Frequently Asked Questions

Researchers at Cornell believe that Earth Source Heat holds the potential for a new sustainable, scalable solution to heating challenges throughout New York state and across the globe.

While Cornell is ultimately interested in reducing its fossil fuel footprint, the university is also keenly interested in understanding the impacts of technology choices like Earth Source Heat. Ongoing monitoring systems as well as the tests and measurements that will be conducted in the exploratory borehole will contribute to ensuring that the methods used to extract heat from deep within the earth do not created unacceptable risks or unintended impacts. Cornell scientists are committed to studying and addressing these issues in a thorough and transparent manner, developing best practices that will minimize risk and provide guidance for others who might implement this technology.

Cornell’s near-term goal is to drill an exploratory borehole that will allow scientists to better understand if the project is feasible by exploring deep surface rock conditions and heat output. If it is determined that the process could safely and effectively advance, the next step is to drill a demonstration well pair. Eventually, the university would hope to begin a phased process to create a full-scale system capable of heating the entire Ithaca campus.

Phase I – Cornell University Borehole Observatory (CUBO)

Earth Source Heat advanced for several years through acquisition and analysis of geophysical data, analysis of archived subsurface data from nearby oil and gas wells, and engineering-economic analyses. While the results were promising, the point was reached at which the technical feasibility of ESH could not be further evaluated without measurements of deep subsurface rock conditions, using an exploratory borehole.

In 2020, Cornell secured a $7.2M U.S. Department of Energy grant to drill a borehole to help verify the feasibility of using a novel geothermal energy system to heat its campus buildings. This grant will create a state-of-the art observatory, the Cornell University Borehole Observatory (CUBO), which will allow researchers at Cornell and from around the world to study the physical, geological, seismic and data science of the subsurface beneath Ithaca. What is learned through this exploratory borehole project will be used to make decisions about whether to move forward with additional wells in which to test geothermal water flow and heat extraction. Download a flyer (PDF) to learn more about CUBO.

The university anticipates breaking ground on the exploratory borehole in 2021-2022. The borehole will be located on Cornell-owned property, by repurposing a small facilities parking lot near Palm Road.

Cornell held a virtual community forum on Jan. 19, 2021 to provide additional details about the first phase of the project.

Phase II – Demonstration Well-Pair

If the exploratory borehole is successful, and funding and other necessary permits are secured, the university would next look to drill a demonstration well-pair.

Analysis of data from the exploratory borehole will be used to further characterize the subsurface hydrogeology and determine the nature of any future work to enhance the flow of water through the hot rock, if warranted.

Frequently Asked Questions

Phase I – Cornell University Borehole Observatory Design & Location

The Cornell University Borehole Observatory (CUBO) is not intended for heat production but rather to gather data needed to make informed plans and decisions, understand and test the geological conditions, and identify the best target zone (depth and drill angle) for future boreholes. From what is known of similar geological settings, researchers expect to find an existing network of natural fractures in the rock that can be used to establish communication between future production wells. It is also anticipated that naturally occurring water in the subsurface will interact with the rock and conduct heat through these natural fractures. CUBO will verify the character of these natural fractures and provide information needed to determine the viability of next steps for the Earth Source Heat project.

An exploratory borehole like CUBO can only probe a small volume of rock near the borehole. Researchers plan to use rock samples and in-situ tests of the bedrock properties around the borehole to create computer models of the wider reservoir that can be used to estimate the thermal and hydraulic performance of future production wells. CUBO will investigate the quality of the geothermal resource at a range of depths between 7,500 and 10,000 feet, where it is anticipated that temperatures are sufficient to be used for campus heating. Once CUBO has characterized the temperature and water flow potential at these depths, if it is determined that the project is viable, a plan for drilling geothermal production wells will be developed which will target the most promising depth interval.

CUBO will be drilled about 10,000 feet deep and 8.5 inches in diameter, and the upper areas of the well (i.e., those in potential aquifer/clean water zones and those through typical gas-bearing layers) will be cased immediately for safety. The deepest portion of the borehole (below about 6,500 feet) will be left uncased to allow a variety of tests to be conducted within the rock layers of interest for geothermal development, including testing for permeability and flow.

The proposed location for CUBO is a repurposed small facilities parking lot near Palm Road on Cornell-owned property. Data and results from the exploratory borehole will determine whether the same location is appropriate for a demonstration well-pair.

Phase II – Earth Source Heat Design & Location

The challenge of harvesting heat submerged deep within the earth and transporting it to more than 250 buildings on campus is exacerbated by the fact that no existing geothermal systems address Cornell’s precise geological circumstance and heating goals. But faculty and facilities engineers do have a conceptual vision of Earth Source Heat.

Cornell can effectively utilize resources across a large temperature range (as low as approximately 70 degrees Celsius, or at least 158 degrees Fahrenheit), although hotter temperatures are, of course, better. To reach underground temperatures in this range, a pair of wells would be drilled. Each well would have a sufficient diameter to accommodate 40 to 80 liters per second of water flow, leaving enough room for thick concrete casing and metal piping. Until more is determined about the rock formations below Cornell’s campus, it is unknown exactly how deep the wells would need to be. Reaching the desired temperature range would likely require drilling at least 1.5 miles below the surface.

Water would be pumped to the surface then be reinjected into the second well, circulating through a network of pores and crevasses within hot reservoir rock and absorbing a portion of its thermal energy. The flow rate between the wells would be determined by the permeability of the rock and the pressure difference between the wells.

Once at the surface, the heated water would enter a heat exchanger—two chambers separated by a thin layer of steel—that would transfer heat from the geothermal fluid to water contained in a second, closed-loop system that would then distribute the supply of heat to a network of campus buildings. A facility would safely house the wells, pumps, heat exchangers and most other visible components of the system. After heat is extracted, the well water is available for recirculation to be reheated at the well depth.

A single well-pair will likely be capable of heating a section of campus. It is anticipated that approximately three well pairs would be required to heat the entire Ithaca campus with the incorporation of geothermal heat pumps.

An initial demonstration well-pair is estimated to serve a portion of the current campus heating load. If successful, the final build-out of Earth Source Heat would be optimally sized to deliver the majority of heat needed for campus. However, during very cold weather, energy storage or another renewable resource, such as biomass, would be used to supply the additional heating needs of campus. Using biomass or another energy system for the infrequent peak heating loads would be far more efficient than over-sizing Earth Source Heat. If a biomass system were to be developed, it could utilize local resources (wood or non-food energy crops, animal waste or food waste) as an energy source.

Cornell has looked at this option. However, the need for this kind of heating would require hundreds if not thousands of heat pumps, a very large geothermal field footprint and significant electricity (which would put the university further behind its goal of a carbon neutral campus). Overall, this solution would not be as financially or environmentally beneficial to Cornell or the region. Additionally, ground source heat pumps are best used for both heating and cooling. Lake Source Cooling already substantially meets Cornell’s cooling needs and is much more environmentally friendly than heat pumps.

No. Cornell would retrofit the existing combined heat and power plant to heat campus using hot water from deep within the earth, thereby eliminating the use of fossil fuels to heat campus. The only new facility would be a pump and heat exchanger facility, similar to, but smaller than, the facility used for Lake Source Cooling. Heat storage tanks or similar supporting facilities could be included in the future, depending on the optimized final design.

Cornell's current distribution systems is a mixture of steam and hot water and the majority of buildings on campus are directly heated with hot water. All existing steam piping will be converted to hot water regardless of whether ESH is successful, as hot water is necessary to transfer renewable heat resources efficiently and economically. The conversion from steam to hot water is occurring incrementally to limit disruption, maintain redundancy and control expenses, but there is not a campus-wide project to convert at this time.

Currently, Cornell envisions an open-loop system where water from the injection well flows freely through cracks and crevasses in the earth’s subsurface.

The Earth Source Heat project is primarily interested in the direct use of geothermal resources for heating, which is very efficient, utilizing close to 100% of the extracted heat. In contrast, the process of converting geothermal heat to electricity would only use around 15% of the extracted heat and would not be an efficient use of the resources available in our area.

Drilling Safety

With respect to possible production ESH well-pairs, stimulation means artificially increasing the permeability of the targeted rock formation so that one can get cool water to flow more controllably though the hot rock to the production well. Stimulation will not be necessary in the CUBO well. It might not be necessary if we decide to produce heat from an already highly permeable sedimentary heat source. We won’t know whether stimulation is necessary in possible production well-pairs in a deeper metamorphic heat source until we have a better understanding of subsurface rock formations which we’ll discover through CUBO.

Should stimulation be required, any activity will be very different from the hydraulic fracturing or “fracking” method sometimes used for extracting oil and natural gas. While both processes increase fluid pressures, weaken the overall rock mass, and create or enhance permeability, there are some very important distinctions.

The purpose of hydraulic fracturing during shale gas operations is to prop open existing natural fractures, joints, spaced meters apart, and bedding planes spaced millimeters apart, in order to release a large fraction of the gases that are trapped in tiny pores very near the surfaces of these discontinuities. To make this process viable, a shale gas well must have thousands of meters of exposure within the shale, hence long lateral portions of a well, and hence the need for tens of millions of liters of stimulating fluid and tens of thousands of tons of proppant per well. These volumes and weights are astronomical in scale compared to what might be required for ESH.

For ESH, if stimulation is needed, the objective is to utilize fractures in the rock that are comparatively widely spaced – an ideal might be 15-30 cm apart. This desired spacing is much greater than the fracture spacing desired in an operation to extract natural gas (millimeters), because the water is intended to contact only enough of the rock for the rock’s heat to warm the water while the water slowly trickles along the fracture past the rock. The difference in objectives of the two fracturing activities leads to different strategies of stimulation.

Tests conducted elsewhere show that preexisting fractures in metamorphic rock can safely be made to open slightly using relatively low water pressures that are sustained for comparatively long times, whereas modern hydraulic fracturing for oil and gas production uses much higher water pressure. Research conducted during the exploratory CUBO and early demonstration phases will be used to determine the specific pressures required. No explosive techniques are under consideration for any phase of this project.

Most importantly, the Earth Source Heat project will not be producing fossil fuels; it will only be mining information, data, and heat through transfer from the hot rock deep within the earth.

The target depths for Earth Source Heat are at least three and a half times deeper than the depth of the Marcellus Shale and at least 450 feet below the Utica Shale, beneath Ithaca. Of several target horizons to be investigated by CUBO, those numbers refer to the shallowest target, while other targets for ESH are much greater distances below those shales. Upward migration of injected fluids, or native fluids liberated by ESH well operations, is highly unlikely because of the target depths and because there are several thick, impermeable layers of rock between their investigation/production zones and freshwater zones. Moreover, neither the Marcellus nor the Utica shale releases strong amounts of natural gas when crossed by a vertical wellbore – that is the reason that these rocks were not used to extract natural gas until the advent of horizontal drilling within them. While Cornell will have to drill through these shales and other rock layers that bear gas elsewhere in New York state, comprehensive measures will be taken to minimize any release of gas from those layers during drilling and to seal off those zones using the casing/cementing approach described elsewhere in the FAQ.

Water Safety

Valuable lessons have been learned from oil and natural gas production about best practices to promote long-term integrity of the well. Cornell is committed to using only high-quality cement, casings and other materials to minimize the probability of leaks.

The casing/cementing process is designed to minimize the probability of unwanted flow between freshwater zones and natural gas zones. The casing process keeps a well open, minimizes the probability of contamination of various rock strata and groundwater and, in combination with cement, shores up the wellbore itself. A steel tube is inserted into the borehole. Cement is pumped down the well and forced up the outside of the steel casing strings to form cement sheaths. Cornell plans to drill and case to depths of thousands of feet below the bottom of the freshwater zones to access hot rock that is far deeper than the Marcellus and Utica Shale layer.

Water for drilling operations for CUBO will be used primarily to make drilling mud. This water will come from Cornell's campus water service through a water line adjacent to the site; no water will be trucked in. Should the project progress to installation and operation of a fully functional demonstration or production well pair, the water used will come from Cornell’s own water treatment plant, with total consumption expected to be much less than what Cornell typically uses in a single day. Should Earth Source Heat become operational for heating the Ithaca campus, water will be recirculated through cracks and crevasses in the subsurface with minimal amounts of makeup water needed to replace any water that infiltrates into the deep bedrock. This makeup water will also be from Cornell’s own water service.

All drilling fluids and water from well development and testing will be contained in tanks or lined sumps to prevent infiltration into the soil. Any fluids that require disposal will be treated as needed (for example, to remove sediment) prior to disposal at a treatment plant. In addition, Cornell requires robust material storage, waste management, and spill response plans from all contractors in order to prevent environmental impacts.

Ground and surface water risks are always possible with drilling operations. Cornell’s plans will minimize risk, and out of an abundance of caution, the swale between the site and local waterways will be actively monitored to verify that runoff is not occurring. Contamination of groundwater is also not expected as the proposed CUBO site is downstream of known groundwater wells and there is no known drinking water aquifer in the selected CUBO area. Additionally, Cornell has installed four shallow groundwater monitoring wells that are 18-33' deep and located near the proposed CUBO site. If deemed necessary, Cornell may also install deeper monitoring wells in the future.

No. Water injected into the well will not discharge into streams or freshwater aquifers. Freshwater is typically found only at shallow depths (up to several hundred feet), although some studies suggest it is possible there may be pockets of deep freshwater at depths approaching 1,000 feet (still well above the geothermal resources). The phase 2 demonstration wells will be cased and cemented into the ground for at least the first 6,500 feet below the surface, with multiple layers of steel casing and cement as required to meet groundwater protection standards.

Some water used in the drilling operation will be lost to the borehole. CUBO would not involve active pumping, but for a future well pair, water would be pumped out of the production well and the same water would injected into a return well. In this case, there is typically no excess water for discharge, and used water is recirculated. If some water does need disposal, it will be contained, tested and disposed of through an appropriately licensed disposal facility, with oversight by Cornell Environmental Health and Safety.

During the lifetime of CUBO and any possible follow-on well-pairs, it is likely that some chemicals other than water will be needed during the various phases of drilling, casing, cementing, possible stimulation, heat production, maintenance, and abandonment. However, Cornell is committed to using only non-toxic materials, to providing complete transparency about any planned chemical additives, to incorporate a safety review of those substances in the environmental assessment, and to incorporate appropriate testing and monitoring into the plan as needed to minimize any potential risk.

Environmental Assessment

Yes. The proper permitting and required studies will be done prior to the drilling of the exploratory borehole and any demonstration or production well-pairs. The New York State Department of Environmental Conservation (NYSDEC) would be the agency responsible for overseeing well and drilling permits and meeting State Environmental Quality Review Act (SEQR) and other state requirements.

For CUBO, the NYSDEC stratigraphic well permit application has a streamlined environmental assessment process. Future demonstration well pairs will include a review of the broad range of environmental, social, and economic impacts typical of a comprehensive SEQR assessment. Additionally, should development proceed beyond the CUBO project, the local municipality would have oversight through their Site Plan Approval process, which also requires a SEQR assessment.


The first phase of the project will involve installation of an exploratory well only. It is very unlikely for this type of drilling to cause a felt earthquake. Should the project advance to subsequent phases, there is a remote chance that moving water through the deep bedrock will cause deep rock to shift enough to be felt at the surface. A number of geologists and engineers are evaluating any risks associated with induced seismicity by actively researching the bedrock in our area to better understand the rock formations under campus and identify any ancient faults. This includes analysis of the “background” rate of small earthquakes resulting from natural forces, and to help identify the location of existing bedrock faults. CUBO will provide critical data about the bedrock geology that will be used to design a drilling program that minimizes the risk of induced seismicity. In addition, prior to commencing any geothermal production, Cornell will have independent experts assess the seismic risks associated with any planned activities.

The ESH work we are planning is unlikely to create earthquake hazards due to many factors, including the local geology, the relatively low local seismicity of our area, the relatively low pressures and quantities of water we intend to use, and the steady, balanced forces that would be the goal of a successful well-pair system. To reduce any risk even further, we are planning a number of activities to better understand our local subsurface systems. First, prior to any drilling, we will continue to study the geology, hydrology and natural seismicity using past wells and surface instruments. Next, we will drill a full-depth exploratory well (CUBO) and thoroughly study the geology, hydrology and existing fracture networks that we encounter. State-of-the-art seismic monitoring equipment will be deployed to provide detailed feedback on any changes in the state of stress at depth during all phases of the project. Such monitoring will allow us to carefully plan and control any significant stimulation actions, thus ensuring that the development of our geothermal resources is accomplished as safely as possible. This stepwise and science-based approach can be a model for future development to reduce seismic risks or concerns.

Friction, imposed by the weight of rock, will diminish the probability of the stimulated natural fractures from growing and extending in an uncontrolled way. Only where water pressure is substantially increased by injection at a well will friction be reduced enough to cause unwanted fracture propagation. As has been recently reported, long-term and continuous forced-pressure water disposal in some areas of the country have created felt seismic events. No such water disposal activities will be part of our system.

Additional Questions

Should Cornell proceed to the installation phase of a demonstration or production system, the site will be restored after drilling, with only the very top of the wells visible, along with valves and piping from the well. Once connected, a water line between 8 and 10 inches in diameter will run from the well head and underground to a single-story pump and heat exchanger building, similar to, but smaller than, the Lake Source Cooling building by Cayuga Lake, which also houses pumps and heat exchangers. The building would likely be sited on Cornell property close to the well head.

There would be some noise and lights associated with the operation during the few months of well drilling and development for CUBO. During that time, Cornell will seek to minimize construction impacts of noise and light, for example by potentially requiring an electric-operated drilling rig, controlling noise with baffling and mufflers to meet local ordinances, and directing lighting to the immediate drilling area to provide a safe work environment for the operators. Once the drilling is complete, there would be essentially no noise pollution and all lighting would meet the local dark sky standards. At that time, CUBO will essentially be a passive campus research project with very low impact on the community.

If a well pair were to be installed in the future, after the drilling and development process were complete, all pumps would be located within a building and the facility would likewise be mostly invisible to the local community with no significant traffic, noise or exterior light associated with the operations.

No. All wells will be located on Cornell property and within a reasonable distance from local residential areas. As such, adverse effects to local property values are not anticipated.

If deemed viable, Earth Source Heat may prove to be a critical renewable asset for decarbonizing our society. Cornell’s intention is to demonstrate the viability of geothermal heating for cold climates around the world, including in New York State. Should the technology be successfully demonstrated at scale, the goal would be for broad development to continue through public and private entities.

As part of both CUBO and any future demonstration project, Cornell expects to create a multi-faceted educational outreach program with materials intended for a variety of age groups. While this may include on-site tours and displays, these plans have not yet been developed.

Yes, data generated by the Earth Source Heat project will be available for public access.