Changing Planet

The Perils of Ignoring the Water-Energy Nexus

Photo credit: Michael Loke/Flickr Creative Commons

As we pump gasoline into our automobiles, we watch the register ring up dollars, but we don’t see the water cost: some 13 gallons for every gallon of fuel.

It’s one of the most inconvenient truths of modern times that it takes increasing amounts of finite water to supply energy and increasing amounts of climate-disrupting energy to supply water.  And too often our search for solutions to one set of challenges is making the other set worse.

This week, National Geographic News provides a comprehensive report on the recent projection by the International Energy Agency (IEA) that, if current trends continue, the volume of water consumed for energy production worldwide will double by 2035.

The recent surge in hydraulic fracturing, or “fracking,” to unlock shale gas plays a part, but the big-ticket items in the equation are coal-fired electricity and the expected rise in biofuel production.

According to the IEA’s assessment, in 2035 biofuels could account for 30 percent of the water consumed for energy production, up from about 18 percent in 2010.  The water-intensity of biofuels varies greatly depending on the fuel stock — corn, sugar cane, or agricultural byproducts — as well as on how and where that fuel source is grown.

According to a 2009 study in Environmental Science & Technology, the 2007 U.S. Congressional mandate to produce 15 billion gallons of corn ethanol a year by 2015 would annually require an estimated 6 trillion liters of additional irrigation water (and even more direct rainfall) – a volume exceeding the annual water withdrawals of the entire state of Iowa.

Flipping the water-energy nexus coin, we find that more and more water “solutions” demand more energy – whether pipelines to transfer water hundreds of miles from one place to another or desalination plants.  Though the energy costs of desalting have come down in recent decades, it still takes about 2 kilowatt-hours of electricity to produce one cubic meter (264 gallons) of drinkable water.

The good news is that saving energy saves water, and saving water saves energy.  And we’ve barely begun to tap the potential of conservation and efficiency improvements to meet new needs.

Now more than ever, real solutions are those that tackle our water, energy and climate problems at the same time.

[For additional information and examples, see the Know the Nexus report by GRACE Communications Foundation.  To calculate the water cost of your energy use, try our National Geographic water footprint calculator.]

Sandra Postel is director of the Global Water Policy Project and Freshwater Fellow of the National Geographic Society.  She is the author of several acclaimed books, including the award-winning Last Oasis, a Pew Scholar in Conservation and the Environment, and one of the “Scientific American 50.”





Sandra Postel is director of the Global Water Policy Project and author of Replenish: The Virtuous Cycle of Water and Prosperity. From 2009-2015, she served as Freshwater Fellow of the National Geographic Society. Sandra is also co-creator of Change the Course, the national water stewardship initiative awarded the 2017 US Water Prize for restoring billions of gallons of water to depleted rivers and wetlands. The recipient of several honorary degrees, she works to bridge science, policy, and practice to promote innovative ways of securing water to meet both human and ecosystem needs.
  • Dave Thomas

    I’m getting so tired of journals printing ludicrous articles like this.

    Let me explain- The United States is not alone on the globe. The United States and Canada are not alone on the globe.
    The United States, Canada, and Western Europe are not alone on the globe.

    Is Sandra Postel so utterly ignorant of the globe she lives on that she doesn’t realize that China and India are industrializing and that South American isn’t far behind to be followed by Africa.

    It doesn’t matter one bit, none at all, what the United States and Western Europe do about clean energy or gloal warming.

    Just last year China and India increased their consumption of coal equal to all of the clean energy power produced in the entire world.

    Next year China and India are going to use even more coal. All of these ludicrous articles about clean energy are a total, complete waste of time. You better focus on CLEAN COAL and natural gas if you want to accomplish anything.

    Sandra and Nat Geo obviously aren’t interested in dealing with reality at all. So keep writing useless nonsense that ignores the REAL WORLD!!!!!

    • We’re all on this ship together, and we all — especially the US, China, India — need to do our part. U.S. per capita carbon emissions and water use are higher than other countries, so we have responsibility to lead. It also makes good economic and environmental sense.

  • Nathan Barber

    “It doesn’t matter one bit, none at all, what the United States and Western Europe do about clean energy or gloal warming. ” – This is exactly the attitude that prevents progress. It only took a couple people ~100 years ago to figure out that we are polluting the Earth. Now each year, more and more people are realizing that we have a problem and becoming more aware of what to do about it. It absolutely matters what anyone is doing. The more we have on board, the more we can do to prevent human-induced climate change and/or fix our obsession with fossil fuels

  • GN

    It seems like the best reason (of many) for denouncing the biofuel approach is that it may force us to confront the carrying capacity of the planet. Various analysts come to somewhat different conclusions, but it seems pretty clear that the amount of land, minerals (e.g. potassium and phosphate) and water needed to provide everyone with biofuels is going to be a large fraction of the resources now going to ordinary agriculture. No one could possibly want to consider how unworkable that scenario might be.

    I’m not trying to say that we are stupid. Instead, it just appears that population problems are challenges beyond our level of intelligence and collegiality.

  • Shafiq Alattas

    Dear Sandra
    I’ve discovered a new technique for generating the electricity from the nature, but since i’m in the arabic world my idea will die unless you handle and the benifet will be for me and you

  • Checker99

    STOP THE MADNESS. Using water to grow plants or mine fossil fuel does not result in its destruction. To suggest we are ‘consuming’ water on farms and fracking is ludicrous – the water is just borrowed and neither created nor destroyed.

  • Anthony Alfidi

    The water-energy nexus demands innovation. Entrepreneurs can make huge money with green infrastructure disruption.

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