Biofuel

[TheDragoon]

For instance, most diesel cars cannot run on straight vegetable oil until it has been through a process called transesterification which, from what I gather, is what happens when you use the oil in a deep fryer,

I did a little biodiesel research while at the UW and I don't think the second part of this sentence is necessarily correct. Maybe I don't know enough about deep fryers, but I don't think that the oil, itself, goes through a chemical reaction while frying. All of the literature I have read indicates that the only real difference between virgin oils and used frying oil is the muck and other nastiness associated with the waste food products that end up in the frying oil and that the frying oil usually has a higher water content and potentially more free fatty acids. Thus, if you want to make biodiesel you have to run the oil through a reactor which can catalyze the transesterification.

Due to the higher water and free fatty acid content in used frying oil, most literature that I came across suggests that you use the slower (but not a big deal for batch processes run at home) acid catalyzed process rather than the faster (but less flexible since it doesn't like water) base catalyzed process if you are using used frying oils. Thus, the normal process is to take your used cooking oil, strain it, let the junk in it settle out and then put it into your reactor along with methanol (the other reagent in transesterification) and acid (the catalyst). Then you heat the vessel for a while (overnight or maybe a couple days) and strain off the appropriate layer which gives you the useable biodiesel.

Obviously this is kind of a general overview off the top of my head so you would want to get more details before going further, but I figured I'd put in my quick 2 cents. :)

EDIT: Also, I know a group at the UW actually was taking used frying oil from the restaurants near the university and doing this acid-catalyzed process to make fuel for their cars in a garage, so I know that if it worked for them, it can probably work for you, too.