How many offshore wind farms does Ireland have?
One: the 25 MW first phase of Arklow Bank, built in 2004. 5 Phase 1 east-coast projects (3,799 MW) are waiting for An Coimisiún Pleanála, and every one is past its statutory decision date.
| Project | Developer | MW | State support | Can serve data centres? |
|---|---|---|---|---|
| Codling Wind Park | Fred. Olsen Seawind and EDF Renewables (50/50; ownership unchecked) | 1,300 | ORESS1 | No |
| Dublin Array | RWE and Saorgus Energy (Kish/Bray Offshore Wind Ltd) | 824 | ORESS1 | No |
| North Irish Sea Array (NISA) | Statkraft and Copenhagen Infrastructure Partners (unchecked) | 500 | ORESS1 | No |
| Sceirde Rocks (Skerd Rocks) | Fuinneamh Sceirde Teoranta (Corio Generation) | 450 | ORESS1 | No |
| Oriel Wind Farm | Oriel Windfarm Ltd (ESB and Parkwind/JERA Nex) | 375 | none | Yes, in principle |
| Arklow Bank Wind Park 2 | Sure Partners Ltd (SSE Renewables) | 800 | none | Yes, in principle |
| Tonn Nua (SC-DMAP site A) | Helvick Head Offshore Wind DAC (ESB and Ørsted) | 900 | Tonn Nua | No |
| South Coast DMAP sites B-D | not yet auctioned | 4,100 | future ORESS (expected) | No |
| Arklow Bank Wind Park (phase 1) | operating since 2004 | 25 | none (existing) | No |
Why can't data centres use State-supported wind?
The CRU's December 2025 rules require 80% of a new data centre's annual demand to be matched by new renewable generation in Ireland. The decision paper is explicit about what does not count:
"Renewable generation which has previously been or is currently contracted through existing support mechanisms (e.g. REFIT, RESS, ORESS) cannot be used" (CRU/2025/236, Large Energy Users connection policy decision, p.64)
Codling, Dublin Array and the North Irish Sea Array won contracts in the first offshore auction (ORESS 1). Tonn Nua won the south-coast auction in late 2025. Those 3,524 MW are excluded for the life of their contracts.
Oriel (375 MW) and Arklow Bank 2 (800 MW) lost that auction. They must find corporate buyers instead, which is exactly what a data centre needs.
Is it enough for data centres?
On paper, nearly. EirGrid deems the two projects' output at about 4.63 TWh a year. Data-centre growth to 2034 needs about 4.16 TWh a year of new renewables to meet the 80% test (EirGrid forecasts as cited by the CRU; our calculation).
In practice, not yet. Neither project has planning consent, and no power purchase agreement has been signed: SSE said in June 2026 it was still "finalising details of a commercial route to market" for Arklow Bank 2.
| End of year | Offshore MW (our estimate) | Of which data-centre eligible | EirGrid base case | EirGrid low case |
|---|---|---|---|---|
| 2026 | 25 | 0 | 30 | 30 |
| 2027 | 25 | 0 | 30 | 30 |
| 2028 | 25 | 0 | 30 | 30 |
| 2029 | 25 | 0 | 30 | 30 |
| 2030 | 25 | 0 | 1,350 | 30 |
| 2031 | 400 | 375 | 1,950 | 30 |
| 2032 | 1,200 | 1,175 | 2,520 | 400 |
| 2033 | 3,824 | 1,175 | 3,120 | 830 |
Our estimate assumes each project's commercial operation date from its planning stage and public statements; EirGrid's figures are from its adequacy assessment.
The goalposts moved
On 27 March 2026 the ORESS 1 contract longstop moved from 31 December 2031 to 31 December 2034, and the planning longstop from June 2028 to June 2029. The 2030 offshore target of 5 GW is now framed as "in construction by 2030". Sceirde Rocks (450 MW) withdrew in December 2025.
Why it matters
Our reading. The State's auction was meant to pick winners. For data centres it did the reverse: losing made Oriel and Arklow Bank 2 the only offshore projects they can buy from. Their bargaining power has risen, and their timing, around 2031–32 at the earliest, now sets the pace for any new data centre that hopes to meet the 80% rule with offshore wind.
Until then, permitted onshore wind without State support is the scarce product. Only about 1.4 GW of it exists in the planning system.