Water is essential to energy resource development; conversely, energy resources are needed for developing, processing, and distributing water resources. As a result, water and energy are interdependent. This “balance” or “nexus” between resources is a critical, yet often overlooked component in evaluating energy resources. Recent technological advancements in horizontal drilling and hydraulic fracturing have unlocked an abundance of deep shale natural gas in the United States. This paper discusses the water efficiency of deep shale natural gas compared to other energy resources. Comparisons will be made by breaking down energy resource efficiency into common units such as gallons of water used per British thermal unit (BTU) of energy produced, gallons of water per megawatt (MW) of electricity produced, and gallons of water per mile driven. Energy resource water use comparisons will be evaluated based on extraction and processing of raw materials into useable fuel sources. Furthermore, comparisons will also be evaluated on power generation water use requirements. Finally, this information will be used to discuss the water efficiency of transportation fuels including plug-in (electrical) hybrids, traditional fuels (gasoline and diesel), biofuels, and compressed natural gas (CNG).
