County Mayo's one data center proposal was refused in mid-September 2026. An Coimisiún Pleanála, the national planning appeals board, overturned Mayo County Council's April 2025 approval of a 50-megawatt data center outside Killala, proposed by Mayo Data Hub Ltd, part of the US firm Avaio Digital. The refusal can only be challenged by judicial review in the courts, filed within eight weeks of the decision being formally published, which puts the deadline around mid-November.
The board said the developer had not shown it had a firm grid connection, enough local power capacity or any deal to buy renewable power, and that the plan clashed with Ireland's Climate Action Plan 2025. "The proposed development is considered to be premature in the absence of this detail," it ruled. The appeal was brought by Colin Doyle of Ennis, County Clare. The novelist Sally Rooney, a Mayo resident, had objected to the council, saying the power demand would add to the "catastrophic planetary crisis that is global warming."
Avaio had described the building of about 29,000 square meters as a €1.5 billion investment with 300 construction jobs and up to 35 permanent ones, placed in north Mayo because of its surplus wind power. Deputy Paul Lawless welcomed the refusal, saying data centers "are placing huge pressure on the grid." Minister of State Alan Dillon called it "disappointing news" for Killala and said he would take up the issues with IDA Ireland, EirGrid and Mayo County Council.
Projects not tied to an area
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Co. Mayo1
| Project | Company | Status | Power | |
|---|---|---|---|---|
| Mayo Data Hub Ltd · KillalaKillala | Mayo Data Hub Ltd (Avaio Digital) | Blocked | 50 MW |
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