page_title: Enhanced geothermal system
section_title: EGS potential in the United States
hierarchical_section_title: Enhanced geothermal system / EGS potential in the United States
context_page_description: An enhanced geothermal system generates geothermal electricity without the need for natural convective hydrothermal resources. Until recently, geothermal power systems have exploited only resources where naturally occurring heat, water, and rock permeability are sufficient to allow energy extraction. However, by far most of geothermal energy within reach of conventional techniques is in dry and impermeable rock. EGS technologies enhance and/or create geothermal resources in this hot dry rock through a variety of stimulation methods, including 'hydraulic stimulation'.
context_section_description: A 2006 report by MIT, and funded by the U.S. Department of Energy, conducted the most comprehensive analysis to date on the potential and technical status of EGS. The 18-member panel, chaired by Professor Jefferson Tester of MIT, reached several significant conclusions:
  Resource size: The report calculated the United States total EGS resources from 3–10 km of depth to be over 13,000 zettajoules, of which over 200 ZJ would be extractable, with the potential to increase this to over 2,000 ZJ with technology improvements — sufficient to provide all the world's current energy needs for several millennia. The report found that total geothermal resources, including hydrothermal and geo-pressured resources, to equal 14,000 ZJ — or roughly 140,000 times the total U.S. annual primary energy use in 2005.
  Development potential: With an R&D investment of $1 billion over 15 years, the report estimated that 100 GWe (gigawatts of electricity) or more could be installed by 2050 in the United States. The report further found that "recoverable" resources (accessible with today's technology) were between 1.2–12.2 TW for the conservative and moderate recovery scenarios respectively.
  Cost: The report found that EGS could be capable of producing electricity for as low as 3.9 cents/kWh. EGS costs were found to be sensitive to four main factors:
  Temperature of the resource
  Fluid flow through the system measured in liters/second
  Drilling costs
  Power conversion efficiency
caption: Geothermal power technologies.
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