The first shots in the potential battle came last Thursday when the union representing the ESB's engineers, Amicus, launched an energy paper that mounted a sustained attack on wind power . . . one of the Green's favoured sources of energy.

The second round is likely to come within weeks as under an agreement to reduce its share of the Irish energy market to 40%, the ESB is due to announce the closure of a number of power stations by 30 June. The ATGWU has already said that there is a possibility that strike action will result.

According to Jerry Shanahan, the national officer of Amicus and chair of the Irish Congress of Trade Unions' energy committee, the Amicus report, which advocates the use of so-called 'clean coal' technology with carbon capture and potentially nuclear power over renewables and natural gas, will probably feed into the ICTU's energy policy.

'Clean' coal technology involves burning coal which has been chemically washed of impurities and then storing the resulting greenhouse gases underground. To date, however, no power plant in the world operates this system.

The paper claimed that the continued widespread use of wind power could lead to the "widespread switching-off of customers" due to its unreliable nature.

It also stated that wind power could lead to increased carbon emissions because back-up conventional plants would operate at below their maximum capacity, reducing their fuel efficiency.

"Ireland must [as well as nuclear] look to clean coal. While clean coal is not at present a proven technology, it will be readily and easily accepted by industry and regulators and produce substantial public benefits, " said the paper.

When asked where Amicus proposed storing the resulting carbon dioxide, Paul Cronin, the union's ESB branch secretary, admitted that "in the document, we still don't cover all the areas that need to be addressed".

He denied that the paper had been drawn up as a defensive move to protect jobs at the ESB and attack its competitors, which mainly produce power from natural gas and wind.

He conceded, however, that more engineers were needed to run nuclear and clean coal plants than were needed at other types of plants.

"That's true, but the volume of power generated by the end product is also greater. You also have to remember that in the past 12 years, the labour force at ESB had been reduced by between 5,000 and 6,000 jobs."

But Eddie O'Connor, chief executive of Airtricity, Ireland's largest wind farm operator, said the report seemed to be "attacking anyone who is their competition" and its contents were complete "science fiction".

He said: "I'd love to have a chance to have a public debate with these guys because their arguments would be so easy to deal with. They are looking after themselves and are trying to prevent innovation.

"They are pushing two technologies: one, clean coal with carbon capture, which doesn't exist, and one, nuclear, which although no-one can deny it delivers the goods, is at least 20 years away in Ireland."

O'Connor said the report's claims about wind energy were "complete garbage".

"Wind is the cheapest thing you can put on the system and what they ignore is the fact that the price of power across the European power exchanges fell dramatically in November and December last year due to wind, " O'Connor said.

A spokesman for Eirgrid declined to comment on the Amicus report but said: "we believe our practical and constructive attitude to wind power, and indeed all renewables, has been correct. We will continue to ensure that this is done while maintaining a stable and secure system".