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Five Friday Facts: Energy Density

Posted on the 15 June 2012 by 2ndgreenrevolution @2ndgreenrev

Five Friday Facts: Energy DensityIn his post earlier this week, Nick mentioned one of the pitfalls of renewable energy. It is not “energy dense” compared to other sources. As a point of reference, today’s Five Friday Facts provide the energy density for the five most commonly used fuels over the past 150 years in the United States: wood, coal, oil (as represented below by gasoline), natural gas, and nuclear. There’s a reason that nuclear energy is so highly sought after despite the negative publicity. Take a look:

  • Wood: 2,760 calories/g
  • Coal: 7,200 calories/g
  • Natural gas: 11,000 calories/g
  • Gasoline: 11,530 calories/g
  • Nuclear: 1 pound of Plutonium equals 1,500 tons of coal (OR roughly 21,600,000,000 calories/g based on my math)

All figures (except for my calculations to convert nuclear into a common measure) come from John Christensen’s Global Science: Energy, Resources, Environment, a text I used for two years as a classroom teacher. See pages 272, 276, and 356 for facts and figures.

For the calculation, I multiplied 1,500 by 2,000 (to find an equivalent measure of weight, tons to pounds). This gave me 1 pound of Plutonium equals 3,000,000 pounds of coal. I then multiplied the energy density of coal (7,200) by 3,000,000, since nuclear energy is essentially 3 million times as energy dense as coal.

(1,500 tons) X (2,000 pounds) X (7,200 calories per gram) = 21,600,000,000 calories per gram

**The units “tons” and “pounds” are not integral to the calculation. It merely is used to demonstrate that Plutonium is 3,000,000 more energy density than coal (as explained above).

Image Source: Metropolitan Museum of Art

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