By Josh Perry, Editor
Boston University (Boston, Mass.) began construction on its new Data Sciences Center on the corner of Commonwealth Ave. and Granby St. and one goal of the project is to make it the largest building in the city to be heated and cooled by geothermal energy.
The first new geothermal wells have been drilled into the subterranean layers of the new BU Data Sciences Center site. (Chris Kenney/Boston University)
According to a report from BU, the center will not be the first building on campus to use geothermal energy, but the 17-story building will need upwards of 30 wells, five times as many as the other BU building using geothermal energy. The wells are being dug at a depth of 1,500 feet where the temperature of the ground is 50-60°F.
A closed-loop piping system will circulate fluids through the building. Heat will be extracted from the fluid in winter and will absorb heat from the building during the summer.
Geothermal systems can be expensive, especially for larger building projects, but BU is testing three methods for drilling wells to evaluate the thermal performance of the well sites. The first two drilling methods turned out to be louder than expected but the third technique, which is supposed to kick off this month, will be substantially quieter. Noise reduction comes from different equipment being used as well as the location, which doesn’t have alleys to amplify the sound.
“The test wells—which are nearly a third of a mile deep yet only six inches wide—will reveal which of three different drilling methods performs best,” the article explained. “The first two wells were created by drilling methods that use compressed air to clear the borehole of bedrock ‘cuttings’ and groundwater—the first well was dug using drilling fluid to keep the borehole open while the second was not. The third test well will be installed using water to clear the bedrock debris cut by the drill bit.”
The first well needed three weeks to be completed, but the second took only four days. In addition to the speed of the process, the tests will show which technique drills the straightest boreholes.
According to the article, “The team will lower sensors into each of the wells to take measurements of ambient underground temperatures every 100 feet…They will also measure thermal conductivity and borehole thermal resistance, which will allow them to estimate the heating and cooling capacity of the planned wellfield.”