The group’s emphasis on energy and the environment focuses on several broad areas:
- Geothermal energy recovery and utilization
- Carbon sequestration in geologic media
- Fossil fuel reservoirs, recovery, conversion, and upgrading
- Waste remediation and treatment
- Clean processing and green chemistry
Thermal spallation of rock using supercritical water
- Researchers: Ivan Beentjes, Sean Hillson
- Principal Investigator: Jefferson Tester
An obstacle hindering implementation of EGS is the large up-front capital costs for drilling and reservoir stimulation. For EGS to become more economically viable, particularly in low grade regions, new drilling technologies such as hydrothermal jet drilling are being developed that could significantly reduce the cost to drill the deeper wells needed for low-grade EGS. Hydrothermal flame drills create a jet of supercritical water which impacts and heats the rock, causing the rock to “spall”, i.e., eject small rock fragments to relieve thermal and mechanical stress. Hydrothermal drilling has the potential to lower drilling costs over conventional methods by increasing penetration rates and avoiding the transit time associated with replacing worn drill bits and transporting the drill string out of the well.
Although focused on experimental studies, the project has also theoretical part in parallel. The drilling rates will be measured by analyzing reactor exit stream chemical compositions, reactor temperature distributions and remnant rock properties. In order to understand drilling mechanics, models of the different chemical processes occurring in the reactor will be made from the current state of the art, and reconciled to experimental results. The developed models will take into account transport of rock spalls in the wellbore and heat transfer effects throughout the process. The research conducted in this project will hopefully lead to an increased understanding of the mechanisms of rock spallation/dissolution, as well as demonstrate the commercial viability of a novel drilling method.
Modeling of Transient Heat Transfer in Geothermal Reservoirs
- Researchers: Adam Hawkins
- Principal Investigator: Jefferson Tester
An Engineered Geothermal System (EGS) can be depleted of its thermal energy after a prolonged draw down period, putting into question the renewability of conductively dominated EGS reservoirs. However, the EGS reservoir will recover a portion of its “farmed” energy if it is left unused. Because heat conduction from the surrounding hot far field rock is slow, the recovery time scale can be between 2-5 times the time scale of extraction. For strategic use of a geothermal reservoir, appropriate modeling of the transient heat transfer within the reservoir is needed. With the appropriate models, a sustainable system of geothermal reservoirs can be implemented such that each single reservoir is allowed to recover long enough before it is used again. Under this operational strategy, the above surface infrastructure’s capacity factor is minimally effected by reservoir depletion and recovery phases. Reservoir modeling is performed using the TOUGH2 numerical code along with a front end program called PetraSim. Another area of importance in reservoir modeling is thermal hydraulic mapping of EGS reservoirs using tracers. Thermal hydraulic mapping can elucidate information of the flow paths, configuration of fractures, and how the fractures thermally interact.
System analysis of innovative geothermal resources
- Researchers: Koenraad Beckers, Maciej Lukawski
- Principal Investigator: Jefferson Tester
In 2006, an MIT-led interdisciplinary panel conducted the study “The Future of Geothermal Energy” in which they estimated that the U.S. geothermal resource base to 10km depth is of the order of 14 million EJ. More importantly, they expected the recoverable resource to be at least 0.28 million EJ, which greatly exceeds the current annual U.S. primary energy demand of approximately 100 EJ. However, the major fraction of this resource is stored in geological formations that lack either sufficient permeability, a fluid present in the pores and fractures, or both. Such geothermal resources, which are not commercially developed yet, are known as Enhanced Geothermal Systems (EGS).
The geographic distribution of the geothermal resources in the U.S. is uneven. The eastern part of the country is characterized by geothermal resources, that although quantitatively sufficient, are stored at greater depth to those available in the western U.S. Due to exponential increase in the cost of drilling with depth, the current drilling techniques favor “low-grade” geothermal resources in the eastern half of the country. Low resource temperatures, it turn, indicate a low conversion efficiency of thermal energy to electricity. This promotes direct use applications and co-generation of electricity and heat.
One goal of our project is to determine the viability of both heat and electricity production from low-grade geothermal resources in the Northeastern United States. Our research involves a techno-economic analysis of innovative uses of geothermal-produced fluids and their potential as an alternative to consumption of depletable fossil fuels. These include direct use of geothermal resources as well as hybrid biomass-geothermal combined heat and power (CHP) plants. In the first phase, our analysis focuses on the implementation of this approach on the Cornell campus. In the second phase, we will generalize this analysis and expand it to other distributed users such as campuses, industrial parks, towns and communities. Large part of this project is done with our collaborators at West Virginia University, Iowa State University and National Renewable Energy Laboratory, whose efforts are led by Prof. Brian Anderson, Prof. Terrence Meyer and Dr. Chad Augustine.
Research area: Geothermal Heat Pumps
- Principal investigators: Prof. Jeff Tester, Koenraad Beckers, Maciej Lukawski
Geothermal (or ground coupled) heat pumps can provide efficiently and environmentally friendly heating and cooling for various applications. In our research group, we are developing models to simulate and optimize heat pump systems with vertical and horizontal borehole heat exchangers. To maximize the accuracy of our models, we will compare and verify them with experimental results from (1) a heat pump with vertical borehole heat exchangers that provides cooling for the electronics of a cellular tower on the Cornell campus and (2) a heat pump system with horizontal heat exchangers that provides space heating and cooling to a residential building in Ithaca.
Geothermal Resource Assessment
- Researchers: Jared Smith, Calvin Whealton, Ein Camp, Gloria Andrea Aguirre, Tim Reber, Elaina Shope, George Stutz
- Principal Investigator: Teresa Jordan and Jefferson Tester
Our research aims to draw a more complete picture of geothermal resources in the United States, specifically in the Eastern United States, by taking into account the potential for lower grade resources. By using both archived and current well data (primarily temperature and depth), coupled with a detailed knowledge of the characteristics of geologic strata in areas of interest, we have created a maps of heat flow and temperature gradients in the subsurface. This thermal resource information has been combined with similar assessments of geological reservoir characteristics and the risk of earthquakes to describe the geological resource potential across much of New York Pennsylvania and West Virginia. These assessments enable further analysis of the infrastructure costs needed to put this naturally available heat to use for projects of interest to communities or commercial firms. Overall, the goal is to better estimate the costs and benefits of geothermal heat in the northeastern U.S..
Relationships of primary sedimentary facies to physical and chemical properties of the Marcellus shale in central New York State
- Principal Investigator: Teresa Jordan
- Researchers: John Mason, Joseph Carloni, Katherine Herleman, John Goulas, David Makee, Louis Caiola, Shefford Baker, Alan Zehnder, James Bisogni, Louis Derry
Production of natural hydrocarbons from organic-rich fine-grained rocks requires not only a hydrocarbon source and stimulation of the reservoir, but also planning to mitigate risks and treat wastewater. For the Marcellus shale, predictability of natural gas abundance, mechanical properties of the host rock, and compositions of the formation waters will improve if the properties of the shale are well understood.
This research team is documenting the sedimentary rock properties of the Marcellus shale in central New York State, especially properties that are of importance to organic matter distribution, fracture behavior, and geochemical parameters. Data include high spatial resolution observations of the Marcellus in active rock quarries and using core from the unit in the subsurface. Analyses include petrographic, scanning electron microscopic, indentation, elastic and fracture properties. Elemental analysis of solutions dissolved from contact of fluids with these rocks are also conducted. From these primary data, we interpret the sedimentological conditions at the time of deposition and the relationship between those initially imprinted properties and the behavior of the shale today, when people undertake work in the Marcellus unit.
Energy Transitions and Sustainability
- Project Led by: Al George, Kieran Donaghy, Rod Howe, David Kay, Michal Moore, Teresa Jordan, Jeff Tester, Christine Shoemaker, Jery Stedinger, Susan Riha
Over the 21st century, there must be a transition from fossil fuels to renewable or minimal impact energy sources. Ongoing activities to develop natural gas production from unconventional rock types, like shale-gas, illustrate the complexity of such a transition, both technologically and socially. Several of the IGERT faculty team members are engaged in a Cornell-wide study of the science, engineering, policy framework, regulatory practices, and public education that all work together as a system in an energy transition. We are interested in better understanding how to facilitate the process by which societies make decisions whose goal is to manage energy sustainably. We are using the example of the transitions to lower carbon unconventional fuel sources as case studies that will be applicable to continued transition to lower carbon, through increased utilization of sustainable geothermal energy resources, and the possible mitigation of carbon emissions from fossil-fuel use via geological carbon sequestration. These technologies are prime current examples of difficult energy choices that require research leading to better technical, economic, and environmental information, as well as research into the conditions under which difficult societal, policy, and regulatory decisions can most effectively assure a sustainable outcome.
Geological Carbon Sequestration
- Principal Investigators: Abe Stroock and Don Koch
We face the dual and completely interwoven challenges of increasing supplies of energy to the world’s population, and reducing the output of CO2 to the atmosphere. Given the abundance of coal in the US and China, it is almost certain that coal will continue to be a very important source of electrical power. We must therefore do all that we can to reduce CO2 emissions from coal-fired power plants. Geological CO2 Sequestration (GCS) is an appealing idea for the permanent storage of CO2 that could be stripped from power plant emissions. But is it feasible?