Geothermal energy is used worldwide primarily for generating electricity,space heating and spas.The geothermal resources that have been developed,however,produce only a small fraction of the available energy stored in the upper few kilometers of the earth\'s crust(Tester et al.,2006).Although heat is present,rocks throughout most of the shallow crust lack the interconnected permeability necessary to form geothermal reservoirs.Attempts to create permeability by hydraulic fracturing were first conducted in the 1970s at Fenton Hill,New Mexico,USA (Wyborn,2011).More than a dozen Enhanced Geothermal System (EGS) projects followed in Great Britain,France,Japan,USA,Australia,Switzerland,South Korea,and China (Tester et al.,2006;Breede et al.,2013;Olasolo et al.,2016) (Fig.1).Despite seismic evidence that large volumes of rock were stimulated,subeconomic flow rates and low thermal recoveries indicate that the fractures were poorly connected (Grant,2016).Furthermore,temperature and drilling data suggest that the primary fluid conduits were preexisting fractures(Fig.2).Although none of the projects demonstrated full commercial viability of EGS,they did underscore the need for specific technological advances.These include:1)geoscientific and rock property characteristics of EGS resources;2) evaluation of in-situ fracture networks and stress fields;3) improved high temperature directional drilling technologies;4) novel zonal isolation tools and reservoir stimulation technologies;5) high-temperature tools for seismic monitoring of reservoir growth and prediction of induced seismicity;and 6) power conversion technologies (Feng et al.,2014;Lu,2018;Moore et al.,2021).