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Digging Deep for a Greener Campus

A closer look at one U.S. college's big power move

Author JACQUELINE DETWILER

You’ll never see it in the recruiting brochures, but a coal boiler belching soot across an otherwise idyllic ivy-covered quad is almost as common a sight on college campuses as undergraduates and oak trees. That is, unless the college is Indiana’s Ball State University, which is in the process of installing the largest geothermal district-heating system in the U.S. By its completion in 2014, the environmentally friendly system will both heat and air-condition every building on campus using plain water that’s been pumped through some 3,600 underground boreholes, cutting the university’s carbon output by 85,000 tons and saving $2 million a year. Here’s how they’ll do it.

1 The system’s main elements are several "large-capacity heat pump chillers," which use the same technology as a refrigerator to make hot water hotter and cold water colder. The heat pump chillers then move the water around campus, transferring energy (heat) from places where it is no longer needed (the cafeteria kitchen) to places where it is (residence halls).

2 During summer months, the heat pump chillers reroute some of the hot water into boreholes that reach 400 to 500 feet into the earth. On its journey, the water cools, returning to the surface at 55 degrees. It can then be used to cool classrooms.

3¬†The reverse happens in the winter. Cold water, around 42 degrees, is heated to 55 degrees by the earth’s energy while it travels through the boreholes. The heat it picks up is amplified by the heat pump chillers and sent out to warm up shivering students.

ILLUSTRATION BY JAMES PROVOST

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