The ESB has warned of significant rises in electricity prices because of new requirements on carbon dioxide (CO2) emissions.
The company has claimed that its quota allocation under the proposed CO2 emissions trading system for Ireland will cause its power generation costs to rise by up to 40 per cent.
This would in turn result in domestic prices rising by up to 20 per cent if the increased costs of production are passed on in full.
Electricity industry sources have indicated a probable rise for consumers of six per cent in the coming years.
The quota system, which is being managed by the Environmental Protection Agency (EPA), will come into force next January. In February the EPA published a draft allocation plan, outlining a quota for each of 102 major Irish factories and facilities.
In a submission to the EPA's public consultation on the plan last month, the ESB said it was concerned that its CO2 allocation "will impose significant costs on electricity consumers".
It was one of a number of submissions from industry groups and firms which criticised various aspects of the plan as being potentially harmful to the economy and competitiveness.
Under the system, which is being introduced across the EU from next January, major energy-using firms are allotted a specific quota of carbon dioxide they are allowed to emit each year. Any firm which wishes to exceed this quota has to buy additional credits on an international market, from firms which have not used up their allocation.
Firms are likely to have to pay a minimum of 8 for each extra tonne of CO2 it wants to produce.
While Irish industry has been awarded an overall allocation roughly equivalent with the amount of CO2 it is currently producing, the power generation plants were awarded quotas significantly less than at present.
Moneypoint, the single biggest source of CO2 here, was given a quota of 4.4 million tonnes per annum, compared with a current 5.9 million tonnes of CO2.
In its submission to the EPA last month, the ESB said electricity generation prices could rise from between 13 per cent and 40 per cent.
Generation costs account for just over half of the average domestic bill. Any rise in consumer electricity prices will be a matter for the Commission for Electricity Generation however, which could decide that the industry must shoulder the additional costs entirely.