The tripe about taking 85 gallons of fuel (or whatever, the numbers vary) is complete nonsense as anyone who has grown corn can tell you.
The number you're looking for is 6.5 not
'65' as I misprinted in another post, this is factoring in all costs involved.
It does take more fuel to make ethanol - especially corn ethanol - than the ethanol returns. (Note I said "fuel" and not "energy.")
Fuel and energy are not the same. All fuel is energy, but not all energy is in the form of a useable fuel.
As the USDA reports says, making corn ethanol probably returns more energy than it consumes. Unfortunately, what the USDA doesn't make obvious is that the excess energy is locked in a waste product of fermentation and distillation called distiller's grains (DG). (Each pound of DG contains about 9600 Btu.)
Unfortunately, the energy in that DG is only useable on a micro level
to livestock farmers in the immediate vicinity. On a macroscale of hundreds or thousands of ethanol plants across the country, the waste DG would start to pile up and ethanol plants would soon look like old coal mines surrounded by slag heaps, except the slag heaps around ethanol plants would be piles of distiller's grain that no one woudl know what to do with.
The critical fuel that corn-based ethanol consumes is natural gas. Few realize it, but growing corn is utterly dependent on nitrogen fertilizers made from natural gas. Take away nitrogen fertilizers and corn ethanol production would soon stop.
And there is a huge problem with using those nitrogen fertilizers: Because the demand for natural gas is rapidly outstripping domestic supplies, more and more of that fertilizer is made overseas from foreign natural gas and imported into the U.S. Estimates from some agricultural economists expect that within ten years we will have to import 100% of the nitrogen fertilizer our corn farmers must depend on - all of that fertilizer made overseas from foreign natural gas.
Do you think a dependence on imported nitrogen fertilizers made from foreign natural gas would be any better than our already ill-advised dependence on foreign oil?
I could go on, but my point is that using any 'food crop' for fuel instead of for food is a loser for an idea... there are much more productive plants that can be used for alcohol/diesel production that do not take away from the food supply (algae, switchgrass, hybrid poplar, chinese tallow - to name 4 off the top of my head), have vastly improved yields per acre & can be grown with much less resource involvement (except for the algae, which to truly maximize its potential requires a high amount of initial investment), and in areas that are generally unusable for traditional agriculture.
I'm partial to algae as its yields can be tremendous and its byproduct is a high-protein edible paste that can be made into many food products(Algae-Os anyone?), except that it does require huge amounts of water (most is re-used, the initial outlay is huge), and Chinese Tallow
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