The ESB is facing a prosecution by the Environmental Protection Agency over leaks of a powerful greenhouse gas called SF6.
The company is facing six charges in relation to leaks of the gas from its power station at Moneypoint, Co Clare.
The charges facing the ESB relate to the company's alleged failure to promptly fix leaks of SF6, a gas with a global warming potential which is 23,500 times greater than that of C02.
Leaks of this gas from the ESB's Moneypoint plant were investigated by the EPA following disclosures by the whistleblower Seamus O'Loughlin in the RTÉ Investigates programme, The ESB Leaks.
The EPA's final report on Moneypoint reveals that over the past six years, the ESB leaked the equivalent of 55,000 tonnes of C02 into the atmosphere.
The EPA's report, seen by RTÉ, found that despite the hazardous nature of SF6, leaks at the plant were not repaired as they arose.
Instead, the ESB simply kept topping up the leaking system with more SF6 gas, making a bad situation worse.
EPA investigator Ian Marnane said: "They didn't repair the leaks; on many occasions the equipment was topped up."
Up until last year, SF6 was used by the ESB as an electrical insulator at Moneypoint. The company was required to report leaks of the gas to the EPA if and when they arose.
However, Mr Marnane said: "None of these leaks were reported to the EPA. The EPA had issued a license. They must report incidents immediately."
SF6 is a highly potent greenhouse gas, he noted. "The lifetime of SF6 in the atmosphere is over 1000 years. It will be in the environment for generations."
Asked about the assistance of Seamus O'Loughlin to their investigation, he said: "The whistleblower was pivotal in bringing this to our attention and allowing us to act on it. We wouldn't have been able to find out about it."
Since this interview with Mr Marnane, the EPA has initiated a prosecution against the ESB on six counts of failing to repair leaks of SF6 without undue delay.
The case is expected to come before the courts in November.
In a statement to RTE Investigates the ESB confirmed it is facing a prosecution and said it could not comment further.
The EPA is now expected to widen its investigation to examine the ESB's historical use of SF6 at up to 200 locations around the country.