The ever-increasing demand for electricity in Ireland forced the ESB to rent five booster generators from the US to support the national grid over the winter months.
The five generators were imported from Chicago last September and the estimated cost to the ESB of leasing and running these diesel generators for the past six months is in excess of £20 million.
This week the five generators are on their way back to Chicago to assist the summer electricity demand there. Three of the generators had been located in Cork and two had been placed in the former Asahi plant in Killala, north Mayo.
"Ireland's demand for electricity is increasing by 250 megawatts annually", said ESB spokesperson Mr Michael Kelly.
"That's the equivalent of about a half a power station and so being prudent, the ESB had no choice but to lease these expensive generators for the six months of the winter to ensure a national supply of electricity.
"Demand for electricity in Ireland is very seasonal," Mr Kelly explained. "Last January Ireland was using 4,000 megawatts of electrical power. In any of the summer months, that demand would fall back to a maximum of 3,000 megawatts.
"We are anticipating now that we will require these generators and more support for the national grid again next winter.
"At the moment we are in discussion with the Commission for Electricity Regulation about this. None of our competitors would consider getting involved in the lease of these booster generators, as the cost involved would be seen as too prohibitive," Mr Kelly said.