Dublin City Council has signed a contract to operate the Poolbeg incinerator even though An Bord Pleanála has yet to give the go ahead.
The move also comes despite criticism of incinerator projects by Environment Minister John Gormley.
Dublin City Council described the signing of the contracts as another major milestone.
It says the plant at Poolbeg in Minister Gormley's constituency will provide heating and electricity for more than 100,000 homes.
The plant would also burn 600,000 tons of waste each year.
Green Party TD for Dun Laoghaire Ciarán Cuffe said he was concerned that council officials were attempting to pre-empt An Bord Pleanála's decision by making financial commitments and guarantees before approval for the plant has even been granted.
