| Abstract |
Since the early 1960s, when geothermal power was first produced in the USA in a dry steam power plant (Unit 1 at The Geysers geothermal field), additional plants were installed at The Geysers, and many more flash-steam and binary power plants have been installed in liquid-dominated geothermal fields. The latter has included: resources in sedimentary environments (including the hyper-saline brines of the Salton Sea field in southern California, and lower-salinity resources elsewhere in the same region); the dilute, moderate-temperature geothermal fluids produced by pumped wells from volcanic and metamorphic rocks in the Basin-and-Range province; and volcanic-hosted resources in California and Hawaii. As of October 2019, the total installed geothermal power capacity in the United States was approximately 3,700 MWe. Geothermal power is produced in the states of Alaska, California, Hawaii, Idaho, Nevada, New Mexico, Oregon and Utah. Together, California and Nevada host the majority (3,478 MWe) of this generation, with 2,683 and 795 MWe in California and Nevada, respectively. Since the last USA Country Update in 2015, competition from low-cost power sources (notably natural gas and solar) and the reduction in tax incentives has favored expansions of existing geothermal projects and development of shallower resources to minimize project development costs. Even so, installed geothermal power capacity in the United States has increased modestly (by 7-10%) during the last five years. In addition, some of the older geothermal power plants have been re-powered, enabling improvements in output without requiring additional geothermal fluid supply. Federal support for R&D in Enhanced (or Engineered) Geothermal Systems (EGS) remains strong via the U.S. Department of Energy’s Geothermal Technologies Office (DOE-GTO), as manifested in the EGS Collab projects (in which National Laboratories collaborate for the development of EGS technologies) and the Frontier Observatory for Research in Geothermal Energy (FORGE) project (an underground laboratory in which various EGS technologies will be implemented and tested). In addition, DOE-GTO is supporting R&D related to conventional hydrothermal resources, including minerals recovery, innovative drilling techniques, expanding geothermal direct use and the application of machine learning for geothermal exploration and operations. The United States continues to participate in the International Geothermal Partnership, the Global Geothermal Alliance and other international geothermal initiatives, and to supply U.S. geothermal expertise for the exploration, development and operation of geothermal power projects in many countries around the world. Significant additional geothermal power can be produced in the United States. DOE-GTO’s recent publication of the GeoVision study concludes that technology improvements – many of which are the subject of active research today – could significantly increase geothermal power generation in the United States, which the GeoVision study estimates could reach 60,000 MW. Some of this capacity is expected to be derived from EGS. Earlier (in 2008), the United States Geological Survey (USGS) estimated that the generation capacity of known but undeveloped conventional hydrothermal resources in the United States is approximately 9,000 MWe, and that the potential of undiscovered resources is on the order of 30,000 MWe, In addition, there is considerable potential for geothermal power generation from resources in deep sedimentary basins. Recognizing the potential for more geothermal power in the United States, many tertiary educational institutions offer geothermal curricula that focus on a wide range of subjects, including regional favorability factors for the formation of exploitable geothermal resources, resource exploration and characterization, drilling methods, reservoir engineering, power cycles, unconventional geothermal systems and more. Collaboration on specific topics between universities, research organizations (such as DOE-GTO) and industry is creating a favorable atmosphere for technical innovations to enable the development of the remaining untapped reserves of geothermal energy in the United States and in other parts of world. Although the past five years have been characterized by modest geothermal growth, current social, economic and political trends provide a level of optimism for the development of additional geothermal power in the western United States. In combination, the near-universal acceptance of climate change (and the recognition of the importance of clean power), the de-stabilizing impacts on the grid from intermittent renewable power, the positive geothermal outlook provided in DOE-GTO’s GeoVision study and earlier work by the USGS, and policy engagement by the geothermal industry are potent forces to drive a new wave of geothermal power expansion in the United States. The impetus is particularly strong in California, which has a mandated renewable power requirement and a mandated cap on CO2 emissions. This, combined with the de-stabilizing effect on the electricity grid from rooftop and utility-scale solar and the massive demand for power in California has led the California Public Utility Commission (CPUC) to recommend the development of at least 2,000 more MW of base-load geothermal power in the near future. Although this amount may be considered modest in comparison to the potential for additional geothermal power in the United States, it is a significant turning point in terms of policy, which – like the U.S. Senate hearings on geothermal power in 2019 – can be credited to work by the geothermal industry, supported by the independent technical evaluations of DOE-GTO and USGS. Legislation to support the growth of geothermal power has been introduced to streamline specific permitting processes (without undermining environmental stewardship), improve access to transmission systems and re-establish parity with tax credits provided to other renewable power sources. Together with the specific mandated requirements in the State of California - which can be served in part by sources generated outside the state – these factors will enable the continued development of geothermal power projects in the western United States. |