The Environmental Protection Agency (EPA) has issued a draft licence to Dublin City Council to operate its proposed Poolbeg incinerator.
The draft licence follows the granting of full planning permission for the incinerator from Bord Pleanála earlier this week.
If the draft licence is confirmed by the EPA after a 28-day period of public consultation, the waste-to-energy incinerator would face one final hurdle, that of the consent of the Commission for Energy Regulation.
While the draft licence was welcomed by Dublin City Council, the Green Party said conditions that it use "residual" waste meant that it was uneconomic.
News of the draft licence was "noted" by Green Party Minister for the Environment John Gormley, whose Dáil constituency includes the Poolbeg site.
Mr Gormley said the proposed permission for a 600,000-tonne Dublin incinerator meant there "is now an obvious over-capacity in this area and this is not sustainable".
The Minister added he was "already on the record as having said that there could be a need for a national capacity of somewhere in the region of 400,000 tonnes for thermal treatment/co-fired".
While Mr Gormley said he was "legally prohibited by Section 60 (3) of the 1996 Waste Management Act from becoming involved in an ongoing waste licensing process", he reiterated that he had ordered a review of waste policy and regional waste management plans.
Green Party chairman Senator Dan Boyle said two specific conditions in the draft licence meant waste going for treatment at the incinerator must be "residual". This meant only residual waste would be incinerated after recycling, reuse, composting and separation. "Once pre-treatment occurs there will not be the 600,000 tonnes of waste needed to feed this monster incinerator," he said. Mr Boyle maintained that "under the terms of the EPA's licence, [ the] proposed plant will also be economically unviable."
However, the Minister's constituency colleague, former Labour leader Ruairí Quinn, said it was "now clear that this environmental monster can only be stopped by action at ministerial level". Mr Quinn said "the obligation on him to act is all the greater because of his previously stated position of total opposition to the incinerator".
Dublin City Council said it and its private-sector partners in Dublin Waste to Energy Ltd would study the conditions and respond to the EPA.