Consumers could see a reduction in their power bills as a result of a single electricity market on both sides of the border which comes into effect today.
Under the system, power will be bought and sold through a pool system and wholesale prices will be no longer set by the regulator.
Companies that generate power will instead compete to supply electricity to this pool system.
Minister for Energy Eamon Ryan says this competition will create greater transparency in the market and could push down prices for ESB customers.