Advancing geothermal exploration at Cornell University

Wanted: a carbon-free energy source with which to heat buildings in populated regions with cold winters.

That is the challenge being tackled by Cornell University as it assesses Earth Source Heat, a vision to heat campus using geothermal energy. A busy year of progress was powered by expertise and efforts within the Department of Earth & Atmospheric Sciences.

Throughout summer 2022, five EAS faculty members, five graduate students and five undergraduates—the students mostly affiliated with EAS—put their efforts to drilling and testing a geothermal exploration well on the Cornell campus. The Cornell University Borehole Observatory (CUBO) was drilled between June 21 and August 13 to a depth of 9,790.5 feet (2,984 meters) and then probed and tested between August 13-21. Monitoring of local seismic activity and surface and shallow ground water that had begun a few years in advance persisted throughout the summer. Petrology, stratigraphy, hydrogeology, seismology, thermal geophysics, aqueous geochemistry, petrophysics: the earth science topics involved daily in the CUBO project read like a catalog of geosciences subdisciplines and drew EAS students and faculty into the heart of a university-wide team working toward Cornell’s sustainable energy transition.

CUBO was funded in large part by a U.S. Department of Energy (DOE) contract, led by Professors Jeff Tester (Chemical & Biomolecular Engineering), Patrick Fulton (EAS) and Teresa Jordan (EAS), and integrally assisted by geologist J. Olaf Gustafson EAS Ph.D. ‘20. Cornell University’s Facilities and Campus Services and central administration stepped in to fill the gap when inflation, supply chain and work to ensure community acceptance drove up the price tag. With the leadership and hands-on efforts of numerous staff well versed in Cornell Facilities’ business and operational practices, partnering with faculty, the project succeeded.

Planning and Monitoring

CUBO was selected for DOE funding after a decade of studies of the potential for direct-use applications of geothermal heat in which Jordan, the J. Preston Levis Professor of Engineering Emeritus, and her students were central figures. That work provided a firm grasp on what to expect of the sedimentary rocks and heat below Cornell’s campus but lacked any firm data for the basement rocks or for the capacity of the rocks to transmit water, an absolute key to extracting heat from the rocks. The background information allowed design of a well with a diameter and structure of steel casing that would be adequate to provide the missing data and later function as an observatory.

Fulton, an assistant professor and a Croll Sesquicentennial Fellow, was the faculty lead on the mechanical, hydrologic and thermal features of the design, which culminated in hydrologic and stress testing as the last step of CUBO’s summer work. This fall Fulton will begin to monitor the subsurface conditions using a fiber optic cable that will monitor temperature throughout the borehole over time. Those data will reveal if and how fluids in the subsurface move naturally and, if more wells are drilled for the ESH project, how the subsurface responds to the activities conducted in those nearby wells.

Starting in 2015, EAS professors Kade Keranen, Larry Brown and Matt Pritchard had begun monitoring of background seismic activity in the Ithaca area, which led to installation of 15 seismograph stations. Supervised by Professor Geoff Abers, an independent firm submitted a weekly report on seismic activity within the network while CUBO was drilled, which was shared with the public. A few years in advance of drilling, Gustafson organized drilling and sampling of water monitoring wells around the future CUBO borehole, and in 2022 began surface water monitoring of nearby creeks. Assistant Professor Nicole Fernandez oversaw the monitoring and analysis of creek samples while CUBO was drilling, as well as participating in the chemical assessment of water from CUBO sampled in the final steps of the summer project.

Drill Site Operations and Student Participation

Cornell contracted with Capuano Engineering Company for design and oversight of the construction of the observatory, Precision Drilling for the equipment and personnel to drill, and Schlumberger Well Services for services ranging from design and management of the drilling mud, to drill bits, cementing of casing, geophysical logging and much more. This set of companies brought dozens of seasoned professionals to the CUBO site at various times during the final steps of planning and execution and kept the operation always moving 24/7 on a staff of at least 10 people.

A key service line that operated full time was “mudlogging”—the monitoring and documentation of all the solids, liquids and gases that came out of the borehole. Mudlogging was staffed 24/7 by Cornell students, working as assistants to a professional Schlumberger mudlogger. The Capuano supervisor, the Precision drillers and the Schlumberger mud engineers relied on continual real-time reports from the mudloggers to adapt to changing rock and fluid properties, and the students learned from those professionals about career, life and the energy industry. The seven Cornell students on shifts—Sean Fulcher, Daniela Pinilla, Roberto Clairmont, Ivan Purwamaska, Juliette Torres, Madeline Fresonke and Reeby Purthur— had the messy job of catching the mud-drenched rock cuttings at the filtration system where the borehole mud was separated into two streams, rock waste and viscous fluid. The students cleaned the samples, catalogued them and assisted with several of the analysis steps.

Throughout the summer, EAS undergraduate Zach Katz reviewed the weekly seismograph data providing an initial quality control check. Summer student trainees Eric Negron Alvarez and George Scheibler collected and analyzed water samples and daily water quality measurements from Fall Creek and Cascadilla Creek.
Former Cornell EAS students also played much appreciated roles. Noteworthy cases were Tomás Zapata Ph.D. ’89 and John Guffey M.Eng. ’00, who used their professional networks and their personal experiences to help the CUBO project team to make sensible decisions and overcome challenges.

Public Interest and Outreach

CUBO was a tremendous opportunity for public education about geology and what lies below everyone’s feet because it was highly visible and because word of activities spread quickly across the community. Professor Jordan worked closely with experts in public education from the Ithaca community—Deborah Hoard of Photosynthesis Productions and Paleontological Research Institution’s (PRI) education leaders Drs. Rob Ross and Don Haas—to produce and release a steady stream of daily progress reports and weekly explanations of the scientific and engineering steps. Faculty members Jordan, Fulton, Abers and Fernández were each featured in a series of weekly videos the Cornell’s central communication unit released to inform the local community (https://EarthSourceHeat.cornell.edu). Graduate student Clairmont starred as one of two regular hosts in videos about CUBO developed by this educational outreach team (https://deepgeothermalheat.engineering.cornell.edu/), while graduate students Pinilla and Fulcher each took a turn as the Earth Source Heat weekly interviewee, describing well cuttings and the role of fractures in water flow, respectively.

An especially close connection to public curiosity was possible via a weekly “office hour” to which the community was invited, adjacent the CUBO fence with a great view of the action. Each week about 20 people came and peppered project staff members with questions. The reutilization of the educational materials created leading up to and during drilling for K-12 teacher education continues, led by our PRI collaborators.

Geological education and energy business education also turned inward at Cornell. Drilling a borehole is far outside of Cornell University’s normal business practices. The facilities staff, most of whom are engineers or contracting specialists, picked up a lot of earth science knowledge as well as an understanding of the technical and financial risks embedded in the energy business.

Ongoing analysis and utilization of the new understanding in ESH analysis
The drill rig is gone and the camaraderie of “summer camp” at CUBO is a memory. Yet the work to maximize the value of the data from CUBO is intense. Supervised principally by Professor Fulton, geological sciences graduate students Pinilla, Clairmont, Fulcher and Purwamaska each is responsible for an initial research theme that is based on CUBO data: in situ stress, hydrogeology, fracture characterization and thermal conditions, respectively. Their efforts develop both a better fundamental understanding of subsurface behavior and provide vital input to ongoing evaluation of the next steps for Cornell’s Earth Source Heat program.