Hello,

I'm a final year student doing my disseration on the feasibility of using Skeletonema costatum as a source of biodiesel. I have run experiments on growth rates and lipid contents under different light and nutrient condtions. i have done simple lipid extraction using chloroforma and methonal sonicating with the diatom pellet. leaving a lipid residue. i ahve had some quite intersesting results. one of my lectures has handed me a GCMS performed on a Skeletonema species, which breaks down the lipid into the different types of fatty acids. I was wondering is there a specific kind of fatty acid that is needed for biodiesel? I have looked through alot of papers and then it seems to be so general saying that it is just lipid that is needed.

Any thing would be of great help.

Thanks

As far as I am aware, any fatty acid can be transesterified and be used for biodiesel. But some are probably better than others, and any source of them will be a mix of several types. This will lead to fuel being inconsistent and that's bad. If we had really good refineries producing biodiesel, they'd work on producing several blends, sort of like we have now with petroleum gasoline.

It's worth noting that not all oils from a plant are fatty acids. For instance, Botryococcus braunii produces practically zero fatty acids, but plenty oil.

When we say 'vegetable oil', we refer roughly to fatty acids, but we ought to be more specific when we can, and say 'fatty acids' or even better, which ones in the mix.

I have some e-books on biodiesel that might be able to provide specifics about which fatty acids compose the oils of various plants, and perhaps which oils make the best candidates for fuel through transesterification. If I can find the time, I'll look through them. 

16s and 18s are the best.  Depending on your climate, unsaturation is also important.  Just like the difference between margarine and olive oil - unsaturated fats flow better.