So we started talking about sustainability in intro to engineering today, and of course we watched Fight Club last friday night, so the idea was still in my mind, and I thought the following:

"Okay there's we'll say 300k americans who are on average 20lbs overweight. That's 6bil lbs * 14,630kJoules/lb

Let's convert a similar volume to gasoline, for reference.

The specific gravity of fat is about 0.9g*cm^-3 (it floats on water), 0.45359237 kilograms to the pound.

8.778E13 kilojoules for the american race from fat. That's 2.722E9 kilograms; converted to volume it's 3.024E9 cubic centimeters, or 3.024E6 decimeters. That is directly equivilent to 3.024E6 liters.

8.778E13 kilojoules per 3.024E6 liters = 2.903E7 kJ/L or 2.9E4 MJ/L

Wikipedia gives gasolene as 34.8 MJ/L.

If everyone in america gave 20lbs of fat via liposuction or similar techniques, I could drive my car for about 7700 miles. Basically, the entire length of the Silk Road.

so what kinds of alternative energy could you come up with?