Questions with some data

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  • Mon, Aug 25, 2008 - 02:08pm



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    Questions with some data

Your presentation is good. Being familiar with the arguments you make leads me to offer correction on the number of hours of human labor that a gallon of gasoline can substitute for.Coming from the book "Food, Energy, and Society" by the Pimentels, pg. 13. "One gallon of gasoline contains about 38,000 kcal of potential energy. When this gasoline fuels a mechanical engine, which is about 20 percent efficient in converting heat energy into mechanical energy, an equivalent of 8.8 kWh of work can be achieved… Further, 1 gallon of gasoline produces the equivalent of almost 3 weeks of human work at a rate of 0.1 HP, or 0.075 kW, for 40 hours a week."
8.8 ÷ 0.075 = 117 hours
You may have left out the conversion ratio from heat to mechanical energy of about 20%.

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