All are in the same general area around the Mississauga-Oakville border, though major opposition has arisen among residents, who say there are already too many air-pollution sources in the area.
Three are in Mississauga's Clarkson neighbourhood and one just across the border in Oakville, at the southern end of the Ford Canada plant. All of the sites are close to residential areas.
The Ontario Power Authority plans to choose from among the four bids to build an 850-megawatt combined cycle plant.
But residents aren't giving up hope the plan can be stopped, Boyd Upper of the Clear the Air Coalition said yesterday. "We are doing our best and there will be a move made next week," Upper said, referring to an expected motion from Mississauga city council asking the province to drop the project entirely.
"We're not going to the courts yet, but that is being considered," Upper added. Opponents point to a 2003-05 Ontario environment ministry study in the Clarkson area that found the neighbourhood's air quality is "stressed" by the effects of traffic, local industry and drifting U.S. pollution.
"The air around here is already heavily polluted," said Laura Mang, vice-president of Clearview Oakville Community Alliance, representing 2,200 households near the Ford plant. Her group is also opposed to the project.
She wonders why the proposed plant, which is supposed to operate only during periods of peak electricity demand, can't be developed using green power.
The OPA maintains the plant will be needed to provide a reliable source of electricity by 2015, or demand could exceed supply. Another 280-megawatt combined cycle gas power plant has already been approved in southeast Mississauga on Loreland Ave.
In response to pollution concerns, the OPA notes that all of the proposals are subject to an environmental assessment.
The successful bidder will be chosen by August 15 and the plant is to be built and running by the end of 2013, based on the OPA's plan.
The bidders and their prospective sites are:
Invenergy Canada Development Partnership: Hazelhurst Rd., north of Lakeshore Rd. W., Mississauga.
Northland Power Inc. site: 2400 Royal Windsor Dr., Mississauga.
Portlands Energy Centre LP: 1500 Royal Windsor Dr., at the Ford Canada plant in Oakville. Portlands and Ford have agreed on a deal for the land if that site is chosen.
Sithe Global Power site: Winston Churchill Blvd., between Royal Windsor Dr. and Lakeshore Rd. in Mississauga.
Sithe's location was approved for an 800-megawatt gas-fired power plant in 2001, but the company subsequently put the project on hold.
It ran into major opposition, but an agreement was reached with residents' groups, specifying the company would build higher stacks to better disperse the pollution and would strictly monitor air quality, among other conditions.
Despite the 2001 agreement, a coalition of 30 Mississauga residents' groups has asked for a ban on any gas-fired power plants in the area, citing the Clarkson air study.
More than 300 residents packed an open house recently to object to the Sithe proposal, the only one made public at the time.
All proponents are scheduling open houses to explain their proposals to the public and answer questions.