The concrete towers of the old IFI plant in Arklow, Co Wicklow, are a familiar sight to drivers on the M11 motorway.

The plant finally closed down almost 20 years ago.

Soon, a new industry will break ground on the site beside the Avoca river.

Echelon Data Centres, an Irish company, plans to build a data centre here to service tech companies which it hopes will locate in a new industrial park. It has an agreement with power generator SSE to use the electricity it plans to generate from an expansion of its offshore windfarm, just off the coast of Arklow.

Some criticise data centres for being heavy users of power at a time when there is much effort being put into reducing the amount of carbon used in the generation of electricity. There are also questions about the relative scale of data centres in Ireland compared to other countries.

Echelon CEO Niall Molloy is aware of the criticism that's levelled against the industry. However he maintains data centres are essential infrastructure and the industry is doing its best to power itself sustainably.

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"It’s essential infrastructure, like roads and sewers are," says Mr Molloy. "We can’t say we don’t want sewers. The question that does arise is how we do them in the most sustainable way possible and how do we ensure they don’t create negative impacts on the grid and on the power infrastructure."

At the moment, according to Eirgrid, data centres account for around 9% of power demand. However, it estimates that around half of all future demand, which is expected to grow by between 19 and 50% over the next decade, will come from big users like data centres. It expects by 2028 that 27% of electricity generated here will be used by data centres.

Ireland's power revolution: Offshore windfarms
Ireland's power revolution: The electricity grid

It is a relatively new industry and a power hungry one. But the view of the IDA is that it's an industry that has underpinned some 20,000 jobs in companies such as Google and Facebook, which both run data centres here.

There are jobs too in engineering and construction, as many Irish companies which honed their skills over the past decade are building data centres abroad.

Ireland has more data centre capacity than any other country in Europe, according to a recent report from construction consultants, Mitchell McDermott. It also forecasts that €7 billion will be spent on new data centres here over the next four years.

This undermines efforts to de-carbonise the electricity grid, says Sadhbh O'Neill of Stop Climate Chaos.

"I think data centres are the elephant in the room," she says.

"There's a whole lot of emphasis from Government messaging on the role individual behaviour can play. We're supposed to go and retrofit our houses and buy electric vehicles but clearly there's a problem with the renewable energy sector if all the renewables we're bringing onto the grid are going to be consumed by data centres."

We're very quickly moving into an economy that will rely more and more upon electricity.

That means questions over who gets what, and at what cost, are going to become more urgent.