In 2008, the USGS estimated that, using modern technology, the U.S. could generate 9,000 Megawatts of electricity (MWe) from identified conventional geothermal systems alone – or roughly enough to power 5 to 9 million homes.
The USGS also estimated that the U.S. likely contains significant undiscovered conventional geothermal resources, including mostly “hidden” hydrothermal systems that aren’t obvious at the surface (unlike hot springs). Undiscovered resources have an estimated untapped potential of an additional 30,000 MWe – enough to power an additional 18 to 30 million homes, or enough to power every home in California - and, at the high end, Texas as well.
The development of geothermal resources has traditionally been centered on these natural hydrothermal systems, where circulating groundwater brings heat closer to the Earth’s surface.
New technologies, however, are opening up the possibility to access geothermal resources in hot rock without natural circulation, vastly expanding the potential to harness the geothermal potential of the Earth (Eliza Malakoff, Seth Amgott).