Introduction to the concepts of energy-water nexus, water withdrawal, water consumption, and impaired water

The chapter evaluates the origin of natural gas, the principles of hydraulic fracturing, and provides the magnitude of water use for hydraulic fracturing, conventional gas drilling, and electricity generation. The chapter presents the changes of the water footprint of hydraulic fracturing and water intensity over time in the USA and China. The chapter draws upon data from emerging scientific reports in the USA to explore the global implications of unconventional energy for other countries with shale gas potential. The chapter presents the major organic constituents associated with frac water used for hydraulic fracturing. The origin, geochemistry, and volume of flowback and produced water and their impact on water resources are also presented. The chapter discusses the chemical composition of produced and flowback waters, the contaminants in these wastes. The chapter explores the debate on the effect of stray gas contamination. The chapter discusses the mechanisms of potential groundwater and surface water contamination. The chapter evaluates the mechanism of coalbed methane extraction and environmental implications. The chapter discusses the different regulations and possible safeguards to protect fresh water resources from hydraulic fracturing.

This chapter presents the anthropogenic global water cycle: the overuse of natural water resources has led to a water deficit that has been further exacerbated by global warming and increasing drought intensity induced by fossil fuel use, combined with large water use for fossil fuels, increased energy generation for water transfer and treatment, and consequently further water use and impact on depleting water resources. The chapter presents a new assessment of global water withdrawal and consumption and wastewater for the different stages of fossil fuel production and consumption, using the most updated information on water intensity and energy production. The chapter highlights the high magnitude of the impaired water intensity derived from water contamination on a global scale. The chapter explores the global emission of carbon dioxide, water vapor, and methane from fossil fuel operations, including natural gas flaring. The chapter evaluates the energy use for water transport, wastewater treatments, and desalination, emphasizing that future water quantity and quality deterioration would require additional treated water and thus additional energy sources that would further exacerbate the anthropogenic water cycle. Finally, the chapter discusses the options for a clean future and transition to renewable energy sources with much lower water intensity and environmental impacts.

The chapter explores the water–energy nexus associated with conventional and unconventional (tight) oil exploration, provides water-intensity values associated with conventional oil drilling and enhanced oil recovery, and hydraulic fracturing. The chapter explores the source, volume, geochemistry, and water quality issues of conventional and unconventional oil produced water. The chapter explains the nature and origins of oil field brines, as well as the inorganic (salts, metals, and naturally occurring radioactive elements) and organic constituents. The chapter evaluates the impact of oil produced water on the environment, as well as the ability to reuse oil produced water for beneficial use. The chapter explores the water use and quality associated with oil sand extraction and processing and possible environmental effects as well as oil refining. The chapter evaluates the impact of oil spills on water resources. The chapter examines policy mechanisms that influence the extent of environmental externalities that have emerged from oil production and exploration, including government regulations, forms of corporate society responsibility, and types of contracts.

An overview of the evolution of different fossil fuel sources, including coal, conventional and unconventional (tight) oil, oil sand, conventional natural gas, unconventional shale gas, and coalbed methane. The chapter provides the data on energy flows and evaluates the global energy consumption for understanding the magnitude of these developments. The chapter also presents the traditional water–energy concept; the amount of water withdrawal and consumption for fossil fuel exploration in the recovery stage (coal mining, oil and gas drilling, mining, hydraulic fracturing, oil enhancement), processing (coal washing, oil refinery), conversion (electricity production), and post-conversion (waste disposal). The chapter examines the water intensity metrics by normalizing the water volume-per-energy unit of electricity, with an emphasis on the distinction between water withdrawals and water consumption, and considering the complete lifetime cycles of water extraction for energy exploration, processing, and generation.

This chapter explores the coal–water nexus with evaluation of the chemical hazards in coals and the magnitude of their emission with coal combustion, the quantity of water use for coal mining and processing and implications for water quality, with an emphasis of the formation of coal mine effluents such as acid mine drainage and the large water-impaired intensity. The chapter describes the different technologies for cooling thermoelectric plants and the associated water intensity and thermal pollution upon the discharge of the cooling water to the hydrosphere. The chapter explores the formation of coal combustion residuals after coal combustion, the enrichment of contaminants in coal combustion residuals, and the volume and quality of effluents associated with coal ash impoundments, and the environmental risks associated with the management of coal ash and leaking coal ash impoundments. Finally, the chapter looks at the different regulations in different countries with respect to coal mining, combustion, and disposal, as well as the transition from coal to different energy sources.