29 EPA licences cover generators at Irish data centres, 20 granted and 4 applied for, with 7,546 MW of thermal input licensed (EPA LEAP, Oct 2026). Backup diesel fleets ran only about 1–6 full-load hours a year, and on-site fuel was 0.3% of reporting sites' energy in 2025. Gas is the bigger story: 7 licences include on-site gas.
Three kinds of on-site generation, and how long each may run
Most of the licensed plant, 5,714 MW thermal, is back-up diesel allowed to run a few hundred hours a year at most; in 2025 the busiest of those fleets burned the equivalent of 6.4 hours at full load. A smaller group of gas plants is licensed to run far longer, up to all year.
EPA licences cover data centres with at least 50 MW of thermal input on site. Back-up diesel fleets are allowed 72–500 hours a year per generator, mostly for testing, and their annual reports show they used a tiny part of that. Gas plants that help the grid run on EirGrid's instruction or at price peaks (one peaking plant expects about 2,500 hours a year), while a site's own power station can run all 8,760 hours of the year. In 2025, on-site fuel was 0.3% of the energy used by the 16 sites that reported; the rest came from the grid.
EstimateAllowed hours are read from each licence's main condition and are upper bounds (8 h/day = 2,920 h/yr; run-on-instruction counted as all year). Fleet full-load hours = fuel burned ÷ rated input, so individual units run longer at part load. Google's ratings are confidential, so it is not plotted.
Combustion plant (diesel, gas, HVO) licensed or applied for at data centres
thermal input, not electrical output · EPA
2 GW
Of it meant to run as main or continuous power
thermal input
1225
Generators, engines and turbines
24 licences held or sought · 29 incl. withdrawn
0.3%
On-site fuel as a share of sites' energy input, 2025
fuel ÷ (fuel + grid electricity) · AERs
Gas as the power station. Equinix's Blanchardstown site ran nine gas turbines as its main power from February to November 2024 while it waited for grid capacity: that year it burned more energy as gas than it bought as grid electricity (fuel in, not electricity out). South Dublin Routing's Ballycoolen site, licensed in July 2026, gets over 99% of its power from on-site engines and has no grid connection for its IT load.
Licensed and applied plant by role, MW thermal
Gas as main power1,455
HVO as main power544
Gas, flexible/on call880
Gas peaker557
Diesel/HVO backup5,714
Thermal input, not electrical output: diesel sets deliver about 0.4 MW of electricity per MW of thermal input. Google's ratings are confidential and excluded.
On-site fuel as a share of energy input, by year
2023 · 14 sites0.31%
2024 · 15 sites2.57%
2025 · 16 sites0.3%
2024's jump is almost all Equinix's gas. The diesel backup fleets at Amazon, Microsoft, Meta, K2 and Google burned the equivalent of roughly 0.6–6.4 hours at full load a year, against 72–200 hours permitted.
Grange Castle Business Park South, Baldonnel Road, Dublin 22
Diesel/HVO backup
Licensed
120240
24
26
Grid MW avg: each site's grid electricity from its latest annual environmental report, as an average load. Read by Claude from EPA documents; every quote checked against its page.
EPA LEAP licences, inspector reports and annual environmental reports · as of 2026-10-03
Gas: the next limit
2,100 MWth
Gas contracted by 11 data centres (max hourly load)
7 connected · GNI, Nov 2024
9.3 GWth
More enquired about, 22 sites
GNI, Nov 2024
5,466 MWth
Pending gas applications (17)
the ones the new rule would hit
799 MWth
Known gas plant that keeps firm supply
4 of 8 sites
The rule mostly misses today's gas burners. The CRU's interruptible-gas proposal applies only to new connections. Gas Networks Ireland has signed no new data-centre contract since July 2022, so sites already on gas, including the islanded Ballycoolen site, keep firm supply. Generators metered separately and selling into the market are exempt.
EPA licence
Operator
Gas MWth
Under the proposal
P1187
Microsoft Ireland Operations Limited
Existing firm contract: GNI's LNCA with Microsoft was executed 17 May 2021 (205 MW peak, 19 barg). The Direction is not retrospective. Gas is still not flowing: 12 engines idle awaiting high-pressure gas.
167
Firm or exempt
P1168
Equinix Hyperscale 1 (DB5) Limited
Already connected and burned grid gas in 2024, so it holds a pre-pause contract; the Direction is not retrospective. Any increase in contracted volume would be interruptible.
168
Firm or exempt
P1113
Echelon Clondalkin DC Services Limited
Gas comes from GNI and it must predate the July 2022 pause, so the original capacity is probably firm. But the 2025 licence swapped the 2020 design (12 x 21.3 = 255.6 MWth engines) for 448 MWth of turbines; any contracted increase would be interruptible. The contract size is not public.
448
Uncertain
P1165
Data And Power Hub Services Limited
Exempt: a gas-fired generator in the SEM. GNI is building a dedicated transmission pipeline to the Milltown AGI for the peaker. This is the design the exemption rewards.
269
Firm or exempt
P1204
EdgeConneX Ireland Limited
Behind the meter and not a SEM generator, so a new or increased connection would be interruptible. No public document shows whether EdgeConneX holds a pre-July-2022 GNI contract for ESSDUB97.
206
Uncertain
P1210
South Dublin Routing 4 No. 2 Limited
Takes gas from the GNI network today (temporary engines power DC1), so the contract predates the pause and stays firm. This is the most gas-dependent data centre in Ireland, and the proposal leaves its supply firm.
195
Firm or exempt
P1227
Vantage Data Centers DUB11 Limited
Behind the meter, so a new or increased connection would be interruptible. A GNI compound on site was re-permitted in Oct 2024, which suggests an existing GNI arrangement; its size and date are not public. EPA application still under assessment.
236
Uncertain
P1202
Crag Arklow Limited
No known GNI contract, and it would need a new transmission connection at Arklow. Interruptible if it re-applies with behind-the-meter generation. Exempt only if the engines are restructured as a separately metered SEM generator.
581
Likely interruptible
CRU202657 consultation · Gas Networks Ireland network plans and winter outlook · Dáil written answer 6 Nov 2024 · EPA licences · quotes checked · as of 2026-10-10