WHY DON'T WE HAVE AUTO GAS AT GAS STATIONS HERE LIKE THEY DO IN AUSTRALIA???

[Pete Masterson]

LeRoy, I'm not a chemist, I only play one on TV...

Frankly, I have my doubts about some of the ecology/greenhouse gas claims for biodiesel -- but there is almost a religious fervor on the topic, so I hesitate to take it on...

The number following the "C" is the number of carbon atoms in the molecule. In perfect combustion, every carbon atom will hook-up with 2 oxygen atoms to create C02 and each hydrogen atom will join with 2 oxygen atoms to create H20 (or water vapor). In general, the ratio of Carbon to Hydrogen is one way to measure the efficiency of greenhouse gas reduction. Methane (natural gas) is highly efficient with 1 carbon atom to every 4 hydrogen atoms (CH4) so the ration is .25. (Keep in mind, no combustion is perfect in the real world. But for the analysis it's ok to pretend that it is.)

Assuming the molecular formulas are correct (I didn't check them) we're comparing 12/23 vs. 19/36 or solving the math: .522 vs .528 (figures rounded) this means that, as far as greenhouse gases are concerned, there's about a gnat's worth of difference -- actually in favor of diesel! The last little 02 in the biodiesel formula appears to suggest that a couple of the hydrogen atoms are already oxygenated -- or less likely (carbon likes to double-bond with oxygen so it's not likely to be where the 02 connects) one of the carbon atoms carries the two oxygen atoms (I didn't look up the chemical structure). In either event, the "improvement" over diesel is pretty minimal, at best, but due to the large number of gallons consumed each year, it may equate to a measurable difference.

There are other, long, economic justifications about bio-diesel and why it's good for the environment. Personally, I'm rather skeptical. Indeed, around the end of the 90s, soybean varieties were developed that could be grown in the tropics. Biodiesel (not from recycled vegetable oil sources) is often processed from soybean oil. The Amazon rain forest is being stripped in vast areas to grow soybeans -- now the number 2 export from Brazil where it mostly goes to Europe to be converted into biodiesel. Personally, I think this is a poor trade off. (Doubts about my info? See the January 2007 issue of National Geographic.)

So, I'm very skeptical about the claims of the advantages of biodiesel. (I owned a print shop in the late 80s when "vegetable based printing inks" became suddenly "very green." Ink is made of pigment (carbon black for black ink) and oil. The heavy, greasy oil used in ink is a byproduct of oil refining. If it isn't used as printing ink it is mixed with lighter oils and burned as "bunker fuel." No oil is refined to create the heavy grease used in printing ink (it wouldn't be very economic). However the greens claimed that vegetable oil based printing ink was "better." So now the printing industry has almost completely converted to vegetable oil based inks, with an enormous economic cost of the conversion (new inks and other new press chemistry had to be developed, etc.). However, the primary source of volatile organic compounds (that form into smog) in printing doesn't come from the ink, but rather comes from the isopropyl alcohol used in the fountain solution and the solvents used to clean ink from presses. The printing industry was already moving toward reducing and eliminating those sources of VOCs when the soybean ink fad hit. Today, printers have significantly reduced the release of VOCs. Soy ink had nothing whatsoever to do with it.

But, the farmers are happy. We all pay a little more for anything that has printing on it. We can all feel good about using "renewable" vegetable oil in our printing ink. And, I'm most certainly a skeptic about soy based fuel/oil products. Soybean oil is great for deep frying french fries, however.

Pete Masterson

'95 Blue Bird Wanderlodge WBDA 42

El Sobrante CA

"aeonix1@mac.com"

On Jun 21, 2008, at 3:06 PM, Leroy Eckert wrote:

Alright Pete, it has been 40 years since I did my college chemistry classes and I have not done a damn thing with it since.  I have a question; don't mean to get into a chemistry class on the forum; just interested in something. If finished bio-diesel has a published average formula of C19H36O2 and average common diesel has a formula of C12H23 how is bio-diesel better for the air we breath? Does something happen in the combustion chamber?? Are the farmers stroking me??  CH4 is clean so to speak. Leroy Eckert 1990 WB-40 Royale Dahlonega, GA Smoke N Mirrors