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Fifteen years after installing its first wind turbine on a hill above campus, the University of Minnesota, Morris this summer became one of the few colleges in the country to become carbon neutral in electricity use.

The western Minnesota campus now produces the most electricity on site per-student in the United States, according to a report from advocacy group Environment America.

With two wind turbines, a smattering of solar panels and a few other green power sources, the school generates about 60% of the energy it uses, said Bryan Herrmann, vice chancellor for finance and facilities.

"We've been working on this for more than a decade," Herrmann said. "What's unique for us is that while a lot of other schools are buying renewable energy off-site, we're generating it right here. You're able to see the turbines on the hill spinning and producing the power you're using for your laptop."

Becoming carbon neutral is not the same as being carbon-free.

About 70% of the school's power comes straight from renewable sources such as wind and solar. But on cloudy and windless days the campus still needs to buy electricity from the grid from coal or natural gas plants.

When the wind is blowing and the sun is out, the campus generates much more power than it needs, pumping electricity back into the grid. The campus is "carbon neutral" because it is putting as much excess renewable energy into the system on windy days as the carbon-based energy it is taking from the grid on windless ones.

Now that the campus is neutral in electricity use, its goal is to become completely carbon neutral, Herrmann said. That would entail eliminating or offsetting greenhouse gas emissions from cars, buildings, heating systems or any other source.

The Morris campus has long been on the leading edge of renewable energy use and research. The hope is to become a model and provide a framework that other rural communities and college or corporate campuses could follow to cut carbon use, Herr­mann said.

"Can everybody put up two wind turbines? Maybe not," he said. "But solar has become so much more affordable and utilities have moved so much that there are opportunities out there to lessen the carbon footprint."

The university's two wind turbines produce more than 10 million kilowatts of power each year, about half of which is used on campus while the other half supplies the local power grid.

The major question in renewable energy is whether technology can develop fast enough to store excess energy to use on days when wind turbine blades are still. If the energy can't be stored — or transported from across the country — at a certain point it doesn't matter how many turbines or solar panels are installed on a campus. That campus would still rely on traditional power plants to get through about 30% of the year when the clouds are out and the air is still.

Researchers at the university have been testing methods of using wind power to create hydrogen and ammonia, which can be stored in tanks and used later as energy sources. They've been trying to find ways to more efficiently heat and cool buildings and capture steam from biomass such as corn cobs and wood chips.

"Getting that last 30% is really challenging," Herrmann said. "But that's what we're trying to do with our 'Morris Model': to keep thinking about how we can store energy, and to demonstrate how we can cut down on waste and be as efficient as possible with the energy we use."

Greg Stanley • 612-673-4882