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Q: Does corn ethanol save energy?
zFact:Three gallons of ethanol saves the fossil energy in a gallon of gasoline.
But.. but... I thought ethanol had a negative energy return
The info on the web is widely all over the place. I've got 1200 WSJ articles to go through. That zFact link just seemed like a decent non-partisan beginning.
Regardless, if ethanol can not be sold at a profit, it is by definition wasting energy (which of cource includes the time and effort expent by humans in production), wasting scarce resources. But still, it'd be nice to have some more exact numbers of how much energy and scarce resources are being wasted in the production of ethanol.
But it was nice that you quoted the Q: and zFact:, but did you click the explanatory links?
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The Net Energy Value of Ethanol
ZFacts uses the Net Energy Values from Argonne National Lab.
1 GGE of ethanol requires 0.74 GGE of fossil input energy.
1 GGE of gasoline require 1.23 GGE of fossil input energy.
WTF? It takes less energy to produce ethanol than it does to produce gasoline? But it costs more to produce ethanol than it does to produce gasoline? It's a free lunch with ethanol but it's the exact opposite of a free lunch with gasoline. And STILL, gasoline costs less than ethanol. Something is b.s.
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zFact:Using 3 gallons of ethanol
saves as much fossil energy as in
1 gallon of gasoline.
Using ethanol save fossil two ways:
(1) One quarter of the energy in ethanol comes from solar (corn), nuclear and hydro (mostly solar).
(2) Replacing a gallon of gasoline replaces about one quarter more energy than in the gallon, becasue fossil used to make gasoline.
The energy in a gallon of gasoline is called 1 GGE of energy.
To save 1 GGE of energy making ethanol, and another GGE of energy using it (2 GGEs all together), we must use 4 GGEs of ethanol. Because ethanol is low energy, this is 6 gallons of ethanol.
So 6 gallons of ethanol saves 2 GGEs of fossil energy, and 3 gallons saves 1 GGE.
I don't really want to as yet get into the detailed chemistry and physics. But make sure you understand you have to put in the equivalent of the energy it takes to manufacture *3* gallons of ethanol to match the energy output of *1* gallon of gasoline. So MULTIPLY 1 GGE of ethanol requires 0.74 GGE of fossil input energy TIMES 3 = 2.22 VERSUS 1.23 for gasoline. And that's just the fossil energy input. There's the Fred Flintstone rub. Why?
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Ethanol has only about 2/3 the energy of gasoline
The lower heating value (LHV) of conventional gasoline = 115,500 Btu/gallon
The lower heating value (LHV) of ethanol = 76,000 Btu/gallon
Hence it takes 115.5/76 = 1.52 gallons of Ethanol to replace the energy in one gallon of gasoline.
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How much energy is used to produce a gallon of ethanol?
There are three useful meanings of "energy used"
1. All energy used.
2. Fossil energy used.
3. Imported fossil energy used.
Because some of our energy comes from uranium, water, wind and sun, "all" is greater than "fossil," which is just coal, natural gas and oil. Because using coal will generally have little impact on energy imports, "fossil" is greater than "imported fossil."
Net energy is the energy in a gallon of ethanol minus the "energy used" to make it.
Often this is stated as a percentage of the energy in a gallon of ethanol.
Here are the most important results:
#1 25% counting all energy used. USDA, 2002.
#2 40% counting all energy used. USDA, 2004.
#3 22% counting all energy used. UCB, 2006.
#4 26% counting only fossil energy used. Argonne National Lab, 2005.
#5 67% counting only imported fossil used. Based on #3 and #4.
There are about 20 other studies. Those by opponents of ethanol report negative values. The above four are by strong supporters of ethanol. The difference between #3 and #4, is not primarily due to the exclusion of nuclear and hydro by #3, but due to other differences.
WTF? How can something seemingly so simple vary so wildly? That's why I'm suspicious and researching in depth now. You could light your house on fire to warm yourself up and while the house burns down it might technically qualify as a "net energy gain", it's surely a "net energy *loss*" over time as you shiver your *** off when the flames die down. I think you'd agree that continuing to buy new houses and light 'em up for heat is a "net economic loss" and a relative "net energy loss" as well over time when you accurately incorporate all the correct calculations into the equation. And if you're measuring economically efficient energy production that will be measured in the form of profit for efficiency, loss for inefficiency.
Or how about the net energy created by the terrorist attack on the twin towers? You've got planes with mass and speed going in combined with fuel and the falling of the towers going out. Are we going to call that a net energy gain? Or was that a net energy loss because of all the post productivity losses of the buildings? If it shows as a loss on the balance sheet it's an unproductive inefficient use of scarce resources.
Regardless, I'd like to see this info:
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Those by opponents of ethanol report negative values.
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I think Monx is confusing "net energy gain" with "net economic gain". The two are completely different concepts.
We gain 38% more energy growing corn and producing ethonol from that corn then it costs to run the entire process (growth through refining through shipping, etc...). But that says nothing about how much it *costs* to do that.
Maybe. Maybe not. If it's an energy gain it should be profitable, plain and simple. How can something which leaves you with 38% more energy be an economic loss?!?!?!? It makes no damn sense, and I intend to find out wtf is up. You compare the price of gas with the price of ethanol. That will tell you which is the more efficient production of energy. Why the hell do you think the USSR never knew how much of what to produce and failed? Because they had no prices directing economic activity. They were copying prices out of American Sears catalogues, but still had absurd inefficient shortages of things people wanted and absurd surpluses of things people didn't want. As good as digging ditches by day and filling those ditches in by night to keep the workers employed. And subsidizing something which is a net economic loss is exactly the same as digging ditches by day and filling those ditches in by night. It's total waste.