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The Carletonian

Facilities to construct geothermal wells

<rting next summer, Carleton will begin construction to transition the steam heating system it currently uses to a hot water based one.

The project will involve installing underground geothermal pumps under the Bald Spot, the Mini Bald Spot and Bell Field, which will be able to support both the heating and cooling systems. In the current steam heating system, natural gas creates steam, which is piped to campus buildings to heat water in radiators.

In the new system, however, only water will be used, making it much more efficient. When water is not used, it will be stored in the geothermal wells, where the temperature of the Earth, around 50˚ Fahrenheit, will naturally heat or cool the water.

According to Martha Larson, Manager of Campus Energy and Sustainability, the new system, once completed, will save 30 to 40 percent  on operating costs and reduce carbon emissions by over 35 percent. Because the new system does not require that water be heated up as much as in the steam-based system, less energy is needed to operate it and this energy can be produced in more efficient ways.

“With steam, really your only option is burning a high heat content fuel like coal, natural gas or oil, whereas with hot water you can use other things” Larson said. “You can use geothermal, which is what we’re going to do. You can also use solarthermal; we will tie the Cassat-James solarthermal panels into the system and any other future technologies are more likely to work with this system.”

“The addition of the geothermal, or ground source heat pump, system allows us to use the underground as a heat source in the winter and a heat sink in the summer,” said Professor of Geology Mary Savina. “Rather than actively using energy to make things hotter or cooler, this system is less energy intensive.”

Larson also said that the new system will make use of water more efficient.

“The cool thing about that is now that we have a water loop on the heating side, it can communicate with the water loop for our cooling side,” she said. “Our cooling system has always been chilled water, but now, when we have to eject or reject heat from the chilled water to make it colder, we can move that heat right into the hot water side and reuse it.”

Larson said that this new efficiency fits into the Climate Action Plan, which mandates that Carleton will go net carbon neutral by 2050.
“We see it as a combination of us reducing our emissions, like we are with this plant, and us buying carbon offsets,” she said.

The geology department has been involved in the planning of the heat pumps. In Savina’s Introduction to Geology class, students analyzed where heat pumps could be placed on campus. Geology professors have also advised Facilities on specific geologic and hydrologic conditions. According to Larson, Facilities even used a 1981 Comps project by Sarah Godfrey ’81 that documented the geology of a boring done in the Cowling tunnel.
Going forward, Savina said that the geology department will have the opportunity to take advantage of the heat pumps.

“We will have opportunities to monitor how well the system functions, how it is affected by the geologic and hydrologic setting and many other things,” Savina said. “I envision projects for both introductory geology classes and for hydrology as the project moves forward. One of the pleasures of teaching at Carleton is the opportunity to have students work on projects that help the campus and larger community, while at the same time helping students learn methods and content appropriate to the course.”

According to Director of Facilities Steven Spehn, the new system will be installed over four years, with work being done only in the summer because construction can only happen when heat is not in use. The construction will also happen in tandem with the new science complex, which will house a sub-basement satellite plant that will contain geothermal heat pumps.

Spehn said that along with the construction of the geothermal wells, work will have to be done on all campus buildings to convert them to the new hot water system.

“When we convert from steam to hot water, we have to make mechanical conversions inside the buildings, and some are more involved than others,” Spehn said.

This summer, Spehn said, work will begin to drill wells on Bell Field and the mini Bald Spot, and mechanical conversions will be done in Myers, Evans, Cassat and James.

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