‘Significant risk’ of power outages due to data centre demand, regulator warns

There is a “significant risk” that the response of data centres to common faults in the power system could result in network outages in Ireland and Northern Ireland, according to the Irish energy regulator.

The Commission for Regulation of Utilities (CRU) has published a document on measures to alleviate the risks – warning there would be “direct negative impacts on costs to consumers”.

The move arose out of concerns raised by EirGrid and Soni (System Operator for Northern Ireland), which are the transmission system operators (TSOs) on the island.

The CRU said that if problems associated with increased data centre demand are not mitigated, there is a risk all customers in Ireland and Northern Ireland would be exposed to a “significant system incident”, including outages.

The document notes the most serious recent incident happened in June with the threat of “credible” potential scenarios being too much for the system to handle.

In some scenarios, the handling of faults by data centres “could result in widespread cascading trips of demand and generation leading to network outages” for consumers across the island, it said.

Sinn Féin MEP Lynn Boylan said the Government has “brought the country to a cliff-edge with its reckless data centre policy”.

She said: “A moratorium is long overdue but instead of stepping in to call a halt to the madness, the Government continues to sit on the sidelines.

“People all over the country rely on the electricity system to survive, but we’re now in the situation where the sheer volume of data centre demand could lead to blackouts impacting the whole electricity system.”

Ms Boylan said Energy Minister Darragh O’Brien “needs to answer what he knew and when” over the Government’s data centre policy.

The CRU said the risk to grid stability arises from the collective response of most data centres to common fault events occurring on the transmission system.

It said when a fault occurs, most data centres – even those remote from the fault – automatically and near instantaneously significantly reduce consumption from the grid and switch to their own temporary back-up sources of supply to ensure continuity of service.

The CRU said: “The simultaneous disconnection of a large volume of demand from the power system can create sudden imbalances between supply and demand, and deviations to frequency levels, which EirGrid is managing in real time, and therefore represents both a significant risk to the security of the system and operational challenges for EirGrid.

“In certain scenarios, fault ride-through (FRT) behaviour could result in widespread cascading trips of demand and generation, leading to network outages, and exposing all consumers in Ireland and Northern Ireland to the risk of a significant incident.”

The CRU warned that because of demand utilisation increases, the system has “moved closer to the point” at which existing “mitigation actions will be exhausted due to the continued growth of demand” that does not have capability for FRT – meaning it can stay connected to the grid during disturbances.

The regulator said: “This is increasing the material risk to system security and urgent action is required to address the FRT challenge.

“In the event of a significant fault, the risk to the security of the system may be to the degree that power outages may occur throughout the system in a way that cannot be managed or controlled by the TSO.

“This would risk impacting all customers, domestic and non-domestic and essential services.

“EirGrid and Soni note in their joint information paper that, based on their analysis of increased data centre demand scenarios, if not mitigated, these scenarios would expose all consumers in Ireland and Northern Ireland to the risk of a significant system incident.”

There was a “significant incident” on June 6 when about 480MW of data centre demand dropped off the grid in response to a “single-phase fault” event at the Poolbeg 220kv station in Dublin.

This represents 52% of total data centre demand.

Four other single-phase faults across 2022-2025 are also documented, with the scale of data centre demand reduction increasing each time.

The report says a “three-phase fault” could result in significantly higher demand reductions and meet the “load rejection limit”.

Imbalances in the system in “credible fault scenarios” could be over 1,300MW if no mitigating actions are taken, with system operators believing a loss of 900MW is the “maximum upper bound” which would be manageable with existing defence measures.

Aggregate data centre demand peaks up to 1,000MW at times in June and August.

The CRU said: “This illustrates very clearly that data centre demand levels have now reached a point where EirGrid has very limited operational tools remaining to maintain operational security limits, except to actively curtail data centre demand levels at times.”

The regulator said it has become “increasingly apparent” over the summer months that the “urgency in addressing this risk has increased” as it introduced a new modification for the grid code which would require demand facilities to remain connected to the power system during short-term disturbances.

Ms Boylan said the measure prevents data centres from increasing their energy demand due to the risk of “catastrophic blackouts” and potential impacts on essential services.

The CRU said a long-term technical solution is “urgently required” on top of the measures it recently announced.

The current measures include pausing elements of work to integrate more renewables on the electricity system.

The CRU said it “has strong concerns about the ongoing impact of these measures, which have direct negative impacts on costs to consumers and in relation to Ireland’s renewable targets”.

EirGrid said the modification to the code will require all transmission connected large energy users in Ireland, including data centres, to be able to ride through faults on the transmission system, remaining connected and recovering quickly to 90% of their pre-fault demand levels to correct the supply-demand imbalance.

It said it has measures in place to ensure that non-FRT compliant data centre demand remains below the 1000 MW threshold – the equivalent 900 MW “load rejection limit”.

It said this was not a limit on data centre growth and instead a limit on the level of demand from data centres that is not compliant with the new measures.

Data centres that can demonstrate full compliance with the new grid code requirements can continue to utilise demand up to their contracted maximum import capacity while future data centre connections also must comply with the new measures.

EirGrid said the transmission system continues to be operated securely while the ESB said it supported the measures, being “aware of the challenges being posed to security of supply”.

The Irish Department of Energy, Northern Ireland’s Department for the Economy and Soni have also been contacted for comment.