But Ontario Energy Minister Dwight Duncan said Wednesday that the shutdown of the biggest plant, the 4,000 megawatt Nanticoke generator on the shore of Lake Erie, will have to wait until 2009 so that sufficient replacement power sources and a revamped distribution network can be put in place.

"As I have said all along, Nanticoke remains our biggest challenge," Duncan told a news conference in Toronto.

"If we can close the last unit sooner than that, we will do it. But we will do it safely and in a way that never ever compromises the reliability of Ontario's electricity supply."

Nanticoke will be shut down gradually, with eight units shut down through 2008 and the last one down early 2009.

Duncan said the province has launched a number of initiatives that will provide necessary generation capacity to replace the plant.

So far, the government said it is on track to secure 7,500 megawatts of new generating capacity to replace the province's four coal-fired plants.

Duncan also said the government is currently reviewing a tentative deal with Bruce Power, a unit of uranium producer Cameco Corp. and several partners, to refurbish two laid-up nuclear reactors, which would represent more than 1,500 megawatts of additional capacity.

Ontario will replace its Thunder Bay generating station with gas-fired generation in 2007. The Atikokan and Lambton generation stations are slated to close by the end of 2007.

Critics have questioned how the government will replace the coal plants demand at a time when the price of oil is soaring.

"Consumers will face skyrocketing electricity prices driven by contracts that give private power-producers a guaranteed profit," the Power Workers' Union said in a statement.