Saturday, July 22, 2006

Doing the Math: Redux

In an earlier post titled "Doing the Math," I attempted to calculate the theoretical amount of ethanol that could be produced from all the corn grown worldwide in one year. Then I calculated how much of our petroleum consumption it could replace. The answer was frightening.

And wrong.

It started like this....
[insert cheesy wavy fade effect for flashback sequence]
According to this link, there were 598 million metric tons of corn produced globally in 2002. (That was the first year I came across. Let's assume it's typical.)

598 million metric tons * (2204.6 lbs/metric ton)
...converts to 1.3 billion lbs of corn.
Someone recently pointed out that that should have read:
...converts to 1.3 trillion lbs of corn.

Yeah, I was never any good at math. So the ending changes from this:
So if we can stop using corn for livestock feed, corn starch, corn syrup, corn oil, corn chips, corn stoves, corn bread, popcorn, candy corn**, corn on the cob, corn dogs, creamed corn... er... sorry, I was channeling Forrest Gump for a second...

If we use all of the corn grown in one year for making ethanol, and production is still propped up by using current (petroleum-heavy) farming practices, it would keep the U.S. running for just under four hours.

To this: would keep the U.S. running for about five and a half months.

So I was off by a few orders of magnitude? Cut me some slack!

Now what I didn't take into account was that 1 gallon of gasoline is really equivalent to 0.6 to 0.8 gallons of ethanol, which would cut that five and a half months to less than four. And corn production is artificially high right now as herbicides and pesticides are becoming increasingly ineffective, and rising fuel costs are making large scale production less and less practical. Without any intervention, I think corn yeilds drop by about 30-50 percent. So accounting for that would bring it down another month. A far cry from the four hours.


Obviously this is a thought exercise. Would we (could we?) really give up every other use of corn? No. There are a lot of uses of corn I'd like to see eliminated, like feedlot use for all manner of livestock. But then again, I don't think ethanol is the right use for it either. The energy return on energy invested is just not worth it.

The bottom line for me is that biofuels are not a complete waste of time, as I had thought before. And corn is a terrible starting point. But clearly, if petroleum becomes too expensive to be of much practical use, significant conservation is still the only real answer.


At 7/22/2006 8:57 PM, Blogger madcapmum said...

Applesolutely. Conservation, becoming small, moderate, frugal. Good for the earth, good for the soul.

I wonder very much what the transition phase is going to look like.

At 7/22/2006 9:36 PM, Blogger e4 said...

Yeah, the transition phase... That's what keeps me awake at night.

No wait, that's my daughter.


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