Exploring Earth Source Heat
What is Earth Source Heat?
What is earth source heat?
Earth Source Heat is our version of an enhanced geothermal system that would use the internal heat of the Earth to warm our campus. Wells would be drilled into “basement rock,” where the internal heat of the earth keeps temperatures near or above the boiling point of water. Water circulated through the wells returns to the surface as hot water for campus heating and potential electricity production.
We believe that the project holds the potential for a research-driven solution, that if proven viable could lead to a scalable solution globally, makes exploration of this technology an ideal candidate for our campus. While Earth Source Heat is extraordinarily promising, this approach has not been pursued in our region and remains one of uncertain costs and ultimate feasibility.
Why is Cornell exploring earth source heat?
Earth Source Heat has been a part of Cornell’s Climate Action Plan since 2009 as a means of moving toward carbon neutrality on campus by eliminating fossil fuels for campus heating. Like other communities with significant seasonal cold, Cornell cannot reach climate neutrality without eliminating the fossil fuels that are used to heat campus, and there are very few potential technologies – utilizing the resources we have here in Ithaca – to do so. It is widely agreed that there is enough natural heat within the earth to sustain us indefinitely, and drilling technology advancements mean that we can realistically reach this heat.
Earth Source Heat has the potential to be a clean, safe, reliable and renewable source of heat for significant portions of the United States and the world. However, because of the deep drilling required, there are challenges and potential issues that will need to be thoroughly and thoughtfully addressed. Cornell has the expertise to study these issues and is committed to address them in a thorough and transparent manner, developing best practices that will minimize risk and provide guidance for others who might implement this technology. It is our hope that the potential benefits of Earth Source Heat will far exceed the potential risks.
What are the goals for earth source heat?
The long-term goal of Earth Source Heat is to create a new regional energy supply to heat our campus using only natural, renewable resources as a demonstration for even broader societal application. However, as exciting as the initial discussion and planning phases may be, this project will be years – possibly a decade or more – in the making. Each step must be balanced with sound research, necessary permits, community engagement and funding. If successful, Earth Source Heat would serve as an exciting demonstration project for other communities seeking renewable, sustainable forms of energy.
Earth Source Heat provides not only an ideal opportunity to conduct research and serve as a demonstration project for others seeking sustainable energy approaches, but also an extraordinary prospect to develop a new sustainable energy industry across New York state that could have a major impact on the upstate economy. While similar projects have been done in other areas, a project of this type and scale has never been attempted at a location with the conditions we have here in upstate New York.
What are the other potential benefits of implementing such a system?
One reason Earth Source Heat is attractive is its potential to integrate with other renewable heating and cooling technologies. Specifically for Cornell, it is a natural complement to the Lake Source Cooling system already in place for cooling the Ithaca campus. In addition, Earth Source Heat can be easily integrated with technologies such as biomass for peak heating, solar thermal, and electric heat pumps to be part of a flexible menu of renewable energy options that can be adapted over time to take advantage of new innovations.
Drilling, Water, and Seismicity
Enhanced geothermal systems use water to stimulate cracks in underground rock. How is this different from fracking associated with natural gas and oil production?
An early phase in Cornell’s Earth Source Heat project is the drilling of a test well. Analysis of data from the test well will be used to further characterize the subsurface hydrogeology and determine the nature of any future work to enhance the resource, if warranted.
The anticipated stimulation is based on the concept of hydroshearing, which is different from the hydraulic fracturing or “fracking” method used for extracting oil and natural gas. While both processes increase ﬂuid pressures, weaken the overall rock mass, and create or enhance fracture porosity and permeability, there are some very important distinctions. The purpose of hydroshearing is to open up natural, preexisting fractures at lower overall pressures sustained for a longer time compared to hydrofracking. Research conducted during the test well and early demonstration phases will be used to determine the specific pressures required.
Most importantly, we will not be producing fossil fuels, but hot water and steam heated by the hot rock deep within the earth. The target depths for Earth Source Heat are at least five times deeper than the depth of the Marcellus Shale beneath Ithaca and there are several thick, impermeable layers of rock between.
Will chemicals be injected into the well?
Until we have completed a test well, we are not sure exactly what additives might be needed to develop the geothermal resource. However, we are committed to using only non-toxic materials, to providing complete transparency about any chemical additives planned, to incorporate a safety review of those substances in our environmental assessment, and to incorporate appropriate testing and monitoring into the plan as needed to minimize any potential risk.
How are wells constructed to protect ground water and avoid other problems?
We have learned valuable lessons from oil and natural gas production about best practices to ensure long-term integrity of the well. We are committed to using only high-quality pipes, casings and other materials to avoid leaks.
The casing process keeps the well open and protects the earth and groundwater. The hard metal casing shores up the wellbore and extends throughout the well to assure the long-term integrity of the well from end-to-end. Cement is then pumped down the well under pressure and forced up the outside of the steel casing until the well column is sealed. The casing process ensures that the producing well is isolated from any fresh water zones and natural gas zones. We will drill and case to depths 9,000 feet or more below the bottom of the water table in the Ithaca area to access hot rock that is at least five times deeper than the Marcellus.
How much water will be used and where will it come from?
The first step in our work will be a test well. Drilling, development and testing of the well will use water 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 campus, water will be circulated in a closed loop 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.
Will any water that we are injecting enter the local watershed?
No. Water injected into the well will not connect to local groundwater resources. The proposed demonstration well will be cased and cemented into the ground for at least the first 8,000 feet below the surface, with multiple layers of steel and cement as required to meet groundwater protection standards. 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 our geothermal resources).
Some water used in the drilling operation will be lost to the borehole; any remaining or returning water will be captured and treated prior to disposal at a treatment plant.
What measures will Cornell take to protect surface water resources?
All drilling fluids and water from well development and testing will be contained in tanks or lined sumps to prevent infiltration into the soil or aquifer. Any fluids that require disposal will be treated as needed (for example, to removed 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.
Will an environmental assessment of the impact of drilling a test well be completed before a test well is constructed?
Yes. The proper permitting and required studies will be done prior to the drilling. This will include a review of the broad range of environmental, social, and economic impacts typical of a comprehensive State Environmental Quality Review Act (SEQRA) assessment.
What research has Cornell been doing to prepare for drilling a test well?
A first step toward gathering better geological data for the Ithaca area began in 2015 when Cornell engineers buried 12 seismometers across the campus to measure seismic activity over the course of a year. While the data is still being analyzed, researchers anticipate that it will give them a better idea of where geological features relevant to geothermal production are located below campus. This would allow engineers to choose locations to conduct more sophisticated experiments such as active seismic surveys, in which Vibroseis “thumper” trucks send vibrations into the ground, resulting in an acoustic, three-dimensional view of what lies below.
In addition, a 2016 Cornell study presents a statistical analysis of a large portion of the Appalachian Basin. Faculty and graduate students from three different Cornell Engineering departments rigorously pored through data generated by the fossil fuel industry, examining nearly 40,000 drilling locations throughout much of New York, Pennsylvania and West Virginia. Informed by oil- and gas-well logs, the scientists were able to map which regions were most likely favorable for direct-use geothermal energy.
Ultimately, we will not know exactly what we are going to find at such depths until the initial test well is drilled. That is why the project will have a series of safety benchmarks. If these benchmarks are not met during each phase, the project will not move forward.
Is the Earth Source Heat demonstration project likely to cause damaging or felt earthquakes?
The first drilling phase of the project will involve installation of a test 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. Installation of the test well will provide critical data about the bedrock geology that will be used to design a drilling program that minimizes the risk of induced seismicity.
How will Cornell mitigate the possibility of earthquakes from project activities?
The 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 plan a number of activities to better understand our local subsurface systems. 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 test well 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 step-wise and science-based approach can be a model for future development to reduce seismic risks or concerns.
Can stimulated fractures grow in an uncontrolled way?
No. Friction, imposed by the weight of rock, will prevent the 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 fracture stimulation. 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.
Project Location and Design
How would the proposed system work?
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.
To reach underground temperatures of ~100-150 C (~200- to 300-degrees Fahrenheit), 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, it is unknown exactly how deep the wells would need to be. Reaching the desired temperature range would likely require delving 3 to 5 kilometers, or 1.8 to 3.1 miles, below the surface.
Water would flow down the first well into a deep reservoir, circulating through a network of pores and crevasses within hot reservoir rock and absorbing a portion of its thermal energy. The water would then be pumped back to the surface through the second well.
Once at the surface, the heated water would enter a heat exchanger—essentially two chambers separated by a thin layer of steel—that transfers heat from the geothermal fluid to water contained in a second, closed-loop system that would 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 depth.
The well pair would only be capable of heating a section of campus; we anticipate that approximately four to six well pairs would be required to heat the entire campus.
Where will the project be located?
We are currently exploring locations for a demonstration well on Cornell-owned property. While we do not have an exact location identified, the criteria for the location of each well pair includes geological and geophysical suitability, distance from private land and adjacency to the designated area of campus it would serve.
What will the well site look like?
Once the drilling is complete, the site can be restored and only the very top of the well will be 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 the Lake Source Cooling building by Cayuga Lake, which also houses pumps and heat exchangers. The building would likely be sited somewhere on Cornell property close to the well head.
Will there be light or noise pollution?
During the few months of well drilling and development, there would be some noise and lights associated with that operation. Noise would be controlled with baffling and mufflers to meet the strict local noise ordinances and lighting will be directed to the immediate drill area to provide a safe work environment for the operators. Once the drilling is done, there would be essentially no light or noise pollution; all pumps will be located within a building and all lighting will meet the local dark sky standards.
Will the project adversely affect local property values?
No. All wells will be located on Cornell property and within a reasonable distance from local residential areas, therefore we do not anticipate any adverse effects to local property values.
Will the project be sized large enough to handle the full heat load for campus?
Our initial demonstration well set will likely only serve about 20 percent 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, an energy system using biomass would be used to supply the additional heating needs of campus. Using biomass for the infrequent peak heating loads would be far more efficient than over-sizing Earth Source Heat. This system would utilize local biomass resources (wood or non-food energy crops) as an energy source. If the biomass is converted to biogas, it could be used in a retooled facility such as our combined heat and power plant.
Will you need to build a new heat/power facility?
No. We would retrofit the existing combined heat and power plant to heat campus using hot water and steam from deep within the earth, and thereby eliminating our usage of fossil fuels to heat campus. The only new facilities would be a pump and heat exchanger facility, similar to the facility for Lake Source Cooling. We could also include some heat storage tanks or similar supporting facilities in the future, depending on the optimized final design.
What is the timeline for this project?
Earth Source Heat is far from shovel ready. Research to determine exactly what the geology under Cornell’s campus looks like has begun and will continue along with other experiments to determine the feasibility of engineering a safe and economical enhanced-geothermal system. The anticipated phases of work include the following:
- Preparation Phase (years 1-2)
- Phase I: Drill and Study Test Well (years 3-4)
- Phase II: Porosity/Stimulation Testing and Analysis (years 4-6)
- Phase III: Drill First Producing Well Set, Build Surface Infrastructure, and Connect (years 7-10)
- Phase IV: Drill Other Well Pairs and Complete Surface Infrastructure (years 11+)
The very first phase is a preparatory phase to conduct research, apply for necessary permits, determine optimal locations, refine system design and engage with the community. Within the next two years, Cornell hopes to proceed with the installation of a single test well that will provide the best understanding yet of the ground beneath campus and what a full-scale system might require. If the test well produces viable results, a subsequent phase would seek to install an adjacent well and heat-exchange facility, creating a small-scale demonstration project that could heat multiple buildings within a section of campus. It is expected to take about ten years to complete these phases and if successful, a full-scale project could then be implemented.
Each phase ends with a decision process to determine if the project moves to the next phase; this process is called a “stage gate.” The stage gate decision process includes a careful consideration of technical, environmental, safety and community feasibility; only if the project meets acceptable performance criteria in each area will work continue.
What stage is the project in?
We are currently in the preparatory phase. Faculty, students and engineers have started the initial planning, including research to better understand the rock formations beneath campus. These efforts are being led by some of the premier experts in geology, seismology and renewable energy production in the world. In addition, faculty and staff engaged in the project have met with several groups in Tompkins County to discuss the project, including a town hall meeting for all community members that was held in downtown Ithaca in March.
Are there similar projects like this in the U.S.?
Large-scale geothermal systems are more widely used in Europe. Today, a small handful of enhanced-geothermal systems exist in the U.S., all of which are in western states where geological conditions are more favorable and basement rock is easier to access. Those systems are serving mostly as experimental, demonstration projects that focus on using the earth’s heat to produce electricity, as opposed to “direct-use heat,” in which geothermal heat is applied directly for use in a heating system.
Why can’t Cornell just install regular ground source heat pumps?
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 further burden the aim of making our grid fossil-free). Overall, this solution would not be as financially or environmentally beneficial to Cornell or the region. Also, the optimal application for heat pumps is for both heating and cooling, but Lake Source Cooling already substantially meets our cooling needs, and is much more environmentally benign than heat pumps.
Are there any long-term benefits to the greater Tompkins County community?
If Earth Source Heat is successful, it would demonstrate the feasibility of using this type of system as a clean energy source almost anywhere in the world. Cornell’s geothermal expertise would then represent a new basis in the Tompkins County area for commercialization of this new energy source. More specifically, these studies will indicate whether Earth Source Heat could be expanded to provide clean, economical heat to the public near Cornell.