[Donaldson Tan]

Given the variation in the chemical composition of Canola oil, I think it's safe to assume that the average of composition of fatty acids and trigylceride is 80% by weight. Using Sulphated Zircona as a catalyst for the transesterification of the fatty acid, the single pass conversion to biodiessel reaches a maximum of approximately 80%. Depending on plant design, the overall conversion maybe increased to at most 90%. You may want to check with Eugenedakin on this overall conversion.

Amount of fatty acid acid and trigylceride  = 1000 * 80% = 800kg ha^-1 year^-1
Amount of biodiessel produced = 90% * 800 = 720kg ha^-1 year^-1

Assuming the biodiessel you use is B100 (ie. 100% biodiessel)
According to Wikipedia, the specific gravity of biodiessel is 0.8, so the density of B100 = 0.8g/cm³
1 US Gallon = 3785cm³

Volume of biodiessel produced = (720*1000)/(0.8*3785) = 238 US Gallon ha^-1 year^-1

Gallons of Biodiessel consumed = 20000/50 = 400 gallons year^-1 vehicle^-1

Amount of land needed = 400 / 238 = 1.68 ha vehicle^-1 year^-1

My calculations suggest we have a very big logistics problem.

Reference
DOI: 10.1002/adsc.200505160
Solid Acid Catalysts for Biodiesel Production --- Towards Sustainable Energy
Anton A. Kiss, Alexandre C. Dimian, Gadi Rothenberg*
vant Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands; Fax: (þ31)-20-525-5604, e-mail: gadi@science.uva.nl

[Borek]

Note that your calculations didn't take into account fuel needed for farming of rapeseed, nor energy needed for conversion.

Estimated number of cars in US: 200 millions
Estimated arable area: 190 millions ha

(these numbers are taken from some obscure Polish book, if someone can provide a link to the reliable reference - please post).

[Donaldson Tan]

Volume of biodiessel produced = (720*1000)/(0.8*3785) = 238 US Gallon ha^-1 year^-1

Note that your calculations didn't take into account fuel needed for farming of rapeseed, nor energy needed for conversion.

Taking in account of Borek's comment, the effective volume of biodiessel produced would be somewhat less than what I had calculated directly. 238 US Gallon ha^-1 year^-1 is unfortunately an overestimate. I believe the actual value should be somehow of the same order in magnitude. Amount of land needed is most probably from 2 to 2.5 ha vehicle^-1 year^-1

[billnotgatez]

so that is about 5 acres for 1 car for a year assuming 20000 miles per year
someday my brain will go metric, but not today

[Borek]

Some additional numerical data:

http://en.wikipedia.org/wiki/Biodiesel

and further interesting reading:

http://en.wikipedia.org/wiki/Algaculture#Biodiesel_production

[constant thinker]

Replacing oil anytime soon sounds like it'll be nearly impossible. 

Better start stocking up on canned food and heavy down parkas for the ensuing ice age we're suppose to get if global warming gets out of control.

[Donaldson Tan]

Better start stocking up on canned food and heavy down parkas for the ensuing ice age we're suppose to get if global warming gets out of control.

I know the numbers sound bad, but I am sure we all will tide it through. Didn't we all survive Y2K not long ago? Feedstock supply is always a problem. Yggdrasil once mentioned to me that Man always seek technology to solve the problem without changing themselves. We need so much land to grow the required plants to produce alternative fuel. There must be changes in public policy and legislature to smooth our route to using a new fuel globally, on top of developing new technologies to resolve the global energy crisis. We scientists and engineers must lobby the government, and not leave the job to economists and politicians alone who cannot figure out the nuts and bolts of advanced technology.

[constant thinker]

I agree geodome.

I know I'll get to see a change in energy sources during my life time. With oil prices this high, chances are they'll never drop and only go up. Maybe it will take people to accept they make not get 300 miles in a fill up and they'll only have to settle for maybe 200 instead.

P.S. Sorry everyone that's metric here.

[silkworm]

The new economy will be based in methanol. Hydrogen is just too impractical. The tank would have to be enormous to get us the range we're used to, and do you really want Joe Citizen traveling everywhere with a huge and highly pressurized tank under his butt?

[billnotgatez]

LH2 possibly

[xiankai]

hydrides are by far better than LH₂ or H₂ gas

http://www.switch2hydrogen.com/h2.htm

[Donaldson Tan]

This must be one of the United Nuclear websites.

[wereworm73]

After reading all this, I was thinking...If you put organic waste in a solution of NH₃^.e^- and subject this to intense sound waves (like with sonoluminescence experiments), then maybe the organic waste molecules would be reduced by the solvated electrons and decomposed from the locally high temperatures within the sonically-produced bubbles.  You might get quite a bit of methane & other light hydrocarbons that way.

[constant thinker]

Problem with hydrides is they have to be heated to release H₂. If you live in an area that gets a true winter, then you'll be cursing at your car in the winter probably.

I went to a Mobil gas station, and the gas pump said, "contains ethanol". At least the ethanol is probably replacing the MTBE.

[Dude]

The comment by silkworm was interesting.  George Olah and some others at USC just wrote a book about how methanol could be a solution.  I haven't read the whole book yet, but it appears to be well researched and not full of hydrogen propaganda.  It does speculate a bit on some technologies regarding CO2 recycling that I haven't really seen documented as feasible yet. 

On another note, I was recently reading about Brazil and the use of ethanol as a transporation fuel.  I heard on a TV show that the primary driving force for success is the much lower per capita usage of transporation fuel  (as opposed to the US) and sugarcane (as opposed to the corn ethanol mandate farce currently occurring in the US).  On several other sites it stated that 96+ % of Brazil's domestic energy is from hydroelectric power, which I believe is the real driving force to enable a non-gasoline economy.  Are there any Brazilians out there?  Is this true?  Do the majority of households have electricity in Brazil?  If any country really wants to switch away from gasoline, it requires a competent government with a long range plan.  The long range plan would involve building an infrastructure that would enable the transition.  I don't see it happening in the US.  The US government is a corrupt, inefficient wasteland that can't even mandate the production (soon to be exclusively importation) of ligher automobiles for increased fuel economy.