Energy Efficient Light Bulbs Save Water, Too
by Collin Dunn, Corvallis, OR, USA on 04.17.08
Photo credit: Getty Images
Here's an interesting new way to think about energy efficiency: a study done by researchers at Virginia Polytechnic Institute and State University revealed that it takes between 3,000 gallons and 6,000 gallons of water to power a 60-watt incandescent bulb for 12 hours a day over the course of a year.
The researchers -- Virginia Tech professor Tamim Younos and undergraduate student Rachelle Hill -- are crunching the numbers to determine the water-efficiency of some of the most common energy sources and power generating methods. The most water-efficient energy sources are natural gas (though we may be just about out of it) and synthetic fuels produced by coal gasification; the least efficient are ethanol and biodiesel -- the biofuels just can't catch a break these days, can they?
Water use winners and losers
The research pair analyzed 11 types of energy sources, including coal, fuel ethanol, natural gas, and oil; and five power generating methods, including hydroelectric, fossil fuel thermoelectric, and nuclear methods; in terms of power generation, Younos and Hill have found that geothermal and hydroelectric energy types use the least amount of water, while nuclear plants use the most. All told, a United States-wide tally shows that power generation requires 655 billion gallons of water a year.
From this calculation, Hill was able to determine the number of gallons of water required to burn one 60-watt incandescent light bulb for 12 hours a day, over the course of one year. She found that the bulb would consume between 3,000 and 6,000 gallons of water, depending on how water-efficient the power plant that supplies the electricity is.
Another reason to switch to compact fluorescent light bulbs
Based on these calculations, a compact fluorescent light bulb will not only save 60-70% in energy costs, using the bulbs will also save between 2,000 and 4,000 gallons of water every year.
Younos noted that the results of this analysis should be interpreted with a grain of salt. “There are several variables such as geography and climate, technology type and efficiency, and accuracy of measurements that come into play. However, by standardizing the measurement unit, we have been able to obtain a unique snapshot of the water used to produce different kinds of energy.” The researchers used British Thermal Units (BTUs) in their calculations.
We recall, from our How to Green Your Water guide, that author John Robbins calculated that a vegetarian diet requires only 300 gallons of water per day, while a meat-eating diet requires 4,000 gallons per day; that means you save more water by not eating a pound of beef than you do by not showering for an entire year. Guess we can put "using incandescent light bulbs" on that list as well. We already knew how many lawmakers, how many bloggers, and how many Jews it takes to change a light bulb, and now we know how much water it takes to power a light bulb, too. ::Newswise via ::CNet
See also: ::Green Stats: 2500 and Water: Saving the Planet One Drop at a Time
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It is interesting to see the inter-dependencies among resources. Water will gain in importance as the subject of carbon emissions becomes more mainstream. It will be a great day when we can readily measure a product by its overall environmental impact - GHG, water, toxins, etc...
Kent
www.ecounit.com
Is the water usage based on BTU's cooled or actual water taken from pipes? As a southern-Californian, I drive by the San-Onofre nuclear power plant occasionally, and I know they use seawater to cool their reactors, meaning the usage of potable water is far less than a strictly BTU based calculation would suggest.
Sidebar: Any thoughts as to how desalination plants can help provide an alternative solution to drought? I'm not sure of the total energy efficiency of the idea, but it makes some sense to tap into the ocean for part of the solution.