The ESB has signed a €1.5 billion deal to purchase electricity from two new independent power stations for up to 10 years.
The contracts with Aughinish Alumina and Tynagh Energy Limited are the largest contracts ever awarded in the Irish electricity business. The new power stations will be built on the Shannon Estuary and in East Galway.
The competition for the contracts was conducted by the Commission for Energy Regulation, which concluded with the signing of contracts today.
General Manager of ESB Customer Supply said: "This represents an historic day...as these are the largest ever contracts entered into by ESB Customer Supply.
He said the contracts would be "very important in meeting the projected generating capacity requirements from 2005."