Water Use in Enhanced Geothermal Systems (EGS): Geology of U.S. Stimulation Projects, Water Costs, and Alternative Water Use Policies

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.