Frequently Asked Questions

Cornell is taking a phased approach to researching and implementing Earth Source Heat. Learn more about the project, including frequently asked questions on several key topic areas.

Topic Areas:

Phase I – Cornell University Borehole Observatory

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.

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.

Graphics explaining dimensions of the borehole.

Using electric drilling rigs, the borehole reached a depth of about 10,000 feet (1.89 miles). At the surface, the borehole is approximately 36 inches in diameter, progressively narrowing to about 8.5 inches in diameter at the deepest point. The upper areas of the well (i.e., those in potential clean water zones and those through typical gas-bearing layers) were cased with steel and cement for safety. Layers in the shallowest part of the subsurface which may contain fresh water (to 300 feet deep) were sealed behind multiple thicknesses of casing and cement. The longest casing extends 300 to 400 feet below the deepest shale that is known in this region to contain natural gas. The deepest portion of the borehole (7,200 feet or 1.36 miles below the surface) was left uncased to allow a variety of tests to be conducted within the rock layers of interest for geothermal development. Proper permitting was completed, and water-monitoring wells and a range of seismometers were installed to provide background data regarding variations in ground water composition and local seismicity to ensure well casing integrity and safe operating conditions of CUBO. With drilling complete, the site may appear inactive but is actually highly utilized for research.

Map of Cornell University Borehole Observatory

CUBO is located on Cornell-owned property near Palm Road in the Town of Ithaca. Drilling at the site did not disrupt plants, trees or sensitive ecosystems because the site was already an open gravel pad (a former parking lot). Additionally, electricity and water services were already available at this site, which eliminated the need for new disruptive construction to connect those resources.

Initial data from CUBO indicates that the temperature, rock type and permeability between 7,500- and 10,000-feet underground are consistent with initial hypotheses. The rock at that these depths have a temperature between 75 to 100 degrees Celsius and low intrinsic permeability (i.e., water does not easily flow through the rock). Due to the low permeability of the bedrock, enhanced geothermal systems (EGS) technology – a current research focus of the U.S. Department of Energy – will be needed in order to efficiently utilize the heat within the rocks at these depths.

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, possibly as soon as 2024.

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.

Phase II – Earth Source Heat

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 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 system 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.

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.

If it is determined that the project could safely and effectively advance, the next step would be to drill a separate demonstration well pair where water circulated through the wells would return to the surface as hot water and heat a portion of Cornell’s Ithaca campus. If successful, the university would move to a phased approach that would create a full-scale system capable of heating the entire Ithaca campus within the next 8 to 10 years.

Drilling Safety

Enhanced geothermal systems allow geothermal heat to be utilized in areas where the subsurface has low permeability. Using this technology, an area of bedrock could be hydraulically stimulated to create interconnected pathways through which water can flow, in order for the slowly moving water to transport heat between a pair of wells. Tests conducted elsewhere show that permeability and connectivity of preexisting cracks and fractures in rocks similar to those beneath Cornell can be greatly increased in a safe and responsible manner so that they can act as the water pathways between wells. One demonstrated method of stimulation involves increasing the water pressure in a well by a small amount and sustaining that pressure over an extended period of time.

An initial demonstration well pair would be drilled into the hot sedimentary or metamorphic rock. Water would be pumped down the first injection well where rock would be hydraulically stimulated using relatively low water pressures. The stimulation would unclog flow pathways along existing fractures as well as connect fractures to create an interconnected and more permeable fracture network for fluid flow and heat exchange. The stimulation would develop a heat reservoir in which there is more surface area available to heat water and ensure strong connection between the wells. The rocks will naturally heat water as it flows from where it is injected in one well to where it is drawn up in a separate well. The geothermal water would then go through a heat exchanger where a secondary closed loop would carry a separate supply of fresh water (heated via the heat exchanger) throughout campus to heat buildings.

Modern hydraulic fracturing for oil and gas production uses large volumes of water and other fluids under very high pressure to create fractures. Oil and gas fracking may involve explosives to generate and force open large fractures and can involve the use of chemicals and proppants that can be harmful to the environment.

This is very different from Cornell’s plans for Earth Source Heat. Data from CUBO will allow researchers to identify the best ways to safely use EGS technology to stimulate fractures, including options that have low operational risk, low seismic risk and low environmental risk. Safety monitoring equipment will allow the water pressure to be quickly decreased if there is any indication that the stimulation might cause unintended seismic activity. No explosive techniques for creating permeability are under consideration for any phase of the Earth Source Heat project.

Differences and similarities between Earth Source Heat and “Fracking”
A.R. Ingraffea, Ph.D., P.E., Dist. Member ASCE
Dwight C. Baum Professor of Engineering Emeritus

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. In the unlikely event that drilling does encounter a pocket of natural gas that requires discharge, it will be safely combusted on site using a flare system. If required, flaring would most likely last for a few hours or less.

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, which will be used to cool the drill as it moves into the Earth. This water will mix with dirt and return to the surface as mud, which will be filter out and back into the ground. The water will come from Cornell's campus water service through a water line adjacent to the site; no water will be trucked in. The total water usage for drilling CUBO is less than one day of typical campus water use.

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 amount of water needed for the system for one year expected to be about 1% of what Cornell’s Ithaca campus 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.

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.

Locations of water monitoring wells
A map of the well locations.

Alternate version of this map

Ground and surface water risks are present with any drilling operation. Cornell’s plans will minimize risk, and a monitoring program has been implemented to establish background conditions as well as ongoing sampling during drilling operations. Four groundwater wells 18-33' deep, one bedrock well 207’ deep and two sites in nearby Cascadilla Creek will be sampled (sites are both upstream and downstream of the CUBO project site). The swale between the CUBO site and Cascadilla Creek will be actively monitored to verify that surface runoff is not occurring during drilling operations.

Routine, frequent field monitoring will be supplemented by robust lab analysis of samples taken before, midway through, and after drilling is complete. A system has been developed that aims to provide operators with a reliable and data-driven method to track water quality in concert with drilling operations. Experts from the NYS Water Resources Institute and Ithaca’s Water Treatment Plant will analyze the data. Information on the sampling parameters and specific results will be available on Cornell’s Deep Geothermal Heat Research website.

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.

When the holes are drilled, walls around the hole called "casing" will be installed. The casing is designed to minimize the possibility that there is any flow of liquids or gases between the well and the rock layers near the surface that contain groundwater (freshwater in the pore spaces of the rock). The casing also keeps the walls of the well solid so that rock doesn't fall into and clog the drilled hole.

There will be four layers of casing made of steel and cement. To make the cement casing, a steel tube will be inserted into the borehole, and cement will be pumped down the well and forced up the outside of the steel casing to form cement walls. There will also be casing at depths at which rocks rich in natural gas occur, including the Marcellus Shale and Utica Shale. This will avoid movement of natural gas into the well hole. The Marcellus and Utica shale layers are hundreds of feet above the target depth at which geothermal heat will be extracted.

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 incorporating a safety review of those substances in the environmental assessment, and to incorporating 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 seismic activity large 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 development of Earth Source Heat 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

  • Prior to moving forward with drilling, Cornell has, and will continue to study, the geology, hydrology and natural seismicity using existing wells and surface instruments.
  • Locations of seismic monitoring equipment
    A map of the seismic monitoring locations.

    Alternate version of this map

  • In June 2022, Cornell 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 has been deployed to provide data on any earthquakes at depth (whether related to the project or not) during all phases of Earth Source Heat. Such data will allow us to carefully plan and control any future stimulation actions, thus ensuring that the development of our geothermal resources is accomplished as safely as possible.
  • While no seismic impacts are anticipated, a system has been developed that aims to provide a reliable and data-driven method to track seismic activity in concert with drilling operations. The system looks at frequency, magnitude and location of events that occur anywhere in the monitoring network during drilling operations relative to typically occurring activity. The seismic monitoring data collected during CUBO will be analyzed by a third party. Information on the network and specific results will be available on Cornell’s Deep Geothermal Heat Research website.
  • 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 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

Heating accounts for 30% of campus greenhouse gas emissions and remains the biggest hurdle to Cornell becoming carbon neutral by 2035. Earth Source Heat would enable Cornell to move beyond fossil fuels and would also reduce Tompkins County greenhouse gas emissions by about 7%. In the Northeast, 20-40% of carbon emissions come from heating. If this technology can be advanced, it could rapidly reduce emissions on a larger scale.

ESH also has the lowest electrical demand of any renewable heating option, freeing up electricity for meeting local and state renewable electricity demands. It would provide a baseload heating solution that can be integrated with other renewable options like biomass, heat pumps or stored solar thermal.

Additionally, Cornell can use existing infrastructure that heats its buildings, reducing the need for new infrastructure or wasting old systems.

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.

Cornell is working with community partners to create multi-faceted educational materials intended for a variety of age groups. In cooperation with the Outreach and Teacher Education experts of Paleontological Research Institution and the Online Education and Documentary Film experts of PhotoSynthesis Productions, we develop materials intended for curious adults and children, and teachers. General information as well as materials for K-16 teachers can be found on the Deep Geothermal Heat Research website.

Yes, data generated by the Earth Source Heat project will be available for public access. Visit the Deep Geothermal Heat Research website for additional data.

While many in Ithaca and the surrounding communities are supportive of clean energy development, as evident in the Tompkins County Energy Roadmap, Cornell understands that this type of project has not been attempted in the region before, leading to many questions about its feasibility and scope. As an academic institution with deep faculty expertise in emerging energy technology, seismicity, geology and the environment, Cornell is uniquely suited to explore Earth Source Heat. Even if ESH is not able to be fully implemented, valuable knowledge will still be gained about rock formations beneath campus as well as possible system designs that could be beneficial to other institutions, businesses and communities considering this technology.