Article

2007-04-19 Science & Technology

Study: Ethanol May Cause More Smog, Deaths

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Posted by Dave D. 2007-04-19 00:00|| || Front Page|| [11130 views since 2007-05-07] Top

#1 You know, one sometimes wonders how far we may be if the grants were used for something constructive.

Posted by twobyfour 2007-04-19 00:19|| 2007-04-19 00:19|| Front Page Top

#2 I believe burning ethanol and methanol creates small amounts of formaldehyde.

Posted by ed 2007-04-19 01:48|| 2007-04-19 01:48|| Front Page Top

#3 ed, incomplete burning produces acetaldehyde, which further oxidizes to acetic acid.

Posted by twobyfour 2007-04-19 01:56|| 2007-04-19 01:56|| Front Page Top

#4 Jacobson's conclusion "is a provocative concept that is not workable," said Hwang, an engineer who used to work for California's state pollution control agency. "There's nothing in here that means we should throw away ethanol."

Posted by Icerigger">Icerigger 2007-04-19 02:26|| 2007-04-19 02:26|| Front Page Top

#5 I blame Castro.

Posted by gorb 2007-04-19 02:47|| 2007-04-19 02:47|| Front Page Top

#6 Don't know about smog.

Posted by gromgoru 2007-04-19 03:49|| 2007-04-19 03:49|| Front Page Top

#7 Yeah, and if we all went back to walking, the press would complain about the effects of increased use of shoe leather.

Posted by DMFD 2007-04-19 09:07|| 2007-04-19 09:07|| Front Page Top

#8 I say we just invent levitation and flying. Those monks can do it, and the only fuel burning would be what you ate normally.

Levitation for Gaia!

Posted by DarthVader">DarthVader 2007-04-19 09:23|| 2007-04-19 09:23|| Front Page Top

#9 I blame Dwayne Andreas and Bob Dole.

Posted by Nimble Spemble 2007-04-19 09:26|| 2007-04-19 09:26|| Front Page Top

#10 If you want to learn fly without mechanical means you must climb a tall building, jump off, aim at the ground, and miss.

Posted by Deacon Blues 2007-04-19 12:31|| 2007-04-19 12:31|| Front Page Top

#11 DB: 42!

Posted by USN, Ret. 2007-04-19 15:09|| 2007-04-19 15:09|| Front Page Top

#12 Don't know about smog, but it sure can create a fog.

Posted by no mo uro 2007-04-19 15:34|| 2007-04-19 15:34|| Front Page Top

#13 As more corn is diverted to ethanol production, meat prices will rise! The energy conversion for corn to ethanol is about 1.7 to 1. What about all the fallow sugarcane fields throughout the South and Hawaii. Sugarcane's energy conversion is 10 to 1. Brazil figured that out.

Posted by GolfBravoUSMC 2007-04-19 16:25|| 2007-04-19 16:25|| Front Page Top

#14 Sugarcane is better as we won't have to hear the speaches about "people dying from hunger so Americans can drive" garbage you just know people are drafting up as we speak.

The price of rum will rise but we can deal with that.

Posted by rjschwarz 2007-04-19 17:28|| 2007-04-19 17:28|| Front Page Top

#15 A while ago some of us in the OC noodled out a napkin estimate of what it would take to replace gasoline with ethanol. Huge amounts of land, we did not get into the water requirements, but the payback sucks. It will not make it.

Posted by Alaska Paul">Alaska Paul 2007-04-19 18:19|| 2007-04-19 18:19|| Front Page Top

#16 Well, it was a tad more than a "napkin estimate"; here's what I wrote in the O Club back then:

OK, let's drag out the ol' calculator and run some numbers, here...

According to Wikipedia, there's about 140,000,000 cars in the U.S. these days.

Assume each one of those cars gets driven 12,000 miles per year, on average, for a total of 1.68 trillion miles travelled.

According to WantToKnow.info, these cars get an average of 20.8 miles per gallon of gasoline, giving us a total annual gasoline consumption of 80.8 billion gallons per year.

Let's assume 1 gallon of ethanol is the equivalent, energy-wise, of 1 gallon of gasoline. I don't know whether it is or not, but let's assume so.

So we'll need roughly 80 billion gallons of ethanol per year to fuel America's automobiles.

Now, if what we're after is to actually save the 80 billion gallons of gasoline we're replacing with ethanol (not much point otherwise, is there?), we need to consider the energy efficiency of the process of growing corn and converting it to ethanol, so we end up producing, in addition to those 80 billion gallons, enough ethanol to fuel the whole corn-growing and ethanol-producing enterprise.

According to this USDA study, ethanol production "yields nearly 25 percent more energy than is used in growing the corn, harvesting it, and distilling it into ethanol."

So for every 25 units of ethanol we take out of the whole corn-growing, ethanol-fermenting enterprise for use as motor fuel, the enterprise must produce 125 units of ethanol-- 25 for our use and 100 units to keep itself going. Thus to produce 80 billion gallons of ethanol for automobile fuel per year, the system will have to produce a grand total of 400 billion gallons per year.

How much corn will this take? According to these 1996 USDA figures a bushel of corn produced, back then, 2.5 gallons of ethanol. Let's assume some improvement in the past decade, and call it 3 gallons of ethanol per bushel of corn.

OK, so we're going to have to come up with about 133 billion bushels of corn per year for this enterprise. How much land will that take?

According to the National Corn Growers Association, yields of 300 bushels per acre are possible. However, a sustained rate of 120-140 bushels per acre is more typical on prime farmland (it was about 100 per acre a decade ago). But all the prime corn-growing land is already in use growing corn, so the land we're going to have available for producing this 133 billion bushels of corn per year for ethanol is going to have much lower yield.

So let's say we can get an average of about 70 bushels an acre out of whatever land we're going to be able to come up with. 133 billion bushels of corn divided by 70 bushels per acre gives us 1.9 billion acres we'll need.

There are 640 acres in a square mile, so 1.9 billion acres is about 3 million square miles-- the equivalent of a square chunk of real estate 1,700 miles on a side-- every square inch of which is devoted to growing corn.

So much for fueling all the cars in America with ethanol.

UPDATE: I ran the ethanol numbers again using a WHOLE bunch of absurdly optimistic assumptions, and still didn't get results that really made my grapefruit squirt: with corn yield increased to 100 bushels/acre (nearly prime farmland), and ethanol yield from the corn doubled (don't ask me how) to 5 gallons per bushel, and assuming the entire corn growing/ethanol processing operation requires absolutely NO energy (or the energy for it is somehow magically free), and increasing average fuel economy of the entire U.S. automobile fleet to 30 mpg, and limiting every vehicle to only 5,000 miles per year, AND PROHIBITING ALL DEMOCRATS FROM DRIVING (something probably worthwhile in its own right), you still need to come up with some 52,000 square miles of prime corn-growing land (about equivalent to the state of Iowa) and the water to grow the corn, to run all cars on ethanol. Case closed, as far as I'm concerned...

Posted by Dave D.">Dave D. 2007-04-19 20:31|| 2007-04-19 20:31|| Front Page Top

#17 Never, ever allow an engineer to run some numbers. It is the death of all pleasant and easy assumptions, however seductive the irrefutably rigorous logic will be. :-)

Posted by trailing wife 2007-04-19 22:18|| 2007-04-19 22:18|| Front Page Top

#18 You're such an optimist Dave. Here are a few more realistic numbers:
140 B gals gasoline (2005) = 210 B gals ethanol
43 B gals diesel = 70 B gals ethanol
25 B gals aviation fuel = 40 B gals ethanol
= 320 B gals ethanol equivalent

In addition, it takes 1 unit of energy to produce 1.3 units (US DOE) of ethanol energy (planting, fertilizer, pesticides, harvesting, transportation, distillation). So to get 1 unit of ethanol energy into your tank, you have to produce 4 units (3 is plowed back into ethanol production, currently the input energy is nat. gas and petroleum).

So the 210 B billion gallons ethanol just to replace the 140 B gals gasoline really becomes 840 B gallons. At 2,7 gals/bushel and 150 bushels/acre gives 2.1 B acres or 3.2 M sq. miles. The entire US land area is 3.5 M sq.

Food based ethanol is only a tiny fraction of the transportation energy solution. The immediately available sources than can produce a significant non-oil proportion of our transportation energy are coal-liquids conversion and electric cars since half the US energy production is electric power vs 25% for petroleum. In the medium term, cellulostic or algal plants to produce ethanol, biodiesel and process gas for F-T synthesis. In the long term, thermal hydrogen production via nuclear plants. Liquid petroleum and F-T fuel use will be reserved for specialized uses like aviation. I think solar and wind will be too expensive to produce hydrogen compared to nuke plants.

Posted by ed 2007-04-19 23:12|| 2007-04-19 23:12|| Front Page Top

#19 PS. Long term, hydrogen will be a fraction of transportation energy used primarily by large, high use, long haul transportation. Personal vehicles will be electric based.

Posted by ed 2007-04-19 23:26|| 2007-04-19 23:26|| Front Page Top

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