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The Energy-Water Nexus

By Leland Keller - Member Inquiry Honcho

Headlines I’ve read this past week warn that 2010 will go down as the third hottest year on record, so it angers me that talks at the U.N. Climate Change Conference in Cancun appear to be ending in a regrettable stalemate. It’s up to us to generate the change we need to see in climate protection.

Not only do greenhouse gas (GHG) emissions reductions matter, but water savings matter as well. I’m writing from the arid high-desert environment of Boulder, Colorado, where we are 30 inches behind on our seasonal snowfall, and 18 percent behind on annual precipitation overall. This pattern may be affecting you, too—because of global precipitation changes and human water-use patterns, many major metro areas are coping with drought or imminent supply shortfall. Many rural areas are also impacted by this crisis—the unsustainable drawdown of massive aquifers is causing well failures for individual farms and entire communities. The long-term freshwater availability forecast gets much worse unless we arrest the climbing GHG concentrations.

Future scarcity of freshwater supplies may dramatically affect electric generation because of the water required for producing electric power—between 541 and 609 gallons per megawatt-hour for coal and nuclear plants. Thermoelectric power production accounts for 48 percent of total water withdrawals, 39 percent of freshwater withdrawals, and 3 percent of freshwater consumption in the U.S. according to the U.S. Geological Survey. Does your strategic planning road map address this water-scarcity concern?

On the flip side, let’s take a look at the substantial amount of energy embedded in simply delivering the potable water we use. Drawing an example from my neighborhood, Fort Collins, Colorado, a city with a relatively clean source of gravity-fed water, supplies water with an energy intensity of 154 kilowatt-hours (kWh) per acre-foot. Other areas in Colorado relying on pumped groundwater from alluvial basins or aquifers require more than 20 times that—3,950 kWh/acre-foot of water delivered according to a 2009 study (PDF) by Western Resource Advocates. Water piped long distances can exceed 4,600 kWh/acre-foot.

Dr. Peter Gleick, cofounder of the Pacific Institute, offered testimony (PDF) last Wednesday to the Select Committee on Energy Independence and Global Warming, explaining that we now face only three options with respect to climate change: mitigate the severity of climate change through reducing GHG pollutants, adapt to unavoidable climatic change, or suffer the consequences of climatic change. Our choice is in how much of each option we do. Let’s light a fire under the mitigation efforts, get serious with communicating the importance of the matter to our customers, and collaborate to dramatically curb wasted energy and freshwater. It’s not only a matter of our national security, but also of habitat preservation (our own).

Conserving domestic hot water is a multiple-win opportunity that addresses both water and energy concerns. The E Source DSMdat database records the details of more than 2,500 active energy demand-side management (DSM) programs—378 of them tied to water impacts. One unique energy utility collaboration aimed at conserving domestic hot water is the Pacific Gas and Electric (PG&E) High-Efficiency Clothes Washer Rebates Program. PG&E launched this rebate program in 2008 in conjunction with 12 water agencies representing 40 water retailers in the greater San Francisco Bay Area. PG&E processes one single rebate application and compensates the customer $50 in addition to the water utility rebates for a total rebate of $100 to $175. This combined incentive makes for a more satisfying customer experience and improves participation in PG&E’s program.

Send us your questions if you would like more information on collaborative water conservation programs, the efficient technology measures they commonly include, or program evaluation data. And, let us know if you are aware of other energy utilities that have partnered with water utilities to extend the reach of DSM programs with joint benefits.



CALMAC just posted an evaluation study of nine pilot programs in California that targeted water efficiency as a means of reducing energy consumption( Across the nine programs, annual embedded energy savings ranged from 0 kWh to over 178,000 kWh per year. And another interesting tidbit (that I looked up after the above study was released): According to page 14 of a California PUC report from 2005 (, 19% (!) of California's electricity and 30% (!) of the state's natural gas are spent on water-related activities (i.e. pumping, treatment, wastewater treatment, agricultural + res + commercial end uses).

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