Vol. 42 Núm. 1 (2020): Boletín de Geología
Artículos de revisión

Sistemas geotérmicos mejorados: revisión y análisis de casos de estudio

Maria Alejandra Palacio-Villa
Universidad de Medellín
Daniela Blessent
Universidad de Medellín
Jacqueline López-Sánchez
Universidad de Medellín
David Moreno
Universidad de Medellín

Publicado 2020-01-22

Cómo citar

Palacio-Villa, M. A., Blessent, D., López-Sánchez, J., & Moreno, D. (2020). Sistemas geotérmicos mejorados: revisión y análisis de casos de estudio. Boletín De Geología, 42(1), 101–118. https://doi.org/10.18273/revbol.v42n1-2020006

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Resumen

En este artículo se hace una revisión bibliográfica de las características de los EGS, fuentes de energía limpia que prometen ser una alternativa para enfrentar los problemas relacionados con el calentamiento global ocasionados por el uso de combustibles fósiles como el petróleo y el gas natural. Actualmente en Colombia los sistemas geotérmicos de interés son de tipo hidrotermal, por lo que no hay EGS planificados aún, sin embargo, este artículo pretende ser una introducción para el lector interesado en los EGS y ser referencia a futuros proyectos desarrollados en el territorio nacional, describiendo los lugares del mundo más significativos donde se ha hecho uso de esta técnica, junto con su percepción social e impactos asociados. Además, busca analizar las diferencias entre la estimulación hidráulica en los EGS y el fracking utilizado para la extracción de gas de esquisto.

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Referencias

Adams, J., and Rowe, C. (2013). Differentiating applications of hydraulic fracturing. ISRM International Conference for Effective and Sustainable Hydraulic Fracturing, Brisbane, Australia.

Allis, R.G. (2000). Review of subsidence at Wairakei field, New Zealand. Geothermics, 29(4-5), 455-478. doi: 10.1016/S0375-6505(00)00016-X.

Al-Muntasheri, G.A. (2014). A critical review of hydraulic-fracturing fluids for moderate-to ultralow-permeability formations over the last decade. SPE Production and Operations, 29(4), 243-260. doi: 10.2118/169552-PA.

Arias, G., y Acevedo, A.M. (2017). Estado actual de la producción de energía geotérmica en Colombia. Universidad Nacional Abierta y a Distancia, Manizales, Colombia.

Ayling, B., Blankenship, D., Sullivan, P., Kennedy, M., Majer, E.L., Villavert, M., Sonnenthal, E., Tang, J., Dobson, P., Hinz, N., Faulds, J., Hammond, W., Mlawsky, E., Blake, K., Tiedeman, A., Sabin, A., Lazaro, M., Akerley, J., Nordquist, J., Sophy, M., Siler, D.L. , Kaven, J.O., Phelps, G., Hickman, S., Glen, J., Williams, C., Robertson-Tait, A., Hackett, L., Pettitt, W., Riahi A., Blanksma, D., Damjanac, B., Hazzard, J., Eneva, M., Witter, J.B., Queen, J., and Fortuna, M. (2018). Phase 2 Update for the Fallon FORGE Site, Nevada, USA. 43rd Workshop on Geothermal Reservoir Engineering. Stanford, California.

Barbier, E. (2002). Geothermal energy technology and current status: an overview. Renewable and Sustainable Energy Reviews, 6(1-2), 3-65. doi: 10.1016/S1364-0321(02)00002-3.

Bendall, B., Hogarth, R., Holl, H., McMahon, A., Larking, A., and Reid, P. (2014). Australian experiences in EGS permeability enhancement – A review of 3 case studies. 39th Workshop on Geothermal Reservoir Engineering. Stanford, California, USA.

Bennett, T.S., and Barker, K. (1989). Operational aspects of placing proppant in a naturally fractured geothermal reservoir. Geothermal Resources Council Transactions, 13, 359-365.

Bertani, R. (2012). Geothermal power generation in the world 2005-2010 update report. Geothermics, 41, 1-29. doi: 10.1016/j.geothermics.2011.10.001.

Bista, S., Jennings, P., and Anda, M. (2017). Cradle to grave GHG emissions analysis of shale gas hydraulic fracking in Western Australia. Renewable Energy Environmental Sustainability, 2(45), 1-6. doi: 10.1051/rees/2017014.

Blankenship, D., Kennedy, M., Majer, E.L., Hinz, N., Faulds, J., Ayling B., Blake, K., Tiedeman, A., Sabin, A., Lazaro, M., Akerley, J., Siler, D., Kaven, J.O., Phelps, G., Hickman, S., Glen, J., Williams, C., Robertson-Tait, A., Hackett, L., and Pettitt, W. (2017). Proposed Fallon FORGE Site: Phase 2 Update. 42nd Workshop on Geothermal Reservoir Engineering. Stanford, California, USA.

Blöcher, G., Cacace, M., Reinsch, T., and Watanabe, N. (2015). Evaluation of three exploitation concepts for a deep geothermal system in the North German Basin. Computers and Geosciences, 82, 120-129. doi: 10.1016/j.cageo.2015.06.005.

BP. (2019). BP Statistical Review of World Energy, 68th edition.

Brace, W.F. (1980). Permeability of crystalline and argillaceous rocks. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 17(5), 241-251. doi: 10.1016/0148-9062(80)90807-4.

Brinton, D., McLin, K., and Moore, J. (2011). The chemical stability of bauxite and quartz sand proppants under geothermal conditions. 36th Workshop on Geothermal Reservoir Engineering. Stanford, California, USA.

Broderick, J., Wood, R., Gilbert, P., Sharmina, M., Anderson, K., Footitt, A., Glynn, S., and Nicholls, F. (2011). Shale gas: an updated assessment of environmental and climate change impacts. Tyndall Centre for Climate Change Research. University of Manchester.

Brown, D.W. (2009). Hot dry rock geothermal energy: important lessons from Fenton Hill. 34th Workshop on Geothermal Reservoir Engineering. Stanford, California, USA.

Brown, D.W., Duchane, D.V., Heiken, G., and Hriscu, V.T. (2012). Mining the Earth’s heat: Hot dry rock geothermal energy. Berlin: Springer.

Burton Jr, G.A., Basu, N., Ellis, B.R., Kapo, K.E., Entrekin, S., and Nadelhoffer, K. (2014). Hydraulic “Fracking”: are surface water impacts an ecological concern?. Environmental Toxicology and Chemistry, 33(8), 1679-1689. doi: 10.1002/etc.2619.

Carr-Cornish, S., and Romanach, L. (2014). Differences in public perceptions of geothermal energy technology in Australia. Energies, 7(3), 1555-1575. doi: 10.3390/en7031555.

Çetiner, Z.S., Ertekin, C., and Gültay, B. (2016). Initial assessment of public perception and acceptance of geothermal energy applications in Çanakkale, NW Turkey. Energy Procedia, 97, 194-201. doi: 10.1016/j.egypro.2016.10.052.

Chamorro-Camazón, C. (2009). Energía eléctrica a partir de recursos geotérmicos. Estado actual y perspectivas a nivel mundial. Dyna, 84(1), 44-51.

Chavot, P., Heimlich, C., Masseran, A., Serrano, Y., Zoungrana, J., and Bodin, C. (2018). Social shaping of deep geothermal projects in Alsace: politics, stakeholder attitudes and local democracy. Geothermal Energy, 6(26). doi: 10.1186/s40517-018-0111-6.

Cladouhos, T.T., Petty, S., Bonneville, A., Schultz, A., and Sorlie, C.F. (2018). Super Hot EGS and the Newberry Deep Drilling Project. 43rd Workshop on Geothermal Reservoir Engineering. Stanford, California, USA.

Clark, C., Wang, M., Vyas, A., and Gasper, J. (2009). Life cycle approach to understanding impacts of EGS. Geothermal Resources Council Transactions, 33, 311-314.

Clark, C., Harto, C., Sullivan, J., and Wang, M. (2011). Water use in the development and operation of geothermal power plants. Argonne National Laboratory. 72.

Conde-Álvarez, C., y Saldaña-Zorrilla, S.O. (2007). Cambio climático en América Latina y el Caribe: Impactos, vulnerabilidad y adaptación. Revista Ambiente y Desarrollo, 23(2), 23-30.

Cuenot, N., Faucher, J.P., Fritsch, D., Genter, A., and Szablinski, D. (2008). The European EGS project at Soultz-sous-Forêts: From extensive exploration to power production. 2008 IEEE Power and Energy Society General Meeting – Conversion and Delivery of Electrical Energy in the 21st Century. Pittsburgh, USA.

Darnet, M., Marquis, G., and Sailhac, P. (2006). Hydraulic stimulation of geothermal reservoirs: fluid flow, electric potential and microseismicity relationships. Geophysical Journal International, 166(1), 438-444. doi: 10.1111/j.1365-246X.2006.03026.x.

de Campos, V.P.P., Sansone, E.C., and Silva, G.F.B.L. (2018). Hydraulic fracturing proppants. Cerâmica, 64(370), 219-229. doi: 10.1590/0366-69132018643702219.

DECC. (2013). Deep Geothermal Review Study Final Report. Department of Energy and Climate Change.

Dincer, I. (2000). Renewable energy and sustainable development: a crucial review. Renewable and Sustainable Energy Reviews, 4(2), 157-175. doi: 10.1016/S1364-0321(99)00011-8.

DiPippo, R. (2012). Geothermal power plants: Principles, applications, case studies and environmental impacts. Massachusetts: University of Massachusetts Dartmouth.

Dubois, M., Ayt Ougougdal, M., Meere, P., Royer, J.J., Boiron, M.C., and Cathelineau, M. (1996). Temperature of paleo to modern self-sealing within a continental rift basin: the fluid inclusion data (Soultz-sous-Forêts, Rhine graben, France). European Journal of Mineralogy, 8(5), 1065-1080. doi: 10.1127/ejm/8/5/1065.

Dusseault, M., and McLennan, J. (2011). Massive multistage hydraulic fracturing: Where are we? 45th US Rock Mechanics/Geomechanics Symposium, San Francisco, California, USA.

Ellsworth, W.L. (2013). Injection-induced earthquakes. Science, 341(6142), 1-7 doi: 10.1126/science.1225942.

Elum, Z.A., and Momodu, A.S. (2017). Climate change mitigation and renewable energy for sustainable development in Nigeria: A discourse approach. Renewable and Sustainable Energy Reviews, 76, 72-80. doi: 10.1016/j.rser.2017.03.040.

EGEC. (2013). Factsheet on Enhanced Geothermal Systems (EGS): Why it’s different to shale gas. European Geothermal Energy Council.

ENGINE. (2008). Geothermal lighthouse projects in Europe. Information gathered during the ENGINE co-ordination action (ENhanced Geothermal Innovative Network for Europe).

Evans, K.F., Zappone, A., Kraft, T., Deichmann, N., and Moia, F. (2012). A survey of the induced seismic responses to fluid injection in geothermal and CO2 reservoirs in Europe. Geothermics, 41, 30-54. doi: 10.1016/j.geothermics.2011.08.002.

Faulds, J.E., Blankenship, D., Hinz, N.H., Sabin, A., Nordquist, J., Hickman, S., Glen, J., Kennedy, M., Siler, D.L., Robertson-Tait, A., Williams, C., Drakos, P., and Calvin, W. (2015). Geologic setting of the proposed Fallon Forge Site, Nevada: Suitability for EGS research and development. Geothermal Resources Council Transactions, 39, 293-302.

Genter, A., Evans, K., Cuenot, N., Fritsch, D., and Sanjuan, B. (2010). Contribution of the exploration of deep crystalline fractured reservoir of Soultz to the knowledge of Enhanced Geothermal Systems (EGS). Comptes Rendus Geoscience, 342(7-8), 502-516. doi: 10.1016/j.crte.2010.01.006.

Guo, C., Wei, M., and Lui, H. (2018). Study of gas production from shale reservoirs with multi-stage hydraulic fracturing horizontal well considering multiple transport mechanisms. PLOS ONE, 13(1), 1-21. doi: 10.1371/journal.pone.0188480.

Gurney, K.R., Mendoza, D.L., Zhou, Y., Fischer, M.L., Miller, C., Geethakumar, S., and de la Rue du Can, S. (2009). High resolution fossil fuel combustion CO2 emission fluxes for the United States. Environmental Science & Technology, 43(14), 5535-5541. doi: 10.1021/es900806c.

Hall, N., Ashworth, P., and Devine-Wright, P. (2013). Societal acceptance of wind farms: Analysis of four common themes across Australian case studies. Energy Policy, 58, 200-208. doi: 10.1016/j.enpol.2013.03.009.

Häring, M.O., Schanz, U., Ladner, F., and Dyer, B.C. (2008). Characterisation of the Basel 1 enhanced geothermal system. Geothermics, 37(5), 469-495. doi: 10.1016/j.geothermics.2008.06.002.

Healy, D. (2012). Hydraulic Fracturing or ‘Fracking’: A Short Summary of Current Knowledge and Potential Environmental Impacts. Department of Geology & Petroleum Geology, University of Aberdeen, United Kingdom.

Hochstein, M.P. (1988). Assessment and modelling of geothermal reservoirs (small utilization schemes). Geothermics, 17(l), 15-49. doi: 10.1016/0375-6505(88)90004-1.

Howarth, R.W., Santoro, R., and Ingraffea, A. (2011). Methane and the greenhouse-gas footprint of natural gas from shale formations. Climatic Change, 106(4), 679-690. doi: 10.1007/s10584-011-0061-5.

Huenges, E., Saada, A., Brandt, W., Moeck, I., Holl, H.G., Zimmermann, G., Blöcher, G., Köhler, S., Legarth, B., and Tischner, T. (2006). Current status of the EGS gross schönebeck project: On the way to demonstrate sustainable brine production from deep sediments of the North German Basin. Geothermal Resources Council Transactions, 30, 341-346.

Johnston, J.E., Werder, E., and Sebastian, D. (2016). Wastewater disposal wells, fracking, and environmental injustice in Southern Texas. American Journal of Public Health, 106(3), 550-556. doi: 10.2105/AJPH.2015.303000.

Kaieda, H. (2012). Ogachi EGS reservoir analysis. Geothermal Resources Council Transactions, 36, 487-492.

Kaieda, H., Ito, H., Kiho, K., Suzuki, K., Suenaga, H., and Shin, K. (2005). Review of the Ogachi HDR Project in Japan. World Geothermal Congress. Antalya, Turkey.

Kagel, A., Bates, D., and Gawell, K.A. (2007). A guide to geothermal energy and the environment. Geothermal Energy Association. Washington DC. 75.

Kelkar, S., WoldeGabriel, G., and Rehfeldt, K. (2016). Lessons learned from the pioneering hot dry rock project at Fenton Hill, USA. Geothermics, 63, 5-14. doi: 10.1016/j.geothermics.2015.08.008.

Kępińska, B., and Kasztelewicz, A. (2015). Public perception of geothermal energy in selected European countries. World Geothermal Congress. Melbourne, Australia.

Khyade, V.B. (2016). Hydraulic fracturing; Environmental issue. World Scientific News, 40, 58-92.

King, J.P., Reid, P.W., and Bendall, B. (2009). Progress at the Paralana EGS Project in South Australia. Australian Geothermal Energy Conference. Brisbane, Australia.

Kraft, T., Mai, P.M., Wiemer, S., Deichmann, N., Ripperger, J., Kästli, P., Bachmann, C., Fäh, D., Wössner, J., and Giardini, D. (2009). Enhanced geothermal systems: mitigating risk in urban areas. Eos, Transactions American Geophysical Union, 90(32), 273-274. doi: 10.1029/2009EO320001.

Lacirignola, M., and Blanc, I. (2013). Environmental analysis of practical design options for enhanced geothermal systems (EGS) through life-cycle assessment. Renewable Energy, 50, 901-914. doi: 10.1016/j.renene.2012.08.005.

Lu, S.M. (2018). A global review of Enhanced Geothermal System (EGS). Renewable and Sustainable Energy Reviews, 81(2), 2902-2921. doi: 10.1016/j.rser.2017.06.097.

Marzolf, N.C. (2014). Emprendimiento de la energía geotérmica en Colombia. Biblioteca Felipe Herrera del Banco Interamericano de Desarrollo 86.

Meier, P.M., Rodríguez, A.A., and Bethmann, F. (2015). Lessons learned from basel: New EGS projects in Switzerland using multistage stimulation and a probabilistic traffic light system for the reduction of seismic risk. World Geothermal Congress. Melbourne, Australia.

Meiners, H.G., Denneborg, M., Müller, F., Bergmann, A., Weber, F.A., Dopp, E., Hansen, C., and Schüth, C. (2013). Environmental impacts of fracking related to exploration and exploitation of unconventional natural gas deposits. Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, 275.

Meng, Q., and Ashby, S. (2014). Distance: A critical aspect for environmental impact assessment of hydraulic fracking. The Extractive Industries and Society, 1(2), 124-126. doi: 10.1016/j.exis.2014.07.004.

McClure, M., and Horne, R. (2014). An investigation of stimulation mechanisms in Enhanced Geothermal Systems. International Journal of Rock Mechanics and Mining Sciences, 72, 242-260. doi: 10.1016/j.ijrmms.2014.07.011.

Min, K.B., Park, S., and Zimmermann, G. (2015). Case Study on Groß Schönebeck EGS Project Research in Germany. Journal of Korean Society for Rock Mechanics, 25(4), 320-331. doi: 10.7474/TUS.2015.25.4.320.

Montgomery, C.T., and Smith, M.B. (2010). Hydraulic fracturing: History of an enduring technology. Journal of Petroleum Technology, 62(12), 26-40. doi: 10.2118/1210-0026-JPT.

Olasolo, P. (2014). Análisis general sobre sistemas geotérmicos mejorados (EGS) para la generación de energía eléctrica. PhD. Tesis, Universidad de La Rioja, España.

Olasolo, P. Juárez, M.C., Morales, M.P., D´Amico, S., and Liarte, I.A. (2016). Enhanced Geothermal Systems (EGS): A review. Renewable and Sustainable Energy Reviews, 56, 133-144. doi: 10.1016/j.rser.2015.11.031.

Popovska-Vasilevska, S. (2003). Drying of agricultural products with geothermal energy. International Summer School on Direct Application of Geothermal Energy, Izmir, Turkey.

Priestley, S. (2018). Shale gas and fracking. House of Commons Library.

Ramírez, E., López, J., Blessent, D., Raymond, J., Malo, M., y Balzán, D. (2017). Percepción social de la población rural en la zona de influencia del posible desarrollo geotérmico en el VNR. Reunión Nacional de Geotermia RENAG, Manizales, Colombia.

Raysoni, N., and Weaver, J. (2013). Long-term hydrothermal proppant performance. SPE Production and Operations, 28(4), 414-426. doi: 10.2118/150669-PA.

Reid, P., Messeiller, M., and Hasting, M. (2012). The Paralana Engineered Geothermal Project – case history and results of the hydraulic fracture stimulation. Australian Geothermal Energy Conference. Australia.

Reiter, M., Weidman, C., Edwards, C.L., and Hartman, H. (1976). Subsurface Temperature Data in Jemez Mountains, New Mexico. New Mexico Bureau of Mines and Mineral Resources. A division of New Mexico Institute of mining & Tecnology. 17 p.

Reith, S., Kölbel, T., Schlagermann, P., Pellizzone, A., and Allansdottir, A. (2013). Public acceptance of geothermal electricity production. Report on public acceptance, GEOELEC. 41 p.

REN21. (2019). Renewables 2019 Global Status Report. Renewable Energy Policy Network for the 21st Century.

Robertson-Tait, A., Villavert, M., Kennedy, M., Blankenship, D., Sullivan, P., Tang, J., Camacho-Lopez, T., Nordquist, J., Akerley, J., Ayling, B., Majer, E., Faulds, J., and Roque-Rivera, R. (2018). Communications and outreach for public acceptance of complex technical projects: Experience from the Fallon FORGE Project. 43rd Workshop on Geothermal Reservoir Engineering, Stanford, California, USA.

Rongved, M. (2015). Hydraulic fracturing for enhanced geothermal systems. Master thesis, Norwegian University of Science and Technology, Norway.

Ruíz-Calvo, F. (2015). Análisis y modelado de una instalación geotérmica para climatización de un conjunto de oficinas. PhD Tesis, Universitat Politècnica de València, España.

Schill, E., Genter, A., Cuenot, N., and Kohl, T. (2017). Hydraulic performance history at the Soultz EGS reservoirs from stimulation and long-term circulation tests. Geothermics, 70, 110-124. doi: 10.1016/j.geothermics.2017.06.003.

Schindler, M., Baumgärtner, J., Gandy, T., Hauffe, P., Hettkamp, T., Menzel, H., Penzkofer, P., Teza, D., Tischner T., and Wahl, G. (2010). Successful hydraulic stimulation techniques for electric power production in the Upper Rhine Graben, Central Europe. World Geothermal Congress. Bali, Indonesia.

Schlumberger (2019). Agente de sustentación o apuntalante. Oilfild Glossary en Español. Consultado el 18 de noviembre de 2019. https://www.glossary.oilfield.slb.com/es/Terms/p/proppant.aspx

Shiozawa, S., and McClure, M. (2014). EGS designs with horizontal wells, multiple stages, and proppant. 39th Workshop on Geothermal Reservoir Engineering. Stanford, California, USA.

Siler, L., Hinz, N.H., Faulds, J.E., Ayling, B., Blake, K., Tiedeman, A., Sabin, A., Blankenship, D., Kennedy, M., Rhodes, G., Sophy, M.J., Glen, J.M.G., Phelps, G.A., Fortuna, M., Queen, J., and Witter, J.B. (2018). The geologic and structural framework of the Fallon FORGE site. 43rd Workshop on Geothermal Reservoir Engineering. Stanford, California, USA.

Stuart, M.E. (2012). Potential groundwater impact from exploitation of shale gas in the UK. Groundwater Science Program. British Geological Survey. Open report OR/12/00.

Sun, Z., Zhang, X., Xu, Y., Yao, J., Wang, H., Lv, S., Sun, Z., Huang, Y., Cai, M., and Huang, X. (2017). Numerical simulation of the heat extraction in EGS with thermal-hydraulic-mechanical coupling method based on discrete fractures model. Energy, 120, 20-33. doi: 10.1016/j.energy.2016.10.046.

Sutra, E., Spada, M., and Burgherr, P. (2017). Chemicals usage in stimulation processes for shale gas and deep geothermal systems: A comprehensive review and comparison. Renewable and Sustainable Energy Reviews, 77, 1-11. doi: 10.1016/j.rser.2017.03.108.

Tenzer, H. (2001). Development of hot dry rock technology. Geo Heat-Center Bulletin, 22(4), 14-22.

Tester, J.W., Anderson, B.J., Batchelor, A.S., Blackwell, D.D., DiPippo, R., Drake, E.M., Garnish, J., Livesay, B., Moore, M.C., Nichols K., Petty, S., Toksöz, M.N. and Veatch, R.W. Jr. (2006). The future of geothermal energy. Impact of enhanced geothermal system (EGS) on the United States in 21st Century. MIT-led interdisciplinary panel. 372 p.

Ucar, E., Berre, I., and Keilegavlen, E. (2018). Three-dimensional numerical modeling of shear stimulation of fractured reservoirs. Journal of Geophysical Research: Solid Earth, 123(5), 3891-3908. doi: 10.1029/2017JB015241.

U.S. Department of Energy. (2004). Geothermal Technologies Program: Enhanced Geothermal Systems. DOE/GO-102004-1958.

Van Noorden, R. (2010). Carbon sequestration: Buried trouble. Nature, News Feature, 463, 871-873. doi: 10.1038/463871a.

Vengosh, A., Warner, N., Jackson, R., and Darrah, T. (2013). The effects of shale gas exploration and hydraulic fracturing on the quality of water resources in the United States. Procedia Earth and Planetary Science, 7, 863-866. doi: 10.1016/j.proeps.2013.03.213.

Watanabe, N., Blöcher, G., Cacace, M., Held, S., and Kohl, T. (2017). Geoenergy Modeling III, Enhanced Geothermal Systems. Cham: Springer International Publishing.

Waters, G., Dean, B., Downie, R., Kerrihard, K., Austbo, L., and McPherson, B. (2009). Simultaneous hydraulic fracturing of adjacent horizontal wells in the Woodford Shale. SPE Hydraulic Fracturing Technology Conference, The Woodlands, Texas, USA. doi: 10.2118/119635-MS.

Waxman, H.A., Markey, E.J., and DeGette, D. (2011). Chemicals used in hydraulic fracturing. United States House of Representatives Committee on Energy and Commerce Minority Staff.

Weinhold, B. (2012). The future of fracking: New rules target air emissions for cleaner natural gas production. Environmental Health Perspectives, 120(7), 272-279. doi: 10.1289/ehp.120-a272.

Wyss, R., and Rybach, L. (2010). Developing deep geothermal resources in Switzerland. World Geothermal Congress. Bali, Indonesia.

Xia, Y., Plummer, M., Mattson, E., Podgorney, R., and Ghassemi, A. (2017). Design, modeling and evaluation of a doublet heat extraction model in enhanced geothermal systems. Renewable Energy, 105, 232-247. doi: 10.1016/j.renene.2016.12.064.

Xu, T., Rose, P., Fayer, S., and Pruess, K. (2009). On modeling of chemical stimulation of an enhanced geothermal system using a high pH solution with chelating agent. Geoflids, 9(2), 167-177. doi: 10.1111/j.1468-8123.2009.00246.x.

Zang, A., Oye, V., Jousset, P., Deichmann, N., Gritto, R., McGarr, A., Majer, E., and Bruhn, D. (2014). Analysis of induced seismicity in geothermal reservoirs - An overview. Geothermics, 52, 6-21. doi: 10.1016/j.geothermics.2014.06.005.

Zhang, D., and Yang, T. (2015). Environmental impacts of hydraulic fracturing in shale gas development in the United States. Petroleum Exploration and Development, 42(6), 876-883. doi: 10.1016/S1876-3804(15)30085-9.

Zimmermann, G., Reinicke, A., Blöcher, G., Moeck, I., Kwiatek, G., Brandt, W., Regenspurg, S., Schulte, T., Saadat, A., and Huenges, E. (2010). Multiple fracture stimulation treatments to develop an Enhanced Geothermal System (EGS) - conceptual design and experimental results. World Geothermal Congress. Bali, Indonesia.