StackPath Ireland

Power · demand and forecasts

How much electricity does Ireland use?

Ireland's grid carried 35.6 TWh in the 12 months to 9 October 2026, an average of 4,064 MW, peaking at 5,912 MW on 5 January 2026 (EirGrid 15-minute data). Data centres were 22.1% of 2025 demand (CSO, Ember); EirGrid forecasts their use rising from 9.4 to 14.6 TWh by 2034.

Updated 10 October 2026 · data build 2026-10-10 · how we know · corrections

Why the grid now limits data centres

Figure 1

Why the grid can only lose 900 MW at once

In a voltage dip data centres can drop off the grid in milliseconds. EirGrid plans for a worst case in which 90% of their demand goes at once (recorded faults dropped 16–52%), so about 1,000 MW of data centres fills the 900 MW limit, and that happened in Jun 2026.

What a voltage dip does to data-centre demand, and the 900 MW limitFour steps: a grid fault dips the voltage; data centres switch to back-up power and about 90% of their demand drops off; frequency rises; they reconnect. Below, a bar shows peak data-centre demand of about 1,000 MW, of which 900 MW could drop, filling the 900 MW load-rejection limit. Then four measures EirGrid uses to stay inside it.01 · 0 MSvoltageA fault on the gridA short circuit on ahigh-voltage line pulls thevoltage down for a fractionof a second. 4 of the 5faults EirGrid has reportedwere in Dublin.02 · MILLISECONDSdata-centre grid demandData centres let goTo protect their servers,sites switch to batteries(UPS) and back-up generators.In some faults, EirGridestimates, up to 90% could goat once.03 · NEXT SECONDSfrequency (50 Hz dashed)Frequency jumpsSupply now exceeds demand, sofrequency rises above 50 Hz.Plant must ride throughchanges up to ±1 Hz/s.04 · THENdemand returns in a rushThey come backSites reconnectautomatically: a second jolt.The CRU's December 2025decision records EirGrid'sconcern that this makesdisturbances worse.The budget: how much demand the grid can lose in one goData-centre demand peaked at about 1,000 MW in late June 2026 (EirGrid to the CRU, CRU202704).90% of 1,000 MW = 900 MW that a single fault could take off the grid.900 MW could drop (90%)limit 900 MWpeak data-centre demand ~1,000 MW (Jun 2026)Reached in Jun 2026. Interconnector exports count against the same 900 MW, so EirGrid cuts exports when data-centredemand is high. A 100 MW campus without ride-through would add about 90 MW to the budget.How EirGrid stays inside it (week 42, 2026)28,000 MWsInertia floorwas 23,000; morespinning plant kept on75%SNSP capinstant share of wind,solar and HVDC imports;80% trial paused200 MWBattery charging capkept as a shockabsorberExports cutInterconnector exportscount against the samelimit
What a voltage dip does to data-centre demand, and the 900 MW limitFour steps: a grid fault dips the voltage; data centres switch to back-up power and about 90% of their demand drops off; frequency rises; they reconnect. Below, a bar shows peak data-centre demand of about 1,000 MW, of which 900 MW could drop, filling the 900 MW load-rejection limit. Then four measures EirGrid uses to stay inside it.01 · 0 MSvoltageA fault on the gridA short circuit on ahigh-voltage line pulls thevoltage down for a fractionof a second. 4 of the 5faults EirGrid has reportedwere in Dublin.02 · MILLISECONDSdata-centre grid demandData centres let goTo protect their servers,sites switch to batteries(UPS) and back-upgenerators. In some faults,EirGrid estimates, up to90% could go at once.03 · NEXT SECONDSfrequency (50 Hz dashed)Frequency jumpsSupply now exceeds demand,so frequency rises above 50Hz. Plant must ride throughchanges up to ±1 Hz/s.04 · THENdemand returns in a rushThey come backSites reconnectautomatically: a secondjolt. The CRU's December2025 decision recordsEirGrid's concern that thismakes disturbances worse.The budget: what the grid can lose at onceData-centre demand peaked at about 1,000 MW in late June 2026 (EirGrid to the CRU, CRU202704).90% of 1,000 MW = 900 MW that a single fault could take off the grid.900 MW could drop (90%)limit 900 MWpeak data-centre demand ~1,000 MW (Jun 2026)Reached in Jun 2026. Interconnector exports count againstthe same 900 MW, so EirGrid cuts exports when data-centredemand is high. A 100 MW campus without ride-through wouldadd about 90 MW to the budget.How EirGrid stays inside it (week 42, 2026)28,000 MWsInertia floorwas 23,000; morespinning plant kept on75%SNSP capinstant share of wind,solar and HVDC imports;80% trial paused200 MWBattery charging capkept as a shock absorberExports cutInterconnector exportscount against the samelimit

When a fault dips the voltage, data centres protect their servers by switching to on-site batteries and generators, so their demand can vanish from the grid in milliseconds and frequency jumps. EirGrid's weekly operating rules cap the demand and exports the system can lose in one event at 900 MW; planning for 90% of data-centre demand at risk, roughly 1,000 MW of data centres uses it all, and EirGrid told the CRU that peak was reached in late June 2026. To stay inside the limit EirGrid keeps more spinning plant on (inertia floor 28,000 MWs), caps the instantaneous share of wind, solar, batteries and HVDC imports (SNSP) at 75%, limits battery charging and cuts interconnector exports. The step sketches are schematic, not measured traces.

Estimate"A 100 MW campus adds about 90 MW" is our arithmetic with EirGrid's 90% assumption.

Sources: EirGrid/SONI Weekly Operational Constraints Update, week 42 2026, 2026-10-09 · CRU202704 (EirGrid figures: ~1,000 MW peak, 90% drop, limit reached), 2026-07-08 · CRU202705, EirGrid FRT update, 2026-06-26 · CRU/2025/236 s.5.1.7, 2025-12-12

Figure 2

Each fault takes more data-centre demand off the grid

The demand lost in a single fault has grown from 74 MW in Jan 2022 to 480 MW in Jun 2026, 53% of the 900 MW the grid can lose at once.

Data-centre demand lost in each reported grid fault, against the 900 MW limit7 Jan 2022, Limerick: Killonan-Kilpaddoge 220 kV Fault: 74 MW dropped, 16% of data-centre demand. 13 Dec 2022, Dublin: Kellystown-Woodland 220 kV Fault: 204 MW dropped, 34% of data-centre demand. 26 Jan 2025, Dublin: Poolbeg 220 kV Reactor Fault: 321 MW dropped, 44% of data-centre demand. 8 May 2025, Dublin: North Wall – Poolbeg 220 kV Fault: 387 MW dropped, 52% of data-centre demand. 6 Jun 2026, Dublin: Poolbeg 220 kV Reactor Fault: 480 MW dropped, 52% of data-centre demand. The load-rejection limit is 900 MW.0250500750MW900 MW limitImplied data-centre demand at the time: about 463 MW (74 MW ÷ 16%, our arithmetic)7 Jan 2022 · Limerick: Killonan-Kilpaddoge 220 kV Fault: 74 MW of data-centre demand dropped (16%)747 Jan 2022Limerick16%Implied data-centre demand at the time: about 600 MW (204 MW ÷ 34%, our arithmetic)13 Dec 2022 · Dublin: Kellystown-Woodland 220 kV Fault: 204 MW of data-centre demand dropped (34%)20413 Dec 2022Dublin34%Implied data-centre demand at the time: about 730 MW (321 MW ÷ 44%, our arithmetic)26 Jan 2025 · Dublin: Poolbeg 220 kV Reactor Fault: 321 MW of data-centre demand dropped (44%)32126 Jan 2025Dublin44%Implied data-centre demand at the time: about 744 MW (387 MW ÷ 52%, our arithmetic)8 May 2025 · Dublin: North Wall – Poolbeg 220 kV Fault: 387 MW of data-centre demand dropped (52%)3878 May 2025Dublin52%Implied data-centre demand at the time: about 923 MW (480 MW ÷ 52%, our arithmetic)6 Jun 2026 · Dublin: Poolbeg 220 kV Reactor Fault: 480 MW of data-centre demand dropped (52%)4806 Jun 2026Dublin52%% = share of data-centre demand that dropped · dashed outline = implied data-centre demand at the time
Data-centre demand lost in each reported grid fault, against the 900 MW limit7 Jan 2022, Limerick: Killonan-Kilpaddoge 220 kV Fault: 74 MW dropped, 16% of data-centre demand. 13 Dec 2022, Dublin: Kellystown-Woodland 220 kV Fault: 204 MW dropped, 34% of data-centre demand. 26 Jan 2025, Dublin: Poolbeg 220 kV Reactor Fault: 321 MW dropped, 44% of data-centre demand. 8 May 2025, Dublin: North Wall – Poolbeg 220 kV Fault: 387 MW dropped, 52% of data-centre demand. 6 Jun 2026, Dublin: Poolbeg 220 kV Reactor Fault: 480 MW dropped, 52% of data-centre demand. The load-rejection limit is 900 MW.0250500750MW900 MW limitImplied data-centre demand at the time: about 463 MW (74 MW ÷ 16%, our arithmetic)7 Jan 2022 · Limerick: Killonan-Kilpaddoge 220 kV Fault: 74 MW of data-centre demand dropped (16%)74Jan ’22Limerick16%Implied data-centre demand at the time: about 600 MW (204 MW ÷ 34%, our arithmetic)13 Dec 2022 · Dublin: Kellystown-Woodland 220 kV Fault: 204 MW of data-centre demand dropped (34%)204Dec ’22Dublin34%Implied data-centre demand at the time: about 730 MW (321 MW ÷ 44%, our arithmetic)26 Jan 2025 · Dublin: Poolbeg 220 kV Reactor Fault: 321 MW of data-centre demand dropped (44%)321Jan ’25Dublin44%Implied data-centre demand at the time: about 744 MW (387 MW ÷ 52%, our arithmetic)8 May 2025 · Dublin: North Wall – Poolbeg 220 kV Fault: 387 MW of data-centre demand dropped (52%)387May ’25Dublin52%Implied data-centre demand at the time: about 923 MW (480 MW ÷ 52%, our arithmetic)6 Jun 2026 · Dublin: Poolbeg 220 kV Reactor Fault: 480 MW of data-centre demand dropped (52%)480Jun ’26Dublin52%% = share of data-centre demand lost

Each bar is one grid fault in which data centres disconnected, as listed by EirGrid in the CRU's July 2026 paper. The drop grew from 74 MW (16% of data-centre demand) in 7 Jan 2022 to 480 MW (52%) on 6 Jun 2026, because, on these figures, there is more data-centre demand and a larger share of it lets go. All five were single-phase faults; EirGrid estimates that up to 90% of data-centre demand could drop off in certain credible faults, and plans the limit around that figure. The dashed outlines show the data-centre demand each percentage implies.

EstimateImplied data-centre demand at the time = MW dropped ÷ share dropped (our arithmetic).

Sources: CRU202704 Table 1 (EirGrid fault ride-through events), 2026-07-08 · EirGrid/SONI Weekly Operational Constraints Update, week 42 2026, 2026-10-09

The grid, every 15 minutes

4,064 MW
Average demand, last 12 months
peak 5,912 MW
22%
Of average demand is data centres
≈ 875 MW from CSO TWh
28%
Of the overnight floor
floor 3,136 MW (1st percentile)
33%
Of demand met by wind
imports avg 558 MW

A typical day: demand by hour (MW)

0k1k2k3k4k5kData centres ≈ 875 MW, flat00:0003:0006:0009:0012:0015:0018:0021:00

Data-centre load is drawn as a flat band at its 2025 average (CSO 7.7 TWh ÷ 8,760 hours). It runs all night, which is why Ireland's overnight floor is so high.

Wind share and imports by month

2025-10 · imports 638 MW32%
2025-11 · imports 592 MW35%
2025-12 · imports 565 MW39%
2026-01 · imports 553 MW33%
2026-02 · imports 473 MW41%
2026-03 · imports 507 MW40%
2026-04 · imports 451 MW38%
2026-05 · imports 561 MW28%
2026-06 · imports 454 MW31%
2026-07 · imports 603 MW22%
2026-08 · imports 745 MW18%
2026-09 · imports 575 MW36%

Wind as a share of demand. Imports are net over the EWIC and Greenlink interconnectors to Britain.

EirGrid Smart Grid Dashboard, Republic of Ireland, 15-minute data 2025-10-10 to 2026-10-09 · operational, not settled, figures

Figure 3

The Republic now imports power around the clock

In 2020 the Republic exported power overnight. Over the last 12 months it imported in every hour of the average day, and on still winter evenings it imports more than the two cables to Wales can carry (1,219 MW on average against 1,004 MW); the rest comes over the North–South line or is measurement difference.

Average net imports by hour of day, 2020 against the last 12 monthsIn 2020 Ireland exported overnight (about -304 MW at the lowest hour) and imported little by day. In the last 12 months it imported every hour, between 524 and 877 MW on average. The two cables to Wales are rated 1,004 MW together.-40004008001,200↓ exporting↑ importingEWIC + Greenlink rating 1,004 MW00:00 · last 12 months 681 MW · 2020 -138 MW01:00 · last 12 months 600 MW · 2020 -226 MW02:00 · last 12 months 621 MW · 2020 -236 MW03:00 · last 12 months 599 MW · 2020 -206 MW04:00 · last 12 months 557 MW · 2020 -219 MW05:00 · last 12 months 524 MW · 2020 -284 MW06:00 · last 12 months 611 MW · 2020 -304 MW07:00 · last 12 months 774 MW · 2020 -146 MW08:00 · last 12 months 847 MW · 2020 -40 MW09:00 · last 12 months 854 MW · 2020 36 MW10:00 · last 12 months 818 MW · 2020 83 MW11:00 · last 12 months 760 MW · 2020 84 MW12:00 · last 12 months 713 MW · 2020 66 MW13:00 · last 12 months 664 MW · 2020 84 MW14:00 · last 12 months 642 MW · 2020 93 MW15:00 · last 12 months 646 MW · 2020 78 MW16:00 · last 12 months 670 MW · 2020 17 MW17:00 · last 12 months 711 MW · 2020 2 MW18:00 · last 12 months 777 MW · 2020 10 MW19:00 · last 12 months 834 MW · 2020 -3 MW20:00 · last 12 months 874 MW · 2020 -15 MW21:00 · last 12 months 877 MW · 2020 -31 MW22:00 · last 12 months 837 MW · 2020 -47 MW23:00 · last 12 months 778 MW · 2020 -43 MWlast 12 months2020Low wind: 1,045 MWStill winter eve: 1,219 MW00:0006:0012:0018:0023:00Both cables to Wales importing at ≥95% of rating, share of quarter-hours00:00 · both links full 18.4% of quarter-hours01:00 · both links full 18.3% of quarter-hours02:00 · both links full 21.2% of quarter-hours03:00 · both links full 18.6% of quarter-hours04:00 · both links full 14.7% of quarter-hours05:00 · both links full 10.4% of quarter-hours06:00 · both links full 10.3% of quarter-hours07:00 · both links full 23.5% of quarter-hours08:00 · both links full 32.1% of quarter-hours09:00 · both links full 34.5% of quarter-hours10:00 · both links full 30.1% of quarter-hours11:00 · both links full 26.2% of quarter-hours12:00 · both links full 26.8% of quarter-hours13:00 · both links full 25.5% of quarter-hours14:00 · both links full 22.5% of quarter-hours15:00 · both links full 21.6% of quarter-hours16:00 · both links full 22.9% of quarter-hours17:00 · both links full 29.6% of quarter-hours18:00 · both links full 32.9% of quarter-hours19:00 · both links full 33.9% of quarter-hours20:00 · both links full 36.1% of quarter-hours21:00 · both links full 33.8% of quarter-hours22:00 · both links full 29.9% of quarter-hours23:00 · both links full 21.6% of quarter-hourslowest 10.3% at 06:00highest 36.1% at 20:00
Average net imports by hour of day, 2020 against the last 12 monthsIn 2020 Ireland exported overnight (about -304 MW at the lowest hour) and imported little by day. In the last 12 months it imported every hour, between 524 and 877 MW on average. The two cables to Wales are rated 1,004 MW together.-40004008001,200↓ exporting↑ importingEWIC + Greenlink rating 1,004 MW00:00 · last 12 months 681 MW · 2020 -138 MW01:00 · last 12 months 600 MW · 2020 -226 MW02:00 · last 12 months 621 MW · 2020 -236 MW03:00 · last 12 months 599 MW · 2020 -206 MW04:00 · last 12 months 557 MW · 2020 -219 MW05:00 · last 12 months 524 MW · 2020 -284 MW06:00 · last 12 months 611 MW · 2020 -304 MW07:00 · last 12 months 774 MW · 2020 -146 MW08:00 · last 12 months 847 MW · 2020 -40 MW09:00 · last 12 months 854 MW · 2020 36 MW10:00 · last 12 months 818 MW · 2020 83 MW11:00 · last 12 months 760 MW · 2020 84 MW12:00 · last 12 months 713 MW · 2020 66 MW13:00 · last 12 months 664 MW · 2020 84 MW14:00 · last 12 months 642 MW · 2020 93 MW15:00 · last 12 months 646 MW · 2020 78 MW16:00 · last 12 months 670 MW · 2020 17 MW17:00 · last 12 months 711 MW · 2020 2 MW18:00 · last 12 months 777 MW · 2020 10 MW19:00 · last 12 months 834 MW · 2020 -3 MW20:00 · last 12 months 874 MW · 2020 -15 MW21:00 · last 12 months 877 MW · 2020 -31 MW22:00 · last 12 months 837 MW · 2020 -47 MW23:00 · last 12 months 778 MW · 2020 -43 MW00:0006:0012:0018:0023:00Both links to Wales ≥95% full, % of quarter-hours00:00 · both links full 18.4% of quarter-hours01:00 · both links full 18.3% of quarter-hours02:00 · both links full 21.2% of quarter-hours03:00 · both links full 18.6% of quarter-hours04:00 · both links full 14.7% of quarter-hours05:00 · both links full 10.4% of quarter-hours06:00 · both links full 10.3% of quarter-hours07:00 · both links full 23.5% of quarter-hours08:00 · both links full 32.1% of quarter-hours09:00 · both links full 34.5% of quarter-hours10:00 · both links full 30.1% of quarter-hours11:00 · both links full 26.2% of quarter-hours12:00 · both links full 26.8% of quarter-hours13:00 · both links full 25.5% of quarter-hours14:00 · both links full 22.5% of quarter-hours15:00 · both links full 21.6% of quarter-hours16:00 · both links full 22.9% of quarter-hours17:00 · both links full 29.6% of quarter-hours18:00 · both links full 32.9% of quarter-hours19:00 · both links full 33.9% of quarter-hours20:00 · both links full 36.1% of quarter-hours21:00 · both links full 33.8% of quarter-hours22:00 · both links full 29.9% of quarter-hours23:00 · both links full 21.6% of quarter-hourslowest 10.3% at 06:00highest 36.1% at 20:00last 12 months2020Low wind: 1,045 MW (average)Still winter eve: 1,219 MW (average)

The lines show average net imports into the Republic for each hour of the day: dashed for 2020, red for 2025-10-10 to 2026-10-09. The 2020 day dipped to about -304 MW (exporting) at night; the recent day never falls below 524 MW and peaks at 877 MW. The Republic was a net importer in 40.1% of quarter-hours in 2020 and 89.4% in 2025. When the wind is low imports average 1,045 MW, and on still winter evenings both cables to Wales were importing at 95% of their rating or more in 95.0% of quarter-hours (a small sample: 219 quarter-hours, about 55 hours).

EstimateNet import = system demand minus Irish generation each quarter-hour, so it includes the North–South line and metering mismatch.

Sources: EirGrid Smart Grid Dashboard, 15-minute demand and generation (operational data), 2026-10-10 · Link ratings: EirGrid/SONI AIRAA 2026–2035 (EWIC), CRU Greenlink review, 2025

Data centres' part of demand

TWh024685%20155.8%20166.8%20178.2%20189.4%201911.2%202014.1%202117.7%202220.7%202321.9%202423.2%2025

CSO MEC02, updated 2026-07-07.

What EirGrid has forecast for data centres

EditionPublishedMeasureForecast
GCS 2019-20282019data centres' share of Ireland's demand, median29% by 2028
GCS 2021-20302021data centres' share of demand, median (high: 30%, per CRU/21/124 p17)23% by 2030
EirGrid letter to CRU2021-05-27data centres' share of demand, median / high, latest forecast25% / 33% by 2030
Government Statement2022-07-27if all contracted capacity connected25-33% by 2030
GCS 2023-20322024-01data centres and new large energy users, median30% by 2032
CRU202504 (citing EirGrid)2025-02-18data-centre and new tech load demand7.1 TWh (21%) in 2023 to 13.3 TWh (30%) in 2032
AIRAA 2026-20352025 (freeze 30 Jun 2025)data centres and new tech loads share of demand, median; MVA 2024 to 203532% by 2030; 959 MVA to 1,870 MVA by 2035

Each forecast as published; earlier editions over-shot or under-shot as the connection rules changed.

Related