system like ours is it’s not air blowing across the coil; it’s hot water. Heat-pump chillers and a massive
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.
understanding that the existing boilers were reaching 70 years in age.
R:
Where did the idea for geothermal come from?
LOWE: Our boilers were old, so they’re capacity was reduced, we couldn’t get parts and we have EPA regulations to fol- low. We knew it was time for a replace- ment. We looked at options and felt like the prudent approach was to install a boiler that would eventually allow us to go to 100 percent renewables. We were going to start out with a pretty healthy percent- age of coal and 30 percent renewables though we hadn’t totally identified what the renewables would be. At that point, we discovered the costs were escalating beyond our appropriation; we couldn’t af- ford our equipment with what needed to be done to replace it. We evaluated going totally to natural gas and our first option, which was the solid-fuel-burning boiler that would someday burn 100 percent renewables. When we started throwing out renew-
able ways to heat the buildings the discus- sion led to geothermal. Geothermal would allow us to replace the four coal-fired boilers and it also would allow us to reuse valuable thermal energy that we previ- ously were throwing away, namely heat from the chilled water side that could be used to make hot water.
R:
Were you intimidated by a campus- wide installation?
LOWE: We started doing some research and talked to the U.S. Department of
18 RETROFIT // September October 2012
Energy, Oak Ridge National Laboratory and the National Renewable Energy Labora- tory. 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 infor- mation 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 geother- mal 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
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 geo - thermal wouldn’t meet your needs?
LOWE: We knew with geothermal we’d be making 150 F water. A lot of campuses, in- cluding 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 equip- ment 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—be- fore 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.
only half of campus can be heated with geothermal?
R:
LOWE: We currently don’t have a com- plete 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 infra- structure 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 cam- pus to hot water geothermal.
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Why is all of campus currently being cooled with geothermal but