A partnership that includes a U.S. company, Canadian municipal utilities and an Ontario Indian tribe say they want to generate 1,120 megawatts of electricity using petroleum coke -- a waste product of mining.

The developers said the $5.7 billion project is driven by cheaper energy costs in Canada and an exchange rate that makes Canadian goods cheaper when sold in the U.S.

The plant would burn petroleum coke, which is a waste product in oil and gas fields in western Canada. Emissions from such plants are usually lower than from coal-fired plants.

The group plans to sell much of the power to markets in Michigan and Illinois by transporting it under Lake Superior, west of Isle Royale, to the Keweenaw Peninsula in Michigan's Upper Peninsula or around the western shore of Lake Superior.

Either way, the power would likely move through Wisconsin on transmission lines.

Any such plan would generate controversy.

"We would have concerns," said Keith Reopelle, program director of Wisconsin's Environmental Decade. "We would want to know how this would affect the Lake Superior ecosystem."

In Wisconsin, a power line that would be built from Wausau to Duluth, Minn., and which has been approved by regulators, continues to face a court battle and public opposition.

And depending on the route, new power lines would have to be built in Wisconsin -- or at least expanded -- to accommodate increased electric flows, a transmission expert said.

Burying cable underwater is not a big problem, said Teresa Mogensen, director of transmission planning and service for the American Transmission Co., Pewaukee, which owns and operates transmission lines in Wisconsin, Michigan and Illinois.

Power is transported to Mackinac Island under Lake Huron, and another line runs under Lake Erie.

"The problem is interconnecting it and making sure that the system can accommodate a new load of electricity," Mogensen said.

Wisconsin's transmission system is now stressed in periods of high demand.

The American Transmission Co. would need to be involved in the project and has not been notified.

The project would be a joint venture between SynFuel of Glen Carbon, Ill.; Fort William First Nation, an Indian tribe and six municipal utilities in western Ontario.

Developers could begin construction with a 120-megawatt plant as early as this fall, according to Larry Herbert, general manager of Thunder Bay Hydro. Two other 500-megawatt plants would be built in the next few years.

The power would provide new supplies of electricity for Indian tribes in the province, as well as for the U.S., Herbert said.

But the project would require numerous approvals, and there were indications this week that not many parties had been told about it. The International Joint Commission had not yet been notified, and neither had the Wisconsin Public Service Commission.

Among other matters, the International Joint Commission, based in Washington, D.C., has approval authority on water quality issues on water that bound the U.S. and Canada. The PSC approves transmission projects in Wisconsin.