Thanks. I have a little too much experience with it. We saw a lot of bio related stuff during the economic mess of '08ish when fuel was nudging $5.00/ gallon. All of a sudden people were brewing fuel at home like bathtub gin during prohibition. Bio has some significant advantages, but for now it probably works best as a blend. In that case it boosts cetane and lubricity significantly. Still have the issues with cold and water.
The other thing that people were fooling with was straight waste vegetable oil. Which some people mistakenly call biodiesel. WVO needs to be heated to well over 100° to flow properly. It also needs an obscene amount of filtering. The major drawback for a vehicle is you can't shut it down with WVO in the system. Once it cools it congeals and sticks everything in the injection system. So you have to start up on biodiesel or Petro diesel, get the system hot, switch to WVO, then switch back before you shut down. Not ideal for a trip to the grocery store. Also, the glycerin in WVO turns into glue when it comes in contact with petroleum.
Of course, if you wade through the catalytic cracking process to separate the plant Esther's from the glycerin to turn it into biodiesel you avoid some of the issues, but the biggest problem with all of it was that when petro fuel got expensive you couldn't find WVO anymore.
We had one customer who was running a generator to power refrigeration on straight WVO. He had an elaborate filtration system that took up more space than the generator. It was a seafood supplier for restaurants so they could collect the used cooking oil on their way out. They would also crack their own bio for startup and shutdown.
We would rebuild a seized injection pump for them once a year.
And as Todd seems to have noticed, it's rough on certain rubber compounds.
That should about cover it. Thanks for listening.