The Geothermal Heating Resource for Cornell University, Tompkins County,
New York: Exploiting and Analyzing Available Geological and Geophysical
Data Sets for Pre-Drill Site Characterization
Abstract
Cornell University aspires to fully heat and cool its main campus with
renewable energy. Cornell is a 30,000-person community, in
>14 million ft2 of buildings, that annually consumes
~240,000 MWth-hrs of heat. Successful geothermal
district heating at Cornell would provide a model for other communities
in the cold-climate Northeast U.S.. A geothermal Play Fairway Analysis
(GPFA) of the sedimentary aquifer geothermal potential of the
Appalachian Basin (https://bit.ly/2JHOiVH) for NY, PA, and WV
demonstrated that Cornell’s campus is located in a favorable sub-region
of the basin. The GPFA found that, for Cornell, the expected rock
temperature at 3 km depth was 70–85°C, with suitable natural
permeability in sedimentary units most likely near 2.4 km depth;
indirect indicators of the propensity for induced seismicity revealed no
unusual risk. In 2017-2018 we have used geological and geophysical data
sets to more robustly analyze the nature of the geological resources,
their potential fit to the heating needs, and risks. Data for deep wells
in Tompkins County and six abutting counties, archived in New York’s
Empire State Organized Geologic Information System, improve the thermal
resource estimate. Within 20 km distance, one well log, assumed
equilibrated, lists 118 °C rock at 3369 m depth, and another borehole
lists a non-equilibrated 93 °C at 3600 m. These underpin revised Cornell
temperature-at-depth estimates. Sedimentary reservoir data for units
from the Ordovician Trenton Formation to the top of metamorphic basement
are under evaluation based on gamma, neutron, sonic and density logs.
The estimated depth to the basement is 2865 +/- 200 m. We are evaluating
potential reservoirs within basement rocks for heat extraction using
Enhanced Geothermal System techniques. Direct basement data are limited
to petrology of cuttings from 5 wells. For pre-drill analysis, those
data are supplemented by analogous metamorphic rocks in the Adirondack
Mountains; we assume a mixture of granitic gneiss, marble, amphibolite
and/or anorthosite. Fracture aperture, spacing, and orientation
dispersion are estimated based on observations in the southern
Adirondacks, to which fracture analysis based on high resolution DEMs is
being added. Seismic, gravity and magnetic field studies of potential
well field sites are in progress.