Three environmental groups will seek leave in the High Court to lodge an appeal for a judicial review of a major decision about data centres made by the Commission for Regulation of Utilities (CRU) last December.
The decision allowed new data centres to go ahead and to be connected to the electricity grid, provided, after six years, they themselves start supplying as much electricity into the grid as they use for their daily operations.
A further strict condition is that 80% of the electricity supplied by data centres must come from renewable energy sources like wind and solar farms.
However, the remaining 20% of power that they supply can come from gas or diesel turbines - which is an increase in fossil fuel use.
Data centres will also be required to develop their own back up energy supplies, including battery storage, to participate in the electricity market and contribute to the stability of the electricity grid when needed.
The decision ensures all new data centres will have to contribute to renewable energy transformation by driving the development of new wind and solar capacity.
Friends of the Irish Environment, Friends of the Earth and ClientEarth have lodged an application for a judicial review seeking to overturn this decision by the CRU.
The three environmental groups want to stop the expansion of data centres in Ireland.
Read more: 80% of data centre energy must come from renewables - CRU
They claim the CRU decision is a breach of the Climate Act and the EU energy efficiency directive because it locks Ireland into a further expansion of fossil fuel use for many years to come.
This is because the new blueprint would allow new data centres to operate fully using only fossil fuels for their first six years.
Also, the 20% of non-renewable electricity supplied by data centres will come from fossil fuels and so add to greenhouse gas emissions.
In addition, data centres need to have a back-up source of electricity to ensure they can operate reliably in all circumstances.
But this back-up process usually involves the use of high intensity gas or diesel generators which again locks in a considerable increase in greenhouse gas emissions.
The environmental groups claim the implications of this need for a back-up electricity generator is not factored into the CRU rules for 80% renewable electricity.
Last December's CRU decision ended a de facto moratorium on new data centre connections in the greater Dublin area that had been in place for the past five years.
That hold up had come about because of significant concerns about capacity constraints on the electricity grid in the region.
About 50% of metered electricity consumption in the Dublin and Meath region in 2024 was attributable to data centres.
The CRU also noted specific technical constraints in Dublin, including short circuit and fault level issues, and a heavier need for fossil fuel generation to manage flows and constraints in the region.
Data centres consumed 22% of Ireland’s electricity in 2024.
This is expected to rise to 31% by 2034 as the sector continues to expand.
