If all proposed data centres projects were completed, they could account for 70% of Ireland's electricity usage by 2030, an Oireachtas Committee has heard.

Dr Patrick Bresnihan, from the Department of Geography in NUI Maynooth, told politicians that data centres currently represent 11% of grid capacity.

Eirgrid has estimated that this will rise to 28% of grid capacity, by the end of the decade, based on existing connections.

Appearing before the Oireachtas Committee on Environment and Climate Action, Dr Bresnihan said that in the last four years alone the annual increase in electricity usage by data centres is equivalent to adding 140,000 homes to the national grid every year.

An average data centre with a load of 60 MW would be comparable to the load usage of a city such as Kilkenny.

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"Achieving ambitious emissions and renewables targets by 2030 will undoubtedly be far more difficult with the addition of more data centres to the grid," he warned.

Ireland is currently committed to achieving 70% renewable energy. However, Dr Bresnihan said that the main source of this energy, onshore and offshore wind, is intermittent. Therefore a more reliable source, most likely natural gas, will have to be available.

Politicians also heard arguments in favour of producing "green hydrogen at a useful scale".

James Carton, Assistant Professor in Sustainable Energy and Hydrogen Technology at Dublin City University told TDs and Senators that balancing out a 100% renewable energy system is "well beyond battery technology, but feasible for hydrogen".

This is based on modelling carried out by DCU.

Professor Carton said that "thousands of jobs that do not exist today, will flow on the development of a hydrogen economy, as many understand to be necessary to fully decarbonise our energy system working hand-in-hand and even supporting clean, secure electricity supply".