ESB chief executive Padraig McManus says the energy industry will spend around €1 billion a year over the next five years to guarantee the country's supply of electricity.
He was speaking at a sod-turning ceremony to mark the beginning of the construction of a new €400m ESB power station at Aghada in East Cork.
Mr McManus said the ESB alone would be spending €3.5 billion upgrading its network between now and 2012, as well spending €500m on the new Cork plant and upgrading the existing Aghada plant.
The Aghada facility, which will be a 400mw gas turbine power plant, will be operational by October 2009. A further €100m is being spent on a major overhaul of the existing Aghada plant.