The Water-Energy Nexus

Looking to cut back on your energy use? Try watering the grass a day or two less each week. And you say water efficiency is becoming more important to you? Try turning off a few lights and setting back the air conditioning. As environmentalists, regulators and electric utilities are beginning to recognize, water and energy use are inextricably linked, and as supplies for both commodities tighten, their relationship to each other is becoming more important.

Put simply, we use an enormous amount of water to make energy—in drilling and mining operations and in cooling thermoelectric generating plants. Conversely, we use an enormous amount of energy in pumping, moving, treating and heating our water. This codependent scenario has been dubbed the “water-energy nexus,” and electric utility executives are beginning to realize some therapy may be in order. The 700 utility executives who participated in the 2011 Black & Veatch “Strategic Directions in the Electric Utility Industry” survey ranked water supply as their top environmental concern, above nuclear waste disposal.

Researchers have begun seeking new ways to reduce demand on both sides of the nexus. Much of their work is being built off a 2006 report prepared by 10 national laboratories for the U.S. Department of Energy (DOE), “Energy Demands on Water Resources.” The data gathered for this document formed the basis for a May 2011 report from the World Policy Institute (WPI), “The Water-Energy Nexus.”

“This is an issue that encompasses all energy, both generation and transportation fuel,” said Diana Glassman, lead author of the WPI report. As she noted, the water-energy connection will affect the developing world even more than water and energy users in the United States. “[It’s] being shared at the World Economic Forum. It’s on the global agenda.”

Experts consider three different aspects of water use when evaluating overall water effects:

• Withdrawal: water that is withdrawn from a river, lake or aquifer and is returned to its source after it has been used. This is how many cooling towers operate.
• Consumption: water that is withdrawn and not returned. It may be lost through evaporation.
• Quality: the effect of withdrawal and use on the water in question. For example, cooling tower water that has been treated and returned is often warmer than at its source, which can have a detrimental effect on plants and fish in the area.

When looking at electricity generation, Glassman and her co-authors focused on identifying the use of water by varying fuel sources. Obviously, water availability differs by region. In the United States, the Great Lakes area has an abundance, while the Southeast and parts of Texas are in a drought. The goal of the WPI report was to understand better how fuel sources can affect an area’s water resources.

Things can become even more complicated when utilities’ carbon-reduction strategies are thrown into the mix. According to a September 2010 report by Jan Dell, energy division vice president for engineering firm CH2M HILL, geothermal steam and concentrating solar technologies consume more water than any other common generating technology. Solar photovoltaic panels and wind turbines use the least. Currently, natural gas plants consume less water than either coal or nuclear options, but that determination is based on the DOE’s 2006 figures, which predate the current rush toward water-intensive hydraulic fracturing in the drilling industry.

The flip side of the water-energy coin is the energy consumption embedded in how we access and use water. California is an extreme example of just how much energy can be required. A 2007 California Energy Commission report noted the state’s water-related energy use consumed 19 percent of all electricity and 30 percent of all natural gas used in the state. The River Network, a Portland, Ore.-based environmental group focused on watershed issues, estimates that, nationally, water-related energy use totals 521 million megawatt-hours per year, equivalent to 13 percent of total U.S. electricity demand.

With a basic understanding that neither energy nor water can be used more efficiently without considering both commodities in the solution, groups now are beginning to talk across their respective constituencies. In one such effort, the American Council for an Energy-Efficient Economy and the Alliance for Water Efficiency (AWE) held a workshop in November 2010 with participants from water and electric utilities, national labs and environmental groups. That workshop was the basis for a report now circulating throughout government and regulatory offices. “A Blueprint for Action and Policy Agenda” outlines areas where more research is needed and policies need addressing. At the top of the list is an intent to increase the level of collaboration between water and energy communities.

“Historically, water and energy utilities have not worked together because of the different ways in which they’re owned,” said Mary Ann Dickinson, AWE’s president and CEO, who noted the eventual cost we will all pay if collaboration doesn’t begin soon. “As the price of energy goes up because of the cost of water for cooling, everything will get more expensive.”

ROSS is a freelance writer located in Brewster, Mass. He can be reached at

About the Author

Chuck Ross

Freelance Writer
Chuck Ross is a freelance writer and editor who has covered building and energy technologies for a range of industry publications and websites for more than 25 years. He specializes in building and energy technologies, along with electric-utility bus...

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