I have a possible butter Fat source. It is butterfat extracted from the curd using petroleum ether, so the waste product I can get is butterfat and petroleum ether. What are the possibilities?

I actually made some butter biodiesel - I had a whole pound of it in my refridgerator and it was going rancid..
Here's the steps you have to take though to make it viable:

Heat the butter up to its melting point, and then let the milk solids settle to the bottom of the vessel, drain off all milk solids - I'd recommend a conical for this, then run the top (fat) portion through a 1 micron filter. After this, you can perform a titration. Mine came out to be about 3.2. Add the necessary methanol and lye - you can use my calculator on http://www.biodieselvideos.com and create a small batch to see how you make out.

I have a picture up on my website of the "butterdiesel" It separated nicely. The picture is in a Dr. Pepper bottle.
http://www.biodieselvideos.com/images/butterdiesel.jpg

enjoy.

-Matt-