The project has already cost the city council €80m, but this will be repaid by Covanta if construction begins.
The council said that the waste to energy project is central to the Dublin region waste plan, which aims to reduce landfill.
It also said it is engaged with the European Commission regarding a complaint alleging breach of State aid rules.
Opponents say the 600,000-tonne facility is too big and could leave the taxpayer with a bill because the city council has to guarantee a minimum amount of waste.
Local Labour TD Kevin Humphreys said the council has "kicked the issue down the road again" and said it is time to walk away from the plan.