The Second Question

I wanted to address Dave A's second question to me about "heavier" molecules in biodiesel emissions. The theory here is that some molecules in biodiesel emissions are more dense, causing them to linger lower in the atmosphere, and therefore creep into our lungs more easily.

Truthfully, I don't know. I haven't yet seen a study that talks about 'heavy' molecule emissions from Biodiesel, but I had heard the theory once before in connection with SVO (Straight Vegetable Oil), which is another alternative fuel. Many people have SVO and Biodiesel confused. Oil (soybean, algael, jatropha or rapeseed for a few examples of the vegetable type, or animal fat-derived, even human fat-derived) is a component of Biodiesel. But in order to make Bio, you have to put the oil and a few other solutions through processes which together consistute transesterification. That's the term for separating the glycerin in the oil/fat from the substances that you've bound in a chemical reaction to create biodiesel through lots of mixing, settling, etc. You can read about how it's done on several websites, but again I will provide the National Biodiesel Board's Basics sheet for reference. If you followed my bad writing above, you might infer that glycerin is a by-product of Biodiesel processing. That's correct. You can make lots of lovely soaps out of that ('Which would probably make excellent inexpensive gifts, wrapped in a hand knit wash rag!' pipes up the Martha Stewart within).

I will certainly look into it more. The idea of a "heavier" molecule does ruffle the few chemistry tailfeathers I possess. It seems like if you changed the 'weight' of a molecule, you'd necessarily be changing the compound itself....?? Scientists? Anything?

--Nellamity, who never actually took chemistry