Water Stress Threatens Future Energy Production

Riverbend Steam Station, a coal-fired power plant on North Carolina’s Catawba River. Nationwide, thermoelectric power production requires more than 200 billion gallons of water a day, most of it to cool the plants. Duke Energy retired the Riverbend plant in April as part of its effort to modernize its power stations. Photo: Flickr/cc/Duke Energy

When we flip on a light, we rarely think about water.  But electricity generation is the biggest user of water in the United States.  Thermoelectric power plants alone use more than 200 billion gallons of water a day – about 49 percent of the nation’s total water withdrawals.

Large quantities of water are needed as well for the production, refining and transport of the fuels that light and heat our homes and buildings, and run our buses and cars.  Every gallon of gasoline at the pump takes about 13 gallons of water to make.

And of course hydroelectric energy requires water to drive the turbines that generate the power.  For every one-foot drop in the level of Lake Mead on the Colorado River, Hoover Dam loses 5-6 megawatts of generating capacity – enough to supply electricity to about 5,000 homes.

In short, energy production is deeply dependent on the availability of water.  And, as a report released last week by the U.S. Department of Energy (DOE) makes clear, as climate change brings hotter temperatures, more widespread and severe droughts, and lower river and lake levels, the nation’s energy supply is becoming more vulnerable.

Consider these examples from the DOE report:

  • In September 2010, Lake Mead dropped to levels not seen since the drought of 1956; as a result, the Bureau of Reclamation cut Hoover Dam’s generating capacity by 23 percent.
  • In 2009, NV Energy abandoned plans for a 1,500 Megawatt (MW) coal-fired power plant that would have used more than 7.1 million gallons of water per hour.
  • In 2007, 2010 and 2011, the Tennessee Valley Authority had to reduce power output from its Browns Ferry Nuclear Plant in Alabama because the temperature of the river into which the plant discharges was high enough to raise ecological risks.
  • In the summer of 2012, low snowpack in the Sierra Nevada curtailed California’s hydroelectric generating capacity by 8 percent.
  • At the Martin Lake Steam Electric Station in Texas, drought so reduced the level of its cooling pond that cooling water had to be piped in from another water source eight miles away.

One particularly interesting figure in the report compares the water requirements of seven different types of electric power facilities – nuclear, coal, biopower, natural gas combined-cycle, concentrated solar, photovoltaic solar and wind.  The last two come out as by far the most water-conserving electricity sources.  In contrast to the 20,000-60,000 gallons per megawatt-hour needed for nuclear and coal plants with “once-through” cooling systems, PV solar and wind require only negligible quantities.

Locations of the 100 coal-fired power plants most vulnerable to water stress. Courtesy U.S. Department of Energy.
Locations of the 100 coal-fired power plants most vulnerable to water stress. Courtesy U.S. Department of Energy.

Of the one hundred coal-fired power plants deemed to be most vulnerable to water shortages, most are located in the southeastern states of Alabama, Florida, Georgia, North Carolina and South Carolina (see map). In these states, water for cooling may be constrained by low river flows, high water temperatures or both – forcing utilities to cut back on power generation.

On balance the study’s findings make a strong case for a more rapid shift to renewable energy sources to shore up the nation’s energy security in the face of climate change.

If there’s a call to action in the DOE assessment, it’s this:  If, by 2050, the United States could get 80 percent of its electricity from renewable sources – with nearly half coming from water-thrifty wind and solar photovoltaic generation – then total water consumption in the U.S. power sector would decline by about half.

Given the projections for climate-related disruptions to the water cycle, there is little time to waste in making this transition.

[A correction to the photo caption: After publication, Duke Energy wrote to let me know that they had retired the Riverbend plant in April, earlier than planned.  My original post indicated it would be retired in 2015.]

Sandra Postel is director of the Global Water Policy Project, Freshwater Fellow of the National Geographic Society, and author of several books and numerous articles on global water issues.  She is co-creator of Change the Course, the national freshwater conservation and restoration campaign being piloted in the Colorado River Basin.

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.
  • J. Mangle

    Let’s look at how these plants “use” water — they don’t destroy it, they just warm it up by a few degrees.

    Second, shutting down plants because they warm the water is a joke. Shutting down a nuke plant for weeks because they raise the water temperature 8 degrees rather than 7 is just stupid and does more harm to the environment because that means more power is generated by nat gas or coal elsewhere.

    • Temperature is an important water quality parameter. When it gets too high, the result can be algal growth, low oxygen and fish kills. And you’re right, the water used for cooling is not destroyed. But that water has to be available to do the cooling, and low-flows can force cutbacks in power generation. And again, temperature matters. Thanks for commenting.

  • Vince Marshall

    We have developed a patent on “Process and Procedure to Reduce Thermal Pollution in Commercial Electric Power Plants”. This would allow commercial power plants to reduce and/or eliminate 100% of outside cooling water requirements. It would also raise power plant efficiency a small amount. I expect the patent to be filed within the next two weeks.

    Would you be interested in discussing further?
    Thank you.

  • Kevin O’Rourke – AWEA

    Wind projects are already saving significant amounts of water by displacing electricity production from the most expensive, least efficient sources on the utility grid – usually older fossil fuel sources. This benefit is especially important for the arid Southwest.

    In fact, when the new wind projects installed throughout 2012 produce power for a full year, the entire U.S. wind fleet will avoid over 37.7 billion gallons of water. That’s the same as over 280 billion bottles of water.

    For more on the benefits of wind, please visit: http://www.truthaboutwind.com .

  • alpha2actual

    Let’s look at Ethanol.After 30 years and 40 Billion Dollars even the Environmentalists have turned on Ethanol yet the Crony Capitalists keeping pushing this boondoggle. Corn ethanol is a net carbon emitter after factoring in land usage, carbon footprint of fertilizer, fuel expenditure etc. Ethanol is corrosive and can’t be transported by pipeline, call in those nasty 18 wheelers. It takes 1 gallon of water to crack out 1 gallon of gasoline while 2650 gallons of water begets 1 gallon of ethanol factoring in the agricultural usage. It takes 195 pounds of fertilizer per acre of corn which adds to runoff into the Mississippi then into the Gulf of Mexico which will have the biggest recorded dead zone this year. For comparison 1 acre of Soybeans uses no fertilizer. It’s astounding to me that 40% of the total US corn production is consumed by this moronic program and after 30 years Congress is just now attempting to shut it down by not subsidizing it.

  • J.H.N

    The idea that solar and wind can replace baseload generation is just that, an idea. It seems almost impossible at this point, to replace millions of megawatts of generation with sources that are intermittent. Barring a break through in battery technology, it will never be feasable to have 80% of power generated by wind or solar.

  • Paul Clieu

    Coastal power stations use sea water for cooling. There is no shortage and none is lost.

    The temperature of river water may increase slightly very close to the plant but very quickly loses its additional heat to the ground and to the atmosphere. There is absolutely no suggestion that waste heat from power stations heats up the World. The amounts are far too little.

    Some large air cooled power stations whose exit temperature is 40C use the waste heat in Greenhouses that produce vast amounts of tomatoes and other lovely salads.

    But hey, you can’t sell this story – shock horror sells!

  • Ed Fraser

    Sandra, I too am concerned about the energy-food-water nexus. The interactions between the three resources is the important element you’re shining light on. At risk of sounding like a fussbudget, I believe there should be differentiation between water types. There exists high carbon high cost water, which should be differentiated from low carbon low cost water.

    The high end would be fresh water pumped over great distances from limited watersheds, which demands large energy inputs. Or water that comes from limited deep aquifers, which take thousands of years to replenish and substantial energy to pump. Or desalinated water, which demands the highest energy input.

    Power plants you describe as “needing,” as if “using up” thousands of gallons per megawatt are in fact low end water users in as much as they don’t take from the high end sources listed above. Instead, power plant cooling water is returned to the same source taken such as rivers, lakes, bays, or oceans. While returned water quality may be warmer, the source’s quantity remains unchanged.

    I would like to see solar electric panels installed on every house (in the southwest at least.) But the “negligible” water demand required to clean sticky filth accumulation to optimize electrical production is by definition high carbon high cost water, which adds up.

  • VInce Marshall

    We have developed a process called “Regenerative Cooling” to capture waste heat from a power plant. The heat is then elevated and recycled back into the same plant it came out of. Any plant equipped with this technology would use less fuel for the same electrical output.
    This technology is similar to Regenerative Braking used in hybrid vehicles. In a hybrid vehicle, when you slow down, kinetic energy is captured and stored instead of being thrown away as heat. The captured energy is then used to help power the vehicle, using less fuel. Regenerative Cooling will also reduce all Greenhouse Gas emissions for the same electrical output and would create a very efficient “Hybrid” power plant.
    Any power plant utilizing this technology would never again shut down or de-rate due to cooling water restrictions. Patent was filed on 30 July 2013

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