Planning permission for Mayo data centre overturned after appeal

An Coimisiún Pleanála has overturned Mayo County Council’s decision to grant planning permission for a proposed data centre in Killala.

The local authority had given the green light to Mayo Data Hub Ltd, part of US firm AVAIO Digital, for the proposal in April 2025 despite a number of objections, including a submission made by international best-selling author and Mayo resident Sally Rooney.

The decision to grant planning was appealed by another objector, Colin Doyle from Ennis, Co Clare, and An Coimisiún Pleanála has now refused permission for the development on the grounds that it breaches a national climate policy.

In relation to the planned facility at the site of the former Asahi factory at Mullafarry and Tawnaghmore Upper, Killala, Pleanála officials said the applicant had failed to demonstrate they had a fixed connection agreement to the grid and there was sufficient capacity in the grid to service the development.

They also highlighted a lack of on-site renewable energy to power the proposed development and a lack of evidence that the applicant had engaged with a Compulsory Power Purchase Agreement.

Furthermore, they said that despite there being a number of renewable wind energy projects in the vicinity, the applicant had not provided any evidence that the data centre could avail of this locally generated renewable power.

They said the applicant failed to demonstrate that the proposed development would be in accordance with the overarching objectives of the Climate Action Plan 2025.

The commission’s ruling also said that the proposed development would likely have significant effects relating to emissions of greenhouse gas from energy generated from fossil fuels.

Making her submission in January 2025, Normal People author Ms Rooney had argued that a data centre such as what had been proposed in Killala would be a ‘waste of energy.’

“What do these centres actually do? They facilitate internet use and store data. No doubt, the internet is an important part of contemporary life, and our emails and photographs have to be stored somewhere,” she said.

“But in 2015, data centres accounted for 5% of Ireland’s energy usage; they now account for over 20%. This gigantic proliferation of data centres has not been matched by any meaningful improvement in the quality or accessibility of internet services, never mind a fourfold improvement.”