by By James McGarry |
The American Water Works Association estimates that the average U.S. household uses approximately 127,000 gallons of water every year. That may seem like a lot, but do you know how much additional water you use every day just to turn on the lights? Everybody has heard about air pollution, climate change, and fossil-fuel depletion, but the silent victim of Americas insatiable energy demand is our water resources.
The American Water Works Association estimates that the average U.S. household uses approximately 127,000 gallons of water every year. That may seem like a lot, but do you know how much additional water you use every day just to turn on the lights? Everybody has heard about air pollution, climate change, and fossil-fuel depletion, but the silent victim of America’s insatiable energy demand is our water resources.
Energy Generation Uses Enormous Amounts of Water
Almost every stage of the energy cycle uses enormous amounts of water including mining [e.g., hydraulic fracturing (aka fracking) for natural gas], cleaning, and refining. Even after burning, some power plants use water to clean out ash and scrub smoke-stacks to reduce air-pollution emissions.
Thermoelectric power plants use nuclear power or fossil fuels to boil water to spin a turbine which drives an electric generator. To efficiently drive the turbine the steam is cooled by heating water drawn from local bodies of water or through evaporative cooling towers (described in more detail later in this article). Together these methods use more than four times the amount of water used by all U.S. residents. Despite the efforts of utilities and system operators to improve their water-efficiency, our electricity-related water use continues to grow and is reaching unsustainable heights.
Even with the industry squeezing more power out of each gallon of water, the absolute water use for thermoelectric power plants has steadily increased from 14.6 trillion gallons in 1950 to about 100 trillion gallons in 2007.1,2 With no abatement in our current trajectory, the risks we face include rising prices for water and electricity, reduced water quality (in many cases caused by heated water), high rates of fish mortality, and the possibility of billions of dollars of economic damages. In fact, if business-as-usual demand growth continues, federal estimates about the cost of upgrading our water infrastructure range from about $250 billion to over $1 trillion over a twenty year time span.3
Maryland alone withdraws 379 million gallons of fresh water per day for electricity, and that makes us look good compared to our neighbors. Pennsylvania and Virginia withdraw approximately 6.98 billion and 3.85 billion gallons of fresh water per day, respectively.4
The Impact on Maryland
So what does this mean for our area? A study published in the Columbia Journal of Environmental Law in July, 2009 placed Maryland’s Montgomery County and Calvert County on its list of national electricity-water crisis areas. Given those areas’ predicted electricity demand, population growth, and water resources in 2025, the authors estimated that Montgomery County would have a 4.45- inch annual water deficit and that Calvert County would have a 2.25-inch annual water deficit to meet their summertime water needs in the next decade. Rising demand for water and electricity and a shortage of available supply will mean higher water and electricity prices and costly infrastructure investments.
How the Thermoelectric Water Cycle Works
To understand how we use so much water, it is important to know how the thermoelectric water cycle works. Water is used by power plants to produce the steam used to spin the turbines, but predominantly for cooling needs. The two main water cooling methods are once-through cooling and closed-cycle cooling, the latter of which is more common in the water-scarce western United States. In once-through cooling, cool water is extracted from a nearby water source and run through a series of pipes to cool surrounding steam before being discharged back into the water source downstream, about 30 degrees Fahrenheit warmer than the surrounding body of water.
In closed-cycle cooling, after the water is extracted and run through the pipes in the condenser, it gets transferred to a cooling tower to be re-used for the same purpose later. While closed-cycle cooling systems use a fraction of the water needed by once-through systems, they ultimately deplete more than twice as much through evaporation in the cooling towers.
The predominant environmental repercussion of the once-through cooling system in the eastern U.S. is thermal pollution. Billions of gallons of heated water recirculating into rivers, lakes, and streams contribute to thermal pollution, which decreases the amount of dissolved oxygen in the water, even while increasing the demand for oxygen in aquatic animals. And like eutrophication, in which an influx of nutrients such as nitrogen and phosphorus alters the water chemistry, thermal pollution may stimulate the growth and decay of simple plants such as algae and plankton. Accelerated growth and decay further deplete dissolved oxygen, reduce water quality, can collapse ecosystems, and complicate the water treatment process. A study conducted by Oklahoma State University found that eutrophication in U.S. freshwater costs $2.2 billion annually in the losses in recreational water usage, waterfront real estate, spending on recovery of threatened and endangered species, and drinking water.
The repercussions of the electricity sector’s water dependence are not a distant threat. North Carolina residents may remember blackouts in the summer of 2007, when Duke Energy had to cut the output of its C.G. Allen and Riverbend coal plants on the Catawba River. In Alabama, the Browns Ferry nuclear power plant has had to drastically reduce its output to avoid exceeding temperature limits on its discharge water and killing fish in the Tennessee River. Climate change means higher water levels in some areas of the country, but it also means longer and more intense periods of drought in others. More fossil fuels to meet energy demand mean more greenhouse gas emissions and increased drought intensity. This in turn increases average global temperatures thus increasing energy demand, which comes full circle back to water depletion.
We are on a self-destructive trajectory driven by a lack of available water to meet a growing energy demand. America’s water resources may be vast, but our increasingly energy-intensive economy may soon outstrip nature’s ability to replenish its resources if we do not start taking water use into consideration when citing and building new power plants.
What We Can Do
Actions we can take today include increased research and development and commercial deployment for alternative cooling technologies; rapid deployment of solar photovoltaics and wind energy generation systems that do not rely on cooling technology; and more investment in efficiency and demand-side energy management. For example, when the 1,250 megawatt plant Yates in Georgia added cooling towers in 2007, it cut water withdrawals by 93%. When new thermoelectric power generation is unavoidable, give preference to low-water power plant design.
Using existing technology, we can sustainably meet our energy needs without compromising the ability of future generations to meet theirs. A failure to act now will impose greater costs later on. Instead, let’s invest in a future that can both meet energy needs and protect our water systems. n
James McGarry holds a Master’s degree in public policy from the University of Maryland.
1 Sovacool, Benjamin K., and Kelly E. Sovacool. “Preventing National Electricity-Water Crisis Areas in the United States.” Columbia Journal of Environmental Law 34.2 (2009): 342-43.
2 Sovacool, Benjamin K. “RUNNING ON EMPTY: THE ELECTRICITY-WATER NEXUS AND THE U.S. ELECTRIC UTILITY SECTOR.” Energy Law Journal 30.11 (2009): 13.
3 Sovacool, Benjamin K., and Kelly E. Sovacool. “Preventing National Electricity-Water Crisis Areas in the United States.” Columbia Journal of Environmental Law 34.2 (2009): 362-63.
4 Sovacool, Benjamin K. “RUNNING ON EMPTY: THE ELECTRICITY-WATER NEXUS AND THE U.S. ELECTRIC UTILITY SECTOR.” Energy Law Journal 30.11 (2009): 20-21.
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