Wow. It's hard to track down real numbers, but these should be in the right ballpark:
250 to 500 gallons of ethanol can be produced per acre of corn, although 75% of that goes back into the production/refining/transport of the resulting fuel, so only 65 to 125 gallons end up as real output.
30 to 90 gallons of biodiesel can be produced per acre of soybeans, but only about 30% of that is used to actually produce the fuel, so you get 20 to 60 gallons of real output.
There are approximately 230 million cars in the U.S. I'm not sure how often they're driven, but if you assume 10,000 miles per year at 30 miles per gallon, 77 billon gallons of fuel would be used per year (that's low—we produced and imported 320 billion gallons in 2002, but that's mostly unrefined crude oil…).
If the farmers were all really lucky and got bumper crops of corn, then produced ethanol, 613 million acres would be needed, and 225 billion gallons would have been used in production.
There are only 932 million acres of farmland in this country.
Update: I haven't been able to find enough data to run numbers, but it appears that switching over to using sugar beets to produce ethanol in this area would be a beneficial move. It looks like more ethanol could be produced per acre with sugar beets, and the ratio seems to be something more like 60% used in production, leaving 40% net output.
In Brazil, which produces the most ethanol of any country, the fuel is produced from sugar cane, and the net energy output appears to be very good. Of course, sugar cane doesn't really grow up here :-pPosted by mike at December 28, 2003 06:25 PM | Car | TrackBack