Data Centre Opposed by Sally Rooney Overturned on Climate Grounds as An Coimisiun Pleanala Cites Grid Failures
An Coimisiun Pleanala has overturned planning permission for a proposed 1.5 billion euro data centre in Killala, County Mayo, finding that the developer failed to demonstrate sufficient grid capacity, adequate renewable energy commitments, or compliance with the Climate Action Plan 2025 — a decision that follows a formal objection from Mayo-born author Sally Rooney, who described the project as wasteful, unnecessary and environmentally toxic.
Background
Ireland's relationship with data centres has become one of the defining infrastructure debates of the decade. The country hosts a disproportionate share of European data centre capacity — driven by its favourable corporate tax environment, its position as a hub for US technology companies, and its historically reliable electricity grid. Data centres now account for a significant and growing share of Ireland's total electricity consumption, with the Commission for Regulation of Utilities estimating that they could account for 30% of national electricity demand by 2030. This concentration has created a genuine tension between Ireland's role as a European technology hub and its climate commitments. The Climate Action Plan 2025 sets ambitious targets for reducing greenhouse gas emissions, and the electricity grid — which must decarbonise rapidly to meet those targets — is under increasing strain from data centre demand. EirGrid has warned that new data centre connections in the Dublin area are effectively paused due to grid capacity constraints, which is why developers have increasingly looked to regional locations — including the west of Ireland — where grid capacity may be more available. The Killala project, proposed by Mayo Data Hub Ltd, a subsidiary of US firm Avaio Digital, was one such regional proposal. The 30,000-square-metre facility was intended to provide 300 construction jobs and 35 permanent positions. Mayo County Council granted planning permission in April 2025, but the decision was appealed by a third party, leading to the An Coimisiun Pleanala review.
Key Developments
An Coimisiun Pleanala's ruling found that the developer had failed on three key grounds. First, it could not demonstrate that there was sufficient capacity in the local electricity grid to support the facility. Second, it could not prove that the site could utilise locally generated renewable energy, nor did it provide evidence of a corporate power purchase agreement with a renewable energy supplier. Third, the project was found to be in breach of the Climate Action Plan 2025, with the authority noting that the facility would likely result in significant greenhouse gas emissions due to reliance on fossil-fuel-generated energy. The authority deemed the proposal premature, given the lack of detail regarding secure and sustainable power sourcing. The decision is final, subject only to a potential challenge via judicial review within an eight-week window. Sally Rooney, a native of Castlebar in County Mayo, was among the vocal objectors to the development. In her submission to the planning process, she argued that the data centre represented a wasteful, unnecessary and environmentally toxic proposal, contending that the facility would increase carbon emissions and contribute to what she described as the catastrophic planetary crisis of global warming.
Why It Matters
The Killala decision is significant for several reasons. It is one of the clearest applications of climate policy criteria to a data centre planning application in Ireland, and it signals that An Coimisiun Pleanala is prepared to refuse permission where developers cannot demonstrate genuine renewable energy commitments — not just aspirations. This raises the bar for future data centre applications across the country and may prompt developers to invest more heavily in renewable energy infrastructure as a precondition for planning approval. The decision also reflects a broader shift in how Ireland is approaching data centre policy. The government has been under pressure from climate advocates, grid operators, and local communities to develop a more coherent framework for data centre development — one that balances economic benefits against energy and climate costs. For rural communities in the west of Ireland, the decision is more ambiguous. The 300 construction jobs and 35 permanent positions that the Killala project would have created are significant in a region where employment opportunities are limited.
Local Impact
In Killala and the wider North Mayo area, reaction to the decision has been mixed. Some residents and local politicians had supported the project on economic grounds, pointing to the jobs and investment it would have brought to a region that has historically struggled with emigration and economic underdevelopment. Others, including environmental groups and local residents who submitted objections, have welcomed the ruling as a vindication of their concerns about the project's environmental impact. Mayo County Council, which had granted the original permission, has not yet commented on the An Coimisiun Pleanala decision. The Department of Enterprise, Trade and Employment has been asked to outline what alternative investment opportunities are being pursued for North Mayo.
What's Next
The developer has an eight-week window to challenge the An Coimisiun Pleanala decision by way of judicial review. If no challenge is mounted, the decision stands and the Killala data centre project is effectively dead. The government is expected to publish a revised national data centre policy framework before the end of the year, which will set out clearer criteria for renewable energy requirements and grid capacity assessments. An Coimisiun Pleanala has indicated that it will apply similar criteria to other data centre applications currently before it.
