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Geothermal Energy: An Important Resource edited by Carolyn B. Dowling Department of Geological Sciences Ball State University 2000 W. University Avenue Muncie, Indiana 47306, USA Klaus Neumann Department of Geological Sciences Ball State University 2000 W. University Avenue Muncie, Indiana 47306, USA Lee J. Florea Department of Geological Sciences Ball State University 2000 W. University Avenue Muncie, Indiana 47306, USA Special Paper 519 3300 Penrose Place, P.O. Box 9140 Boulder, Colorado 80301-9140, USA 2016 Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/961808/spe519-00.pdf by guest on 23 April 2020 Copyright © 2016, The Geological Society of America (GSA), Inc. All rights reserved. Copyright is not claimed on content prepared wholly by U.S. government employees within the scope of their employment. Individual scientists are hereby granted permission, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in other subsequent works and to make unlimited photocopies of items in this volume for noncommercial use in classrooms to further education and science. Permission is also granted to authors to post the abstracts only of their articles on their own or their organization’s Web site providing that the posting cites the GSA publication in which the material appears and the citation includes the address line: “Geological Society of America, P.O. Box 9140, Boulder, CO 80301-9140, USA (http://www.geosociety.org),” and also providing that the abstract as posted is identical to that which appears in the GSA publication. In addition, an author has the right to use his or her article or a portion of the article in a thesis or dissertation without requesting permission from GSA, provided that the bibliographic citation and the GSA copyright credit line are given on the appropriate pages. For any other form of capture, reproduction, and/or distribution of any item in this volume by any means, contact Permissions, GSA, 3300 Penrose Place, P.O. Box 9140, Boulder, Colorado 80301-9140, USA; fax +1-303-357-1070; [email protected]. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, sexual orientation, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society. Published by The Geological Society of America, Inc. 3300 Penrose Place, P.O. Box 9140, Boulder, Colorado 80301-9140, USA www.geosociety.org Printed in U.S.A. GSA Books Science Editors: Kent Condie and Richard A. Davis Library of Congress Cataloging-in-Publication Data is available from the Library of Congress. ISBN 978-0-8137-2519-2 (paperback) Cover: Energy stations contain the geothermal heat pumps, which are the workhorses of the ground- source geothermal system installed at the Ball State University campus (Muncie, Indiana). They use the Earth as a heat source or sink, depending on the university’s requirements. White, yellow, and green pipes are part of a district-wide distribution system that exchanges energy or heat between the ground and campus buildings. The white pipes (not shown) circulate water through the borehole fields to dissipate or retrieve stored heat. The yellow pipes serve the heating needs on campus, and the green pipes are used for the campus’s cooling demands. Photo courtesy of James Lowe. 10 9 8 7 6 5 4 3 2 1 Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/961808/spe519-00.pdf by guest on 23 April 2020 Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v 1. Utility of geological and pedological models in the design of geothermal heat pump systems . . . .1 Kevin M. Ellett and Shawn Naylor 2. The characterization of flooded abandoned mines in Ohio as a low-temperature geothermal resource . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Joshua Richardson, Dina Lopez, Timothy Leftwich, Mike Angle, Mark Wolfe, and Frank Fugitt 3. Thermogeologic performance of a large-scale, district geoexchange system in southeast Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 Martin F. Helmke, Jacqueline A. Wilson, Denise C. Gatlin, and Kirsten O. Moore 4. Petrographic and hydrogeologic investigations for a district-scale ground-coupled heat pump—Ball State University, Indiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51 Andrew Siliski, Lee J. Florea, Carolyn B. Dowling, Klaus Neumann, Alan Samuelson, and Marsha Dunn 5. Evaluation of a discrete-depth heat dissipation test for thermal characterization of the subsurface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67 Stephen M. Sellwood, Jean M. Bahr, and David J. Hart 6. Physical modeling of coupled heat transfer and water flow in soil-borehole thermal energy storage systems in the vadose zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81 Tuğçe Başer, Thierry Traore, and John S. McCartney 7. Thermal conductivity, thermal gradient, and heat-flow estimations for the Smackover Formation, southwest Arkansas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 Lea M. Nondorf 8. Stochastic exploration and the geologic context of enhanced geothermal system viability on the Snake River Plain, Idaho . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115 Alex Moody, Jerry Fairley, and Mitchell Plummer iii Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/961808/spe519-00.pdf by guest on 23 April 2020 Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/961808/spe519-00.pdf by guest on 23 April 2020 The Geological Society of America Special Paper 519 2016 Preface Nationally and globally, geothermal energy is a crucial resource. Included in this GSA Special Paper are important complementary investigations from geothermal heat pumps to enhanced geothermal systems. Geothermal heat pumps (GHPs), also called ground-source heat pumps (GSHPs), are often closed sys- tems with vertical or horizontal borehole heat exchangers (BHEs) (Haehnlein et al., 2010). GHPs use the relatively constant soil and bedrock temperature to store and release thermal load in the summer and the winter, respectively (Lund et al., 2004; Haehnlein et al., 2010). These systems commonly consist of a series of sealed pipe that is installed as loops in the ground, through which water and/or antifreeze is circulated, and which are connected to a heat pump or energy exchanger (Diao et al., 2004). GHPs are a rapidly grow- ing application of renewable energy with more than 900,000 units operating in the United States and annual increases of 10% in ~30 countries over the past ten years (Lowe et al., 2010; Lund et al., 2004). The main advantage of GHPs is the use of ambient ground temperatures. While deep geothermal applications (about >400 m depth; discussed later) are often large scale and geologically specifi c (i.e., hydrothermal vents and areas of high heat fl ux), GHPs are deployed in relatively shallow environments (<400 m depth) that do not require unusual geological settings or high geothermal gradients, and are therefore possible around the world. The use of shallow geothermal energy is considered an environmentally friendly alternative to fossil fuel (e.g., coal, oil, or gas) for residences and universities, as well as government and commercial buildings. A small amount of electricity input is required to run compressors for GHPs, but the energy gained is four times greater (Lund et al., 2004; Haehnlein et al., 2010). Current research focuses on aspects of GHP design and application; this GSA Special Paper mainly concentrates on sustainability and effi ciency. In terms of sustainability and long-term usage, researchers are concerned that the use of shallow geothermal energy may result in thermal plumes (hot or cold) in local groundwater (Haehnlein et al., 2010; Rybach and Eugster, 2010; Helmke et al., this volume; Siliski et al., this volume). Changes in groundwater temperature can infl uence its physical properties, chemical reactions, microbiology, and the interaction of these factors, as well as reduce the effi ciency of the energy system. From the effi ciency viewpoint, planning GHPs of the right size and arrangement is not a simple task because heat transfer between a BHE and its surrounding environment is complicated. Besides the confi guration of borehole fi elds, other variables infl uence the systems’ performance, such as the distribution of thermal con- ductivity with depth, moisture content of the soils, and groundwater movement (Diao et al., 2004; Olfman et al., 2014; this volume [Ellett and Naylor; Richardson et al.; Helmke et al.; Siliski et al.; Sellwood et al.; Başer et al.]). Current design tools are based on the assumption that only bulk heat conduction is important and do not consider the implications of these other factors. As a consequence, natural variables (e.g., groundwater fl ow) are neglected in GHP designs, even though modeling, laboratory experiments, and fi eld studies suggest that the impact of the surrounding environment on the GHPs may be prominent (Diao et al., 2004; Olfman et al., 2014; this volume [Ellett and Naylor; Richardson et al.; Helmke et al.; Siliski et al.; Sellwood et al.; Başer et al.]). Enhanced geothermal systems (EGS) are also used in direct-use applications for power generation. They are restricted to regions with high heat fl uxes and usually involve large-scale facilities. Iceland, California, and Nevada are well-known locations where in situ geothermal energy is exploited. Geothermal electricity Preface, 2016, in Dowling, C.B., Neumann, K., and Florea, L.J., eds., Geothermal Energy: An Important Resource: Geological Soci- ety of America Special Paper 519, p. v–vii, doi:10.1130/2016.2519(00). For permission to copy, contact [email protected]. © 2016 The Geological Society of America. All rights reserved. v Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/961808/spe519-00.pdf by guest on 23 April 2020 vi Preface production accounts for 4% of the renewable electricity production of the United States, which translates to ~0.5% of the entire U.S. electricity production; however, usage has increased by 20% since 2005 (Lund et al., 2010). Two aspects of augmenting geothermal systems are discussed in this volume: the expansion of geothermal use to U.S. states (i.e., Arkansas) other than the already engaged western states (i.e., California, Nevada, etc.) and the improvement of current and future applications (Nondorf, this volume; Moody et al., this volume). Both topics are still in their experimental stages and depend on data from heat fl ux studies of the impact and effectiveness of methods such as the use of hydraulic fracking. This volume covers many aspects of geothermal energy research: high and low temperature as well as fi eld, lab, and modeling approaches. However, the papers commonly address the sustainability and effi - ciency of geothermal energy usage. The fi rst six papers describe fi eld studies and modeling in the fi eld of geothermal heat exchange and ground source geothermal systems, with a focus on better understand- ing heat dissipation within the ground. “Utility of geological and pedological models in the design of geothermal heat pump systems” by K.M. Ellett and S. Naylor describes how extensive measurements of soil temperature and subsequent modeling can save signifi cant amounts of money in the construction of ground heat exchange systems. Their studies at several sites in Indiana suggest exchange loops are up to 45% longer than needed for obtaining design specifi cations. “The characterization of fl ooded abandoned mines in Ohio as a low-temperature geothermal resource” by J. Richardson, D. Lopez, T. Leftwich, M. Angle, M. Wolfe, and F. Fugitt looks into the innovative usage of abandoned underground coal mines located in proximity to population centers in eastern Ohio. The geothermal system would exploit water in fl ooded mines with a higher heat capacity than saturated soils or bedrock. Based on their study, 147 mine sites have been deemed usable for geothermal systems in eastern Ohio. “Thermogeologic performance of a large-scale district geoexchange system in southeast Pennsylvania” by M.F. Helmke, J.A. Wilson, D.C. Gat- lin, and K.O. Moore outlines an already established GHP project. In their study of West Chester University’s 16 MW, 529 BHE system, they describe how monitoring temperatures and heat fl ux helped characterize the performance of the fi eld. They determine that BHE design caused the temperature of the borehole fi eld to increase from ~13 °C to ~34 °C, which is close to the maximum effi cient temperature for geothermal heat pumps. A. Siliski, L.J. Florea, C.B. Dowling, K. Neumann, A. Samuelson, and M. Dunn discuss an even larger, 3600 borehole district-wide geothermal system at Ball State University that is designed to heat and cool an entire campus (“Petrographic and hydrogeologic investigations in a district-scale ground-coupled heat pump—Ball State University, Indiana”). They conducted detailed thermal conductivity measurements on core samples and compare those data to bulk thermal response tests (TRTs). The data show that the TRTs do not capture the full heterogeneity. When analyzing data from the inception of GHP operations at Ball State University, it is evident that the thermal loading of the subsurface happened at varying rates and depths, and those differences correlate with “thermofacies” of different thermal conductivity. Focusing development on zones with high heat capacity may enhance performance of geothermal systems. While the last four papers describe the successes and problems of already established facilities, the next two papers introduce experimental setups. Variations in heat capacity and transfer are also the target of fi eld and modeling studies by S.M. Sellwood, J.M. Bahr, and D.J. Hart (“Evaluation of a discrete-depth heat dissipation test for thermal characterization of the subsurface”). Because traditional TRTs do not allow for evaluation of the depth-variability of heat transfer, the authors study heat dissipation from water-fi lled holes at discrete depths using electrical heaters. Their fi eld data are analyzed alongside numerical and solute transport models to account for groundwater fl ow and the thermal conductivity of the bedrock, and simula- tions suggest that an effective method to characterize thermofacies is through heat dissipation tests. Lab-scale experiments are integral to the study by T. Başer, T. Traore, and J.S. McCartney in “Physical modeling of coupled heat transfer and water fl ow in soil-borehole thermal energy storage systems in the vadose zone.” The authors concentrate on improving coupled thermo-hydraulic fl ow models by developing data sets that center on boreholes in unsaturated soil layers. Triangular arrays of heat exchangers in various arrangements, deployed in cylindrical silt-fi lled tanks, provide these data. Results suggest that the spacing of heat exchang- ers can infl uence the hydraulic behavior of the system, including moisture distribution and thermal conduc- tivity of the soils. Chapters 7 and 8 of this volume shift the focus to enhanced geothermal systems, where heat extraction is the main concern. In “Thermal conductivity, thermal gradient, and heat-fl ow estimations for the Smackover Formation, southwest Arkansas,” L.M. Nondorf describes how thermal conductivity measurements of core samples and thermal gradient data from borehole data are combined to estimate heat fl ow in various counties Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/961808/spe519-00.pdf by guest on 23 April 2020 Preface vii of Arkansas. The author fi nds the highest thermal gradient (3.51 °C/100 m) and heat fl ow (72.3 mW/m2) in Columbia and Lafayette Counties. A. Moody, J. Fairley, and M. Plummer (“Stochastic exploration and the geologic context of enhanced geothermal system viability on the Snake River Plain, Idaho”) describe an area in the Snake River Plain of southern Idaho with a heat fl ux of ~110 mW/m2. The emphasis of their study is the characteristics and distribution of fractures in welded tuff reservoirs. The factures’ behavior under stress is crucial for the implementation of enhanced geothermal systems, where hydraulic fracturing augments permeability. We hope that the investigations included in this volume will provide valuable information and offer a basis for close examination of future GHP and EGS designs; and thereby will help enhance the sustainability and effi ciency of these systems. Lund, J., Sanner, B., Rybach, L., Curtis, R., and Hellström, G., REFERENCES CITED 2004, Geothermal (ground-source) heat pump—A world overview: Geo-Heat Center Quarterly Bulletin, v. 25, Diao, N., Li, Q., and Fang, Z., 2004, Heat transfer in ground no. 3, p. 1–9. heat exchangers with groundwater advection: Interna- Lund, J., Boyd, T.L., Gawell, K., and Jennajohn, D., 2010, The tional Journal of Thermal Sciences, v. 43, p. 1203–1211, United States of America update: Geo-Heat Center Quar- doi:10.1016/j.ijthermalsci.2004.04.009. terly Bulletin, v. 29, no. 1, p. 2–11. Haehnlein, S., Bayer, P., and Blum, P., 2010, International legal Olfman, M.Z., Woodbury, A.D., and Bartley, J., 2014, Effects status of the use of shallow geothermal energy: Renew- of depth and material property variations on the ground able & Sustainable Energy Reviews, v. 14, p. 2611–2625, temperature response to heating by a deep vertical ground doi:10.1016/j.rser.2010.07.069. heat exchanger in purely conductive media: Geothermics, Lowe, J.W., Koester, R.J., and Sachtleben, P.J., 2010, Embracing v. 51, p. 9–30. the future: The Ball State University Geothermal Project, Rybach, L., and Eugster, W.J., 2010, Sustainability aspects in Filho, W.L., ed., Universities and Climate Change: Ber- of geothermal heat pump operation, with experience lin Heidelberg, Springer, p. 205–220, doi:10.1007/978-3 from Switzerland: Geothermics, v. 39, p. 365–369, -642-10751-1_17. d oi:10.1016/j.geothermics.2010.08.002. Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/961808/spe519-00.pdf by guest on 23 April 2020 Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/961808/spe519-00.pdf by guest on 23 April 2020 The Geological Society of America Special Paper 519 2016 Preface Nationally and globally, geothermal energy is a crucial resource. Included in this GSA Special Paper are important complementary investigations from geothermal heat pumps to enhanced geothermal systems. Geothermal heat pumps (GHPs), also called ground-source heat pumps (GSHPs), are often closed sys- tems with vertical or horizontal borehole heat exchangers (BHEs) (Haehnlein et al., 2010). GHPs use the relatively constant soil and bedrock temperature to store and release thermal load in the summer and the winter, respectively (Lund et al., 2004; Haehnlein et al., 2010). These systems commonly consist of a series of sealed pipe that is installed as loops in the ground, through which water and/or antifreeze is circulated, and which are connected to a heat pump or energy exchanger (Diao et al., 2004). GHPs are a rapidly grow- ing application of renewable energy with more than 900,000 units operating in the United States and annual increases of 10% in ~30 countries over the past ten years (Lowe et al., 2010; Lund et al., 2004). The main advantage of GHPs is the use of ambient ground temperatures. While deep geothermal applications (about >400 m depth; discussed later) are often large scale and geologically specifi c (i.e., hydrothermal vents and areas of high heat fl ux), GHPs are deployed in relatively shallow environments (<400 m depth) that do not require unusual geological settings or high geothermal gradients, and are therefore possible around the world. The use of shallow geothermal energy is considered an environmentally friendly alternative to fossil fuel (e.g., coal, oil, or gas) for residences and universities, as well as government and commercial buildings. A small amount of electricity input is required to run compressors for GHPs, but the energy gained is four times greater (Lund et al., 2004; Haehnlein et al., 2010). Current research focuses on aspects of GHP design and application; this GSA Special Paper mainly concentrates on sustainability and effi ciency. In terms of sustainability and long-term usage, researchers are concerned that the use of shallow geothermal energy may result in thermal plumes (hot or cold) in local groundwater (Haehnlein et al., 2010; Rybach and Eugster, 2010; Helmke et al., this volume; Siliski et al., this volume). Changes in groundwater temperature can infl uence its physical properties, chemical reactions, microbiology, and the interaction of these factors, as well as reduce the effi ciency of the energy system. From the effi ciency viewpoint, planning GHPs of the right size and arrangement is not a simple task because heat transfer between a BHE and its surrounding environment is complicated. Besides the confi guration of borehole fi elds, other variables infl uence the systems’ performance, such as the distribution of thermal con- ductivity with depth, moisture content of the soils, and groundwater movement (Diao et al., 2004; Olfman et al., 2014; this volume [Ellett and Naylor; Richardson et al.; Helmke et al.; Siliski et al.; Sellwood et al.; Başer et al.]). Current design tools are based on the assumption that only bulk heat conduction is important and do not consider the implications of these other factors. As a consequence, natural variables (e.g., groundwater fl ow) are neglected in GHP designs, even though modeling, laboratory experiments, and fi eld studies suggest that the impact of the surrounding environment on the GHPs may be prominent (Diao et al., 2004; Olfman et al., 2014; this volume [Ellett and Naylor; Richardson et al.; Helmke et al.; Siliski et al.; Sellwood et al.; Başer et al.]). Enhanced geothermal systems (EGS) are also used in direct-use applications for power generation. They are restricted to regions with high heat fl uxes and usually involve large-scale facilities. Iceland, California, and Nevada are well-known locations where in situ geothermal energy is exploited. Geothermal electricity Preface, 2016, in Dowling, C.B., Neumann, K., and Florea, L.J., eds., Geothermal Energy: An Important Resource: Geological Soci- ety of America Special Paper 519, p. v–vii, doi:10.1130/2016.2519(00). For permission to copy, contact [email protected]. © 2016 The Geological Society of America. All rights reserved. v Downloaded from https://pubs.geoscienceworld.org/books/chapter-pdf/980114/spe519-v.pdf by guest on 23 April 2020

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Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.