posted
Some people here said the oppisitte, but The Argonne National Lab and Department of Energy say you make more energy by making Ethanol, than you do by making Gasoline. (Not counting the Solar energy that went into it in the first place)
Posts: 11895 | Registered: Apr 2002
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posted
Solar energy isn't "free," because it takes time to grow the corn. Oil is ready for the refinery straight out of the ground.
I believe, though, that you may be thinking of comments that I and others have made about using ethanol reforming to produce hydrogen for fuel cells, which is less efficient than using gasoline.
If you just use the ethanol... well, it certainly burns more cleanly than gasoline, but it's still a fossil fuel. Still, people are working on ethanol-powered vehicles (at my alma mater, for instance).
quote:In a review of the study, the U.S. Department of Energy said it takes 0.74 million British thermal units (Btu), a measure of heat energy, of fossil energy input to turn corn into 1 million Btu of ethanol, while it takes 1.23 million Btu of fossil energy input to turn petroleum into 1 million Btu of gasoline.
I can't tell - does this include the petroleum needed to plow/sow/reap and transport the corn? Also, does it include the energy of the petroleum used in fertilizers?
I think it was BtL who posted that corn was produced at a slight caloric advantage when taking all petroleum into account, so this seems possible. I wonder what the sustainable amount of net energy would be based on the greatest amount we could produce without hurting food production.
posted
I'm thinking of all that heat of the sun that was stored in the Earth as oil... and now we've been releasing that energy and heat for the past century or so.
Posts: 4953 | Registered: Jan 2004
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posted
I think that was the intent, but since we can now make hydrocarbon fuels from non-fossil sources (like ethanol from corn), people like me sometimes use it more sloppily to reference hydrocarbon fuels in general.
Edit: Oh yeah, and natural gas (methane) doesn't come from fossils, but because it's a hydrocarbon it's still a "fossil fuel."
posted
Proponents of ethanol and biodiesel, though, say that the net effect of burning such fuels on the amount of greenhouse gases is zero--or at least much smaller than gasoline--because the carbon released back into the atmosphere was just recently fixed.
Posts: 4534 | Registered: Jan 2003
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quote:Proponents of ethanol and biodiesel, though, say that the net effect of burning such fuels on the amount of greenhouse gases is zero--or at least much smaller than gasoline--because the carbon released back into the atmosphere was just recently fixed.
In either case it's certainly much smaller than gasoline. For ethanol, anyway.
Posts: 10886 | Registered: Feb 2000
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Last I heard, ethanol had a slightly negative net return. Perhaps this is new data, or perhaps they're not taking things like fertilizer into account. But even if the balance is somewhat better than break-even, ethanol production is useless as a primary energy source unless they can significantly increase the return. By contrast, biodiesel production returns something like three times the amount of energy put in.
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quote:Proponents of ethanol and biodiesel, though, say that the net effect of burning such fuels on the amount of greenhouse gases is zero--or at least much smaller than gasoline--because the carbon released back into the atmosphere was just recently fixed.
Indeed. Do opponents say otherwise? Admittedly, if the objective is to minimize the amount of CO2 in the atmosphere, it would be better just to grow algae and other crops and then not burn their by-products. But if you're gonna burn something... Posts: 1810 | Registered: Jan 1999
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quote:I think that was the intent, but since we can now make hydrocarbon fuels from non-fossil sources (like ethanol from corn), people like me sometimes use it more sloppily to reference hydrocarbon fuels in general.
Huh?
A hydrocarbon is a chemical that contains only hydrogen and carbon, so ethanol is not a hydrocarbon, because it contains oxygen. A petrochemical is a chemical obtained from petroleum or natural gas (that is, from fossil fuels). Ethanol is not a petrochemical, because it does not come from petroleum.
Carry on.
[ April 01, 2005, 04:47 PM: Message edited by: Jon Boy ]
Posts: 9945 | Registered: Sep 2002
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posted
Though methane can be synthesized -- eg coal-gas -- it is usually pumped from the ground as a fossil fuel: ie a long buried decay product of once-living organic material.
Ethanol is a polar molecule with a high affinity for the polar "universal solvent" water -- ie it can't be distilled* to a higher purity than ~96%alcohol&~4%water -- which makes the mixture more capable of dissolving a wider variety of materials than gasoline. It is also more volatile, becomes gaseous more readily than gasoline. Combined, ethanol as fuel attacks&dissolves engine components and seals, fuel-lines and seals, storage tanks and seals, etc with far greater effectiveness than gasoline.
Ethanol-fuel's corrosiveness and volatility also increases the likelyhood that it will escape into the atmosphere, which -- alone and with photochemical recombination with other pollutants -- becomes an especially unwanted component of smog.
It's corrosiveness, higher volatility, heavier-than-air gaseous state, and easier-to-achieve flash point makes it more likely to be accidentally ignited by sparks, open flames, etc than gasoline. In other words, that totally fake PulpFiction ignition of the gasoline trail to the fuel tank explosion is VASTLY more likely to occur if ethanol were to be used as fuel. And since ethanol volatilizes more easily and into a greater concentration with air, fuel tank explosions will occur FAR more commonly after an accident, which is mostly** action-movie/television nonsense in the case of gasoline. As well, automobiles will be more dangerous to garage.
None of those problems are technologically unsolveable, but nonetheless the solutions are some of the additional costs which must be considered before jumping on the ethanol-for-fuel bandwagon.
However, cheaper is always a relative term. For those who support themselves by working at minimum wage jobs, there is little left as disposable income. So, excepting extraordinary circumstances, it is less expensive to cook at home than to dine out. But as one moves up the income scale, the more disposable income one has: ie the more ones income can be expended for lifestyle choices rather than for basic necessities. For most FirstWorlders, it is cheaper to dine out than to cook for themselves. But most FirstWorlders also prefer to spend a large portion of their disposable income on a lifestyle which includes nicer housing in more prosperous neighborhoods, better schools, newer and multiple automobiles, stereos and big-screen televisions, vacation trips, concert tickets, a wider array of new clothing, etc. Eventually the income level saturates even the commonly held lifestyle preferences of FirstWorlders. By the time one is in the upper quintile(20%) of personal income, the choice is pretty much purely between "prestige"purchases, investment, and dining out. In other words, if one weighs the amount of time it takes for upper quintile FirstWorlders to earn their disposable income -- even after subtracting the cost of decent housing in a prosperous neighborhood, good schooling, a serviceable&clean low-maintenance automobile for each household driver, more "vege out" entertainment than could possibly be considered healthy, etc -- against the time it takes to prepare a meal, it would be far less expensive for them to have meals delivered to their home than to cook those meals themselves.
Which may seem like a digression, but it will be very relevant to my next section on the hard economics of using ethanol as fuel, including the political considerations one must make. As usual, the politics is really really REALLY HARD.
* Excluding distillation with benzene, a known health hazard ** Yeah, it can happen. If ya set the car on fire, then let the car burn until the gas tank ruptures from the pressure of boiling gasoline.
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