Previous assessments of the sustainability of geothermal energy have focused on resource management and associated environmental impacts during plant operations. Within these constraints, studies have shown that overall emissions, water consumption, and land use for geothermal electricity production have a smaller impact than traditional base-load electricity generation technologies. 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 increase nearly threefold, from 2.37 GW to 6.30 GW, by 2035 (EIA 2012). With this potential for significant growth in geothermal electricity production, there is a need to improve understanding of the environmental impacts across the life cycle of geothermal energy production systems.
This paper assesses the use of freshwater in construction, drilling, and production activities of various geothermal power plants. Four geothermal technologies were evaluated: air-cooled enhanced geothermal systems (EGSs), air-cooled hydrothermal binary systems, evaporative-cooled hydrothermal flash systems, and air-cooled geopressured systems that coproduce natural gas. The impacts associated with these power plant scenarios are compared to those from other electricity generating technologies as part of a larger effort to compare the lifecycle impacts of geothermal electricity generation to other power generation technologies.