Preparing for a Warmer, Drier Planet: Water is the Hidden Cost of Energy

Think about the environmental impacts of energy use, and your mind probably jumps immediately to obvious ills: greenhouse gases, acid rain, air pollution, radioactive waste, or landscapes ravaged by coal mines or tar sands pits or fracking fields.

You probably don’t think a whole lot about water, unless you’re picturing a once-rollicking whitewater river backed up into a placid lake behind hydroelectric dams. Or maybe some gulf waters coated by that iridescent sheen of an oil slick.

Truth is, some of the most severe impacts of energy consumption—whether it's the gas we pump into our cars or the electricity coming out of our sockets—have to do with the staggering amounts of water needed to produce and harness the energy that powers our modern lives.

The raw numbers are practically beyond comprehension. We’re talking about roughly 583 billion cubic meters of freshwater withdrawn annually to produce energy, according to the International Energy Agency (IEA), which for the very first time included a section on water in its annual World Energy Outlook. That figure represents about 15 percent of total water use worldwide, second only to agriculture as an overall industry.

In real world terms, water is withdrawn from the world’s rivers, lakes and aquifers for energy use at roughly the same rate as it flows down the Ganges or Mississippi Rivers.

Sure, a bunch of that is returned to the environment—after serving to cool power plants, for instance—but the initial withdrawal still stresses local ecosystems, as does the spent water that often carries a whole bunch of waste heat.

The problem is only getting worse. As reported by National Geographic, the amount of freshwater consumed (that’s the stuff that doesn’t flow back into local hydrological systems) by energy production is projected to double by 2035. This in a time when freshwater shortages are beginning to threaten all corners of the globe, and ever-increasing temperatures promising to cause even greater water stress to billions.

So where is it all going?

  • The typical 500 megawatt coal-burning power plant sucks up about 300 million gallons of water every day. Most of that is released—at a considerably higher temperature—but about 3 million gallons are gone for good.
  • An average nuclear power plant churns through 720 gallons of water for every megawatt-hour of electricity that it produces. So say it’s a 500 megawatt plant, that’s 360,000 gallons for every hour of operation.
  • For every gallon of gasoline you pump into your car, anywhere between 2.8 and 6.6 gallons of water were spent to extract and refine it.
  • Short for “hydraulic fracturing,” it’s not surprising to learn that hydrofracking is water-intensive. The typical deep shale well requires 4.5 million gallons of water to drill and release the gas within.
  • Biofuels are enormous water hogs. A single gallon of corn-based ethanol demands roughly 780 gallons of water for irrigating the crops alone.
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So how can we keep our lights on and our cars running, while keeping water flowing from our taps? (And, crucially, how can we turn the lights on and get tap water flowing in communities in the developing world where there aren’t yet outlets or faucets to speak of?) Technology has some answers. Advanced cooling systems in power plants help a lot; the newest combined-cycle natural gas plants, for instance, drink up a whole lot less water than old coal plants.

Better still would be to focus on those fuel sources that require little-to-no water at all. The IEA report suggests putting some serious restrictions on biofuels, especially in areas where food and water shortages already exist. It also makes the case for solar and wind, which sip, don’t gulp, from freshwater supplies. Of course, the best way to cut water use in energy production is to cut consumption itself. The great and immediate gains we can achieve in efficiency and conservation can go a long way in ensuring that we’ll have enough water and power to go around.

original image via wikimedia commons

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