Energy and water are inextricably linked, both at the crux of the U.S. economy and way of life.
Energy is required to secure, treat and distribute water; conversely, energy production depends on an abundant and reliable source of water.
This intersection is commonly called the “energy-water nexus,” a phrase that has reached buzzword status and is the focus of current policy decisions and scientific research.
As population increase and climate change put additional stress on the environment, the nexus acknowledges that any solution for one problem must equally consider the other.
Energy-Water Legislation
The energy-water nexus is not new to political agendas – but it is rapidly gaining popularity:
- In 2004, the House and Senate Appropriations Subcommittees on Energy and Water Development requested a report from the Department of Energy on “the interdependency of energy and water focusing on threats to national energy production resulting from limited water supplies …”
- The Department of Energy’s Sandia National Laboratory has taken the lead in energy-water nexus research. Sandia National Laboratory (2005) estimated that electricity production requires about 136,000 million gallons of freshwater per day, or approximately 40 percent of all daily freshwater withdrawals in the nation.
- Bipartisan legislation in the Senate supports increased energy-water efficiency; the Energy Savings and Industrial Competitiveness Act, co-sponsored by Sen. Jeanne Shaheen (D-N.H.) and Sen. Rob Portman (R-Ohio), was introduced to the Senate in July 2013 in an attempt to update and replace the Energy Independence and Security Act of 2007.
The Shaheen-Portman bill would be the most comprehensive energy bill passed since 2007, with its purpose to reduce energy and water waste by increasing efficiency technologies across the nation.
Sen. Tom Udall (D-N.M.) proposed amendments in the bill to promote water efficiency. One of his amendments included authorizing the EPA WaterSense program, similar to that of the Energy Star program, to improve labeling systems for efficient water appliances, plumbing and landscaping.
He also proposed establishing a “Blue Bank” to provide grants to help water and sewer utilities invest in water efficiency and reuse.
The Shaheen-Portman bill is expected to pass both houses of Congress – it has been delayed, however, due to more pressing budgetary matters.
Federal Agency Support
It is important to recognize that not all low-carbon technologies benefit water resources. According to a 2008 report (Webber), to produce one megawatt-hour of electricity:
- Gas and steam combined cycle plants must use 7,400 to 20,000 gallons of water.
- Coal- and oil-fired power plants require 21,000 to 50,000 gallons.
- Nuclear power plants require 25,000 to 60,000 gallons (Webber, 2008) – nuclear power is one of the most water-demanding forms of energy creation, with consumption approximately three times that of gas.
- Carbon capture and storage technology and biofuels also are very water intensive. For example, in some parts of the world people may use as much water powering their homes as they use taking showers and watering their lawns (Sandia, 2005).
Consequently, there is urgency in further research to quantify total national water resources as well as each energy sectors water use.
Through the Omnibus Public Land Management Act of 2009, Congress called for a national assessment of water availability and use. The U.S. Geological Survey (USGS) launched the National Water Census, a comprehensive look at national water availability, the first since 1978.
To start, the agency is focusing on the Colorado River Basin, Apalachicola-Chattahoochee-Flint River Basin and Delaware River Basin due to water competition from surrounding dense populations. The USGS is working with the U.S. Energy Information Administration to improve the quality and usefulness of data from power plants’ water use.
To aid in the water census, the USGS recently announced it would reinstate the rule to report the amount of water consumed in the production of thermoelectric power.
This reinstatement will significantly benefit the progress in the national census of water.
According to the USGS, thermoelectric energy water withdrawals accounted for 41 percent of total freshwater withdrawals and 50 percent of total fresh plus saline withdrawals for the nation.
Without a national assessment of water supply it is difficult to gauge and understand the interdependencies of water and energy.
Conclusions
The energy-water nexus catchphrase taps the potential for policy makers, scientists and industry leaders to better understand the interdependencies of energy and water.
Current legislation to increase water and energy efficiency, the National Water Census and the reinstatement of the rule to report water use in thermoelectric plants are federal initiatives to address the interlocking nature of the two. Understanding the linkage of water and energy is key in determining efficient use of these critical resources, both for economic benefit and environmental resilience.
Wastewater reuse has a strong potential to boost water supply and lessen energy consumption. Wastewater treatment plants discharge approximately 32 billion gallons per day in the United States, with approximately 12 billion gallons of that going to an ocean or estuary.
Reusing this treated water, rather than discharging in coastal areas, would increase the U.S. total water supply by about 6 percent.
With population increasing and water becoming scarcer, water reuse and increased water efficiency prove to be a cost-effective means to provide water.