For 82 years, Ford has powered its St. Paul assembly plant with Mississippi River water. The water rushes over Lock and Dam 1 into Ford's hydro plant, which generates electricity.
The U.S. Army Corps of Engineers finished the dam in 1917 with an attached platform, which was built in anticipation of hydro power.
No one from Ford agreed to be interviewed for this story. But in June 2004, Minnesota Public Radio spoke with company manager Ron Gray about Ford's history with the hydro plant.
"The St. Paul city fathers at that time ventured to Dearborn, Michigan, to talk to Henry Ford, and offered this site as potential, as a manufacturing facility with the benefit of the hydro power."
Henry Ford was sold on the promise of cheap power. The company closed down its Minneapolis factory, where it had been since 1912, and moved across the river to its current site in St. Paul. Ford finished construction on the hydro plant in 1924.
While other Ford plants have been built on or near rivers, Gray says the St. Paul plant is the only one in the Ford system using hydro power.
"Comparing ourselves to other facilities, that is one thing that's really on our side, is a clean, renewable source of power at relatively cheaper cost," says Gray.
The hydro plant cost Ford just over $1 million to build 82 years ago. It currently produces a maximum of 18 killowatts of energy, more than enough electricity to power the assembly plant.
In fact, the plant uses about 13 killowatts total. The rest is sold back to the grid, to Xcel Energy. To get an idea of how much electricity that is, 13 killowatts could power up to 10,000 Minnesota homes for a year.
With the cost of building the hydro plant long ago paid for, Ford essentially powers its plant for free, and also makes money from selling the excess power. Ford's records say the hydro plant provides a $4 million direct benefit to the assembly plant each year.
"That's what brought Ford Motor here in the first place, and that could be the asset that keeps Ford Motor here in the long run," says Michael Noble, executive director of Minnesotans for an Energy Efficient Economy, a environmental policy think tank.
Noble says the hydro plant is a compelling reason why Ford's St. Paul assembly plant is the perfect place to manufacture the kind of car he says everybody wants -- fuel efficient and environmentally sound.
"If I were a CEO of an auto company, I would be marketing this renewable energy car of the future -- that it not only runs on renewable energy, it's made with renewable energy," says Noble.
That kind of talk encourages auto workers who are trying to save the assembly plant. Auto analysts say the facility is vulnerable for closure because sales of the Ford Ranger truck, which is built there, declined 23 percent last year.
Rob McKenzie, president of the United Auto Workers Local 879, says the workers have brought up the clean energy angle with Ford management.
"Ford Motor Company is in the process of changing from an automobile manufacturer who was identified primarily with big trucks and big SUVs, to one that is more associated with small cars, flexible fuels and ecologically friendly vehicles," McKenzie says. "And we think that lines up with a lot of the strengths of our plant."
Starting with hydro power. McKenzie ticks off a handful of other environmental measures at the plant, including wastewater treatment and conservation. McKenzie says the plant is truly "green," and deserves Ford's consideration to build the car of the future -- a hybrid that runs on electricity and alternative fuels like ethanol.
McKenzie estimates it would cost Ford between $500 million and $750 million to refit the plant with flexible manufacturing equipment to make a new product.
"What we're asking for, of course, is not something little," McKenzie says. "We're asking for something very big, in terms of new investment and new product."
Ford officials say they're reviewing the union's proposal. But they aren't saying much more than that about either the ethanol hybrid or hydro power, and how they fit in to Ford's future plans in St. Paul.