Energy Production Depends on Water

Energy production depends on water. Which technologies are the most water-efficient, and which are the least? Power plants require water to scrub pollutants, cool machinery, produce the steam necessary to turn huge turbines and generators, and more. Even some alternative energy sources, such as ethanol and hydrogen, require large volumes of water.
By Rachelle Hill and Dr. Tamim Younos
August/September 2008
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Energy production depends on water. As electricity demand rises, so does the demand for water. Read on to find out how much water is used by various energy production technologies.
Photo by Istockphoto/David Joyner


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Energy production depends on water. Power plants require water to scrub pollutants, cool machinery, produce the steam necessary to turn huge turbines and generators, and more. Even some alternative energy sources, such as ethanol and hydrogen, require large volumes of water.

Energy Production Depends on Water

Ecologist Jacques Cousteau once said, “Sometimes we forget that the water cycle and the life cycle are the same.” What he meant was that not only human survival, but all life on Earth, totally depends upon water.

Our modern world is also driven by energy use — we need energy for producing food and clean water; for providing electricity in our homes, businesses and industries; and for transportation.

But did you know that energy production depends on water? Conventional production of energy and power requires a huge amount of water. Power plants require water to scrub pollutants (generated from burning coal, for example), to produce the steam necessary to turn huge turbines and generators, and more. Even some alternative energy sources, such as ethanol and hydrogen, require large volumes of water. As electricity demand rises, perhaps as much as 50 percent in the next 25 years, the demand for water also will increase.

Crunching Water and Energy Production Numbers

So how much water is used by various energy production technologies? To illustrate the water use for various technologies in a consistent unit, the chart at right shows water usage in gallons of water used per British thermal unit (Btu), which indicates pure energy as heat. Btu is applicable to all energy production and power generation methods.

The Water Use Efficiency Chart shows that in terms of fuel production, soy-based biodiesel is the least water-efficient energy source, followed by corn-based ethanol. Natural gas is the most efficient. In terms of electricity generation, nuclear energy is the least efficient while hydroelectric power is the most efficient system.

Consider the example of the common incandescent light bulb: If we assume that a household will burn a single 60-watt light bulb for 12 hours, it adds up to 0.72 kilowatt hours (kWh). If this light bulb is powered by electricity from a fossil-fueled plant (as is the case for most of the power produced in the United States), that converts to 10,022 Btus per kWh. (The conversion rate of kWh to Btus depends on the efficiency, or heat rate, of the various fuel sources or power generation methods.)

Hence, a single light bulb will consume about 7,200 Btus in one day. From the chart, it can be estimated that fossil fuel thermoelectric plants use between 1,100 to 2,200 gallons of water per million Btu to generate power. This equates to approximately 8 to 16 gallons of water used to make the power needed to run one 60-watt light bulb for 12 hours! Over the duration of one year, this one incandescent light bulb would require about 3,000 to 6,300 gallons of water. Furthermore, it is estimated there are about 111 million occupied housing units in the United States. If each housing unit burned only one light bulb for 12 hours a day, over the course of a year it would add up to about 300 to 650 billion gallons of water.

Think About the Future of Water Energy

In the near future, increased energy development will compete for available water resources with other water demands, such as agricultural irrigation and domestic water supplies. As the chart shows, some new initiatives, such as biodiesel and ethanol production, require very large amounts of water. Future production and the cost of energy will be impacted by water availability. There is an urgent need to consider water availability in proposed energy policies.


Reprinted with permission from Virginia Tech.


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Post a comment below.

 

davisonh
10/2/2008 7:54:13 PM
Uh oh,be careful about how this water for driving steam turbines is used..I've been to many,many power plants,coal and otherwise for what I used to do for a living(test machinery used for feeding the coal into the boilers)and all of them use cooling towers for cooling the drive steam for driving the massive turbines.Some also pipe the drive steam from the power plants to municipalities to be used for local central heating of buildings or use it for process steam.These cooling towers then use river water or air to cool and condense the steam.But yes the equivalency number you give is correct,thing is that water is usually condensed back and reused.

Russell Lowes
9/6/2008 7:50:17 PM
This article is very impressive. Where did the chart come from specifically -- that is, where from the EIA? Thank you!








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