Water we waiting for

The unrecognized link between water and energy 2

power plant along riverPhoto: rutloOur nation is in the midst of some serious energy and water problems, but what many may not realize is that these two issues are very closely linked (see the recent Wall Street Journal article on this topic). The truth is that energy and water are related in just about every way you can imagine and in ways that affect our lives everyday—down to the lights and water in our homes that we too often take for granted. The water supply sector utilizes large amounts of energy to transport, treat, and deliver water.  On the flip side, vast quantities of water are required to generate power.

First let’s start with how much water is used for energy. The United States thermoelectric industry uses 3.3 billion gallons of water every year [PDF].  That is 20 percent of all the water consumed in the country for non-agricultural uses.  This number is currently predicted to grow to 7.3 billion gallons by the year 2030.  Water is used in all stages in the creation of energy—to extract, process, refine, and transport the fuels to power-generation sources. The power plant itself also uses vast amounts of water [PDF], particularly for the towers that cool the water heated in the generators.

Next, consider the energy used to produce and deliver water.  California was among the first states to take a close look at this [PDF]. They discovered that almost 20 percent of all the electricity used in the state was used to supply and treat water. On average, 75 percent of the costs of producing municipal water are electricity costs related to capturing, treating, distributing, and using water.  After the water is used, more energy is required to treat the wastewater.

To illustrate this point for Texas, I recently authored a report with the University of Texas to provide guidance for how the state can better integrate water and energy supply planning for the future. Check out the report to see our recommendations for steps Texas can take now to create a framework for more collaboration between energy and water planners and guidelines for improving data on the energy-water relationship.

As cities continue to grow, particularly in water scarce areas, these linkages between water and energy use are becoming more important. A growing community needs more power, which requires more water, which uses more power, and so on.  Understanding this relationship highlights the importance of conserving water and practicing energy efficiency.  For every kilowatt saved, water is also saved.  For every gallon of water not used, energy demand is reduced. Investments in and incentives for energy and water conservation must be our highest priority.

Amy Hardberger is an attorney with Environmental Defense Fund.

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  1. Sean Casten's avatar

    Sean Casten Posted 1:33 pm
    17 Apr 2009

    A point that needs to be kept in mind but is too often overlooked is that the water use in power plants is a direct function of their (in)efficiency.  Heat that is put into a steam power plant (roughly 70% of the US fleet) as fuel, but not recovered as electricity gets sent to a cooling tower as soggy steam where it is condensed with prodigous water use.  This is where the overwhemling majority of the water gets used / wasted in a modern power plant as those cooling towers evaporate water into the sky.  (Think about the plume atop a nuclear cooling tower.)Without in anyway disparaging the value of electricity conservation, it bears keeping in mind that the larger opportunity for water conservation is in the power plant itself.  If you build those power plants as combined heat and power plants instead, replacing that cooling tower with a heating loop going onto industrials, district thermal loops and any other purpose you eliminate the need for substantially all of that cooling tower water - and save a fair amount of fossil fuel as well.At the other end of the wire, there are many opportunities within industrial facilites to replace process coolers at their end (which also are big water hogs) with heat recovery, either to provide space heating or else - at the somewhat more technologically-adventurous fringe - stick organic rankine cycles that can make power with working fluids that boil at low temperatures.  This brings more efficient generation on line (displacing some of the load on those upstream generators, just like end-use conservation does) and also gets rid of water use at the industrial itself.  The opportunity for that approach is pretty massive - we've been looking at projects using ORCs in chemical plants, atop their distillation & stripping columns.  (Fun fact: for every ~5 MW of electricity consumed by a modern ethanol plant, you could pull 1 MW out via this approach.)This isn't meant to be exhaustive, nor overly specific as to the solution - just to make sure we don't make the mistake of assuming that the miserably-low generation efficiency of our electric sector is immutable - but do appreciate the water conservation benefits of bringing that sector into the 20th century. 

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  2. Subaru's avatar

    Subaru Posted 8:57 am
    18 Apr 2009

    Someone will need to think to make power out of water, after all there is more water on earth than anything else. But then again, this will be utopia, free energy, no capital... since everyone have access to water. Industry want monopoly and cash. Water as energy is not good for them.

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