Earth Day provides an occasion to draw attention to the interdependence of energy and water resources, also known as the energy-water nexus. Energy and water are inextricably linked.
The management of water resources requires considerable energy resources. In 2005, California estimated that sourcing, moving, treating, heating, collecting, re-treating, and disposing of water consumed 19 percent of the state’s electricity, 30 percent of its natural gas, and 88 billion gallons of diesel fuel each year.
In a similar fashion, a significant portion of the U.S. electric production is dependent on the availability of water for use in steam-driven turbines and cooling systems. According to U.S. Geological Survey estimates, nearly 50 percent of the nation’s total water withdrawal, or 201,000 million gallons per day, are used to produce thermoelectric power (see Figure 1). The thermoelectric power sector has been the largest withdrawer of water sources in the United States since 1965. While much of the water returns to its source, the continued access to this water source is not certain regardless of how little is actually consumed in the process.
Figure 1: Trends in total withdrawals by water-use category, 1950-2005
In 2012, energy’s reliance on water resources became evident during a prolonged drought fueled by the warmest spring and second warmest summer on record. Overall, average temperatures for the contiguous United States in 2012 were 3.2 degrees Fahrenheit above the 20th century average and 1.0 degrees Fahrenheit above the previous record from 1998. As extreme conditions drove electric demand to cool homes and businesses, lower water levels and higher water temperatures impacted plant operations. The drought resulted in:
In the near term, the National Oceanic and Atmospheric Administration (NOAA) forecasts continued drought conditions through June in the southwest and south-central United States. In addition, the U.S. Government Accountability Office recently added the need to limit the federal government’s financial exposure to climate change to its biennial high risk list. It is clear that despite disagreements over the cause, climate change will require a focused attention on the interdependence of energy and water resources in our economy.
In the long term, a number of factors such as climate change, drought, increased upstream withdrawals, urbanization, increased consumptive use (e.g., cooling towers), and more restrictive environmental flow and temperature limits all pose a risk to power plant operations. Understanding the nature and extent of that risk is critical. Armed with this knowledge, plant owners can take concrete actions to manage those risks.
ScottMadden can assist power plant owners in evaluating water availability under various long-range scenarios as well as in developing programs and strategies to manage the risks. To learn more about ScottMadden’s model for ensuring adequate planning and risk management for water availability, please contact us.
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