And next week, a device that looks a bit like an eggbeater turned sideways will be lowered into the water here to catch the energy of the rushing water, spinning a generator that, come September, is scheduled to begin sending power to the grid.       

It is an experimental, expensive and promising project, fueled by the knowledge — shared by Roosevelt, who spent summers across the bay on Campobello Island, and modern engineers — that the tides here are both powerful and predictable.       

“When the wind blows, you get electricity, but you don’t know when that’s going to be,” said Chris Sauer, the chief executive of the Ocean Renewable Power Company, which built and will operate the turbine generator unit, called TidGen.       

The Bay of Fundy has some of the world’s highest tides, causing extreme currents that are pushed even faster by the inlets and islands that speckle this rocky coast. They will propel the turbine’s blades, which twist around like the helix shape of DNA.

“Another advantage is, you don’t see a thing,” Mr. Sauer added, speaking to a criticism that has dogged many wind farms.       

When this project starts delivering electricity to the grid under a power-purchasing agreement, it will be the first tidal-power turbine to do so in the United States, says Steven G. Chalk, the deputy assistant secretary for renewable energy. The Department of Energy has put up $10 million of the roughly $21 million in costs, hoping that tidal power can establish itself as part of the country’s arsenal of energy alternatives.       

“It’s a big milestone for our water power program, where we’re getting something in the water that’s grid-connected,” Mr. Chalk said. “A big demonstration, under real operating conditions.”       

The first turbine generator unit has a maximum output of 180 kilowatts, which would power about 30 homes. That is one-sixth the output of a typical wind turbine, although TidGen will turn more than a wind turbine, since the currents will push more consistently than wind.       

The company plans to add two more turbine generators. If they survive, they are considering another stretch of water, where the current moves even faster, for an array that could hold up to 18 additional generator units.       

When the whole project is done, projected for 2016, the array could power up to 1,500 homes, Mr. Sauer said.       

This 1,322-person city, accessible only by hundred-mile ribbons of two-lane highways, has been waiting for years to become a renewable-energy laboratory.       

“We’ve got deep water,” said Robert Peacock, the City Council president, who has lived in this region for much of his life. “That’s the best thing we’ve got.”       

On a recent summer evening, Mr. Peacock, who is also a harbor pilot, and a power company official drank pisco sours with their wives on the deck behind his house, watching bald eagles nest and awaiting Sergio Versalovic, a marine energy specialist arriving from Chile to view the installation site. Chile is one of many foreign countries interested in how the Maine experiment might work in their own waters — Mr. Versalovic said the Straits of Magellan could be a good candidate.       

The deep water of this coniferous coastline has already given the city’s port a steady stream of shipping traffic. But the effort to use it to produce energy has a choppy history, and for some residents the current project is unfolding in its shadow.       

A large model of the Depression-era Passamaquoddy River Project is preserved in a storefront museum on Eastport’s tiny main street. Roosevelt championed the endeavor, often called the Quoddy Dam.       

The model is the ghost of a failed idea. Initial construction on the Quoddy Dam began in 1935, but the project died a year later when a Depression-weary Congress refused Roosevelt’s request to continue financing it.       

Joyce Kinney, 87, who was born here, remembered how an estimated 5,000 workers and their families came from all over the country when she was in grade school, hoping to get construction jobs on the project’s first phases. Her father was a city official at the time.       

“People had gotten courage from the building of the dam,” she said. “They had started painting their homes, and fixing up things that were falling apart.” When the project ended, the city fell into bankruptcy.       

The project would re-emerge: John F. Kennedy’s administration studied the possibility of continuing it, and President Jimmy Carter later considered the idea. But it was never restarted.       

“It’s kind of like a vampire — put a stake through its heart, and it just doesn’t die,” said Wayne Wilcox, 58, a bus driver who has studied the project for Eastport’s Border Historical Society.       

Mr. Peacock, the Council president, said: “All my life I’ve heard about it. Now we’re seeing a new one, and maybe it will work.”       

The rate set by the Maine Public Utilities Commission for power generated by the project is 21.5 cents per kilowatt-hour for the first year — about 8 cents higher than the average rate here. Mr. Sauer says he expects the price to fall as the company perfects its technology, moves out to speedier water and lowers its operating costs.       

And officials will have to keep a careful eye on safety concerns, the chief issues being the turbine’s effect on sea life and the possibility that anything dragged by boats could be snagged on it.       

A handful of other companies are developing their own tidal power projects, like Verdant Power, which has tested turbines in the East River.       

But for now, to some in this city, jaded by the failure of the Quoddy Dam, the project offers a moment to marvel, if guardedly.       

“It’s almost miraculous to me that they can do what they’re doing,” Ms. Kinney said. “The tides are terrible, have terrible force. To me, it’s almost an unbelievable concept.”       

 Story by Jess Bidgood

 This article has been revised to reflect the following correction:

Correction: August 10, 2012

An earlier version of this article misstated the location where Verdant Power has tested its turbines. It is in the East River, not the Hudson River.