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Carleton on track to meet interim emissions goal as geothermal project enters second phase

For the first time in over a century, Carleton’s utility system received a makeover. Starting in the summer of 2019, a new geothermal energy system has been providing heating, cooling and hot water to all east campus buildings, from Anderson Hall to the Recreation Center.

The system’s implementation culminates Phase 1 of the project: constructing the East Energy Station in the basement of Anderson, converting east campus systems from steam to hot water heating and drilling three bore fields on Bell Field, the Mini Bald Spot and the Bald Spot. Phase 2 will entail updating the west campus mechanical systems, such as tunnels, pipes and radiators, as well as converting the central facilities plant from steam to hot water. By the fall of 2021, the geothermal system will heat and cool the entire campus, fully replacing a steam heating system that was installed in 1910.

Construction of the geothermal system is the hallmark of the Utility Master Plan (UMP), which was developed to replace outdated equipment and push Carleton towards its goal of net zero carbon dioxide emissions by 2050. Carleton seems to be on track to hit its first interim goal: reducing emissions to 17,000 MTCDE (metric tons of carbon dioxide equivalent) by 2020. Sustainability Program Coordinator Alex Miller reported that “for the 2019 fiscal year, our net emissions were at 17,363 MTCDE, and we expect to see a dip in our emissions when Phase 1 of the UMP is counted.” In part, this comes because the new system transitions towards relying on electricity instead of natural gas. “We’re betting on electricity as a greener source of energy,” said Miller.

The geothermal system—technically called a ground source heating and cooling system because it doesn’t draw all its energy from the earth—uses hot water to transfer heat. The ground acts as both a “sink” by storing and transporting hot and cold water, and a “source” by heating and cooling the water in the bore fields. A heat pump in the East Energy Station accumulates the heated water, cooled water, and geothermal water; from there, the pump distributes it where it is needed. Martha Larson, the Manager of Campus Energy and Sustainability, noted that the campus is an ideal place to implement such a system: “Carleton has great geology for geothermal bore fields. It was relatively easy to drill the bores, and we have very active groundwater flow under the surface. The bore fields are therefore very good at transferring heat.”

The UMP is both financially and environmentally sustainable. Construction of the geothermal system is the hallmark of the Master Plan (UMP), which was developed to replace outdated equipment and push Carleton towards its goal of net zero carbon dioxide emissions by 2050. Carleton seems to be on track to hit its first interim goal: reducing emissions to 17,000 MTCDE (metric tons of carbon dioxide equivalent) by 2020. Sustainability Program Coordinator Alex Miller reported that “for the 2019 fiscal year, our net emissions were at 17,363 MTCDE, and we expect to see a dip in our emissions when Phase 1 of the UMP is counted.” In part, this comes because the new system transitions towards relying on electricity instead of natural gas. “We’re betting on electricity as a greener source of energy,” said Miller.

Phase 1 of the UMP was completed between 2017 and 2019: constructing the East Energy Station in the basement of Anderson, converting east campus systems from steam to hot water heating and drilling three bore fields on Bell Field, the Mini Bald Spot and the Bald Spot. Phase 2, which will be underway from 2020-2021, entails updating the west campus mechanical systems, such as tunnels, pipes and radiators, as well as converting the central facilities plant from steam to hot water.

Jordan Shapiro ’20, a geology major who has been involved with the project as a Sustainability Assistant (STA), stated, “All the buildings are in communication, working together. Instead of just producing heat and producing cooling and losing all the excess, this new system ties all the buildings together.” Larson added, “When there isn’t enough waste heat to serve the total campus heating need, the geothermal loop contributes heat from the ground, which acts like a giant thermal battery.” If that still isn’t enough, two high efficiency boilers in the East Energy Station kick in on very cold days to provide energy, and existing chillers are used to provide additional cooling on very hot days.

Overall, about 70 percent of the energy for heating and cooling will come from the geothermal loop, with the other 30 percent from the boilers and chillers. In mild fall and spring weather, there is enough excess heat to recycle and the geothermal system can run on its own.

Along with being environmentally efficient, the UMP is financially sustainable. Construction of the geothermal system is projected to break even by 2037 as compared to what the steam plant’s maintenance cost would have been. The new system will help the College save money after that date too, a prospect which Miller said is unheard of for facilities projects.

The new system also distributes heat more evenly. Larson pointed to Skinner Chapel as an example; the steam system heated the Chapel with a series of small, hot radiators, whereas now, heat comes from panel radiation on the walls. “I think of it as wrapping the Chapel in a nice, warm blanket instead of stoking it with a series of red-hot campfires,” said Larson.

Larson noted that there have been a few challenges to implementing and controlling the new equipment, but that the facilities office has been committed to resolving them as quickly as possible. “Faculty, staff and students are often some of our best resources,” she said, “as they engage with the new systems and let us know when something doesn’t seem quite right.”

Faculty, staff and students have also been working closely with the project. Mary Savina ’72, Charles L. Denison Professor of Geology, said that the geology department has been involved at every stage, from providing research about the geologic conditions of campus to installing monitoring cables for future study. Savina and her colleagues Dan Maxbauer and Bereket Haileab have all taught about the project in their classes, and students Taiyi Wang ’19 and Natasha Dietz ’19 both studied the geothermal system for their comps projects. Jake Gallant ’21 is currently working to analyze data from the geothermal wells.

Savina noted the importance of involving students in the process. “I see this as part of an effort to connect Carleton students with the place where they are studying for four years,” she said. “It’s somewhat unusual to have close ties between the academic mission of the college and the facilities infrastructure. We are incredibly fortunate that Martha Larson and Steve Spehn in Facilities are eager to work with students.”

The Sustainability Office hopes to keep connecting with students by giving tours of the East Energy Station during New Student Week, Reunion and Earth Day. At the same time, the Office is expanding its outreach efforts. At the Upper Midwest Association for Sustainability (UMACS) conference in September, they presented to other schools who are thinking about transitioning to a similar energy system, answering questions and getting people excited about geothermal.

“We should embrace this historic transformation that Carleton is undergoing,” Miller said. “The last time we did something like this to our utilities was in 1910. It’s amazing that we are all here on campus witnessing history in the making!”

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