Thermal electricity generation is a major consumer of freshwater for cooling, fuel extraction and air emissions controls, but the life cycle water impacts of different fossil fuel cycles are not well understood. Much of the existing literature relies on decades-old estimates for water intensity, particularly regarding water consumed for fuel extraction. This work uses contemporary data from specific resource basins and power plants in Texas to evaluate water intensity at three major stages of coal and natural gas fuel cycles: fuel extraction, power plant cooling and power plant emissions controls. In particular, the water intensity of fuel extraction is quantified for Texas lignite, conventional natural gas and 11 unconventional natural gas basins in Texas, including major second-order impacts associated with multi-stage hydraulic fracturing. Despite the rise of this water-intensive natural gas extraction method, natural gas extraction appears to consume less freshwater than coal per unit of energy extracted in Texas because of the high water intensity of Texas lignite extraction. This work uses new resource basin and power plant level water intensity data to estimate the potential effects of coal to natural gas fuel switching in Texas' power sector, a shift under consideration due to potential environmental benefits and very low natural gas prices. Replacing Texas' coal-fired power plants with natural gas combined cycle plants (NGCCs) would reduce annual freshwater consumption in the state by an estimated 53 billion gallons per year, or 60% of Texas coal power's water footprint, largely due to the higher efficiency of NGCCs.

The United States (US) energy system is a large water user, but the nature of that use is poorly understood. To support resource comanagement and fill this noted gap in the literature, this work presents detailed estimates for US-based water consumption and withdrawals for the US energy system as of 2014, including both intensity values and the first known estimate of total water consumption and withdrawal by the US energy system. We address 126 unit processes, many of which are new additions to the literature, differentiated among 17 fuel cycles, five life cycle stages, three water source categories, and four levels of water quality. Overall coverage is about 99% of commercially traded US primary energy consumption with detailed energy flows by unit process. Energy-related water consumption, or water removed from its source and not directly returned, accounts for about 10% of both total and freshwater US water consumption. Major consumers include biofuels (via irrigation), oil (via deep well injection, usually of nonfreshwater), and hydropower (via evaporation and seepage). The US energy system also accounts for about 40% of both total and freshwater US water withdrawals, i.e., water removed from its source regardless of fate. About 70% of withdrawals are associated with the once-through cooling systems of approximately 300 steam cycle power plants that produce about 25% of US electricity.

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