r: Were you intimidated by a campuswide installation?
LOWE: We started doing some research and talked to the U.S. Department of Energy, Oak Ridge National Laboratory and the National Renewable Energy Laboratory. This eventually led us to a consulting firm [MEP Associates, Eau Claire, Wis.] that understands how to design a geothermal borehole field for the actual closed-loop installation that would be inserted in the ground. We started coupling all information together to determine we could convert our campus to a hot-water-based heating system. In other words, we’d no longer need to make steam. We would make hot water directly from the geothermal by means of York heat-pump chillers that are not much different than a typical chiller that has a compressor, evaporator and condenser.
r: Can you explain how heat-pump chillers work?
LOWE: A typical chiller is a compressor system much like your refrigerator. What we bought is your refrigerator on steroids. We’re extracting heat from the air stream and it’s picked up in a refrigerant cycle. In your refrigerator the heat is blown out the back of your refrigerator through a blower blowing across the coil that contains your refrigerant. The only difference in a big system like ours is it’s not air blowing across the coil; it’s hot water.
Heat-pump chillers and a massive distribution system make geothermal very efficient for a campus because we
have multiple buildings, each with a different heating/cooling need at any given moment. All we need to do is reach into the building with an extended new infrastructure so hot water can supply the buildings and tap into our existing system to heat or cool it.
r: Were there any concerns that geothermal wouldn’t meet your needs?
LOWE: We knew with geothermal we’d be making 150 F water. A lot of campuses, including Ball State, had built systems around the need to ratchet your water temperature up to perhaps even 180 F to sufficiently heat a building when it got terribly cold. We knew there was another piece of equipment that was much more expensive to buy and more expensive to operate that can produce 170 F, but there’s not many of them out there and we didn’t want to install that type of equipment without some history behind its use. About three years ago—before the geothermal—we limited our supply reset temperature inside every one of our buildings to 150 F. We wanted to find out if this would work by trying it for one winter, and we didn’t have any trouble. We will maintain a natural-gas-fired steam system as backup for the geothermal if for some reason it can’t keep up with that 150 F water.
r: Why is all of campus currently being cooled with geothermal but only half of campus can be heated with geothermal?
LOWE: We currently don’t have a complete hot-water distribution system; it’s still steam-based. We do have a complete chilled-water distribution system so we’ve been successful in installing the infrastructure to connect up to 50 percent of the buildings on campus but that other 50 percent have no hot-water infrastructure to them. We’re heating close to half of campus with hot water made from the geothermal process and we’re cooling all of campus with this system. As we obtain the funding, we’ll convert the rest of campus to hot water geothermal.