First, Carleton College built a wind turbine on a field not far from its Northfield campus.Then St. Olaf College, the school's rival across town, countered with its own.

Now, Carleton wants to put up a second turbine.

Northfield has become, perhaps, Minnesota's Home of the Collegiate Wind Turbine, fueling student pride as well as a bit of friendly rivalry.

"To be honest, I don't really understand it," said Carleton grad Chris Erickson. But when St. Olaf's turbine went up in 2006, two years after its twin, some of his classmates said "St. Olaf is just copying Carleton."

The new turbine would stand near Carleton's recreation center. It could start spinning as early as October if plans go forward, but factors such as obtaining permits could push that back to 2010, the college said.

It's not a competition, said Erickson and others at both schools. The colleges share an interest in renewable energy, and they've traded ideas about the turbines. But with two colleges in town, it's a safe bet that students spend a fair amount of time comparing sports teams, school rankings -- and wind turbines.

One point of debate: St. Olaf's turbine looks taller because it stands near campus buildings instead of in a field. "Early on, we heard rumors that Carleton students thought we put up a bigger one to show them up, but the truth is they're the same model," said Pete Sandberg, St. Olaf's assistant vice president for facilities. "It would be fairly easy to perceive that ours might be bigger, but they're the same."

The first two turbines are indeed the same height -- 370 feet. But there is one major difference: The electricity from St. Olaf's flows directly into college buildings, while Carleton sells its wind power to Xcel Energy.

The turbines have become beloved landmarks for both colleges. "Once we put up the first one and it kind of became Carleton's thing, people really fell in love with it," said Erickson, who now serves on the college's environmental advisory committee.

Carleton's turbine is a marker for students when they go running. St. Olaf students driving back to school know they're almost home when they spot their turbine's blades from the highway.

But there's plenty of sky to share, said Lisa Foster, a St. Olaf senior. "If Carleton gets another wind turbine, that's great, because it's saving carbon for all of us."

Carleton has been looking into a second turbine for a while, but demand is so high that few makers are willing to bother with a client that wants just one, said Rob Lamppa, Carleton's director of energy management. "They'd love to sell you 50 or 20 or 100."

That's slowing down some Minnesota colleges that want turbines, he said. Right now, the University of Minnesota-Morris and Macalester College in St. Paul are among those that have them.

The push to build Carleton's new turbine, which would be smaller than the first, but send power directly to the campus, gathered steam when a donor expressed interest in helping foot the $2 million bill, Lamppa said.

The college has asked Northfield to change its zoning rules to allow the turbine, which would be within city limits near the intersection of Hwy. 19 and Spring Creek Road.

St. Olaf's turbine, which supplies about a quarter of the college's electricity, isn't getting a companion anytime soon, Sandberg said. "We put enough cable out to this one to be able to do two more, but for us, already, winter evenings with good wind, our machine will run the whole campus and generate excess power."

Sarah Lemagie • 952-882-9016