Reply #14: How much diesel, natural gas, gasoline and coal is embodied in that ethanol?

[kristopher]

Using Wangs 1999 (because they're handy) numbers and rounding to nearest 100.
Energy input for 1 acre of corn to ethanol = 64,500 BTU
Net energy value = 29,800 BTU
Therefore total energy value is 94,300 BTU

Less the "coproducts energy value" that is embodied in that net energy value = 22,500 BTU

Actual ethanol energy value = 61,800 BTU

Compare to energy input of 64,500:61,800

So you input 64,500 BTUs of gasoline/diesel/natural gas/coal and you get back 61,800 BTUs of liquid ethanol and some "coproducts" (aka feed for cattle).

So you see and as I said earlier, ethanol is not an energy source - it is energy storage. At least, it isn't an energy source in any meaningful sense of the word. At 1.6:1 you need to produce a gallon of ethanol to get a 6/10th of a gallon of fuel to do something else with - if it were all in the form of fuel. However, since all of the energy credits that push ethanol into the net positive energy balance realm are NOT in the desired form of liquid fuel, what the fuck is the point?


Numbers from Wang entry at table 1 here:
http://www.azimuthproject.org/azimuth/show/Energy+return+on+energy+invested#cornbased_ethanol_8