We don’t think much about water when we flick on a light, power up our computer, or open the fridge for a drink. But there’s some H2O hiding behind every activity that uses energy – which, of course, includes almost everything we do.
In fact, the single biggest draw on U. S. rivers and lakes is not toilets, golf courses, or even irrigated farms. It’s thermal power plants that generate electricity to light our homes and cities, run appliances and factories, and generally keep our plugged-in society humming.
Thermoelectric generation accounts for 49 percent of the water withdrawn from the nation’s water sources, according to the U.S. Geological Survey. On average it takes about 23 gallons of water to produce 1 kilowatt-hour of electricity. That means a typical refrigerator can use 40 gallons of water a day – not at your home, but at the power plant that produces your electricity.
Thermal power plants – fueled by coal, oil, natural gas, or uranium – boil water to produce steam, which then drives a turbine to generate electricity. These fossil fuel and nuclear plants produce about 90 percent of the electricity used in the United States.
The vast majority of these plants are situated on a river, lake, estuary or bay because they require copious amounts of water for cooling. In contrast to irrigation, which “consumes” a great deal of water due to evaporation losses and crops’ transpiration of water back to the atmosphere, most thermal power plants consume little of the water they withdraw. Most operating plants use the older “once-through” systems that release cooling water back to its source. But the heavy extractions and discharge of wastewater warmed by as much as 20-30 degrees can degrade water quality and kill large numbers of fish and other aquatic organisms.
The Indian Point nuclear power plant, located along the Hudson River 38 miles north of New York City, kills nearly a billion aquatic organisms a year, according to New York State officials. Among them are shortnose sturgeon, an ancient fish that has plied Earth’s rivers for millions of years, but is now at high risk of extinction. As river water is sucked into the plant, fish get impaled against the intake screens, while smaller plankton and larvae get gobbled up by the plant’s machinery.
Indian Point’s two operating reactors together withdraw an astonishing volume of Hudson River water – some 2.5 billion gallons a day. That’s nearly two-and-a-half times the daily water use for all of New York City.
Last year New York officials ruled that operation of the Indian Point reactors killed so many fish and degraded water quality to such a degree as to violate federal and state water standards. Entergy Corporation, the plant’s owner, now faces the prospect of having to invest $1.1 billion to upgrade the plant’s once-through cooling system to a closed-cycle (or re-circulating) system, which requires about a tenth as much water and kills far fewer fish. Entergy’s licenses to operate the two reactors expire in 2013 and 2015, respectively, and a state-issued water quality certificate is needed for a 20-year renewal of the licenses.
(On the heels of the nuclear crisis in Japan, New York’s Governor Andrew Cuomo said on March 16 that Indian Point should be closed, because one of its reactors sits on a fault line and poses unacceptable safety risks.)
Along with fish kills and water quality, there is also growing concern about the reliability of river flows needed to cool thermal power plants. During the severe drought in the southeastern U. S. in 2007, the Browns Ferry nuclear plant along the Tennessee River in Alabama reduced electricity production due to high water temperatures and low river flows. The previous year, Alabama Power Company went to court over worries that a federal plan to release water from Georgia reservoirs to protect endangered mussels downstream in Florida would leave too little flow to cool its Farley Nuclear Plant.
Electricity, of course, is only a portion of our energy use. Fuel for heating and transportation require water, too. Hidden within each gallon of gasoline we pump into our automobiles is about 13 gallons of water. All together, energy accounts for about 35 percent of the average American’s water footprint.
It’s critical that our political leaders and we begin to grapple with the reality that energy and water are tightly entwined. All too often policies and choices aimed at solving one problem make the other one worse.
For example, a study by Rosa Dominguez-Faus at Rice University and colleagues found that the 2007 mandate by Congress that 15 billion gallons of corn ethanol be produced yearly by 2015 would annually require an estimated 1.58 trillion gallons (6 trillion liters) of additional irrigation water – a volume exceeding the annual water withdrawals of the entire state of Iowa. Viewed strictly through the lens of energy independence, ethanol production might make some sense. But overlaying a water lens gives a very different picture.
Likewise, it makes no sense to site nuclear power plants where water supplies are scarce or unreliable. Even solar energy can take on a different hue when its water footprint is factored in. A number of thirsty solar thermal plants are slated for the sunny southwest, a region climate scientists are predicting will become much drier in the decades ahead.
Sorting out this nexus of energy-water challenges will not be easy. We will have to make some uncomfortable trade-offs. But through it all the good news is that saving energy saves water – and there are still many opportunities to reap gains from this win-win. Improving the efficiency of our lighting, heating, appliances, cars and transportation systems can save billions of gallons of water and protect fish and other aquatic life, too. It’s something to think about this World Water Day – and, for that matter, every day.
Sandra Postel is director of the Global Water Policy Project and lead water expert for National Geographic’s Freshwater Initiative. 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.”