve to meet likely contingencies.
EirGrid has always maintained that the emergency plants would only be used as a backstop when no other options are available. The four power plants can be switched on quickly to respond to potential electricity shortages.
As they are designed to deal with emergencies, they do not sell electricity to the market.
The four can generate a total of 505 megawatts (MW) between them, slightly more than the average Irish natural gas-fired power station can produce.
Two of them, located on Dublin’s North Wall and on Energia’s site in Huntstown in the north of the county, run on gas.
The other two, in Tarbert and one in Shannonbridge, Co Offaly, run on distillate, a form of diesel.
EirGrid commissioned them following several years in which peak winter demand for electricity reached the point where it severely narrowed the gap with available supplies.
This prompted formal warnings to suppliers during those periods.
The temporary emergency generators were among several measures taken by EirGrid and the Commission for Regulation of Utilities (CRU) to avoid shortages.
They have cost about €1 billion to date. EirGrid, which counts them as part of the Republic’s available electricity supplies, has not had to call on them before this year.
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There are also signs that imports from Britain, which provides about 12.5 per cent of electricity used here, face pressure.
EirGrid acknowledged that imports from Britain were “tight” during the eclipse. The UK’s National Energy System Operator (NESO) also shut off exports from Britain to the for a short period in July.
However, rules governing the use of power lines connecting Ireland and Britain prevent NESO from taking similar action with exports to this country.
The CRU plans to seek bids from energy companies to build new power plants able to supply electricity here in 2030 and 2031.
