Master of Science in Mechanical Engineering, Cleveland State University, 2022, Washkewicz College of Engineering

Water main geothermal systems have the potential to bring geothermal heat pump systems to a larger scale and drastically reduce carbon emissions. Current research supports this by showing that the quality of water produced by these systems remains unchanged (Smith and Liu 2018). There have been studies that show some form of economic feasibility without an in-depth design, evaluation, and economic analysis (Ambort and Farrell 2020). This research will provide that analysis and help determine any next steps to achieve the feasibility of the design and implementation of these systems on a larger scale and the impact these systems will have on reducing carbon emissions. The main objective of this research is to design, evaluate, and provide an economic analysis of a water main geothermal system in a residential space using TRNSYS 18 with the TESS component library package. Provide concrete data that supports the economic feasibility of owning and operating this type of geothermal system. The water main geothermal system was designed using TRNSYS 18 with the TESS component library package. A detailed guide, explaining the procedure for using TRNSYS 18 with the TESS component library package is given. The guide will allow researchers to understand the overall system design including results. This research work will determine the economic feasibility of implementing a water main geothermal HVAC system in a residential space using TRNSYS 18 to simulate the performance.

Committee: Yong Tao Dr. (Advisor); Wei Zhang Dr. (Committee Member); Navid Goudarzi Dr. (Committee Member); Ungtae Kim Dr. (Committee Member) Subjects: Mechanical Engineering

Master of Science (MS), Ohio University, 2021, Geological Sciences (Arts and Sciences)

Past geological, geochemical and geophysical studies by LaGeo have shown the presence of a 12 km2 geothermal reservoir at San Vicente Geothermal Field (SVGF) . This reservoir has an estimated thickness of 600 to 1200 m underneath a 600 to 800 m thick capping rock. All this located under the northern flank of San Vicente volcano. Potential drilling targets for geothermal exploitation are determined through visual geographical correlation of geological, geochemical and geophysical variables. However there are statistical methods such as geographical weighted regression and cluster analysis that allow us to establish statistical correlation between the geochemical and geophysical variables that are related to fluid storage and flow. Carbon dioxide (CO2) diffuse degassing and other gases, and geophysical variables such as resistivity and gravity, are related to high permeability areas, such as faults, and underground fluid movement within a geothermal field. In order to establish more accurate drilling targets for geothermal exploitation, a better and more objective data interpretation can be achieved by establishing the statistical correlation of CO2 diffuse degassing to other geochemical or geophysical variables. We have used Geographically Weighted Regression (GWR) models via computer program GWR4 to determine the statistical correlation between the space dependent geophysical and geochemical variables. Data from San Vicente Geothermal Field in El Salvador was used to determine the spatial correlations between CO2 soil concentration and the concentrations of He, 222Rn, 220Rn, Hg, resistivity and gravity measurements. Bivariate GWR showed statistically significant correlations between CO2 diffuse degassing, He concentration, Hg concentration, 222Rn concentration, 220Rn concentration and Magneto-telluric measurements. He concentration had the greatest statistical weight (푅푝 2 = 0.55, F = 7.21, p < 0.001). Stepwise multivariate GWR was applied and the most stati (open full item for complete abstract)

Committee: Dina Lopez Dr (Advisor); Katherine Fornash Dr (Committee Member); Schenk Xizhen Dr (Committee Member) Subjects: Earth; Energy; Environmental Geology; Geochemistry; Geographic Information Science; Geology; Natural Resource Management; Statistics

Doctor of Philosophy, The Ohio State University, 2024, Civil Engineering

The human-induced increase in greenhouse gas (GHG) concentrations is the primary driver of recent global warming, leading to a series of climate changes, including sea level rise, ocean acidification, and more frequent and severe weather extremes. These changes have profound impacts on global ecosystems and human societies. The world has recognized the necessity for countries to cooperate in combating climate change, resulting in international treaties such as the Kyoto Protocol and the Paris Agreement. The success of international cooperation depends on a portfolio of various approaches to eliminate, reduce, substitute, and compensate for GHG emissions. The transition from fossil fuels to renewable energy can effectively mitigate GHG emissions. Wind and solar energy have experienced substantial growth over the past decade, yet the development of geothermal energy remains stagnant despite its immense potential. Considering its additional advantages, such as the dual benefits of generating both electricity and heat, the stability of energy generation, and the synthesis with carbon capture and storage, more focus should be placed on geothermal energy. Meanwhile, most efforts to address climate change have focused on mitigating carbon dioxide (CO2) emissions and removing their accumulation from the atmosphere. While there is ~210x more CO2 than methane (CH4) in the atmosphere, the atmospheric concentration of CH4 has increased faster and alone contributes an amount of radiative forcing that is about 30% of the contribution from CO2. With positive temperature-driven feedbacks that release CH4 to the atmosphere as temperatures rise, a shorter atmospheric lifetime than CO2, and continued reliance on natural gas, a portfolio approach is urgently needed to slow, stop, and reverse the accumulation of CH4 in the atmosphere. To provide insights to address the above issues, this dissertation focuses on optimizing strategies for geothermal heat mining and CH4 control. Cha (open full item for complete abstract)

Committee: Jeffrey Bielicki (Advisor); Gil Bohrer (Committee Member); Jordan Clark (Committee Member); Daniel Gingerich (Committee Member) Subjects: Civil Engineering; Environmental Engineering

Doctor of Engineering, University of Dayton, 2021, Mechanical Engineering

One way to reduce conventional energy consumption is through the use of a vertical ground-coupled heat pump (GCHP) systems where heat is charged/discharged to/from the ground by an array of grouted vertical borehole heat exchangers. Although this technology is promising to increase the efficiency of heat-pumps, the main obstacle is the high initial cost. This work examines the viability of one possibility means to overcome the first cost challenge, which is to add micro-encapsulated, paraffin-based phase-change material (PCM) to the borehole grout to dampen the borehole heat exchanger (BHE) peak fluid temperatures. As with any thermal energy storage scheme, its purpose is to reduce the size of equipment and devices required to meet peak loads, and thus the purpose of PCM in this study is to dampen peak temperature response of the borehole, and potentially allow for reduction in design borehole length, and therefore cost, of the borehole array. A numerical analysis of the heat transfer characteristics of a GCHP systems is performed to investigate the effects of adding micro-encapsulated PCM into the borehole grout. The numerical model was completed in COMSOL, where the apparent heat capacity method is used, and validated against experimental data. A parametric study of the PCM thermal properties was conducted to establish design recommendations for the vertical heat exchange borehole grout. Results of this study show that adding PCM into the borehole does not always improve the overall performance of the GCHP system; rather, it could deteriorate the system performance if the PCM thermal properties and melt temperature are not correctly chosen. An optimum mass of PCM exists for borehole grout due to the competing factors of PCM thermal conductivity and its latent heat capacity, but to be effective, the PCM thermal conductivity should be approximately equivalent to that of the grout material. Further, the optimal melt temperature of the PCM was found to be that which (open full item for complete abstract)

Committee: Andrew Chiasson (Advisor); David Myszka (Committee Member); Muhammad Usman (Committee Member); Gilbert Robert (Committee Member) Subjects: Energy; Geophysics; Mechanical Engineering

Master of Science (MS), Ohio University, 2020, Environmental Studies (Voinovich)

Ground source heat pumps (GSHPs) have been used for heating and cooling applications in areas where the thermal gradients are normal. Unlike conventional heating and cooling systems, ground source heat pumps rely on ground or underground water temperature which is more constant than air temperature. Abandoned underground coal mines (AUMs) have been used as heat exchangers for ground source heat pumps in countries such as Nova Scotia, the Netherlands and states like Pennsylvania. Ohio has around 147 abandoned underground mines located close to towns and with sufficient water and heat available in the groundwater for heat exchange using ground source heat pumps. This project characterizes the potential of the AUM AS-029 located in Athens, Ohio, as a reservoir for GSHP technology in Ohio University or The Plains. Monitoring of the hydraulic and thermal response of groundwater wells around the mine was performed and a hydrogeological model was constructed in Visual MODFLOW to better understand the flow of water through the mine. Additionally, a thermal model of the mine was created considering the overburden thickness of the mine. Three monitoring wells were studied, one to the north of the mine and 2 to the South in The City of Athens well field in the Hocking River valley. Groundwater in the 4 wells respond to precipitation and changes in ambient temperature with a higher response in the wells with lower depth. One of the City of Athens wells, A10, has an unusual response with a high conductivity due to a nearby underground salt deposit. Ground water modeling and modeling of the heat absorbed by the mine shows that mine AS-029 can be used to receive heat, it cannot be used to give heat due to the low temperature of the groundwater in this area. The volume of water that circulates through the mine is not easily exchanged since only 0.03% is exchanged every day and it takes 2,900 days to substitute 100% of the water within the mine. For a change in temperature in the mi (open full item for complete abstract)

Committee: Dina López Dr. (Advisor); Natalie Kruse Daniels Dr. (Committee Member); Daniel Che Dr. (Committee Member) Subjects: Energy; Environmental Geology; Environmental Science; Environmental Studies; Geology; Hydrologic Sciences; Hydrology

Doctor of Philosophy (Ph.D.), University of Dayton, 2020, Mechanical Engineering

This dissertation focusses mainly on loads determination, building informatics, and geothermal energy systems. The first chapter is Low-Energy Opportunity for Multi-Family Residences: A Simulation-Based Study of a Borehole Thermal Energy Storage System. In this chapter, we propose a district borehole thermal solar energy storage (BTES) system for both retrofit and new construction for a multi-family residence in the Midwestern United States, where the climate is moderately cold with very warm summers. Actual apartment interval power and water demand data was mined and used to estimate unit level hourly space and water heating demands, which was subsequently used to design a cost-optimal BTES system. Using a dynamic simulation model to predict the system performance over a 25-year period, a parametric study was conducted that varied the sizes of the BTES system and the solar collector array. A life-cycle cost analysis concluded that is it possible for an optimally-sized system to achieve an internal rate of return (IRR) of 11%, while reducing apartment-wide energy and carbon consumption by 46% The promise for district-scale adoption of BTES in multi-family residences is established, particularly for new buildings. In the second chapter (Alternate Approach to the Calculation of Thermal Response Factors for Vertical Borehole Ground Heat Exchanger Arrays Using an Incomplete Bessel Function), we presents another methodology for the calculation of dimensionless thermal response factors for vertical borehole ground heat exchanger (GHX) arrays, which is a concept introduced by Eskilson (1987). The presented method is based on a well-known solution to an analogous problem in the field of well hydraulics. This solution method, known mathematically as an incomplete Bessel function, and known in the field of well hydraulics as the `leaky aquifer function', describes the hydraulic head distribution in an aquifer with predominantly radial flow to a well combined with vertical (open full item for complete abstract)

Committee: Kevin P Hallinan Professor (Committee Chair); Andrew D. Chiasson Professor (Committee Member); Robert J. Brecha Professor (Committee Member); Robert B. Gilbert Professor (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2019, Environmental Science

Reducing carbon dioxide (CO2) emissions is one of the most pressing issues facing the electricity system. Towards this end, prior work investigated generating electricity with geologically stored CO2 by using it to extract heat from sedimentary basins geothermal resources. This dissertation expands on this idea by developing and valuing approaches for CO2-based energy storage. In the first chapter, we investigate the value that three bulk energy storage (BES) approaches have for reducing system-wide CO2 emissions and water requirements: CO2-Bulk Energy Storage (CO2-BES), which is a CO2-based energy storage approach that uses a concentric-ring, pressure based (CRP-BES) design, Pumped Hydro Energy Storage (PHES), and Compressed Air Energy Storage (CAES). Our results suggest that BES could decrease system-wide CO2 emissions by increasing the utilization of wind, but it can also alter the dispatch order of regional electricity systems in other ways (e.g., increase in the utilization of natural gas power capacity and of coal power capacity, decrease in the utilization of nuclear power capacity). While some changes provide negative value (e.g., decrease in nuclear increased CO2 emission), the system-wide values can be greater than operating cost of BES. In the second and third chapters, we investigate two mechanisms for using CO2 for energy storage: storage of (1) pressure and (2) heat. For pressure storage, we investigated the efficacy of the CO2-BES system using the CRP-BES design over cycles of varying durations. We found that CO2-BES could time-shift up to a couple weeks of electricity, but the system cannot frequently dispatch electricity for longer durations than was stored. Also, the cycle duration does not substantially affect the power storage capacity and power output capacity if the total time spent charging, discharging, or idling is equal over a multi-year period. For thermal energy storage, we investigated the efficacy of using pre-heated CO2 and pre-h (open full item for complete abstract)

Committee: Jeffrey Bielicki (Advisor); Ramteen Sioshansi (Committee Member); Gil Bohrer (Committee Member); Brent Sohngen (Committee Member) Subjects: Alternative Energy; Energy; Engineering; Environmental Economics; Environmental Science

Master of Science (M.S.), University of Dayton, 2017, Renewable and Clean Energy

Photovoltaic-thermal (PVT) technology is a relatively new technology that comprises a photovoltaic (PV) panel coupled with a thermal collector to convert solar radiation into electricity and thermal energy simultaneously. Since cell temperature affects the electrical performance of PV panels, coupling a thermal collector with a PV panel contributes to extracting the heat from the latter to improve its performance. In order to ensure a sufficient temperature difference between the PV cells and the working fluid temperature entering the thermal collector, the circulated water has to reject the heat that has been removed from the PV cells into a relatively colder environment. Borehole thermal energy storage (BTES), which is located underground, often serves as this relatively colder environment due to the stability of underground temperatures, which are usually lower than the working cell temperature. Use of BTES is especially beneficial in summer, when the degradation in cells efficiency is highest. In this thesis, the electrical, thermal, and economic performances of a PVT system are evaluated for three types of buildings -- residential, small office, and secondary school -- in two different climates in the United States, one of which is hot and the other is cold. For each case, two different scenarios are considered. In the first, a PVT system is coupled with BTES, and a ground-coupled heat pump (GCHP) is in use. In the second, a PVT system is coupled with BTES and no GCHP is in use. Each scenarios' GCHP performance is assessed as well. Both the PVT collectors and GCHP performances are evaluated over short and long-term to study the effect of continued ground heat imbalance on both technologies.

Committee: Andrew Chiasson Ph.D. (Committee Chair); Youssef Raffoul Ph.D. (Committee Member); Robert Gilbert Ph.D. (Committee Member) Subjects: Energy; Engineering; Mechanical Engineering

Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Mechanical Engineering

Combined heat and power (CHP) systems are increasingly used in conjunction with traditional grid power for industrial and residential applications. This technology most often involves the on-site combustion of primary fuel, such that both electrical and thermal energy can be utilized to increase overall efficiency. It is also possible to create electrical and thermal energy from solar radiation, using hybrid photovoltaics and thermal (PVT) collectors. These are designed to lower the photovoltaic temperature, improving electrical efficiency, while providing useful thermal energy. One of the key steps in deploying CHP technology is optimal sizing and energy dispatch for a particular application. This work considers these problems for a natural gas powered CHP in a multi-family residential building in North America, and PVT for desalination in remote areas in the Kingdom of Saudi Arabia (KSA). It has already been established that CHP for building applications can reduce grid power requirement and lower overall energy costs. However, no comprehensive study has considered optimizing CHPs for multi-family residences. Although this type of building represents a significant fraction of overall energy consumption in the US and world, they have been shown to be significantly less efficient than other types of residences. Also, due to significant thermal demand in the form of hot-water, multi-family residences are particularly well-suited for CHP. Two separate natural gas powered CHP designs for a multi-family residence are presented in this work, both conceived as retrofits to an existing building. These designs use historical demand data from an all-electric 120-unit multi-family residence in Columbus, Ohio, US that was built in 2008 to minimum code standards. The first design uses a CHP that operates intermittently to meet partial loads for electricity and hot water in order to reduce overall energy cost, when considering a demand sensitive grid power cost prici (open full item for complete abstract)

Committee: Hallinan Kevin (Committee Chair) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2016, Civil Engineering

Sedimentary basins are emerging candidates for geothermal deployment due to their widespread presence in the subsurface, large storage capacity, and high temperatures. These geothermal systems rely on the temperature of the reservoir—and thus the temperature of the extraction fluid produced to the surface—but these temperatures can decrease if the rate at which heat is extracted from the reservoir exceeds the rate at which the natural geothermal heat flux increases the temperature. In this context, sustainability is often synonymous with extracting heat at a rate that maintains the temperature of the production fluid at a desired level. This perspective of sustainability focuses on the physical/environmental performance of the geothermal reservoir. But preserving heat in the reservoir may not be economically viable. Environmental and economic performance are interconnected, and systems must consider both of these metrics when determining an optimal operation strategy to conserve both the longevity of the resource and the associated economic profit. Natural resource economics focuses on developing strategies for resource management and/or allocation that weighs the environmental and economic benefits of a system. The following thesis presents a natural resource economics model for the optimal management of a geothermal resource using conventionally used water or carbon dioxide (CO2) as a heat extraction fluid. I investigated the performance of a sedimentary basin geothermal resource under a variety of scenarios, parameterized those results to accurately predict change in geothermal performance, and implemented those results in a natural resource economic model. The Non-isothermal Unsaturated- saturated Flow and Transport (NUFT) code simulates a sedimentary basin geothermal reservoir under a range of geologic conditions and was used to understand and parameterize geothermal performance. I combined the simulation outputs from all the scenarios by normalizing the pr (open full item for complete abstract)

Committee: Jeffrey Bielicki (Advisor); Ethan Kubatko (Committee Member); Gopalakrishnan Sathya (Committee Member) Subjects: Environmental Engineering

Master of Science, The Ohio State University, 2016, Environmental Science

In this project I worked with a team of analysts, and together we sought to develop new ways to analyze geologic, geochemical, and geophysical data that would increase the prospects of geothermal exploration and development. We collected, organized, and analyzed data sets from southwest New Mexico in the context of an integrated framework that combines the data sets for various signatures of a geothermal resource into a cohesive analysis of the presence of heat, fluid, and permeability. We incorporated data sets on structural characteristics (earthquakes, geophysical logs, fault location and age, basement depth), surface topography, water table elevation, conservative ion concentrations, and thermal information (heat flow, bottom hole temperature, discharge temperature, and basement heat generation). These data sets were combined to create maps that indicate structural analysis, slope, geothermometry, and heat. We also mapped discharge areas (to constrain elevations where groundwater may be discharged through modern thermal springs or paleo-thermal springs) and subcrops: possible erosionally- or structurally-controlled breaches in regional-scale aquitards that form the basis of our hydrogeologic windows concept. These two maps were particularly useful in identifying known geothermal systems and narrowing the search for unknown geothermal prospects. I further refined the “prospectivity” of the areas within the subcrops and discharge areas by developing and applying a new method for spatial association analysis to data on known and inferred faults, earthquakes, geochemical thermometers, and heat flow. This spatial association analysis method determines the relationships of the location and magnitudes of observations of these data with known geothermal sites. The results of each of the six spatial association analyses were weighted between 0 and 1 and summed to produce a prospectivity score between 0 and a theoretical maximum of 9, with 9 indicating highest geothermal (open full item for complete abstract)

Committee: Jeffrey Bielicki Prof. (Advisor); Gajan Sivandran Prof. (Committee Member); Desheng Liu Prof. (Committee Member) Subjects: Environmental Science

Master of Sciences (Engineering), Case Western Reserve University, 2015, Macromolecular Science and Engineering

Geothermal technology has gained wide attention as a new source of renewable energy but its optimum utilization is limited by accelerated corrosion. Solutions for this problem are often reactive such as regular preventive maintenance and replacement for corrosion affected components. A proactive way to solve this problem is by utilizing anti-corrosion polymers designed for geothermal brine chemistry. In this study, two different types of polymer application, an inhibitor and a coating, were evaluated for the corrosion protection of carbon steel in acidic geothermal brine. Polyvinylpyrrolidone(PVP) was used as a corrosion inhibitor while a nanocomposite composed of Polybenzoxazine, rubber and montmorillonite (PBZ-R-MMT) was synthesized for coating application. Various characterization techniques such as Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy(XPS),Fourier Transform-Infrared ( FT-IR), X-ray Diffraction(XRD), Thermal Gravimetric Anaysis(TGA), and Differential Scanning Calorimetry(DSC) were done to determine the applicability and effect of these polymers to carbon steel immersed in simulated acidic geothermal brine. The anti-corrosion properties of both the inhibitor and the coating were tested further using electrochemical techniques.

Committee: Rigoberto Advincula (Advisor) Subjects: Energy; Engineering; Materials Science

Master of Science, The Ohio State University, 2014, Geological Sciences

The overarching objective of this study is to document the water-rock interaction at the Coso geothermal area where the U.S. Department of Energy Enhanced Geothermal Systems (EGS) experiments are conducted to better understand the thermal evolution of this system. This effort quantifies the relationship between mineralogy and the pore/fracture network in order to track the evolution of water-rock interaction as a function of space and time. The relationship among the size, shape and distribution of pores relevant to mineralogy and mineral abundance are used as indicators of how fluids migrate through and react within the micropore environment. This paper summarizes petrologic and geochemical characterizations on well cuttings from three East Flank wells, and one West Flank well, with the focus on one of the East Flank wells, Navy II well 42A-16, to better understand the geologic process of hydrothermal alteration, its evolution, and how changes in mineralogy impacted porosity and permeability. Several alteration types in these well cuttings are observed with the two most important being: NaAlSi3O8 • CaAl2Si2O8 + H4SiO4 + Na + = 2NaAlSi3O8 + Al+3 + Ca+2 + 4OH- (1) (xNa, yCa)AlSi3O8 + K+ + Na+ + Fe+3 + Mg+2 + H2O -> (2) (K, Na)2(Al, Fe, Mg)4Si6O20(OH)4 + (x+mNaAlSi3O8, y-mCaAlSi2O8) +2mCa+2 where albitization of calcic-plagioclase is represented by (1), and sericitization after plagioclase is represented by reaction (2). Collectively these reactions are two of the most significantly occurring over the range of depths in Navy II well 42A-16. This albite-sericite alteration tends to be associated with the potassic alteration, and often occur together especially in quartz diorite and granodiorite host rocks. Secondary albite and sericite formed at the mid-stage of mineral paragenesis in this system. The earliest minerals to form were epidote, titanite, rutile/anatase, and chlorite (perhaps of earlier metamorphic origin); whereas the most recently formed mine (open full item for complete abstract)

Committee: David Cole Prof. (Advisor); Michael Barton Prof. (Committee Member); Ann Cook Prof. (Committee Member) Subjects: Geochemistry

Master of Science (MS), Wright State University, 2014, Earth and Environmental Sciences

The temperature of groundwater in aquifers is relatively stable when compared to the water temperature in surface-water bodies. However, in aquifers that are hydraulically connected to rivers that have water flux into the aquifer, the local aquifer temperature can show seasonal variation. This project focused on the thermally-altered, near-river zone of such an aquifer, and used numerical methods to examine the extent of seasonal variation in temperature into the aquifer, and the attenuation and phase shift of the signal with distance from the river. The results show that the extent of alteration by diffusive heat flow is negligible compared to the advective component of heat flow. Therefore, because heat transport is driven primarily by advection, the extent of seasonal variation in temperature into the aquifer, as well as the attenuation and phase lag of the signal are significantly dependent on the hydraulic gradient between the river and aquifer. Furthermore, the extent, attenuation, and phase lag of seasonal variation in temperature within the aquifer was found to be strongly dependent on heterogeneity. Considerable differences in the expression of the seasonally varying temperature signal were found to occur as a result of the local presence of high and/or low hydraulic conductivity material. Finally, for the Miami Valley aquifer (which the models used in this study were based upon), seasonal variation in groundwater temperature is expected only within a lateral distance of about 135 meters from the river and there only within a depth of about 25 meters.

Committee: Robert Ritzi Ph.D. (Advisor); David Dominic Ph.D. (Committee Member); Chris Barton Ph.D. (Committee Member) Subjects: Environmental Geology; Environmental Science; Geology

Master of Science (MS), Ohio University, 2014, Geological Sciences (Arts and Sciences)

Traditionally, geothermal resources have required access to large amounts of heat, often in tectonically active basins. More recently, Ground Source Heat Pumps (GSHP) have been used for heating and cooling applications in basins with less heat available in the shallow crustal material. Conventionally, GSHPs exchange heat with either saturated or unsaturated soils or bedrock, or water, at an increased efficiency compared to traditional heating and cooling systems. This study is focused on characterizing the potential of using flooded abandoned underground mines (AUM) in Ohio for heat exchange using GSHP technology. This study identified 147 possible mine sites, spanning 21 counties, which might be used for GSHP installations in Ohio. The mines have an estimated average maximum residence time of 6 years and an estimated average minimum residence time of 3.5 years. It was estimated here that, on average, 1010 kJ/°C of heat energy could be extracted from the mine waters. An individual site study was investigated for possible GSHP application, at the Corning Mine Complex in Perry County, Ohio. Temperature and hydraulic head sensors were installed into monitoring wells drilled into the mine void. The results from the Corning study show that the mine is thermally stable throughout the year and that the average temperature within the mine void is related to the thickness of overburden above the void. The residence time of water within the mine is 3.6 years with an extractable heat of 3.45 x 1010 kJ/°C. Overall, this study has shown that there is sufficient heat available within AUMs for heat exchange using GSHP technologies and that these mines could be a valuable resource for heating and cooling applications in Ohio.

Committee: Dina Lopez (Advisor) Subjects: Environmental Geology; Geochemistry; Geology; Hydrology

MA, Kent State University, 2013, College of Arts and Sciences / Department of Geography

Food is globalizing, placing national identity and food security in jeopardy. With economic crises, environmental hazards, increasing population, and international warfare, food security should be of increasing global concern, yet it remains an oversight in many countries. There is specific neglect in developed nations where the more obvious signs of food insecurity, such as food shortages, malnutrition, and starvation, are not present. Instead the danger lies in interrupted import systems, sudden environmental disasters, global economic crises, and a myriad of other threats. One method of safeguarding against these less obvious threats is to cultivate a sustainable, internal food source. Geothermal greenhouse agriculture presents an opportunity for countries in cold climates with non-arable land to have such a food source. Low-enthalpy geothermal sources are abundant in most countries and can easily be used to naturally heat soil for agriculture. It is surprising that countries in cold climates are not taking greater advantage of this inexpensive, sustainable method of agriculture. Could a greater emphasis on geothermal greenhouse agriculture in developed countries such as Iceland increase food security and restore national identity?

Committee: David Kaplan Ph.D. (Advisor); Chris Post Ph.D. (Committee Member); Sarah Smiley Ph.D. (Committee Member) Subjects: Geography

Master of Science (MS), Wright State University, 2012, Earth and Environmental Sciences

Subsurface heat flow was simulated to study the effect of hyporheic exchange on groundwater intake temperatures of open-loop geothermal wells in glacigenic-outwash aquifers in the North American midcontinent. The model represents an aquifer kilometers wide, on the order of 100m thick, and directly connected to a perennial river. The aquifer has bimodal hydraulic conductivity with a geometric mean on the order of 100m/day, an effective thermal conductivity of 2.33W/mK, and specific heats on the order of 106J/(m^3 K) for water and 103J/kgK for solids. The aquifer is initially set to a temperature of 12.85 ¿¿¿¿C and the river is fixed to 26.85 ¿¿¿¿C. Results show that the ambient zone of hyporheic thermal influence spans the entire depth of the aquifer and extends laterally for approximately a half a kilometer from the river. Temperatures within this zone decrease, as a linear approximation, at about 1 ¿¿¿¿C per 50 m distance from the river. Aquifer heterogeneity strongly influences the extent of and the temperatures within the hyporheic zone. A well pumping at 500 m^3/day had intake temperatures as much as 2¿¿¿¿C greater than ambient levels and, depending on location, slightly extended the range of the river's thermal influence. However, this increase of intake temperature was not instantaneous, drifting upward on the order of 1 ¿¿¿¿C per century before achieving thermal equilibrium. A realistic distribution of 25 wells pumping at variable rates extended the range of thermal influence to a kilometer, produced intake temperatures as much as 16 ¿¿¿¿C greater than ambient levels, and increased spatial variability in aquifer temperatures.

Committee: Robert Ritzi PhD (Committee Chair); David Dominic PhD (Committee Member); Chris Barton PhD (Committee Member) Subjects: Environmental Engineering; Environmental Geology; Environmental Management; Environmental Science; Environmental Studies; Hydrologic Sciences; Hydrology

Master of Science in Engineering (MSEgr), Wright State University, 2011, Renewable and Clean Energy

The rise in fossil fuel consumption and green house gas emissions has driven the need for alternative energy and energy efficiency. At the same time, ground loop heat exchangers (GLHE) have proven capable of producing large reductions in energy use while meeting peak demands. However, the initial cost of GLHEs sometimes makes this alternative energy source unattractive to the costumer. GLHE installers use commercial programs to determine the length of pipe needed for the system, which is a large fraction of the initial cost. These commercial programs use approximate methods to determine the length of pipe mainly due to their heat transfer analysis technique, and as a result, sometimes oversize the systems. A more accurate GLHE sizing program can simulate the system correctly, thus, reducing the length of pipe needed and initial cost of the system. We feel a more accurate GLHE sizing program is needed. As part of a DOE funded project Wright State University has been developing a ground loop geothermal computer modeling tool, GEO2D, that uses a detailed heat transfer model based on the governing differential energy equation. This tool is meant to be more physically detailed and accurate than current commercial ground loop geothermal computer codes. The specific work of this Master's thesis first includes a detailed literature search of GLHE sizing techniques. Secondly, this work contains a detailed description of commercial GLHE sizing codes currently available and compares some results to GEO2D. Additionally, this work has developed a g-function program; a GLHE sizing technique used by many commercial programs, and compared results to GEO2D. Next, this work has developed subroutines to develop a three-dimensional grid system for a horizontal and vertical GLHE. Lasty this work has developed computer code for the boundary conditions and material property allocation used in GEO3D.

Committee: James Menart PhD (Advisor); James Menart PhD (Committee Member); Rory Roberts PhD (Committee Member); Haibo Dong PhD (Committee Member) Subjects: Mechanical Engineering

Master of Science in Engineering (MSEgr), Wright State University, 2011, Renewable and Clean Energy

The use of the earth's thermal energy to heat and cool building space is nothing new; however, the heat transfer approximations used in modeling geothermal systems, leave uncertainty and lead to over sizing. The present work is part of a Wright State effort to improve the computer modeling tools used to simulate ground loop geothermal heating and cooling systems. The modern computer processor has equipped us with the computation speed to use a finite volume technique to solve the unsteady heat equation with hourly time steps for multi-year analyses in multiple spatial dimensions. Thus we feel there is more need to use approximate heat transfer solution techniques to model geothermal heating and cooling systems. As part of a DOE funded project Wright State has been developing a ground loop geothermal computer modeling tool that uses a detailed heat transfer model based on the governing differential energy equation. This tool is meant to be more physically detailed and accurate than current commercial ground loop geothermal computer codes. The Wright State code allows the geothermal designer to optimize the system using a number of outputs including temperature field outputs, existing fluid temperature plots, heat exchange plots, and even a histogram of the COP data. Careful attention to the algorithm speed allows for multi-year simulations with minimal computation cost. Once the thermal and heat transfer computations are complete, a payback period calculator can compare any conventional heating and cooling system to the designed geothermal system and payback periods are displayed. The work being presented as part of this thesis deals with five issues that were required to make the Wright State geothermal computer code a reality. The five aspects of this modeling tool addressed by this thesis work are: energy load calculations, GUI (graphical user interface) development, turbulence model development, heat pump model development, and two-dimensional numerical grid deve (open full item for complete abstract)

Committee: James Menart PhD (Committee Chair); Hong Huang PhD (Committee Member); Chung-Jen Tam PhD (Committee Member) Subjects: Mechanical Engineering

Master of Science (MS), Ohio University, 2008, Geological Sciences (Arts and Sciences)

The Berlin hydrothermal field in El Salvador, Central America is located in the San Simon River Basin on the northwest slope of the Berlin-Tecapa volcanic complex, in the eastern portion of the country. This hydrothermal field is a liquid-dominated system governed by fault structures allowing infiltration and transport of meteoric fluids. Exploitation involves the removal of hot fluids from the geothermal reservoir and re-injection of lower temperature fluids. This study analyzes the surficial hydrology and groundwater storage change (since exploitation) in the hydrothermal reservoir to produce a water budget. Field monitoring of springs, fumarole activity, domestic wells, tributaries to the San Simon River, and meteorologic data provide constraints on the hydrology. A correlation between the composition of the fumarolic gases and the diffuse flux of soil CO2 was performed to complete the balance. An analysis of the increase in chloride concentration with time in the deep aquifer and the net mass withdrawn from this aquifer allow an estimation of the decrease in storage in the hydrothermal aquifer. This water balance will assist future operations in optimization and sustainability of the geothermal reservoir and could be used to evaluate extraction and re-injection procedures.

Committee: Dina L. Lopez Ph.D. (Advisor); Gierlowski-Kordesch Elizabeth (Other); Gregory Nadon (Other) Subjects: Geology