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Ethanol More Trouble Than It's Worth?
call -151 writes "Yahoo reports this story by researchers from Cornell and Berkeley who show what a number of people had suspected- it takes significantly more energy (at least 29%) more energy to produce ethanol than it yields. Since ethanol production plants don't use ethanol themselves for their own energy needs (with presumably negible delivery costs) this has been widely suspected but not so bluntly stated: "Ethanol production in the United States does not benefit the nation's energy security, its agriculture, the economy, or the environment." Ethanol producers dispute the study, predictably, which deducts the multi-billion US dollar subsidy. It's not clear how this compares with this earlier Union of Concerned Scientists article that claims that the yield from corn kernels is net 50% positive- and the UCS is usually quite unbiased on these things."
It depends how and from what you make your ethanol. And how you farm your feedstock of course...
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Brazil does just fine with it's sugarcane:
http://www.eroei.com/articles/16_jun_05_brazil_fu
Gasoline takes more energy to produce than you can get from it. That energy just came from the sun a million (?) years ago. Gasoline is a means by which we can transfer solar energy to our cars without sail-ssized solar panels.
Consider ethanol as a means to store energy from nuclear, solar, wind, tidal, hydro or other clean energy sources and transport it to your auto's engine.
I'd like to see ethanol compared to chemical batteries, fuel cells or others on an basis of efficency & cost.
TFA doesn't tell us who paid for the research.
AND we have what could be an easy way to generate hydrogen from water using sodium. Now, with this in mind, tell me why ethanol is needed?
Because hydrogen isn't a practical energy carrier. Even at tremendous pressures (like 500 atmospheres) it doesn't even come close to the gravimetric or volumetric energy density of gasoline.
Ethanol has about 2/3rds the volumetric energy density of gasoline. This is worth while over hydrogen, even if the stuff takes more energy to make than it yields. Just think of the energy required to compress hydrogen to 10kpsi. One might joke about running an automobile on this pressure alone.
The bottom line is that energy input versus output will be moot once everyone realizes that we'll need nuclear to be sustainable. We just need a good, dense energy carrier.
FWIW, hydrides have become the hydrogen carrier of choice in nickel metal hydride batteries because you don't need tremendously high pressures to get good volumetric density. But to put it in perspective, they're still only carrying about 2 percent hydrogen by weight. Some day, a nanotech breakthrough may make it possible to increase that by an order of magnatude. When this happens, we'll have electric cars that you'll take in after a few thousand miles to get the battery changed.
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While you can produce ethanol from many sources, current US corn-based ethanol production could not survive without heavy subsidies. With the current subsidies in place there is no incentive to improve efficiencies.
Modern field corn production requires large amounts of fertilizer, in particular anhydrous ammonia, to produce the 150+ bushels per acre that we currently enjoy.
Ammonia prices have steadily climbed over the past decade as the price of natural gas climbs. Ammonia is made using the Haber process to combine nitrogen from the air with hydrogen obtained from natural gas.
I come from a long line of farmers:
In my great-grandfather's day, corn production rates were pitiful.
In my grandfather's day, the Haber process and corn hybridization produced bumper crops.
In my father's day, he stopped growing corn. Combined with the US embargo of Canadian beef it just wasn't worth the effort.