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A close-up look at Carleton’s wind turbines

When winter winds bite and your fingers freeze in the bitter cold of the Minnesota February, you can find solace in the fact that the gust of wind that just knocked the air out of your lungs is in fact powering about 40% of Carleton’s total electricity load, according to the Facilities Management’s fact sheet on the college’s wind turbines.

Carleton is the proud owner of two wind turbines, 1.65 and 1.6 megawatts respectively, that reduce the college’s CO2 emission by 1.5 million tons over its 25 year life-span, according to Facilities Management. With approximately 6.6 tons of greenhouse gases emitted per person per year and about 82% of those emissions created from burning energy to power electricity and cars, Carleton’s sustainability efforts make a real difference on campus.

According to the Department of Energy, wind turbines convert wind energy into electricity by capitalizing on the aerodynamic force from the rotor blades as the difference in pressure on the sides of a blade simultaneously causes lift and drag. Since the lift is stronger than the drag, the rotor, connected to a generator, begins to spin, producing electricity.

Carleton’s first wind turbine was erected in 2004 and its second was built in 2011. The turbine costs $1.8 million, which Carleton is covering using college funds and a Minnesota Department of Commerce $150,000 grant. Xcel Energy Company buys the turbines’ energy at 3.3 cents per kilowatt-hour for all energy produced, with the 1.65 megawatt turbine producing 5,000,000 kilowatt-hours a year.

The second turbine was financed through a grant provided by alumni Richard and Laurie Kracum (both ’76).

According to Martha Larson, Carleton’s Manager of Campus Energy and Sustainability, plans to build more wind turbines are not in the near future.

“A lot will change with renewable energy when battery technology becomes truly commercially viable, when it becomes safe enough and small enough and affordable enough to be used en masse,” explained Larson. “For us, that would mean when the turbines are producing a lot of energy at night, which is when our loads are the lowest and we don’t need it all, instead of selling it back for this really cheap wholesale rate, we would store it in batteries and use it the next day when we need it. We’re keeping an eye on battery technology and energy storage technology of all types in general.”

“If such technology was available, then the college would only be faced with the siting issue, not the economic issue,” said Larson. Since wind turbines need to be close enough to the school to be tied into the electrical grid but far enough away that they are not close to a road or house, finding a location for the massive structure requires some creativity. Larson explains that the only available place would be in the Arboretum, which is not a truly available space as the college wants to maintain the natural environment and not install a huge, man-made object.

As for non-wind turbine related future plans, Larson said, “an obvious first step would be with energy conservation. We want to get LED lights in and upgrade mechanical equipment and controls.”

After conservation, Larson wants to focus on how to make more green energy.

“We have a 10 year old Climate Action Plan and we ended up doing very different things than we thought we might do. We’re working on what those next 10 years will look like now and our hope is that that can be a whole campus conversation, not just a Sustainability Office conversation. Since the last 10 years looked so different than we thought they would in 2010, we’re really trying to figure out how to plan for the next 10 years. I can’t wait to have those conversations and ask the campus what they want to see.”

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