Rob Hanson quoted in Star Tribune piece on geothermal innovation from Minnesota college campuses
Hanson is manager of campus energy at Carleton.
Rob Hanson, manager of campus energy, is quoted in a Star Tribune piece titled, “Minnesota college campuses lead the way on geothermal innovation.”
A heating and cooling pilot project at Macalester College could illuminate a new way to heat and cool in the urban core.
Other colleges and universities, such as Princeton University, Cornell and Carleton College, heat their campuses with thermal energy networks. Rob Hanson, manager of campus energy at Carleton, said it is easier to incorporate thermal energy networks on campuses than in other locations where individual buildings are privately owned.
Carleton was the first college campus in Minnesota to switch to geothermal heating and cooling. Since 2020, 75% of the campus has been connected to a geothermal district energy grid. The campus still burns natural gas when temperatures dip below about 20 degrees, but their natural gas use has decreased by about 70%, according to Hanson.
Instead of the Darcy method, which was not yet available when Carleton began its project, the campus used a geothermal exchange system that pumps water through a system of underground pipes. Carleton’s geothermal system required digging 95 horizontal trenches, which are 510 feet long and 15-30 feet deep, and 211 vertical holes, which are 520 feet deep. After digging, the school installed loops of pipes, which use water to carry energy from the soil to buildings.
While a geothermal system like Carleton’s would not be impossible in an urban setting like Macalester, the costs to install traditional geothermal systems on limited land masses may be prohibitive, Ed said. Carleton, in Northfield, sits on about 1,000 acres of land while Macalester covers only about 60 acres. The Darcy system makes geothermal energy more accessible in tighter urban settings.
Carleton installed Darcy wells in August to heat four residential buildings that were not connected to the geothermal grid. The college plans to continue expanding its geothermal system by updating buildings to interact better with the geothermal system and incorporating any new buildings to the grid.