Monday, September 5, 2011

Energy Efficiency



What's the most efficient form of transportation?



A 140 lb. person walking 3 miles per hour uses about 80 food calories per hour.

The same sized bicyclist, traveling at a brisk 16 miles per hour uses 43 calories per hour.

Compare this to automobiles.

Walking:  360 mpg

Bicycling: 732 mpg

Missing from this picture:  airline travel.   Since the last entry was about a visit to Germany, this deserves a post of it's own ...  to be continued ...

The math:  One food calorie contains 4.184 kiloJules of energy (a kJ equals 1,000 (10-to-the-3rd-power) Joules).  One gallon of gasoline contains 114,000 British Thermal Units (BTUs), or 120 MegaJoules (MJs) of energy (a MJ equals 1,000,000 (10-to-the-6th) Joules).  Sources:  http://www.exploratorium.edu/cycling/humanpower1.html; http://auto.howstuffworks.com/question527.html; http://en.wikipedia.org/wiki/Fuel_efficiency_in_transportation



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