According to the Energy Information Administration (EIA) of the U.S. Department of Energy (DOE), geothermal energy generation in the United States is projected to more than triple by 2040 (EIA 2013). This addition, which translates to more than 5 GW of generation capacity, is anticipated because of technological advances and an increase in available sources through the continued development of enhanced geothermal systems (EGSs) and low-temperature resources (EIA 2013). Studies have shown that air emissions, water consumption, and land use for geothermal electricity generation have less of an impact than traditional fossil fuel-based electricity generation; however, the long-term sustainability of geothermal power plants can be affected by insufficient replacement of aboveground or belowground operational fluid losses resulting from normal operations (Schroeder et al. 2014). Thus, access to water is therefore critical for increased deployment of EGS technologies and, therefore, growth of the geothermal sector. This paper examines water issues relating to EGS development from a variety of perspectives. It starts by exploring the relationship between EGS site geology, stimulation protocols, and below ground water loss, which is one of the largest drivers of water consumption for EGS projects. It then examines the relative costs of different potential traditional and alternative water sources for EGS. Finally it summarizes specific state policies relevant to the use of alternative water sources for EGS, and finally explores the relationship between EGS site geology, stimulation protocols, and below ground water loss, which is one of the largest drivers of water consumption for EGS projects.

This report is the third in a series of reports sponsored by the U.S. Department of Energy Geothermal Technologies Program in which a range of water-related issues surrounding geothermal power production are evaluated. The first report made an initial attempt at quantifying the life cycle fresh water requirements of geothermal power-generating systems and explored operational and environmental concerns related to the geochemical composition of geothermal fluids. The initial analysis of life cycle fresh water consumption of geothermal power-generating systems identified that operational water requirements consumed the vast majority of water across the life cycle. However, it relied upon limited operational water consumption data and did not account for belowground operational losses for enhanced geothermal systems (EGSs). A second report presented an initial assessment of fresh water demand for future growth in utility-scale geothermal power generation. The current analysis builds upon this work to improve life cycle fresh water consumption estimates and incorporates regional water availability into the resource assessment to improve the identification of areas where future growth in geothermal electricity generation may encounter water challenges.

This report is the third in a series of reports sponsored by the U.S. Department of Energy Geothermal Technologies Program in which a range of water-related issues surrounding geothermal power production are evaluated. The first report made an initial attempt at quantifying the life cycle fresh water requirements of geothermal power-generating systems and explored operational and environmental concerns related to the geochemical composition of geothermal fluids. The initial analysis of life cycle fresh water consumption of geothermal power-generating systems identified that operational water requirements consumed the vast majority of water across the life cycle. However, it relied upon limited operational water consumption data and did not account for belowground operational losses for enhanced geothermal systems (EGSs). A second report presented an initial assessment of fresh water demand for future growth in utility-scale geothermal power generation. The current analysis builds upon this work to improve life cycle fresh water consumption estimates and incorporates regional water availability into the resource assessment to improve the identification of areas where future growth in geothermal electricity generation may encounter water challenges.

This report examines life cycle water consumption for various geothermal technologies to better understand factors that affect water consumption across the life cycle (e.g., power plant cooling, belowground fluid losses) and to assess the potential water challenges that future geothermal power generation projects may face. Previous reports in this series quantified the life cycle freshwater requirements of geothermal power-generating systems, explored operational and environmental concerns related to the geochemical composition of geothermal fluids, and assessed future water demand by geothermal power plants according to growth projections for the industry. This report seeks to extend those analyses by including EGS flash, both as part of the life cycle analysis and water resource assessment. A regional water resource assessment based upon the life cycle results is also presented. Finally, the legal framework of water with respect to geothermal resources in the states with active geothermal development is also analyzed.

Previous work by the U.S. Geological Survey (USGS) developed models to estimate the amount of water that is withdrawn and consumed by thermoelectric power plants (Diehl and others, 2013; Diehl and Harris, 2014; Harris and Diehl, 2019 [full citations listed in srcinfo of the metadata file]). This data release presents a historical reanalysis of thermoelectric water use from 2008 to 2020 and includes monthly and annual water withdrawal and consumption estimates, thermodynamically plausible ranges of minimum and maximum withdrawal and consumption estimates, and associated information for 1,360 water-using, utility-scale thermoelectric power plants in the United States. The term “reanalysis” refers to the process of reevaluating and recalculating water-use data using updated or refined methods, data sources, models, or assumptions. For this case, new estimates of withdrawal and consumption were made using new data sources and methods which involved taking existing historical data and subjecting it to a thorough review and revision to improve accuracy, completeness, and consistency. Reanalysis included incorporating new datasets, refining methodologies, and adjusting for changes in technology, regulations, or knowledge. The goal of reanalysis was to provide more accurate and up-to-date water-use estimates that reflects the most current understanding of water-use patterns and factors affecting water usage in the United States. This historical reanalysis was completed by running thermoelectric water-use models that are based on linked heat-and-water budgets (models contained within this data release). The linked heat-and-water budgets are constrained by the following data (also contained within this data release): power plant generation and cooling system technologies, the quantity of fuels consumed and electricity generated, as well as environmental variables. The heat-budget component of the models calculates the amount of waste heat (fuel heat that is not converted to electricity) that is removed from the steam used to drive the turbines that generate electricity. The waste heat is transferred to the cooling system in a thermoelectric power plant’s condenser, which is defined as the condenser duty (Diehl and others, 2013). The water-budget component of the models calculates the amount of water that is withdrawn and consumed based on plant-specific condenser duty, and environmental variables (air temperatures, water temperatures, wind speed, and elevation). The models were updated using the same formulation previously developed (Diehl and others, 2013) and updates include enhancements of automatic data collectors, nationally consistent and operational environmental variables, and simulated water temperatures for plant intakes provided by the USGS National Hydrologic Model (Regan and others, 2018; Hay and others, 2023). These new features enable reproducibility and are an important step toward an operational modeling framework for making nationally consistent historical and forecasted future water-use estimates that are independent of Federal plant-operator reported water withdrawal and consumption data. Total estimated water withdrawal (including fresh and saline sources) ranged from 132 billion gallons per day (Bgal/d) in 2008 to 80 Bgal/d in 2020. Total estimated water consumption (including only fresh sources; consumption at coastal saline plants was not modeled) ranged from 3.6 Bgal/d in 2008 to 2.7 Bgal/d in 2020. Gorman Sanisaca and others, 2023, provides monthly condenser duty estimates and associated information from 2008 to 2020 that are used by the models reported here for estimating withdrawals and consumption.

Previous work by the U.S. Geological Survey (USGS) developed models to estimate the amount of water that is withdrawn and consumed by thermoelectric power plants (Diehl and others, 2013; Diehl and Harris, 2014; Harris and Diehl, 2019 [full citations listed in srcinfo of the metadata file]). This data release presents a historical reanalysis of thermoelectric water use from 2008 to 2020 and includes monthly and annual water withdrawal and consumption estimates, thermodynamically plausible ranges of minimum and maximum withdrawal and consumption estimates, and associated information for 1,360 water-using, utility-scale thermoelectric power plants in the United States. The term “reanalysis” refers to the process of reevaluating and recalculating water-use data using updated or refined methods, data sources, models, or assumptions. For this case, new estimates of withdrawal and consumption were made using new data sources and methods which involved taking existing historical data and subjecting it to a thorough review and revision to improve accuracy, completeness, and consistency. Reanalysis included incorporating new datasets, refining methodologies, and adjusting for changes in technology, regulations, or knowledge. The goal of reanalysis was to provide more accurate and up-to-date water-use estimates that reflects the most current understanding of water-use patterns and factors affecting water usage in the United States. This historical reanalysis was completed by running thermoelectric water-use models that are based on linked heat-and-water budgets (models contained within this data release). The linked heat-and-water budgets are constrained by the following data (also contained within this data release): power plant generation and cooling system technologies, the quantity of fuels consumed and electricity generated, as well as environmental variables. The heat-budget component of the models calculates the amount of waste heat (fuel heat that is not converted to electricity) that is removed from the steam used to drive the turbines that generate electricity. The waste heat is transferred to the cooling system in a thermoelectric power plant’s condenser, which is defined as the condenser duty (Diehl and others, 2013). The water-budget component of the models calculates the amount of water that is withdrawn and consumed based on plant-specific condenser duty, and environmental variables (air temperatures, water temperatures, wind speed, and elevation). The models were updated using the same formulation previously developed (Diehl and others, 2013) and updates include enhancements of automatic data collectors, nationally consistent and operational environmental variables, and simulated water temperatures for plant intakes provided by the USGS National Hydrologic Model (Regan and others, 2018; Hay and others, 2023). These new features enable reproducibility and are an important step toward an operational modeling framework for making nationally consistent historical and forecasted future water-use estimates that are independent of Federal plant-operator reported water withdrawal and consumption data. Total estimated water withdrawal (including fresh and saline sources) ranged from 132 billion gallons per day (Bgal/d) in 2008 to 80 Bgal/d in 2020. Total estimated water consumption (including only fresh sources; consumption at coastal saline plants was not modeled) ranged from 3.6 Bgal/d in 2008 to 2.7 Bgal/d in 2020. Gorman Sanisaca and others, 2023, provides monthly condenser duty estimates and associated information from 2008 to 2020 that are used by the models reported here for estimating withdrawals and consumption.