I think the main potential for mathematical error here is in the conversion of barrels of petroleum to various fuels (and other products), some of which aren't necessarily replaceable by biofuel.
For example, from a single barrel of crude oil (and the 19.65MM bbl/day figure includes other petroleum products) we get 19.5g of gasoline and about 9.2g of fuel oil (http://www.energy.ca.gov/gasoline/whats_in_barrel_oil.html); a "ground transportation use" yield of about 68%. Roughly equivalent numbers for actual gasoline and diesel fuel consumption are 160 billion gallons gasoline / 60 Bg diesel fuel per year. If we were to make some adjustments wrt the efficiency gain of converting gasoline engines to diesel engines (and allowing for the slight drop in energy going from petroleum diesel to biodiesel, see http://www.unh.edu/p2/biodiesel/article_alge.html), you get an equivalent of about 141 billion gallons of transportation biodiesel consumption per year. Using rapeseed as a feedstock (~102gal / acre biodiesel yield), we'd need about 1.38 billion acres of land, still about 4x the number of acres of *prime* farmland in the US (335.5MM). The prime farmland figure doesn't include all of the arid land that could be used for growing feedstock, and growing oil-producing algae changes the numbers entirely since it doesn't require farmland, and has a much higher yield per acre. But, as far as I'm concerned, none of this really matters. My only consideration for whether a biofuel is "scalable" is not whether it can, today, replace current energy usage, but whether it's fundamentally energy positive from feedstock to wheels (biodiesel is, very few others are). There is no biofuel that can replace petroleum at our current consumption rates. But we're still going to run out of oil in the not-too- distant future. Eric. ----- Original Message ----- From: "Tim Castleman" <[EMAIL PROTECTED]> To: <biofuel@yahoogroups.com> Cc: <[EMAIL PROTECTED]> Sent: Monday, June 30, 2003 11:17 AM Subject: [Burnveggies] Help with some simple numbers? > Can I get some help with these simple calculations? > > US petroleum consumption is 19.65 Million Barrels per day, or about 7 > Billion barrels per year. > (http://www.bts.gov/publications/national_transportation_statistics/2 002/htm > l/table_04_01.html) > > If we could get 2 barrels (88 gallons) of biofuel from each acre of > farmland, we would need 3.5 Billion acres to meet our demand. > > We only have 335 Million acres of Farmland in the US. > (http://www.nrcs.usda.gov/technical/land/meta/m5970.html) > > That means that even if we stopped growing food entirely, we would still > come up over 3 BILLION acres short. > > If we find a way to get 10 barrels from each acre (440 gallons), we could > nearly cover our consumption, but would have no place to grow any food. > > If we find a way to get 20 barrels per acre (880 gallons), we could do it > with about half of the farmland available. > > Do these simple numbers look right? > > _______________________________________________ > Burnveggies mailing list > [EMAIL PROTECTED] > http://goblin.punk.net/mailman/listinfo/burnveggies > ------------------------ Yahoo! Groups Sponsor ---------------------~--> Get A Free Psychic Reading! Your Online Answer To Life's Important Questions. http://us.click.yahoo.com/Lj3uPC/Me7FAA/ySSFAA/FGYolB/TM ---------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
